OzVMX Forum

Marque Remarks => Suzuki => Topic started by: Ken 737 on January 26, 2014, 09:45:25 am

Title: Fuel:oil mixture for RM 125 B
Post by: Ken 737 on January 26, 2014, 09:45:25 am
Hi guys,

Fuel:oil ratio for RM125B?

Owners Manual states 20 to 1, others advise 32 to 1.

Thanks for your continued advice and support.

Cheers

Ken
Title: Re: Fuel:oil mixture for RM 125 B
Post by: Ted on January 26, 2014, 10:04:26 am
If you want it to last use MAXIMA 927 Castor at 30:1 and run 98 octane

That's what I use. My B doesn't go too bad  ;D

This motor is fresh isn't it? The secret is stick to whatever oil you decide on. Don't chop and change.

Title: Re: Fuel:oil mixture for RM 125 B
Post by: oldfart on January 26, 2014, 01:02:06 pm
Unless they stop selling it like they have with    "Castrol R "   NLA
Title: Re: Fuel:oil mixture for RM 125 B
Post by: bazza on January 26, 2014, 01:28:47 pm
Teds on to it don't chop and change
Personally Motul 800 (a 50.1 Oil) but I run at 32.1
Title: Re: Fuel:oil mixture for RM 125 B
Post by: SON on January 26, 2014, 02:39:55 pm
Teds on to it don't chop and change
Personally Motul 800 (a 50.1 Oil) but I run at 32.1
Motul 800 at 40:1
Title: Re: Fuel:oil mixture for RM 125 B
Post by: Ken 737 on January 26, 2014, 11:35:23 pm
Yes Ted, all new engine.
Now I have to find a 927 distributed in Brizzzie.
Cheers
Ken
Title: Re: Fuel:oil mixture for RM 125 B
Post by: Tahitian_Red on January 27, 2014, 06:20:40 am
I run 32:1 Maxima Super M in everything, including my RM125B.  ;)
Title: Re: Fuel:oil mixture for RM 125 B
Post by: steve7406 on January 27, 2014, 07:56:52 pm
I run Motul 800 at 32.1 in my 125b no worries
Title: Re: Fuel:oil mixture for RM 125 B
Post by: Lozza on January 27, 2014, 10:40:42 pm
Change oil brands when I find something better, showed a fellow how different oil made less spooge at 25:1 than another oil at 50:1. What isn't in doubt is the castor synthetic blends out perform plain synthetic or mineral oil, 927, A747, Motorex castor synthetic blends are all very good oils. 20 or 25:1 is best for HP.
Title: Re: Fuel:oil mixture for RM 125 B
Post by: Davey Crocket on January 28, 2014, 12:09:27 am
I have Maxima 927 for sale at work, Coopers Plains, you can ring me on   0412 747 729....BTW I have been using 927 for years and my 125A would kick Teds arse all the way back to NSW. :)
Title: Re: Fuel:oil mixture for RM 125 B
Post by: bazza on January 28, 2014, 07:11:35 am
Davey better put steel caps on to kick teds arse, those alloy swing arms are strong
Title: Re: Fuel:oil mixture for RM 125 B
Post by: Ted on January 28, 2014, 07:25:40 am
Hey Bazza he should be kicking the medication he's on Its clearly not working
Title: Re: Fuel:oil mixture for RM 125 B
Post by: FourstrokeForever on January 28, 2014, 06:55:38 pm
Buy or build a bloody fourstroke before all this talk on oil ratios and what the best brand is does your head in. It's an age old conversation that goes round and round....
Title: Re: Fuel:oil mixture for RM 125 B
Post by: suzuki59 on January 28, 2014, 08:42:22 pm
Davey was just spotted heading out on a date,he will reply post love making
See below for the horrible truth:
(http://i659.photobucket.com/albums/uu317/suzuki43/e4a94621fa1214c3e3003a93f2835a7f_zps4802f47e.jpg)
Title: Re: Fuel:oil mixture for RM 125 B
Post by: Rossvickicampbell on January 29, 2014, 09:53:38 pm
looks a bit more like your backyard there Craigy than DC's!
Title: Re: Fuel:oil mixture for RM 125 B
Post by: davidmc on February 03, 2014, 05:08:16 pm
40 to 1 on Motul is chancing your luck,
I would not recommend any leaner than 30 to 1 with a 125cc screamer,
sorry Son
Title: Re: Fuel:oil mixture for RM 125 B
Post by: Ted on February 03, 2014, 05:17:38 pm
40 to 1 on Motul is chancing your luck,
I would not recommend any leaner than 30 to 1 with a 125cc screamer,
sorry Son

Exactly.

Ken, if you can hold this thing pinned everywhere, go to a 9 plug as well. If you can't use a 8
Title: Re: Fuel:oil mixture for RM 125 B
Post by: Ken 737 on February 03, 2014, 05:42:55 pm
An 8 it is Ted :)

Cheers

Ken
Title: Re: Fuel:oil mixture for RM 125 B
Post by: Ted on February 03, 2014, 06:18:59 pm
I'm hearing ya ;D
Title: Re: Fuel:oil mixture for RM 125 B
Post by: Ted on February 03, 2014, 06:25:21 pm
Davy Crocket( Qld ) on here sells the 927 Maxima. He's a good guy, just doesn't have many friends 8)

If you can't get it for whatever reason ring these guys. They import it. Ohlins 0395809465 
Title: Re: Fuel:oil mixture for RM 125 B
Post by: searbs on February 03, 2014, 07:48:19 pm
Retro Rocket, this is one of the best threads I have read here:

Dispelling the mystery between BR MC1 and other 2T oils ,by shortshifter

25:1, for me in bikes chainsaws brushcutters and leafblowers for me seems to work, more oil means more cooling,
I don't race VMX though,
Searbs
Title: Re: Fuel:oil mixture for RM 125 B
Post by: 80-85 husky on February 03, 2014, 08:38:37 pm
I disagree, more oil means hotter running as there is less fuel per charge. im running 80:1 and up to 100: 1 in a husky 400 and its been great, jetted nice and lean, it runs as smooth as a baby's bum down low, pulls off the bottom like the Scottish flyer and revs like a 125b (no thanks to ol mate with the porting tool!!) so I would use a full synthetic at 40:1 and ease out to 50:1 I use motorex...) no splooging, easy starting and cooler running.....

its a constant argument but im happy using less of a very high quality oil (2 years and so far so good) also runs my whipper snipper, blower vac, chain saw and Kato 300 (4 years and no drama)
Title: Re: Fuel:oil mixture for RM 125 B
Post by: Ted on February 03, 2014, 09:20:01 pm
So why do go karts run at 16:1

Simple answer.....because they rev to the moon
Title: Re: Fuel:oil mixture for RM 125 B
Post by: JohnnyO on February 03, 2014, 09:40:30 pm
KTM recommend 50:1 in all their 2 strokes and they offer full warranty! I can't see a problem running Motul or Motorex at 40:1 in a RM125b.
Title: Re: Fuel:oil mixture for RM 125 B
Post by: mudguard on February 03, 2014, 10:18:42 pm
Just seized my 83 YZ125 last weekend, after replacing the cylinder & piston last July, as piston nipped up then. NEVER using MOTUL 800 again. Have always been mixing at 32:1 and has always been hard to start, if not started after sitting for more than a week. ( Even with fresh fuel mix ). Usually have to take the bowl off the carby, take out the pilot jet, clear the blockage from the fuel/oil, then it will start.
Took the cylinder & piston to get rebored and old mate gave me some good info. Motul oil at 32:1 is not lubricating my cylinder, the inside of my piston is dry but should have an oily film coating it. Take mixture back to 25:1 and re-jet to suit, motor should have more power, run cooler and last longer as well. (Going by his years of engine rebuilding knowledge)
Sure the modern oils say can be used at 32:1, 50:1 or higher, but the fine print also says to Refer to the Vehicle Manufacturers Recommendations.
Title: Re: Fuel:oil mixture for RM 125 B
Post by: Lozza on February 03, 2014, 10:23:48 pm
I disagree, more oil means hotter running as there is less fuel per charge. im running 80:1 and up to 100: 1 in a husky 400 and its been great, jetted nice and lean, it runs as smooth as a baby's bum down low, pulls off the bottom like the Scottish flyer and revs like a 125b (no thanks to ol mate with the porting tool!!) so I would use a full synthetic at 40:1 and ease out to 50:1 I use motorex...) no splooging, easy starting and cooler running.....

its a constant argument but im happy using less of a very high quality oil (2 years and so far so good) also runs my whipper snipper, blower vac, chain saw and Kato 300 (4 years and no drama)

Not correct engines conduct heat to the cylinder wall via the rings the better the ring/bore seal the better the heat is wicked away. Oil is still the best for that.  Unless you put your bike on a dyno or give it to a GP level rider there is no objective way to determine what is "better" Gordon Jennings did all of this back in the 70's and we have yet to see anyone do the same tests with low oil ratios.More oil more power engine runs cooler.

"Spooge" out the exhaust is a symptom of  jetting and ignition.
Title: Re: Fuel:oil mixture for RM 125 B
Post by: JohnnyO on February 03, 2014, 10:59:46 pm
Just seized my 83 YZ125 last weekend, after replacing the cylinder & piston last July, as piston nipped up then. NEVER using MOTUL 800 again. Have always been mixing at 32:1 and has always been hard to start, if not started after sitting for more than a week. ( Even with fresh fuel mix ). Usually have to take the bowl off the carby, take out the pilot jet, clear the blockage from the fuel/oil, then it will start.
Took the cylinder & piston to get rebored and old mate gave me some good info. Motul oil at 32:1 is not lubricating my cylinder, the inside of my piston is dry but should have an oily film coating it. Take mixture back to 25:1 and re-jet to suit, motor should have more power, run cooler and last longer as well. (Going by his years of engine rebuilding knowledge)
Sure the modern oils say can be used at 32:1, 50:1 or higher, but the fine print also says to Refer to the Vehicle Manufacturers Recommendations.
I've been using Motul 800 at 40:1 in my vintage race bikes for 10 years with none of the problems you've  had and I worked in the Husqvarna race team for several years where we used Motul 800 at 40:1 in the National race bikes with never a problem..
You've got other issues.. It's not the oil.
Title: Re: Fuel:oil mixture for RM 125 B
Post by: 80-85 husky on February 04, 2014, 09:40:19 am
ive yet to see a oil related seize, there is always a mechanical reason...generally an air leak causing a hot spot or poor jetting in the midrange.
Title: Re: Fuel:oil mixture for RM 125 B
Post by: JohnnyO on February 04, 2014, 11:06:49 am
ive yet to see a oil related seize, there is always a mechanical reason...generally an air leak causing a hot spot or poor jetting in the midrange.
Yep or even an ignition problem. Oils are very good these days, we're not back in the 70's
Title: Re: Fuel:oil mixture for RM 125 B
Post by: FourstrokeForever on February 04, 2014, 01:50:11 pm
Too much oil can result in seizure as well. The unburnt oil glazes up the ring landings and piston walls, causing premature wear. Personally, I have all my 2 smokers (including whipper snipper) on Motul 800 at 40:1 for years,  and I have never had a seizure. I ran my 74 Elsinore at 40:1 and the piston and rings lasted 2 entire seasons without any signs of scuffing. Shite, my whipper snipper is at least 10 years old and it revs to the moon and back without any dramas so I don't see why a 125 would require more oil than any other 2 stroke.
Title: Re: Fuel:oil mixture for RM 125 B
Post by: SON on February 04, 2014, 05:42:43 pm
40 to 1 on Motul is chancing your luck,
I would not recommend any leaner than 30 to 1 with a 125cc screamer,
sorry Son

Exactly.

Ken, if you can hold this thing pinned everywhere, go to a 9 plug as well. If you can't use a 8
I would not run the 8 or the 9
I would run the 85
I keep them in stock
Title: Re: Fuel:oil mixture for RM 125 B
Post by: davidmc on February 04, 2014, 05:51:12 pm
The metalurgy is better in the modern engines, Nickasel Bores, higher silicone content in the Piston Material,
Hey its your money and your call!
Title: Re: Fuel:oil mixture for RM 125 B
Post by: Ted on February 04, 2014, 06:50:32 pm
40 to 1 on Motul is chancing your luck,
I would not recommend any leaner than 30 to 1 with a 125cc screamer,
sorry Son

Exactly.

Ken, if you can hold this thing pinned everywhere, go to a 9 plug as well. If you can't use a 8
I would not run the 8 or the 9
I would run the 85
I keep them in stock

And that's your perogative.

When I ride it it has a 8 When Liam rides it it has a 9 Works a treat for us 8)
Title: Re: Fuel:oil mixture for RM 125 B
Post by: suzuki27 on February 04, 2014, 08:13:18 pm
Belray or Motul at 40/1 for many years with no problems. DT and MX.
Title: Re: Fuel:oil mixture for RM 125 B
Post by: mudguard on February 04, 2014, 09:21:55 pm
ive yet to see a oil related seize, there is always a mechanical reason...generally an air leak causing a hot spot or poor jetting in the midrange.
ive yet to see a oil related seize, there is always a mechanical reason...generally an air leak causing a hot spot or poor jetting in the midrange.
Yep or even an ignition problem. Oils are very good these days, we're not back in the 70's
Thats what is so good about this forum! A wealth of knowledge from members to help solve issues with our bikes. Thanks to JohnnyO
and John Cahill for the info.
Title: Re: Fuel:oil mixture for RM 125 B
Post by: SON on February 04, 2014, 09:43:09 pm
Just seized my 83 YZ125 last weekend, after replacing the cylinder & piston last July, as piston nipped up then. NEVER using MOTUL 800 again. Have always been mixing at 32:1 and has always been hard to start, if not started after sitting for more than a week. ( Even with fresh fuel mix ). Usually have to take the bowl off the carby, take out the pilot jet, clear the blockage from the fuel/oil, then it will start.
Took the cylinder & piston to get rebored and old mate gave me some good info. Motul oil at 32:1 is not lubricating my cylinder, the inside of my piston is dry but should have an oily film coating it. Take mixture back to 25:1 and re-jet to suit, motor should have more power, run cooler and last longer as well. (Going by his years of engine rebuilding knowledge)
Sure th
Just seized my 83 YZ125 last weekend, after replacing the cylinder & piston last July, as piston nipped up then. NEVER using MOTUL 800 again. Have always been mixing at 32:1 and has always been hard to start, if not started after sitting for more than a week. ( Even with fresh fuel mix ). Usually have to take the bowl off the carby, take out the pilot jet, clear the blockage from the fuel/oil, then it will start.
Took the cylinder & piston to get rebored and old mate gave me some good info. Motul oil at 32:1 is not lubricating my cylinder, the inside of my piston is dry but should have an oily film coating it. Take mixture back to 25:1 and re-jet to suit, motor should have more power, run cooler and last longer as well. (Going by his years of engine rebuilding knowledge)
Sure the modern oils say can be used at 32:1, 50:1 or higher, but the fine print also says to Refer to the Vehicle Manufacturers Recommendations.
I've been using Motul 800 at 40:1 in my vintage race bikes for 10 years with none of the problems you've  had and I worked in the Husqvarna race team for several years where we used Motul 800 at 40:1 in the National race bikes with never a problem..
You've got other issues.. It's not the oil.
e modern oils say can be used at 32:1, 50:1 or higher, but the fine print also says to Refer to the Vehicle Manufacturers Recommendations.
if you really think the oil was at fault contact Link International the OZ Motul Distributor with your concerns, you might be surprised with their diagnosis.
Also an aircooled 125 even if ridden by an old slow person is capable of being peak revved in the lower gears on a MX or Dirttrack, I don't believe you should run the 8 plug unless it is in a wet Vinduro.
Most competitors don't know the 8 and one half exists nor do most spare parts kids, even my current NGK rep didn't know they existed until I ordered a few more boxes, they are the right plug for most VMX aircooleds
Title: Re: Fuel:oil mixture for RM 125 B
Post by: Mick D on February 04, 2014, 09:50:09 pm
That is good to know.
I definitely want my spares kit to have some in amongst the eights and nines.
I will be around to get a few tomorrow.
Title: Re: Fuel:oil mixture for RM 125 B
Post by: SON on February 04, 2014, 10:06:24 pm
ive yet to see a oil related seize, there is always a mechanical reason...generally an air leak causing a hot spot or poor jetting in the midrange.
ive yet to see a oil related seize, there is always a mechanical reason...generally an air leak causing a hot spot or poor jetting in the midrange.
Yep or even an ignition problem. Oils are very good these days, we're not back in the 70's
Thats what is so good about this forum! A wealth of knowledge from members to help solve issues with our bikes. Thanks to JohnnyO
and John Cahill for the info.
You still have to be carefull of the information provided
I was a member for years without posting anything
But I had to correct some crap written by someone who didn't know what they were talking about
I have been a Suzuki dealer for over 30 years,
In my last Dirttrack TM125 I ran it with a 10 plug because that was the heat range that the compression / timing required just to keep 6 speed Elsinores in sight.
Just for fun I will repeat myself RM125 Aircooled on VMX Motul 800 at 40:1 with a NGK B85EGV plug with standard timing.
Title: Re: Fuel:oil mixture for RM 125 B
Post by: Mick D on February 04, 2014, 10:07:43 pm
Slightly on/off track.
A little story about Yamaha, two strokes, oil and metallurgy.

This is back a few years now, when Yamaha briefly specified and bragged a mix ratio of 100:1 for their 2 smoker out boards.

Friends at Karuah own oyster leases. I doubt many two strokes clock up the hours quicker or harder than their oyster barge engines.

Yamaha would give them free engines, on the condition they gave back their old ones for analysis.
The agreement was to use Yamaha lubes, service schedules and keep logs books.

At first the 100:1 era was proven as an outstanding success, even under duress.
Then it all went pear shaped. Outboards were recalled, re-jetted and fitted with new stickers instructing 50:1 fuel/oil mix.

Yamaha had build a bearing manufacturing facility in China.
The problems of failure, had been traced to the poorer quality Chinese metals used in the Chinese manufactured bearings as compared to the Japanese bearings used in the earlier successful models. I doubt Yamaha would admit that, and I probably should not have mentioned my friends at Karuah.
Title: Re: Fuel:oil mixture for RM 125 B
Post by: Mick D on February 04, 2014, 10:11:31 pm
Huuummmm, I probably should change Friends at Karuah and Oyster-leases to something else? but what?
Title: Re: Fuel:oil mixture for RM 125 B
Post by: SON on February 04, 2014, 10:25:05 pm
That is good to know.
I definitely want my spares kit to have some in amongst the eights and nines.
I will be around to get a few tomorrow.
At the Mr VMX Dean Burt fouled his plug at the pit gate,
I pulled an 85 from Beetles or Gilesys tool box,
I didn't ask Dean if he noticed a difference in his RM400, but it did run sweet,
It just makes sense,
8's range between 7 & 9
9's range between 8 & 10
85's range between 7.5 &  9.5
Just where Air cooled VMXers live
Except for young hired guns who tend to live higher up the rev / heat range
Title: Re: Fuel:oil mixture for RM 125 B
Post by: Ted on February 04, 2014, 10:31:15 pm
Young hired guns, here we go

Have you ridden over 30 VMX meetings in the last 4 years.

 No. Didnt think so.
Title: Re: Fuel:oil mixture for RM 125 B
Post by: Mick D on February 04, 2014, 10:41:40 pm
Your like a bull terrier Ted, you just cant let political correctness go,,,,,can ya ;D

Now, I cant speak for SON, but I imagine, it would be politically correct if he had said young gun ;)
Title: Re: Fuel:oil mixture for RM 125 B
Post by: Ted on February 04, 2014, 10:44:38 pm
Political correctness or blatant snipe....you think what you want
Title: Re: Fuel:oil mixture for RM 125 B
Post by: SON on February 04, 2014, 10:50:02 pm
Young hired guns, here we go

Have you ridden over 30 VMX meetings in the last 4 years.

 No. Didnt think so.
Sorry Ted wasn't even thinking of you
I was thinking of Beau Ralston and Danny Ham
But in 1977 I did ride 30 VMX Race meetings in 32 weekends
Title: Re: Fuel:oil mixture for RM 125 B
Post by: SON on February 04, 2014, 11:06:00 pm
Political correctness or blatant snipe....you think what you want
Ted last weekend at Easter Creek there were 3 kids on Yamaha R15s that I assisted massively,
Current AMA Youth rider of the year Tommy Edwards, Hunter  and Zane Ford.
Those 3 plus Current Australian Junior Speedway/Roadrace/Dirttrack Champion Max Croker will all ride the Juniors at the World Superbikes at the end of the month,
Over the last 30 years I have assisted a few other young champions,
I think I know a little on hired guns!
By the way Have you ever used an 85 plug before?
Title: Re: Fuel:oil mixture for RM 125 B
Post by: Paul552 on February 05, 2014, 06:15:58 am
Am I reading this correctly?? SON I use BR8ES so would that be BR85ES???

Does that make sense??


Title: Re: Fuel:oil mixture for RM 125 B
Post by: SON on February 05, 2014, 06:36:55 am
The 85 or 8.5 that I stock is a NGK Racing plug not the standard type
Title: Re: Fuel:oil mixture for RM 125 B
Post by: 80-85 husky on February 05, 2014, 05:16:26 pm
Wish I new about these years ago. every year in my Gemini Boss 80, the bloody 8 plug would whisker on the first hot day of spring and I would use a 9 until the autumn cooled and it would pooh that so back to an 8.

I was using BP zooooooom phut as fuel.....this was 73 - 76 :o
Title: Re: Fuel:oil mixture for RM 125 B
Post by: SON on February 05, 2014, 09:04:49 pm
Plug is B85EGV
Title: Re: Fuel:oil mixture for RM 125 B
Post by: Lozza on February 05, 2014, 11:32:26 pm
Too much oil can result in seizure as well. The unburnt oil glazes up the ring landings and piston walls, causing premature wear. Personally, I have all my 2 smokers (including whipper snipper) on Motul 800 at 40:1 for years,  and I have never had a seizure. I ran my 74 Elsinore at 40:1 and the piston and rings lasted 2 entire seasons without any signs of scuffing. Shite, my whipper snipper is at least 10 years old and it revs to the moon and back without any dramas so I don't see why a 125 would require more oil than any other 2 stroke.
Unburnt oil is from improper jetting and ignition, if your Elsinore had 50hp at the wheel you would have an entirely different story to tell. Whippersnippers have no load to speak of on the engine. Go to a local kart track and listen to a ICGP kart hitting 18,000 rpm and you will understand why some engine need more oil 

Plug is B85EGV

That's not a race plug  ;)
Title: Re: Fuel:oil mixture for RM 125 B
Post by: SON on February 06, 2014, 06:29:24 am
NGK have Racing on the box
They are a dearer plug, not from the standard range
Title: Re: Fuel:oil mixture for RM 125 B
Post by: Branchy on February 06, 2014, 07:16:18 am
http://www.ebay.com.au/itm/261384134756?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

go karts are probably the most hammered engines around tuned to an inch of the life check out their plugs oils etc
Title: Re: Fuel:oil mixture for RM 125 B
Post by: djr on February 06, 2014, 08:16:43 am
Bring back the 2 stroke  AUTOLUBE system , that's what I think .
 then you only need to argue over what brand of oil to buy , not premix ratios.
I once read a Yamaha technical article which said with there autolube system the equivalent oil / fuel ratio at idle was something like 200:1 but at full throttle it was 15:1 .
 this would seem to back up the theory that higher revving engines need more oil, but I don't know what the extra oil is doing ,maybe it is giving the bearings & piston rings more lubrication or maybe the oil is just absorbing heat and then going out of the exhaust ?
 I would think  a 125 single cylinder bike would be getting revved harder than a 500 single cylinder bike by most riders , so if the theory is correct then  the smaller engine may need more oil.
also its easy to forget to check your air/fuel ratio {jetting} when you try different premix ratios as one affects the other {I am sure you already know this }
anyway good luck ,dave
Title: Re: Fuel:oil mixture for RM 125 B
Post by: 80-85 husky on February 06, 2014, 09:03:05 am
its all about the film of oil on the working surface... high quality synthetic oils have a much stronger base than cheap oils and as such maintain a good film over working surfaces even at lean ratios. cheaper oils have lighter base and need more oil to maintain a lubricating film.
Title: Re: Fuel:oil mixture for RM 125 B
Post by: Digga on February 07, 2014, 02:46:08 pm
That is good to know.
I definitely want my spares kit to have some in amongst the eights and nines.
I will be around to get a few tomorrow.
At the Mr VMX Dean Burt fouled his plug at the pit gate,
I pulled an 85 from Beetles or Gilesys tool box,
I didn't ask Dean if he noticed a difference in his RM400, but it did run sweet,
It just makes sense,
8's range between 7 & 9
9's range between 8 & 10
85's range between 7.5 &  9.5
Just where Air cooled VMXers live

Interesting thread on tuning. I have little or no idea how to tune a bike so trying to take in all of this from you guys but some of it is going over my head. I have a YZ125G that I have just finished & about to take it for its first run this weekend.

The book says run at 20:1 which I did when I first started it up. Blew a bit of smoke & oil so thinking of going up incrementally to 25:1 & then stop at 30:1 The plug recomended in the Clymer manaul & the original owners servcie manual is a Champion N-59G but the plug in the bike is a NGK R BR8ES. So question is would I be wise to get an 85 so I have some roon to tweek with this all?

PS - the original Yamaha Genuine Parts catalogue calls up an NGK B10EV plug????
Title: Re: Fuel:oil mixture for RM 125 B
Post by: Ted on February 07, 2014, 04:05:19 pm
Maxima 927 at 30:1. BR8ES IS FINE

If you are a lightning fast teenager go to a BR9ES

All my bikes run the same brand oil , same oil ratio and same plugs. They range from 125cc to 500cc in size

Whatever oil you choose stick with it....that is the secret
Title: Re: Fuel:oil mixture for RM 125 B
Post by: pmc57 on February 07, 2014, 09:12:22 pm

I'm surprised there hasn't been more input into this thread from others given it's done the rounds more than once on this forum, but anyway, here's my two bobs worth.

How I understand two stroke tuning and fuel:oil ratios is they are two seperate issues but have distinct links.

We often hear the comments about backing off oil / fuel ratios with underlying belief from the authors this leans the fuel mix and helps to stop plug fouling. This is exactly the opposite of reality, by decreasing the amount of oil in the fuel mix it actually allows more fuel molecules to air molecules during the carby atomisation stage which richens the fuel mix. This richer fuel mix decreases combustion performance which increases the event of unburnt fuel (spooge) occuring and poorer peformance.

Think about it... less oil in the fuel increases the amount of fuel within the air/fuel mix after the carby has done it's bit.... give it time it will come to you.

In my opinion if the "book" says run 20:1, stay with it and concentrate on your jetting as a means of solving any plug fouling and spooging issues. The oil in your mix is there to lube the bearings and cylinder/ piston walls as well as a cooling element only. Don't think that by reducing the amount of oil in your fuel mix it will solve your tuning problems, all it will do is cause you to chase your tail.

I say stay with the book recommended fuel mix ratios regardless of oil brand or oil type and adjust your jetting and plug to ensure correct and best performance. Best performance is obtained by optimal sealing around the piston rings by the oil (good compression) and by clean and efficient combustion (good jetting).
Title: Re: Fuel:oil mixture for RM 125 B
Post by: SON on February 07, 2014, 10:41:14 pm
And the quality of base oils in 1977 was ???
Leaded Petrol v Unleaded ??
Back then there was only a few oils that you ran at 40:1 or 50:1
Now so many more,
I have been asked about the 85 plug, as previously explained they are perfect for an aircooled 250/500 MXer 125s should have 9 if it is ridden correctly, but if you are older, heavier, slower, run the 85.
Motul 800 is far more available than the Maxima in most Oz cities.
Title: Re: Fuel:oil mixture for RM 125 B
Post by: Ted on February 07, 2014, 10:58:45 pm
Maxima 927 oil available from

Teknik Racing NSW 0247322626

Daley Crockets shop QLD

Or ring the importer, OHLINS 0395809465  Victoria   They will let you know who stocks it in your town
Title: Re: Fuel:oil mixture for RM 125 B
Post by: SON on February 07, 2014, 11:01:00 pm
Your G looks good, same as my previous post if you can ride the bike like it was designed run a 9, the S is OK but the 9EG or 9EGV is better,
If the engine is fairly fresh and ridden regularly run the good oils at 40:1.
If its not so fresh run synthetically fortified oil at 32:1
If you run mineral oil run it at 20:1 as was recommended.
If you don't have X ray vision I suggest some plug chops at quarter, half and full throttle
Title: Re: Fuel:oil mixture for RM 125 B
Post by: Ted on February 07, 2014, 11:04:27 pm
Good advice
Title: Re: Fuel:oil mixture for RM 125 B
Post by: SON on February 07, 2014, 11:16:29 pm
Your G looks good, same as my previous post if you can ride the bike like it was designed run a 9, the S is OK but the 9EG or 9EGV is better,
If the engine is fairly fresh and ridden regularly run the good oils at 40:1.
If its not so fresh run synthetically fortified oil at 32:1
If you run mineral oil run it at 20:1 as was recommended.
If you don't have X ray vision I suggest some plug chops at quarter, half and full throttle
For Dirttrack and high revs run a 10
Title: Re: Fuel:oil mixture for RM 125 B
Post by: Digga on February 08, 2014, 09:33:01 am
Thx SON, much appreciated
Title: Re: Fuel:oil mixture for RM 125 B
Post by: Lozza on February 08, 2014, 10:43:23 am
NGK have Racing on the box
They are a dearer plug, not from the standard range
;D a proper race plug is a platinum/iridium NGK R7282 standard fitment RS/ TZ 125 and 250( some kx250/125). They add 0.5-1hp across the range on a 85cc

http://www.fastech-racing.com/ngk-r7282-105-racing-spark-plug.html
Title: Re: Fuel:oil mixture for RM 125 B
Post by: oldyzman on February 11, 2014, 08:06:01 pm
The BR8ES referred to is a resistor plug at approximately 4.8K OHMS. Not to be confused with Race... I recently purchased B10ES for a 250 air cooled running AVGAS and this had racing written the box, but i dont believe its a race plug. Are we better of using a B8ES or B9ES than the BR...?
Title: Re: Fuel:oil mixture for RM 125 B
Post by: Ted on February 11, 2014, 08:19:42 pm
I was using B8 ES for years, then BR8ES, now BP 8 .... Whatever my mate has in stock at time. Can't notice any difference.
Title: Re: Fuel:oil mixture for RM 125 B
Post by: Lozza on February 15, 2014, 09:34:59 pm
An ignition needs either a resistor in the plug (the R in the model code) or in the plug cap not both. The spark will be very weak with resistor cap and plug.
If you can't notice any difference in plugs or plug gap your a long way off optimum tuning. A wider gap should (from memory) work better at low end and smaller gap top end. With heat range if the engine is working better the longer it's ridden the plug is to cold if it gets slower the the longer it's ridden the plug is to hot..   
Title: Re: Fuel:oil mixture for RM 125 B
Post by: oldyzman on February 15, 2014, 09:53:35 pm
Interesting Lozza,
What can happen if the bike has no resistor in the plug or in the cap?
Title: Re: Fuel:oil mixture for RM 125 B
Post by: Lozza on February 16, 2014, 12:42:00 am
Run it and find out  ;)







not much just a weaker spark the resistor makes the ignition work harder therefore it easier for the spark to jump the gap
Title: Re: Fuel:oil mixture for RM 125 B
Post by: JohnnyO on February 16, 2014, 09:46:17 am
Interesting Lozza,
What can happen if the bike has no resistor in the plug or in the cap?

PVL ignitions have no resister in the cap and they stipulate to use a non resister plug
Title: Re: Fuel:oil mixture for RM 125 B
Post by: Lozza on February 16, 2014, 10:05:44 am
Model T Ford had a service guide recommending you install a coat button in line on the high tension lead when oil consumption was high. The resistor is the basis for all those "spark intensifiers" for sale on the shelf  right next to the snake oil. 5k Ohm resistor plug or cap is going to increase the voltage in the secondary of the coil before it will jump the gap.
Title: Re: Fuel:oil mixture for RM 125 B
Post by: 80-85 husky on February 16, 2014, 05:11:40 pm
Whats this got to do with the fuel oil mix of a RM 125 Keh?? ;) :D ;D
Title: Re: Fuel:oil mixture for RM 125 B
Post by: davidmc on February 17, 2014, 11:50:06 am
P  means Projected Core for use in 4 Strokes to aid cooling of the Plug, (exposed to incomming charge),
first seen in TT500 Yamaha.
DO NOT use in a 2 Stroke, too close to top of piston and may burn a hole in it!
Title: Re: Fuel:oil mixture for RM 125 B
Post by: Ted on February 17, 2014, 05:22:02 pm
We had no problem at the CRC ( where it was revving its tits off ) or Nats with a BP, but I will ask the question. Thanks for the heads up.
Title: Re: Fuel:oil mixture for RM 125 B
Post by: SON on February 17, 2014, 09:26:42 pm
There is too much mis information re spark plugs even from qualified people
That is why manufacturers have recommendations and tuners stretch their limits
Title: Re: Fuel:oil mixture for RM 125 B
Post by: Sweep Rider on February 17, 2014, 10:39:26 pm
My RM125A, RM370A, and IT250D all say 20:1..... for a reason. Dyno's have proven that you obtain more power with the higher oil content, it's safer when your tuning and go that bit lean and the biggest advantage is the oil dissipates HEAT out the exhaust.
It's not all about lubrication. Any mineral based oil will be fine.
I just finished the Murphies Creek Vinduro where it was 40 deg + and gnarly hills. I felt better knowing the IT was running 20:1
 ;D ;D
Title: Re: Fuel:oil mixture for RM 125 B
Post by: SON on February 18, 2014, 12:38:49 am
Once again mis information
You guys just can't help yourselves
Back in the early 90s I would escape from work every time the Lucky Strike GP Team came to OZ testing
I can't remember them mixing fuel at 20:1 but maybe I am wrong
Title: Re: Fuel:oil mixture for RM 125 B
Post by: John Orchard on February 18, 2014, 12:48:59 am
All my bikes, chainsaws & brushcutters use 25:1 Valvolene Mineral racing oil, $9.95 per litre.  125's & 250's use B9ES, 400 uses B8ES.

The bikes are fast & reliable, never any noticeable wear anytime I tear them down.  Main reason's I use this oil is good plug colour for tuning and it's available at many local shops.

Works for me.
Title: Re: Fuel:oil mixture for RM 125 B
Post by: JohnnyO on February 18, 2014, 07:38:57 am
You guys are living in the past with your 20:1 and mineral oils. Your Suzuki manual that recommends 20:1 was printed in 1977 based on the oils that were available back then.
Modern oils have improved out of sight since 1977 and today's bikes make a lot more horsepower and rev a lot harder and the manufacturers use and recommend 40 or 50:1 and there are far less engine failures today using that mix than back in the day.
Title: Re: Fuel:oil mixture for RM 125 B
Post by: FourstrokeForever on February 18, 2014, 10:42:15 am
You guys are living in the past with your 20:1 and mineral oils. Your Suzuki manual that recommends 20:1 was printed in 1977 based on the oils that were available back then.
Modern oils have improved out of sight since 1977 and today's bikes make a lot more horsepower and rev a lot harder and the manufacturers use and recommend 40 or 50:1 and there are far less engine failures today using that mix than back in the day.

AGREE 100%
Title: Re: Fuel:oil mixture for RM 125 B
Post by: davidmc on February 18, 2014, 10:24:38 pm
FYI; We always ran HRC NSR500 on Castrol A747 at 28 to 1 , that was the safe limit;
You may get away with leaner oil mixs , But if you are recommending from a reliability point of view that will cover all situations.
Title: Re: Fuel:oil mixture for RM 125 B
Post by: Rossvickicampbell on February 18, 2014, 10:30:14 pm
JO - I agree with you but have a question - as the years marched on and 2 stroke mixtures got leaner - how much do you think this was driven by the enviromental movement and oil smoke pollution?  At all - I just hear rumours of the return of the 2 stroke at oil rations of 100:1 being environmentally acceptable?
Title: Re: Fuel:oil mixture for RM 125 B
Post by: davidmc on February 19, 2014, 12:29:26 pm
1981 Maico 490 manual recommends;
special high Quality oil mixture,

1;20 with 2 stroke oil
1;50 with Bel Ray MC1
1;100 with Maico MC-GP-100 Mix oil
and cautions never to mix Mineral and Synthetical oils.

Keep in mind a 490 does not rev as high as a 125cc
Maico oil must have been special stuff taken from either whales or vestal virgins.

Title: Re: Fuel:oil mixture for RM 125 B
Post by: Ktm181 on February 19, 2014, 01:23:10 pm
1981 Maico 490 manual recommends;
special high Quality oil mixture,

1;20 with 2 stroke oil
1;50 with Bel Ray MC1
1;100 with Maico MC-GP-100 Mix oil
and cautions never to mix Mineral and Synthetical oils.

Keep in mind a 490 does not rev as high as a 125cc
Maico oil must have been special stuff taken from either whales or vestal virgins.

Best talk to GB about running a 490 at 100:1.... i wouldnt, Geoff's nipped up,cant remember the brand of oil though.
 I dont understand a discussion like this, or some others appearing on here, its pretty obvious there are lots of ways to skin a cat, lots of oil ratios "will work", some produce better performance, some produce less wear, its not rocket science. Its smarter, if using plain mineral to run it on the cautious side with more rather than less oil, if your running the super duper stuff then you might be happy with lesser amounts, you just need to remember the oil and its film strenght is all thats keeping your engine alive, NONE of this is meant to be an argument you HAVE to win.
I reckon some of you gentlemen need to re focus and remember to enjoy your "sport" a bit more, its not meant to be taken too seriously after all.

Kt.
Title: Re: Fuel:oil mixture for RM 125 B
Post by: SON on February 19, 2014, 09:00:06 pm
FYI; We always ran HRC NSR500 on Castrol A747 at 28 to 1 , that was the safe limit;
You may get away with leaner oil mixs , But if you are recommending from a reliability point of view that will cover all situations.
Dave I thought it was 32:1 at HRC
I remember Schwantz RGV500 with Motul at 40:1
I have used that ever since NEVER had a hint of a problem
Old bike or new
Remember Unleaded Modern Fuel v Leaded Old Fuel
Title: Re: Fuel:oil mixture for RM 125 B
Post by: Ted on February 19, 2014, 09:25:14 pm
v Shell URT
Title: Re: Fuel:oil mixture for RM 125 B
Post by: davidmc on February 22, 2014, 01:43:26 am
As I remember it was 28:1,  as big ends tend to let go any less oil mix, you can get away with a leaner mix in most cases on the dirt where you are on and off the throttle, and of course 500 singles don,t run high RPM,
but I wouldn,t like to run my aircooled 125 flat out in sand at 50;1,
and after all this was about a question of recommendation??
Title: Re: Fuel:oil mixture for RM 125 B
Post by: Ted on February 22, 2014, 10:17:31 am
Which it was answered in the very first post and which he has subsequently done
Title: Re: Fuel:oil mixture for RM 125 B
Post by: 80-85 husky on February 24, 2014, 02:36:43 pm
it is good to have a huuuuge far ranging discussion though, interesting to see what people do and what the results are...

watching some vinduro clips, its easy to see who is still 20: to 1 and who isn't (or who forgot the oil completely!!!)

I like hearing what the high level guys did then and now as they tend to have the best intelligence (or sponsers)

As for running a 125 in sand at 50: 1.. absolutely no problems AS LONG AS YOU JET IT RIGHT!

any desert riding I have done I always drop the needle 1 clip and take a few bigger main jets. ( I always tread carefully for the first few k's to listen for that noise!! )

I fear the midrange seizure on throttle close in sand more than any other potential malfunction as it tends to be without warning.

Hopefully it rains soon and we can stop typing and go riding.....