Fuel:oil mixture for RM 125 B

[SON]

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

[davidmc]

The metalurgy is better in the modern engines, Nickasel Bores, higher silicone content in the Piston Material,
Hey its your money and your call!

[Ted]

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

[suzuki27]

Belray or Motul at 40/1 for many years with no problems. DT and MX.

[mudguard]

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.

[SON]

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

[Mick D]

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.

[SON]

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.

[Mick D]

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.

[Mick D]

Huuummmm, I probably should change Friends at Karuah and Oyster-leases to something else? but what?

[SON]

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

[Ted]

Young hired guns, here we go

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

 No. Didnt think so.

[Mick D]

Your like a bull terrier Ted, you just cant let political correctness go,,,,,can ya

Now, I cant speak for SON, but I imagine, it would be politically correct if he had said young gun

[Ted]

Political correctness or blatant snipe....you think what you want

[SON]

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