OzVMX Forum
Clubroom => Tech Talk => Topic started by: VMXSteve on October 07, 2014, 05:22:24 pm
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Just brought a mint 82 YZ250J. In the day they ran 24:1
If I use a good quality 100% synthetic modern oil, what ratio should I use with 98 fuel?
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This is going to be interesting, everyone seems to be an expert on fuel oil mix.
I would stick with 25:1 and use an older type oil. Some synth oils are ok it seems but stick with the Yamaha recommended mix ratio.
Have a crank here that lasted 2 races using the most commonly sold synth oil at 50:1.
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Had one back in the day.
For me i just use a premium oil like Maxima and use some oil with my fuel. I dont get anal about it, just aroundist 100ml per 5 liters. If your bike blow chunks after that it will be mostly your 30 year old carby sucking air because its fu*cked/
If you dont fit a new carby your oil petrol issue is a non issue
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40:1 with a good synthetic oil like Motul 800. Don't waste your time using an outdated oil at 25:1, modern technology is a wonderful thing!
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Castrol TTS at 32:1 (ish) in the older bikes works for me, but oil/fuel ratio opinions are like bellybuttons as alluded to previously. ;)
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use a modern oil and run it like Johnny O says at 40:1 it will stop the power valve from gumming up and siezing and giving you grief.
i used TTS for years and its shitful compared to modern oils. they burn cleaner leave less deposits.
I think KTM even recommends 50:1 with Motorex on new a 2T KTM300EXC from memory.
Let the Fun Begin.
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Kawasaki recomended 25:1 for their KX125 up until 08 and Motul was not on their recomended list.
The YZ125 crank I have here was using Motul 800 and the bigend is a blue mess.
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Irrespective of what oils we may use I think that the sponsors of the 2013 Classic Nats, Lucas Oils and the sponsors of the 2014 Post Classic Nats and Conondale Classic, Maxima, should be the only ones getting a mention.
Without sponsors there are no events. Look after the people that look after you.
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Kawasaki recomended 25:1 for their KX125 up until 08 and Motul was not on their recomended list.
The YZ125 crank I have here was using Motul 800 and the bigend is a blue mess.
Ha, that ain't from using Motul 800.. The big end was obviously ready to shit itself and no particular brand of oil would've saved it.
Just because Kawasaki and Motul aren't in bed together doesn't mean the oils no good either.
Do they recommend Motorex? Ktm do, at a mixture of 50:1 and they sell more 2 strokes than anyone!
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The crank in that engine was pretty fresh.....and Teds right, MAXIMA RACING OILS and LUCAS OILS are what you should be using....they support VMX, the others don't. Maxima have been the main sponsor of QVMX for 3 years now. In the USA the biggest selling oil for motorbikes is Maxima. Mitch Payton has won more championships than any other team owner and has used Maxima from day one. Also , MAXIMA 927 is a synthetic caster based oil that has that awesome smell to it. Go kart guys all use 927 and they are revving the bejesus out of them. Using good oil does cost more but it's way cheaper than an engine rebuild. I run all my bikes at 25 to 1 and have never blown or seized an engine. It's not how much oil you use that gums up parts and leaves thick carbon deposits, it's the poor quality of oil that does that. My RM125A gets a new piston every season and when I pull it down , it's as clean as a whistle. The worst carbon build up I have ever seen is from TTS......you might be riding a 1970's bike but you don't have to use 1970's technology, we have come along way since then......Go the MAXIMA or LUCAS OILS.
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I run MAXIMA OIL 25:1 , great stuff.... ;D
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Castrol R 30 at 20:1 :) and I rev the bejesus out of my motors with no failures . I had a faulty new piston that dropped a skirt when it running in recently, of which no brand of oil could of fixed.
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you had to with my 400 up your clacker , that kx250 was on song.... ;)
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When I said use an older style of oil I should have said don't use a ester based oil. The caster synth blends have been around for years and work very well , also some of the semi-synth oil work very well but are more prone to carbon build up. An other issue is internal corrsion which is best looked after by mineral-synth oils.
I'll tell you about another failure I repaired a little while ago. A classic road race 125, turns it to around 13500 rpm and was using castrol 747. Never had a problem, switched to Rock Oil Castor Cart 100 because it was a little cheaper and I could get it for him. Never had a problem, he swapped to the top of the line ester based Rock Oil synth on well meaning advice from the wholesaler. Very next meating it failed the almost a fresh big end turning the bottom half of the rod blue and the cage and rollers just melted together.
Off went emails to RockOil in pommy and the answer come back, Ester based can only be used in engines reving to 14000 rpm but the castor based are good to around 23000 rpm. The mineral based semi's are in the middle but they don't like to talk about that.
Problem is with the rolling element bearings need to keep the rollers turning to keep the temp under control but the ester based oils are so full of aditives to reduce drag and detergents to keep everything clean that at high rpm the rollers start to skid which very quickly over heats the rollers and cage resulting in a molten mess.
The bike in question went back to the Castor Cart 100 with a new rod kit and and has not had the problem again. Castor Cart 100 is a castor synth blend which is probably similar to the Maximer 927 and others.
I have been re-building cranks for about 30 years and i always ask what oil and mix ratio have been used. I have seen a very definate coralation between mix ratio and the rate of wear as well as type of oil against failure type.
So keep using those high mix ratios (40+:1) cause it just means more work for me and other crank builders and more money for the parts sellers.
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Well said George.
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Listen to Prof Sleepy,the best engine builder around,the rest are just clowns :)
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You are on the money Sleepy,
Lot of people scratch their heads when they have problems with old Cranks,
there are a lot of factors come into it that most people are not aware of,
and expect the same results from vintage motors as modern motors.
Haven't we been here before?
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Only been saying Castor/synthetics been the go for ...............nearly 10yrs ;) However the very best and most powerful two strokes ever made Aprilia RSA 125(and ridden by the best riders) use Elf either castor/synthetic or the synthetic 987x (or something like that).
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My modern KTM 250 exc 2t piston had worn by 0.02mm at 150 hrs, rings replaced each 50 hrs. Wear limit 0.06 mm.
Torco synthetic oil 40:1. Good enough for me!
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In an old banger air cooled 2T.. I have been using Motorex Full synth 2T at 40:1... works very well...makes plenty of power and I have only put rings in now for about 2 years..same piston..
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My 490 Maico gets a new piston about every 3 years and has never needed a big end since I built the motor 10 yrs ago..In fact in 20+ yrs of racing vmx I've never had a failed big end in any of my bikes.
Using Motul 800 @ 40:1. Works for me!
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I love this debate - must be about the 6th time we have done it. I use Silkolene Comp Pro 2 Plus - or whatever the latest name is - at 40:1 - have never had a failure and bike just being pulled down for first rings and maybe piston now after way too many reliable hours. Used Motul at one time - same ratio as the Silkolene - and bike "smoked" very badly.
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My 2 bobs
I use Motil 800 at around 30:1 in EVERYTHING.
Motorbikes (Old & new), chainsaws, brushcutter, etc.
No failures.
People who try & run lean mixes (Higher ratios) in the pursuit of horsepower are just fooling themselves.
Yes the higher mix MAY result in more HP but also more wear & heat. The lower ratio is better for your engine & if the rings are a little down will actually aid in compression so it is possible to make more HP with more oil.
As long as you jet to suit. More oil actually means leaner fuel to air ratio.
Alright 3 bobs worth.
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I run motorex at 75 to 100: 1 in everything and no drama at all. I only use it as a few mates went desert running with Leisky years ago and that was what he used (100:1). 5 days straight topped out in 6th and not a drama.
ive got a 4 y/o kato 300 and a husky 400 that have both been belted and they run sweetly and cleanly. no complaints. its all about what your happy with.
I would recommend 40 - 50 to 1 using motorex full synth.
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I USE 20:1 castrol m and methenol bike runs sweet and never fouls plugs.1973 cr250m dirttracker.it revs hard as well
jim
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Make of this what you like.
2014 Port Augusta Classic Nats. Same rider. Same day. Same track. Three different bikes.
1977 RM 125 B 29.8 hp at 11,500 rpm ( dyno figures ) Completed three motos. Best lap 2:06 Maxima 927 Castor oil @ 30:1
1977 YZ 250 D No hp figure. Completed one moto. Seized. Big end toast. Best lap 2:12
Silkolene @ 35:1
1977 AW 440 No hp figure. Completed one moto. Seized. Best lap 2:13
Bel Ray @ 40:1
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sounds just like a trip back in time.... ;D
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Make of this what you like.
2014 Port Augusta Classic Nats. Same rider. Same day. Same track. Three different bikes.
1977 RM 125 B 29.8 hp at 11,500 rpm ( dyno figures ) Completed three motos. Best lap 2:06 Maxima 927 Castor oil @ 30:1
1977 YZ 250 D No hp figure. Completed one moto. Seized. Big end toast. Best lap 2:12
Silkolene @ 35:1
1977 AW 440 No hp figure. Completed one moto. Seized. Best lap 2:13
Bel Ray @ 40:1
What condition were the engines in though Teddles? Freshly rebuilt, ring gap checked, bored with correct tolerances, perfectly jetted etc...more than a few variables to consider.
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No idea Paul. They were definitely being ridden quicker than they normally are.
Like I said, make of it what you wish.
Wonder why cart guys spin their engines to 20,000rpm and run 16:1. But then again what would they know 8)
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Make of this what you like.
2014 Port Augusta Classic Nats. Same rider. Same day. Same track. Three different bikes.
1977 RM 125 B 29.8 hp at 11,500 rpm ( dyno figures ) Completed three motos. Best lap 2:06 Maxima 927 Castor oil @ 30:1
1977 YZ 250 D No hp figure. Completed one moto. Seized. Big end toast. Best lap 2:12
Silkolene @ 35:1
1977 AW 440 No hp figure. Completed one moto. Seized. Best lap 2:13
Bel Ray @ 40:1
The RM was set up the best, the rider loved it.
The YZ engine was tired.
The Maico was too lean.
Simple!
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Sold a 81 YZ125 H to a fast club member at start of the year. I supplied the fuel and oil Maxima 927 @ 30:1 for it the whole year. No problems. End of year he pays me for it and uses his own mix. Silkolene @ 35:1. It seizes. Just another coincidence I suppose.
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I'm sure there are good and not-so-good oils Ted, just pointing out that all the other components/tuning that go into a sweet running engine play a big part. Plus having a rider that's revving the ring out of it compared to normal use :o
I spent a while playing around with jetting on my GasGas ec200 and thinking it was close but not quite right. Ended up taking a step back, putting new rings in, adjusting the squish measurement and the jetting i had settled on was perfect.
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So how do you explain when this guy races it all year on 927 and then first time he puts Silkolene at 35:1 it shits itself. Don't give me " It's tired "
A 250 and a 440 being circulated at 6 and 7 seconds a lap slower than a 125 are hardly revving the ring out of it. The only thing that was revving it ring off was the 125.
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Dunno Ted, maybe aliens took it away and probed it in between fuel/oil mix changes
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Make of this what you like.
2014 Port Augusta Classic Nats. Same rider. Same day. Same track. Three different bikes.
1977 RM 125 B 29.8 hp at 11,500 rpm ( dyno figures ) Completed three motos. Best lap 2:06 Maxima 927 Castor oil @ 30:1
1977 YZ 250 D No hp figure. Completed one moto. Seized. Big end toast. Best lap 2:12
Silkolene @ 35:1
1977 AW 440 No hp figure. Completed one moto. Seized. Best lap 2:13
Bel Ray @ 40:1
Many bikes & 20 yrs of racing
NO seizures or blowups to report.
Plenty of trophies :D
Motul @ 40:1
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That's good. I am only taking the advice of Nick Dole and Ross McWatters.
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Something a wise old man once pointed out to me, was that the arguments for lean oil:fuel ratios are about cost, smoke and emissions. They never mention power, longevity or reliability.
KTM recommends 60:1 or some-such nonsense, and you hear plenty of stories along the lines of "my trail ridden KTM is rooted after 700km"... I've seen a Beta run at 60:1 be trashed after 800km. My own Beta with double the hours is like new after 1400km - always run at 35:1... ;)
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That's good. I am only taking the advice of Nick Dole and Ross McWatters.
Ross who? Haha
Whatever works for you Ted..
I run that combo cos it works for me :)
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Teddles ... Suzuki's they are built to last and are bloody bullet proof. I'll vouch for that.
And of course it would be doing better lap time's, because it had the factory option swing arm fitted.
The Suzuki has been set up on a Dyno to extract the best results and would of been and turned to perfection ;) I take it the motor was newish with a bit of port ::)
If the Yz and Aw had the same amount of Dyno time spent on them, they would of been tuned to perfection also. ie plug readings would of showed what's going on.
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No plug readings were done on dyno. After one run they said it is too rich. Dropped one jet size and instantly one more hp. Was asked how good I am at reading plugs and jetting at the track and was decided to leave as is. Still a bit rich. Ross said there is still more power to be attained through jetting but because Nick or himself weren't to be there they let it be. These two blokes have forgotten more about the ways to get reliable performance out of these old bikes than most blokes know. When either of them give advice I sure as shit listen.
You want a performance tuning tip Stewy, smash a couple of fins off your Suzuki head 8)
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Nah .... just get fit and loose a couple Kg and that should be equal to 5hp gain ;D
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How many pre78 125's have nearly 30 HP?.....they only had about 21 std......geez you must have some good advice how to extract that many needies Ted ;).....Ross McWatters, Nick Dole and George McKenzie would know more about engines than anyone else on here, the fact that some people have run really lean oil ratios and got away with it for years tells me that they are not revving the engine very hard for very long [1st gear in the pits maybe ;D], put a "PRO " on it and see how long it lasts.....1 lap?...maybe 2.....I put Kirk Hutton on 2 of my 125's 2 years ago at the Conondale Classic, he smoked everyone naturally...[YZ125A and RM125A]....you could not touch the engines or exhausts for about half an hour after the races they where that hot.....there still running today. Most people think they are riding fast but in reality are just wobblers......I have been out of action for about 15 months or so but ride 3 or 4 bikes at every meeting [average 17 per year]...year in, year out, there wouldn't be to many on here that ride the same bikes that many times per year without issues [admittedly I'm a wobbler but do hold the throttle wide open on occasion].....but hey, if it works for you then keep doing it. :)
Oldfart, you know that ain't going to happen
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My semi-educated 2 cents worth.. ::)
I remember reading an article some time back where they Dyno'd the same VMX bike using different fuel mixes.
The 20:1 gave the highest HP reading all other things being equal.
You have to remember that the higher oil content dissipates more heat as well as lubricating everything.
Cooler running and good lubrication..... sounds good to me. :) :)
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http://www.bridgestonemotorcycle.com/documents/oilpremix6.pdf
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ive never heard of an engine seizure due to oil issues only ever fuel air issues. failed seals, cracked intake manifolds. run no oil and the motor is totalled no doubt about that. all these stories of it only did x hours and seized or was knackered is always due to a mechanical issue...poor airfilter fitment for 1 dusty ride can junk a bike and the owner never even notices he fitted it wrong until the bike is not going as good and then he strips it and finds its worn out...blame the oil.
change of oil could affect a crankcase seal and make it suck air, lots of mechanical things can go wrong in a performance two stroke but as long as there is some oil in the mix at a ratio thick enough to cover the bearings and dissipate heat there is usually no probs. the trick is assessing the oil and running at the appropriate mix for the oil.
ive held the husky wfo in the deep wet gluggy sand at Hopetoun for several kms in top gear for 3 long laps. no dramas at 75 to 1. If anything is gunna destroy a 2/ that will!
I wouldnt use that mix with any other brand than motorex as I got it from the horses mouth. if ktm recommend 60:1, they are being conservative and the inside run is 100:1 and well tested. im happy to use it. I dont recommend anyone else go to these extremes. im just saying there are other options than a cloud of smoke that makes a cfa volunteer nervous....
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Read a good comment from (I think an oil company) one of the earlier endless oil debates that went along the lines of high revving road bikes need more oil then trail bikes that aren’t always at full noise.
It made a lot of sense to me, road bikes are always screaming and trail bikes can often be at half throttle flicking between trees so there will always be arguments about oil ratios because what a 15 grand revving engine will need will always be different to a trials bike.
‘Back in my day’ I ran my 125 in the Vic enduro series, the four day, club MX and a couple of opens, a few interclub events and also trail rode it all on TTS at 40;1 (the good old days when I rode every weekend)
Didn’t run that mix because I thought I was getting more power, it was all that seemed to be needed and about a clean engine that wasn’t going to foul a plug at the bottom of a ravine after riding down some mother hill with the throttle chopped all the way.
I put 2 pistons in it for the year but it was always within spec when I pulled it down.
If engines need all this oil in the mix to keep it cool than how do the oil injected bikes get away with such lean mixtures?
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http://www.bridgestonemotorcycle.com/documents/oilpremix6.pdf
http://www.klemmvintage.com/oils.htm
I found this interesting.
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Here you go. A well jetted bike running maxima at 40 to 1 with a non wobbler aboard.
https://www.youtube.com/watch?v=AqEYkES17rY
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We knew the motor wouldn't let go but we were hoping the gearbox would that day. Sorry Mick ;D
Christian Horwood, great rider.
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nice ride, I hate it when the mud gets the lens.....old mate on the mx250 goes alright to !