Fuel:oil mixture for RM 125 B

[davidmc]

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

[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

[Ken 737]

An 8 it is Ted

Cheers

Ken

[Ted]

I'm hearing ya

[Ted]

Davy Crocket( Qld ) on here sells the 927 Maxima. He's a good guy, just doesn't have many friends

If you can't get it for whatever reason ring these guys. They import it. Ohlins 0395809465 

[searbs]

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

[80-85 husky]

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)

[Ted]

So why do go karts run at 16:1

Simple answer.....because they rev to the moon

[JohnnyO]

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.

[mudguard]

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.

[Lozza]

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.

[JohnnyO]

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.

[80-85 husky]

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.

[JohnnyO]

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

[FourstrokeForever]

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.