Excessive smoke on 2 stroke?

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2/19/2019 9:22 PM

So I recently did a top end a found a lot of in burnt oil inside of cylinder. So I figured it was transmission fluid. So I replaced the crank seal. My spark plug wasn’t crazy bad but it may have been a little dark. No signs of bad jetting. Runs great. Well my buddy took a video of me at my race and off the start I noticed it smoked like crazy. Could it be I just need to put a fresh spark plug in? Can jetting be to rich but not cause any symptoms? Was the bike just loaded up a little cause I didn’t clear it out before cutting off? (Hare scramble racing starts from a dead engine). What do y’all think? Photo

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2/19/2019 9:27 PM

And this was later in the race. In the video I’m on the gas. No smoke. Bike runs fine. Just wondering if I damaged the crank seal when putting it in (don’t know how cause the thing was hard as crap to get out and was hard as a rock) or if it’s actually unburnt oil I found in the cylinder. I mix my ratio 32/1 yamalube. Been doing it since I was on 50’s. Photo

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2/19/2019 9:37 PM

Do a leak down test on it and if it holds around 5-6psi for a prolonged period of time (30-45minutes) than you know its not motor related, its jetting related. 32:1 is quiet rich. For yamahas i like to run 40:1. It seems to do better and run cleaner especially in the woods where its not always constant load on the bike. If you want try 40:1 and a new plug and see how it goes.

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2/19/2019 10:56 PM

32:1 is absurd on a 250 woods bike. Try 40:1 or even 50:1
You'll need to rejet for the new oil ratio.
Looks like it was loaded up off the start. Are you losing trans oil?

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2/20/2019 7:27 AM

colintrax wrote:

32:1 is absurd on a 250 woods bike. Try 40:1 or even 50:1
You'll need to rejet for the new oil ratio.
Looks like it was loaded up off the start. Are you losing trans oil?

Exactly what i recommended. 32:1 in the woods is literally loading it up because its not rung out wide ass open like on a track. 40:1-50:1 is PERFECT in the woods especially for harescramble tracks (they are more mellow vs hard enduro type tracks).

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2/20/2019 10:00 AM
Edited Date/Time: 2/20/2019 10:03 AM

You guys do realize that the difference between 32:1 and 40:1 is really not that much.

128oz/gal

32:1 = 128oz : 4oz
40:1 = 128oz : 3.2oz

A difference of 0.8oz per gallon of fuel.

0.8oz = 23.66ml aka less than half of a shot glass of oil per gallon

There are 3785ml per gallon (roughly)

In other words, a correctly jetted bike will do fine on 32:1 in the woods. It will not be "literally loading it up".

Oils with a lower flash point are recommended for woods riding for this very problem...Anything with castor oils will carbon up woods bikes much wuicker.

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Tomac and/or Anderson for 2020.....

2/20/2019 11:23 AM

BobPA wrote:

You guys do realize that the difference between 32:1 and 40:1 is really not that much.

128oz/gal

32:1 = 128oz : 4oz
40:1 = 128oz : 3.2oz

A difference of 0.8oz per gallon of fuel.

0.8oz = 23.66ml aka less than half of a shot glass of oil per gallon

There are 3785ml per gallon (roughly)

In other words, a correctly jetted bike will do fine on 32:1 in the woods. It will not be "literally loading it up".

Oils with a lower flash point are recommended for woods riding for this very problem...Anything with castor oils will carbon up woods bikes much wuicker.

Its a ~20% difference. And even 40:1 is too much oil but better. Rememeber OP is riding a 250, doing east coast woods races, and looks like hes racing C class.

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2/20/2019 11:36 AM

BobPA wrote:

You guys do realize that the difference between 32:1 and 40:1 is really not that much.

128oz/gal

32:1 = 128oz : 4oz
40:1 = 128oz : 3.2oz

A difference of 0.8oz per gallon of fuel.

0.8oz = 23.66ml aka less than half of a shot glass of oil per gallon

There are 3785ml per gallon (roughly)

In other words, a correctly jetted bike will do fine on 32:1 in the woods. It will not be "literally loading it up".

Oils with a lower flash point are recommended for woods riding for this very problem...Anything with castor oils will carbon up woods bikes much wuicker.

colintrax wrote:

Its a ~20% difference. And even 40:1 is too much oil but better. Rememeber OP is riding a 250, doing east coast woods races, and looks like hes racing C class.

Good call. It is actually exactly 20% more oil haha. I think if it is smoking excessively during a race there may be other issues. I know I ran 32:1 forever in the woods with no issues...Just some dirty power valves here and there.

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Tomac and/or Anderson for 2020.....

2/20/2019 1:45 PM

Also, dead engine start = cold engine temps = more smoke. Later in the race, no smoke? It's starting to make sense.

Your oil mixture ratio probably isn't the culprit here, so much as the engine temp. (Yamalube R is a little smoky sometimes, too.) As long as your bike is running right, I bet it's a warmup issue and not an engine problem.

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Braaapin' aint easy.

2/20/2019 9:57 PM

BobPA wrote:

You guys do realize that the difference between 32:1 and 40:1 is really not that much.

128oz/gal

32:1 = 128oz : 4oz
40:1 = 128oz : 3.2oz

A difference of 0.8oz per gallon of fuel.

0.8oz = 23.66ml aka less than half of a shot glass of oil per gallon

There are 3785ml per gallon (roughly)

In other words, a correctly jetted bike will do fine on 32:1 in the woods. It will not be "literally loading it up".

Oils with a lower flash point are recommended for woods riding for this very problem...Anything with castor oils will carbon up woods bikes much wuicker.

colintrax wrote:

Its a ~20% difference. And even 40:1 is too much oil but better. Rememeber OP is riding a 250, doing east coast woods races, and looks like hes racing C class.

2 stroke A

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2/20/2019 10:03 PM

Thanks guys for the reply. I’m going to take a little longer when I warm it up and put a new plug in before I ride this weekend and see how that goes. If that doesn’t work then I may lean my ratio out. But I don’t think it’s loading up because I’ve had this specific bike for over a year and have fouled 1 plug. And that was the night I got it cause I let it idle (which it’s not supposed to do I know). Ive always ran 32/1 and ive been racing for 16 years and I’ve probably fouled MAYBE 10 plugs. I never have had a problem with plugs. Guess we will see ??‍♂️

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