What is going on here??

Flux3D · Feb 10, 2008

My yz250 has always smoked a lot when warming up. So much that it actually bogs pretty badly. But once it is fully warmed up there is almost no smoke at all, the throttle response is great, and no bogging. My spark plug is prefect with a light cocco brown color just like it's supposed to have and I don't really get any spooge. So I don't think that it is a jetting problem, but then again my jetting skills are basic.

Maybe I am worrying over nothing but is the initial smoking and bogging bad? Is there a way to fix it? I have heard that this is just what 2 strokes do until they warm up but my friend's yz250 never does this and runs just about the same as mine.

Any ideas?

BigRedAF · Feb 10, 2008

Perhaps separated pre mix. Grab your front brake and rock your bike around to mix the fuel. This will help if your fuel/oil was an old batch and separated.

Flux3D · Feb 10, 2008

BigRedAF said:
Perhaps separated pre mix. Grab your front brake and rock your bike around to mix the fuel. This will help if your fuel/oil was an old batch and separated.

Maybe. I usually don't ever have fuel in my bike that is more than 2 weeks old. I also use semi-sinthetic pre-mix oil. I thought castor based oils were the ones that would separate. I guess I should try draining the fuel from my bike and putting in a nice fresh batch to see if that helps.

Any other ideas to what could be causing my problem?

stumanarama · Feb 10, 2008

mine does the same thing, its just warming up

Filthy_McNasty · Feb 10, 2008

It's perfectly normal for a two-stroke to smoke heavily during initial warm-up. The engine isn't yet hot enough to burn the oil.

whenfoxforks-ruled · Feb 10, 2008

What color and smell does the initial billowing of smoke have? You could just have issues with your float valve. It may be getting too much fuel dumped into the engine while it sat?

Flux3D · Feb 10, 2008

whenfoxforks-ruled said:
What color and smell does the initial billowing of smoke have? You could just have issues with your float valve. It may be getting too much fuel dumped into the engine while it sat?

It's a white color and smells like normal exhaust just more dense I guess. I always turn the gas valve off when not riding my bike so I don't think that much gas could be dumped into the engine.

whenfoxforks-ruled · Feb 10, 2008

Are you intentionally burning anti freeze? That would make white smoke.

JD_MXRacer · Feb 10, 2008

i have another question related to this. after i have been riding a while my exhaust starts to smell different. it goes from normal exhaust to smelling like burning.

is it just from riding hard for a while or do you think i need to replace the packing? i havent opened it up to check yet and if i did i probably wouldnt know if it did need replacing.

BigRedAF · Feb 10, 2008

Does it smoke after it's been shut down. If so it could be oily packing that's burning from the heat of a hard ride.

Flux3D · Feb 10, 2008

whenfoxforks-ruled said:
Are you intentionally burning anti freeze? That would make white smoke.

The color of the smoke is the same that most 2-strokes give out. It looks whiteish to me but maybe that is not the best way to describe it.

Flux3D · Feb 10, 2008

BigRedAF said:
Does it smoke after it's been shut down. If so it could be oily packing that's burning from the heat of a hard ride.

I just repacked my silencer like a week ago. It only smokes really badly when starting the engine after it is completely cooled down.

EDIT: I think I mistaked this quote as a response to my question when it was really for that other guy's question. Sorry about that.

whenfoxforks-ruled · Feb 10, 2008

Yes, there was a thread hacker in here. Next time, before you get done, turn the gas off and lay it on its side to drain the carb. When it is cold turn on the gas and start it up. See if it smokes the same. I am trying to rule out the float valve. You could still have a bad seal on the right crank.

Flux3D · Feb 10, 2008

whenfoxforks-ruled said:
Yes, there was a thread hacker in here. Next time, before you get done, turn the gas off and lay it on its side to drain the carb. When it is cold turn on the gas and start it up. See if it smokes the same. I am trying to rule out the float valve. You could still have a bad seal on the right crank.

Will do. I wont be able to try this out until next weekend but I'll eventually respond with the results.

JD_MXRacer · Feb 10, 2008

BigRedAF said:
Does it smoke after it's been shut down. If so it could be oily packing that's burning from the heat of a hard ride.

yes but barely. when i shut it down i look at the silencer and i see a little white smoke rolling out. its not much though.

chevyss_98 · Feb 10, 2008

mine did the same thing upon warmup, its a 2 stroke thing, and a carb thing, between oil and a cold plug and a cold cylinder and carburetor, thats the result

What is going on here??

Flux3D

BigRedAF

Flux3D

stumanarama

Filthy_McNasty

whenfoxforks-ruled

Old MX Racer

Flux3D

whenfoxforks-ruled

Old MX Racer

JD_MXRacer

BigRedAF

Flux3D

Flux3D

whenfoxforks-ruled

Old MX Racer

Flux3D

JD_MXRacer

chevyss_98

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