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  #1  
Old 12-09-2004, 09:31 AM
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Default 2-stroke Smoking big time!

I've got a little Zuki LT80 4wheeler that I' need to sell. It runs really good but it jsut smokes like crazy. Big solid stream of smoke.

Here's what I do know:
The compression is fine. I don't remember PSI .

I disconnected the oil pump and tested it with pre-mix. That did not make any difference.

Good oil an Gas mix, new plug, clean air box....

What can I try next, Can the carb or jets cause this?

Air Leak? I don't see any air leak but I could keep looking.
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  #2  
Old 12-09-2004, 09:40 AM
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Default Re: 2-stroke Smoking big time!

My kdx smokes a lot before you "clean it out" by getting on the throttle for a few minutes. Does yours continue to smoke even after it's cleaned out? I mean does it smoke the same amount throughout a say 30 minute ride? Or does it lessen after a few minutes?

Maybe some of the 2 stroke experts on this site can chime in...
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Old 12-09-2004, 09:44 AM
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Default Re: 2-stroke Smoking big time!

I can't say that I've stood on it for 30 mins. but I've road it up and down the street a few times.
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Old 12-09-2004, 09:46 AM
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Default Re: 2-stroke Smoking big time!

oh what I meant to say was it doesn't change with what I've done so far.
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  #5  
Old 12-09-2004, 10:17 AM
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Default Re: 2-stroke Smoking big time!

You have a leaking crankshaft seal on the transmission side. It is allowing oil from the transmission to leak into the lower end. The result is that you are running a very rich mix. I'm betting that the smoke is almost blue.
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Old 12-09-2004, 10:20 AM
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Default Re: 2-stroke Smoking big time!

Gotta split the case to fix that Dave?

Dave, when does a bike gain "vintage" designation?
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Old 12-09-2004, 10:35 AM
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Default Re: 2-stroke Smoking big time!

Don't necessarily have to split the case. It depends on the design of seal area. If the entire seal can be seen behind the primary gear, it usually can be replaced without splitting the cases.

"Vintage" is a bike with 7" front 4" rear travel with a model year of 1974 or earlier.

"Evolution" bikes are model years 1975-1983.

There are sub-classes in each designation.
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  #8  
Old 12-09-2004, 10:51 AM
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Default Re: 2-stroke Smoking big time!

I have a two-stroke Polaris Scrambler 400 that smokes when it is first started, but after it warms up the smoke goes away. Would this still be a bad transmission seal too?
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Old 12-09-2004, 10:58 AM
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Default Re: 2-stroke Smoking big time!

Quote:
Originally posted by Crunk
I have a two-stroke Polaris Scrambler 400 that smokes when it is first started, but after it warms up the smoke goes away. Would this still be a bad transmission seal too?
No, that is normal. Most two stroke riders smoke during warm up...I mean most two stroke engines smoke when cold. A few minutes. Once the engine warms up, the smoking stops. The problem is when it doesn't stop like TPinTX's situation.
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Old 12-09-2004, 12:43 PM
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Default Re: 2-stroke Smoking big time!

Okay....well the good news is that stops me from tearing into the carb like I was about to do..

Thanks for the valuable info.
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Old 12-09-2004, 12:49 PM
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Default Re: 2-stroke Smoking big time!

Maybe it is just running rich.. like my bike, its running rich. but the smoke doesnt pour out. its just every time i blip the throttle, this is because i am running rich...
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  #12  
Old 12-09-2004, 12:54 PM
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Default Re: 2-stroke Smoking big time!

hey Dave would you mind looking at one or more of these schematics and see what you think

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tanks buweet
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  #13  
Old 12-14-2004, 06:30 PM
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Default Re: 2-stroke Smoking big time!

You know what fellas, this thing doesn't have a tranny. There is no crank oil to burn.

Any other suggestions?
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  #14  
Old 12-14-2004, 06:34 PM
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Default Re: 2-stroke Smoking big time!

I was thinking rich jetting. I dont know why no one said that... maybe im missing something. Jetting it would be a whole lot easier then splitting the cases though. Clean the carb real good before you put any money into fixing it.
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Old 12-14-2004, 07:06 PM
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Default Re: 2-stroke Smoking big time!

Replace part #14 on the last link you posted. That is the tranny side crank seal.
Looks like it can be replaced without having to split the cases.

It may not have a manual transmission, but if it goes forward or reverse it has to have some sort of transmission. That's how power makes it from the crankshaft to the rear wheel.

It's not jetting. Jetting problems cause BLACK smoke. Crank seal issues cause BLUE or WHITE (on air-cooled engines) smoke.
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Old 01-03-2005, 08:58 AM
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Default Re: 2-stroke Smoking big time!

hey guys, I was reading the thread and realized that I may have the same problem (leaky crank seals). I have a CR250R 2002. The question is: Do I fill the crank oil up to the "level bolt" or there is a "specific measured amount" of oil. I have noticed the"white" smoke but it appears to end after 45 min run. Probably just swallowed it all. thanks...
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  #17  
Old 01-03-2005, 09:49 AM
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Default In response to Caribe

You should drain your tranny oil completly and then fill it back up with 650ml of new 85w tranny oil. And yes, if your oil is doing a dissapearing act, then it is crank seals for sure.

Last edited by HondaOnly; 01-03-2005 at 09:52 AM.
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  #18  
Old 01-03-2005, 11:06 AM
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Exclamation Re: 2-stroke Smoking big time!

I'm going to repeat a question... Can they be replaced WITHOUT spliting the cases?? I'm asking specifically for the cr250r 2002. Can it be done by an average john with mechanical skills and regular tools?? thanks again...
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  #19  
Old 01-03-2005, 11:44 AM
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Default Re: 2-stroke Smoking big time!

Yes they can both be replaced without splitting the case. you will have to remove the flywheel on the left side and the magneto. Im not sure of what comes off the other side but the pictures show they both go in from the outside. Good luck.
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  #20  
Old 01-10-2005, 08:33 PM
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Default Re: 2-stroke Smoking big time!

Hardly ever see black coming from a two stroke exhaust and I sure see lots and lots of them running too rich. Too much whiteish blue can definitely be too rich, and if it just began it or progressed into it would indicate float problems either setting, sticking, worn seat, or junk on the seat of the float valve and needle. In the case of an injected bike though you can indeed see black smoke (snowmachines are where i see it the most).

I am betting though that there is some kind of transmission with oil in it with a wet clucth etc that holds oil,,and some is getting passed the seal that VD indicated.
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