Change the case oil and see if you notice it again. Also check to make sure there's a good seal between the waterpump and the engine. I'd bet you just have some bad oil in there.

 

actually, i drained it COMPLETLY and when i filled it back up it still did it again! I would guess that either 1: there was still enough water in the mixture to make it turn white (becuase it doesnt take much) or 2: THere is a bad seal like you said.

Also, 1 more thing, i recently was having problems with the bike wanting to rev really high on me, even if i was not gving it any throttle at all... its really weird! i checked teh cable and there was nothing abnormal there, i dont know what it could be! like, once it warmed up and rean for a like 15 minutes, the revs will got to WOT even if i am not doing that with my wrist... any ideas???

 

Like Carnage said.

I have an 02YZ250 and currently have the engine sitting in my basement in about 400 pieces.. F'ing transmission problems.

I would guess its your throttle cable causing the revs. Not sure what else it could be unless you have some super weird carb problem.

 

Like Carnage said.

I have an 02YZ250 and currently have the engine sitting in my basement in about 400 pieces.. F'ing transmission problems.

trannys can always get you down!

 

Ok...since you drained and refilled the oil, I'd go with the bad seal.

The auto-revving problem is either a cable routing issue like Flounder suggested or the slide in your carb (holding the main needle) getting stuck. Check both and a carb clean never hurts on our dirty bikes. :cheers

 

The water pump seal is bad. They are pretty easy to repair.

If the idle went up and then went back down all on it's own you have an air leak and it's causing a lean condition that is causing the run up and the motor typically won't last long doing that. The air leak is either: at the reed valve, at the base gasket, or between the engine cases. Typically, it's the one between the cases which is unfortunte cause it's a bitch to get to.

 

sweet. thanks guys for the input... hopefully dring christmas break i will have enough tiem topull some stuff out and see what the deal is... I am going to get a new cable, and clean teh carbs first of all... if that does not solve the issue, I will have to go from there... but a good through carb clean will definetly be good either way.... i wouldnt mind it being a reed valve either... i have always wanted to pull moror apart and see waht i can see... i know my 4 strokes, but still a noob on the 2 strokes! thanks guys...

also, I found it intersting that after i changed teh oil the high reving went away completly... but i got a few days of riding in and revving issue came back!?? what do you think that is all about... could it be something with the oil level being way too high? becuase of water getting in? what do you think?

 

I'm thinking that the revving is only a carb of cable issue. I don't see how the oil could possibly have anything to do with it.

 

I'm thinking that the revving is only a carb of cable issue. I don't see how the oil could possibly have anything to do with it.

I can almost swear its a cable issue. My bro's 88 does it sometimes.

Edit: My bro's cable issue is with where the cable goes into the throttle tube. Just something to maybe look at........

 

Your air leak is probably coming from the crank seal. If the oil is high it may just suck oil thru, but if it is low it will suck air and make your revs go up. Does the exhaust look or smell different, you may be burning engine oil, or coolant. You def. have a water pump seal out, but easy to fix. The air leak will probably be a bitch,and you will need to split the case.. The good news is that it will cost about 1/3 less than a 4 stroke to fix.. Thats why I bought a new 2 stroke.. Those four strokes take way to much maintnance..:cool

 

alrighty. thanks for the input... ya, i seriously think that it is not a big deal... seems like a carb issue more then anything, cuz the bike sat for quite some time, we shall see

 

gotcha... doesnt sounds toooo good for me.... hm, how hard is a crank seal to do? sounds like no fun at all... but I will have a month of nothing to do during break, so i guess i will have some work ahead of me... and, also, SUN HESTER.... it never revs up by itself... only if i am out riding and i get on it and let off, then it wants to hang up there... bit i have never been just sitting at idle and had it do that... dont know it that helps clairify... but thanks....

 

Not sure about his model but I just split the case on mine.. no problems whatsoever.. $9 bolt puller kit from harbor freight and a dead blow hammer to help with crack the seal and tap out the transmission.. Im sure all models have slight variations though.

 

dude change the oil every 20 hrs and dont worry about it...its an 89 when it goes it goes (and when it does might i suggest an 06 yz 450 f

 

LOL!!!! Funniest thing is they are fastest when they are about to blow!!!!!!!!!!!!!:lol

 

For Christ's Sake Man, this is an 89 RM. Needs a complete rebuild.

You have looseness in your top and most importantly bottom crank bearing and the looseness destroyed your crank seal. A bad water pump seal is also going on probably aloong with a grooved impeller shaft. The loose lower crank bearing probably did your center case seal in or you have a leak on the intake.

This motor needs to be taken apart and all seals and bearing replaced along with a balancing of the crank.

Oldie but goodie

 

it had a comlete rebuild 7 years ago, and it had only been ridden 10 times since the rebuild, so i dont think its in too bad of shape...