Motorcycle Forums banner
1 - 14 of 14 Posts

·
Registered
Joined
·
5 Posts
Discussion Starter · #1 ·
I have a 90 yz250, it has power, but had trouble idling. I cleaned the carb and everything, changed the oil. But it blows which smoke (radiator fluid i believe). Right now there is just water in the radiator. and it seems that one: it's getting into the chamber and being burned causing the white smoke, and two: is getting into the transmission oil, causing it to get that cloudy color and thick, which in time bogs on the clutch, so that it won't idle with he clutch in, only in neutral. Any ideas of fixes, or easy tests I can do to know? Maybe a dye in the radiator fluid?
 

·
The Toad
Joined
·
17,451 Posts
It's almost 20 years old. Get a manual. Pull the engine. Replace all the seals. Clean it up. Mike it out and replace anything out of tolerance.

Be thankful it's a 2 stroke. The rebuild won't cost much. A 4 stroke might cost thousands.
 

·
Registered
Joined
·
5 Posts
Discussion Starter · #4 ·
I figured as much as the head gasket or something so I planned on doing that, seems to be a pretty common problem. I was more concerned about the transmission oil thickening up, I put 30W-10 or something close to it in, but after a few rides it comes out like 140w, just really thick, and the bike won't idle, i think it's because of the pressure on the blutch, because it's fine right after new oil is put in
 

·
The Toad
Joined
·
17,451 Posts
Blown head gasket? That would allow the motor to suck the water in and blow out white smoke, as well as getting blowby into the bottom end.
But it wouldn't cause the tranny oil to thicken. Safest bet is to tear it down completely. Not hard on a single 2 popper. I've done enough of them.
 

·
Aging Cafe` Racer
Joined
·
8,715 Posts
It's clearly a bad battery. I'd get one of the saturated glass mat replacements for it.
No, it's obviously the clutch...the fluid thickens up because the 30w10 oil is mixing with the water and the resultant steam is causing the clutch plates to dissolve. That's why it gets thick, probably turn into oatmeal if you left it long enough.
 

·
The Toad
Joined
·
17,451 Posts
No, it's obviously the clutch...the fluid thickens up because the 30w10 oil is mixing with the water and the resultant steam is causing the clutch plates to dissolve. That's why it gets thick, probably turn into oatmeal if you left it long enough.
He'll try to get away cheap. And when it blows up a $300 rebuild job will become a $4000 new motorcycle.
 

·
The Toad
Joined
·
17,451 Posts
Hokay.

wait, what are you suggesting the solution is here?
The symptoms suggest that you have a leak that allows water to get into the tranny, the usual cause of oil thickening. The safest bet is to pull the engine and split the cases, inspect everything and then put in all new gaskets and seals. It is not a difficult job given a proper shop manual and the ability to follow the instructions to the letter. If you don't solve your oil problem in the tranny it will catastrophically fail eventually. It's much cheaper to do the job now than wait and have a worthless bike on your hands. That's my 2 cents. It's based on person experience on 2 strokes and having blown one up myself.
 

·
Registered
Joined
·
7,116 Posts
wait, what are you suggesting the solution is here?
Dawg, before you start, decide if you want to put the time, energy, and money into a rebuild on this bike, or if you want to move on. I once started to restore a 1969 Triumph Spitfire. A pretty smart guy told me: "Kenneth, when it's perfectly restored, it's still going to be a POS 1969 Spitfire." I went and got a 911 to play with instead. Just a thought.
 

·
Registered
Joined
·
3,875 Posts
Water pump seal. Try that first. Very common problem on water cooled two strokes. Also replace water pump bearing while you're at it. On this bike, you will have to pull the clutch cover and dissassemble off the bike.

Inspect impeller shaft while you're in there. Usually, it's best to replace all 3 components while you'e on Bikebandit.com ordering parts, anyway.

Oh, hell, get a head gasket/O-ring while you're at it. That's an easy fix.
 
1 - 14 of 14 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top