Need help - YTZ250 of 1986 - Engine is throwing the crank oil from the muffler

[CrossadaMan]

Hello everyone,

I need help with this matter.
I buy a ytz250 a week ago, already take out carb, and clean it, check main jet and pilot jet (both stock) neadle in the lower possition.
The bike is throwing the crank oil all out from the muffler, not talking about some minor oil, but lots and lots of it.
The bike runing almost cant acelerate in lower RPM, and only in high RPM after like 10 secounds it fire up and show a little more power, in a 10 minute ride, my jacket is all black in the back.

I open yesterday the engine, looking for a bad crack seal, but all parts inside look new, and the bike sould be rebuild in past and never runing.
I found out a hole, uper the crack spocket, that is open, and in the crank side and crack case cover it looks like some part is missing like a big Pin that goes from the crack side to the crack case cover, so that the hole that goes to the cylinder does not suck the oil and throw it for the exhaust.
I have the tri-z250 service manual, but from the grey picture, can´t understand if there hole is open and normal, or it should have a closure for it.

I show you the pictures so you all can understand what im talking about.

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Thank you all for your help

[RIDE-RED 250r]

I'm no Tri-Z expert, but it certainly looks like something is missing to me. The engine crankcase and transmission should be sealed off from each other. Hopefully someone who has experience with Tri-Z's will chime in for some definite answers for you.

[Grahm]

mine is open like yours..

[TimSr]

Nothing is missing. That is normal. There are only 3 possibilities I can think of to cause your problem. The easiest one to fix is to replace the crank seal on the clutch side. You can easily replace it without tearing everything apart.

If it is not the crank seal, you either have a cracked case half, or a bad seal between the case halves. Either way, you will have to split the cases to find out. The case has a wall between the crank area and the gearbox that can be cracked when you shatter a piston or rod bearing, and the crank shoves a piece though the wall. You would be able to see this when you split the cases. The other possibility is a leaking seal between the case halves. The TriZ does not use a gasket between the cases, and requires a good quality, hard drying gasket sealer. Silicon won't do the job.

[CrossadaMan]

The bike is almost new, no rocks or dots in nowere, and plastics almost new. I think this bike was of a fireman, that use it with Farm Gas/oil like the old ones. I take out the muffler and if i shake it, it make a sound of liquid inside, but it does not get out, even with air compressor. Maybe the problem is that the exhaust and muffler are full of black greasy oil, and there is nothing wrong with engine.
How can i clean the exhaust and muffler, and take out that oil from inside? Put gasoline and then burn it?

I will buy the crank seal to change it to eliminate possibilitys. Can you tell me if i can change it, without taking off the clutch and clutch plate ?

Best regards

[TimSr]

The bike is almost new, no rocks or dots in nowere, and plastics almost new. I think this bike was of a fireman, that use it with Farm Gas/oil like the old ones. I take out the muffler and if i shake it, it make a sound of liquid inside, but it does not get out, even with air compressor. Maybe the problem is that the exhaust and muffler are full of black greasy oil, and there is nothing wrong with engine.
How can i clean the exhaust and muffler, and take out that oil from inside? Put gasoline and then burn it?

I will buy the crank seal to change it to eliminate possibilitys. Can you tell me if i can change it, without taking off the clutch and clutch plate ?

Best regards


Are you sure its oil that is blowing out the exhaust? Are you losing lots of oil from the gearbox after you run it? TriZ's on occasion have been known to flood the top end and pipe with with gas while sitting overnight. Its happened to me a few times, so that I always turn the gas off when I park it. If you can hear liquid sloshing around in the pipe, that would be my guess. The gas will turn black from the buildup in the pipe when it blows out. Take the whole pipe off. It should pour right out. If it is oil, you'll need gasoline or some solvent to rinse it out, by my guess is its mostly gasoline. It should pour out, and then give it time to dry. You can dry up the tar with a propane torch, but keep in mind you have fammable liquid in there! The silencer will also be saturated. For test purposes, you can take it off and test run without it, but you'll need to take it apart, remove the glass packing, clean it up with a propane torch and wire brush, and repack it before reinstalling it.

If you are sure that its oil in there and not gas, you can refer back to my first post, but I would clean up the exhaust first and verify whether its gas or oil in there. You will need to remove the clutch to get the gear off the crankshaft before you can replace the seal.

[ge259]

I am looking for some tri z250 parts