giordano

Member
Nov 30, 2004
4
0
I'm looking at getting back into riding... kinda looking for a project too seeing as I don't have the space to take apart my truck. I'm going to look at a 1990 YZ 250 tomorrow... supposedly the complete bike was rebuilt (bearings, seals, brakes, bottom/top end, brakes... etc) and then it got stolen, beat on, and recovered. The guy doesn't seem to know what's wrong but says it "blew a piston" and is unsure of the condition of the bottom end. He wants a few hundred dollars for it as is and I was wondering what I should be looking for to see if the engine is salvagable or not. Any advice is good, even if that is to "use the search function".

I can't wait to pull apart this guys bike to see how it looks inside. Thanks for all the help!

Richard
 

bikepilot

Member
Nov 12, 2004
804
0
Basically keep in mind that pistons are cheep (>$100 dollars), cylinders are more expensive (>~$250 to get replated) and cranks are about the same price as cylinders, but much harder to install. With a professional installation if you bring them the motor a crank will run you about 600-800 dollars. Without taking the bike apart it will be very dificult to determin the extent of the damamge. Presumeably the bike is either locked up or has no compression. If its locked up then it is likely that at the very least the cylinder is scored and will need to be replated (I think its a plated cylinder, not steel sleeved, but not 100% sure) and its reasonably likely the bottom end was damaged as parts of the piston could have made their way down into the crank bearings or the rod coud have bent when the pistion seized. If the bike is just low on compression it is likley that you could get buy with just a top end.

things to check when looking at the bike (assuming you can't pull the top end off at this time)
- Chassie bearings, is there much play in the rear suspension linkage, steering head bearings, wheelbearings etc?
- suspension, do both ends move up and down smoothly when you push on the bike? Is there any sign of oil leakign from the fork or shock seals?
- does the bike look like its been maintained (clean, chain properly adjusted, air filter clean, antifreeze clean etc?
- Transmission (assumeing the engine is locked up). Put the bike on a stand and see if the rear wheel spins in neutral (it should). shift through the gears (you will probably have to move the rear wheel to get it to shift, once in gear the rear wheel should not spin). It should have 5 gears not including neutral.

Considering that the bike was stolen, it is likely that the bike was run without pre-mix, which means that it most likely will need a top and bottom end.

good luck:)
 

Speedfreek

Member
Nov 3, 2003
153
0
1990 yz250 is not a plated cylinder.Just thought I'd let you know. Where in Canada are you?
 

Lissa

"Am I lost again?"
Apr 28, 2002
562
0
Just remember that you can easily spend more repairing a bike then what it's worth. NADA value on a '90 YZ250 is a mere $675. Also the older the bike the more exspensive and the longer the wait for parts. The bike is now 15 years old. Take that into consideration.
 

bikepilot

Member
Nov 12, 2004
804
0
Given that its not plated (thanks speedfreek), it will be cheeper to do a top end. Boreing a cylinder will probably run you between $40-70 US dollars. So a complete top end should not be over $200. The only rear worry would be the botom end, trans and chassie.

good luck
 

giordano

Member
Nov 30, 2004
4
0
Speedfreek said:
1990 yz250 is not a plated cylinder.Just thought I'd let you know. Where in Canada are you?

I'm in Vancouver... I didn't end up buying that bike but I got an '85 YZ250 that had a bunch of money blown on it. So I got a running bike for a little more than I was going to spend on the '90. Thanks,
 

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