Hi, just signed on, and this site is bloody awesome... though lets get to the point.

this is the first bike ive decided to actually look into, basically because ive had to.

i own a 1987 Honda NSR250, MC16.

I ran the bike 2 tanks without oil, and you guessed it shes lost compression in the left exhaust. i know this because i put my hand at the back of the exhausts to feel the air flow and the left is FAR less than the right.

so, and many thanks to your site parts manual, i have managed to get right down to the cylinder and expose the piston.. i have to add the mc28 rebuild section helped tremendously removing the cylinder.... anyways...

what i would like to know is, how i can tell my rings arew buggered?

i can scrape about a 1mm thick layer of carbon or whatever it is from the top of my piston.

there is oil leaking from my exhaust gasket/seals and 150mm of oil leaked from my left exhaust when i pulled the silencer off.. also i noticed oil at the top of the piston, above the rings. the oil is a very black color.

also every time i wish to start the bike i need to clean both spark plugs.

i have not ordered parts yet as im not fully sure what to order, my knowledge of engines is very minimal but slowly getting there thanks to this site.

i believe i need the mc16 topend rebuild kit. any suggestions help would be much appreciated, thank you.

First thing to do for us please, is go to the Technical Resources page and check the MC16 carburettor settings and compare them with yours.

Sounds like it's not been firing on that cylinder for some time, and the settings could be rich.

It's actually going to be a little tricky as you've already dismantled it, but I'm sure we can help.

When it did run (with new plugs), did it run on both cylinders? How did it rev? Would it make the "red-line"?
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Andy.
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You "ran it two tanks without oil"? Do you mean without two stroke oil? I'm amazed it didn't sieze. Isn't there any scoring on the barrels?
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MC21SP Plaything
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yes she has been dismantled, but the other day i put her back together...

with the redline issue, i started the bike, waited a few minutes while she was running and whilst giving full throttle didnt actually make redline, let her idle then tried again and she did(hit redline).

taking note a new problem has developed and that is when i hit the kill switch the engine kept reving up and up on its own without throttle... thankfully the key off worked.

yes, that was without 2stroke oil... im suprised she didnt sieze either.

i believe there is no scoring on the pistons or inside the cylinder.

zemerdon wrote:
with the redline issue, i started the bike, waited a few minutes while she was running and whilst giving full throttle didnt actually make redline, let her idle then tried again and she did(hit redline).


yes, that was without 2stroke oil... im suprised she didnt sieze either.

i believe there is no scoring on the pistons or inside the cylinder.

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MC21SP - Roth-tax
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Sounds like the bike may be very rich, which is probably what saved the engine. If you never loaded the engine real hard without the oil, the excess fuel could have kept all the temps under control and kept things from seizing.

I would check the compression and see how the cylinders/rings are. You may be OK. Just hope there is no scoring on any of the crank/rod bearing surfaces.
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Paul Herr
'88 FZR4/GSXR/YZF Frankenbike
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