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82 RM250 piston blew - options?

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Alright, so the genius I bought this off of said "it just needs a piston! I think its overbored so I got a new one and it didnt fit so I put the old one back in with low compression and it doesnt run. Damn liar...ripped the whole thing apart for a project and just started on the engine, and heres what I found. Pics.

Piston skirt went out on the intake side. Loaded it up with metal. Heres something weird, though, I was turning the engine over by hand today and it locked up. I pulled the plug out and tried a bit harder...nothing. so I went to take the nut off the sprocket and accidentally left it in gear, and that freed up the engine. Does that mean my bottom end is fried too? Crank has no play in it and turns freely with no issues. No up and down play in the con rod.

Also, metal is plugging one of those two small holes on either side of the con rod in one of the pictures. What is that? For lubrication of bottom end?

Ive heard about flushing engines with blown top ends with diesel...how would I go about this? Is it worth it?

Edit: dont say it isnt worth it because its an 82. Heres the story, I traded it for a TTR90 that I was $300 into, and he gave me this RM and $200.

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Edited by lethalweapon100

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I don't think anyone will say it not worth fixing, because it's a very desirable bike.

 

The small holes help lubricate the main bearings.

 

You could try flushing it, but I wouldn't recommend anything less than tearing it down and starting fresh.  You bought it super cheap and it looks like a great project bike.

 

 

This may interest you....

 

http://racetech.com/html_files/SUZUKI_83RM250PROJECT.html

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I don't think anyone will say it not worth fixing, because it's a very desirable bike.

The small holes help lubricate the main bearings.

You could try flushing it, but I wouldn't recommend anything less than tearing it down and starting fresh. You bought it super cheap and it looks like a great project bike.

This may interest you....

http://racetech.com/html_files/SUZUKI_83RM250PROJECT.html

Alright...well I guess I wont sit around and just wait til somebody says what I want to hear. Guess im doing a rebuild...im gonna have a ton of questions.

Here's a picture of it. Complete. I have it torn down now. Someone went to great lengths to do things the wrong way. I.e. all the tapped threads with barely any metal left, with all these weird 13mm bolts.

1407109512686.jpg

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As far as flushing it goes I'd use premix gas considering that its the fuel and lube that is gonna go in it anyway. My 2bits ;)

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As far as flushing it goes I'd use premix gas considering that its the fuel and lube that is gonna go in it anyway. My 2bits ;)

Hmm, good point. Maybe ill buy regular gas and weedwacker premix so I don't have to waste my good 32:1. Im still debating splitting or flushing.

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Flushing is not going to have good long-term results.  You have bits of metal in the bottom end, some of which will certainly find their way into the main bearings and the con-rod bearing.  This will result in far more damage than you currently have.  Split the cases and have the crank rebuilt.  Re-nickasil the cylinder if it's not in spec.  Replace the lower end bearings with good quality ones from Japan or the US.  Then you can really enjoy riding one of the most desirable vintage bikes out there.

 

Flushing works when you've accidentally dropped a circlip or nut in the bottom end, not for a powdered piston.

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Flushing is not going to have good long-term results. You have bits of metal in the bottom end, some of which will certainly find their way into the main bearings and the con-rod bearing. This will result in far more damage than you currently have. Split the cases and have the crank rebuilt. Re-nickasil the cylinder if it's not in spec. Replace the lower end bearings with good quality ones from Japan or the US. Then you can really enjoy riding one of the most desirable vintage bikes out there.

Flushing works when you've accidentally dropped a circlip or nut in the bottom end, not for a powdered piston.

See, the more I look at the carnage in the piston, I conclude that it smacked the crank and detonated the skirt. Also, the ring is fried on so it was probably leaned out. Which makes me think theres play somewhere in there. When payday rolls around ill get a case splitter and open it up.

Whats your source for bearings? I found some from a shop in eurpoe...

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Likely there are local bearing shops near you.  I've found that for the most part, standard size bearings are used in our bikes. 

I've also found that some sizes are really common in bikes.  For example, I ordered several extra bearings for the water pump on one of my bikes to have as spares.  Later, I split the cases on another one and found that the power valve used the same size bearing.  The only difference was the seal, which was easily pried out.  Perfect fit.

 

Here are a couple places that I've ordered bearings from:

http://www.vxb.com

http://www.bocabearings.com

 

Make sure you're getting the good quality ones, like Nachi, Koyo, SKF, etc.  I have not found a good place to order seals from, but will at some point in time.

 

 

Rockymountainmc.com has good prices on case splitters and crank installers, btw.

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Likely there are local bearing shops near you. I've found that for the most part, standard size bearings are used in our bikes.

I've also found that some sizes are really common in bikes. For example, I ordered several extra bearings for the water pump on one of my bikes to have as spares. Later, I split the cases on another one and found that the power valve used the same size bearing. The only difference was the seal, which was easily pried out. Perfect fit.

Here are a couple places that I've ordered bearings from:

http://www.vxb.com

http://www.bocabearings.com

Make sure you're getting the good quality ones, like Nachi, Koyo, SKF, etc. I have not found a good place to order seals from, but will at some point in time.

Rockymountainmc.com has good prices on case splitters and crank installers, btw.

Great, what a help you are. Thanks a ton. So no good leads on seals?

Also, who do you recommend rebuild the crank?

...what size nut is the one holding down the basket and inner hub?

Also...do I even have an 82? Guy says its an 82...blue frame, black engine, yet somebody painted the water pump over in black, it was originally blue. I can tell. The engine, however, has just black. When I rough it up with sandpaper it stays either black or bare metal, no trace of another color. I can get the 10th # on the vin or whatever in the AM if you know what it could be.

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Just use the vin number. 1981 and later- 17 digit serial # - 10th number (2001 up) or letter (1981 to 2000) designates the year model. #1 is 2001, #2 is 2002, and so on.
B = 1981, Z = 1982, D = 1983, E = 1985, F = 1985, G = 1986, H = 1987, J = 1988, K = 1989, L = 1990, M = 1991, N = 1992, P = 1993, R = 1994, S = 1995, T = 1996, V = 1997, W = 1998, X = 1999, Y = 2000.

 

For rebuilding the crank, I would use one of these folks:

http://www.goforwardmotion.com/2Strokes.php

http://www.cookseycrank.com/

http://www.kenoconnorracing.com/Crankshaft%20Rebuilds.html

If you can find a good deal on a new OEM crank that's a good bet.  Hot Rod cranks seem to be okay, but don't use their bearings.  Wiseco cranks are like Namura pistons- crap.

 

For seals, get the prices from partzilla.com, but I've heard enough about parts taking forever to arrive from them that I would have rocky mountain or TT price match.

 

I don't know the nut size.  23, 27mm? 

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Just use the vin number. 1981 and later- 17 digit serial # - 10th number (2001 up) or letter (1981 to 2000) designates the year model. #1 is 2001, #2 is 2002, and so on.

B = 1981, Z = 1982, D = 1983, E = 1985, F = 1985, G = 1986, H = 1987, J = 1988, K = 1989, L = 1990, M = 1991, N = 1992, P = 1993, R = 1994, S = 1995, T = 1996, V = 1997, W = 1998, X = 1999, Y = 2000.

For rebuilding the crank, I would use one of these folks:

http://www.goforwardmotion.com/2Strokes.php

http://www.cookseycrank.com/

http://www.kenoconnorracing.com/Crankshaft%20Rebuilds.html

If you can find a good deal on a new OEM crank that's a good bet. Hot Rod cranks seem to be okay, but don't use their bearings. Wiseco cranks are like Namura pistons- crap.

For seals, get the prices from partzilla.com, but I've heard enough about parts taking forever to arrive from them that I would have rocky mountain or TT price match.

I don't know the nut size. 23, 27mm?

I dont know either...I just dont have the right socket to fit. :darn:

Thanks so much.

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