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Discussion Starter #1
Hey everyone. New to the forums. Just have a quick question.

Rebuilding a motor. Cylinder sleeve is cracked. Bought a used jug off the same year/make/model bike. Going to swap that into the bike with the cracked sleeve. Going to keep the same pistons in the bike.

Will the bike have any issues running with mismatched pistons/jugs? Its just something to putt around the town. Not doing any cross country trips. Commute five miles to work and back. Simple.

I can't justify ~$500 on piston rings, another $500 on pistons, and whatever else I may need for this cheapo bike.

Thanks.
 

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Save them all!
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Personally I would do it - nothing to lose but a bit of time. I would give the cylinders a light hone, even with the re-used pistons/rings.
 

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Ace Tuner
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Might not hurt to measure the piston and cylinder bore to check your clearances???
If clearances are good would flex honing the bore and new rings be affordable? (Only if you want it to work and get you to work of course).
 

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Discussion Starter #6
Piston rings cost 500 clams???

Holy mackerel, what kind of engine are you rebuilding?
Old school Yamaha.

Its a piece of **** bike I got stuck with. For what it will cost to do this "right" I'll part this bike out and buy something else.
 

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ZAMM Fanatic
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I tried putting bigger jugs on my bike. It's didn't work worth a crap. Thing constantly wanted to wheelie on me.

 

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Discussion Starter #9
That's what I was wondering. Many complete top end rebuild kits (piston, rings, gaskets, bearing) for a single cylinder cost less than $130.
Just finished the top end. It was by chance I decided to pull the jug and saw the damage.

Working on pricing for rings right now. The pricing I gave was for all pistons; not each. I did find a few places as low as ~$50 a piston.

Perhaps I'll suck it up, hone it out, and spend the couple hundred.
 

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Dont get carried away with it.
Inspect the used parts for wear and tear. Make sure they are within tolerances.
Hone the cylinders and slap new rings on the used pistons.

I just dont think you could get the used rings to seal again, once removed.
But for a beater to ride around town, should be fine.
Dont go around advertising it as a rebuilt engine.
Just replace what is broke and enjoy it for what it is.
 

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Ghost in the machine
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You would probably get better advice if you were more specific. "Yamaha" or "old school" doesn't mean much.
Year? Model? Engine size? The more info you give, the better the advice will be that you receive.
 

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Ace Tuner
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You would probably get better advice if you were more specific. "Yamaha" or "old school" doesn't mean much.
Year? Model? Engine size? The more info you give, the better the advice will be that you receive.
What jag13 said. ^^^
 

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Gone.
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Just finished the top end. It was by chance I decided to pull the jug and saw the damage.
Maybe we're just using different terms, and I'm trying to understand what you're saying, but I missing something here.

You finished a top end re-build, (which includes the cylinders and pistons,) and THEN you decided to remove the cylinder and saw that it was damaged?

It can be VERY hard to get your ideas across on the Internet, to be sure.:biggrin:
 

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Retired twice: Navy and as a govt contractor
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He probably means a valve job
 

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Discussion Starter #18
Alright. I fibbed in my OP because I was trying to keep this on the DL, but I guess I'll get into now that I realize I just got ****ed on CL.

I bought an '82 Yamaha XJ650R Seca on CL. Ran a bit rough. Was obviously dropped. A fixxer upper for sure. Winter project. Guy told me it could use a carb cleaning.

Started the tear down. Pulled the head. Lapped the valves. New gaskets. Cleaned all the ports.

Pulled the carbs. Cleaned them 100%. Bench synced.

Pulled the jugs, found this:
NOT ENOUGH POSTS TO PUT IMAGES

The bottom of the sleeve had a chunk taken out of it.

Pulled the oil pan, found this:

Bits of metal in the small of my hand. Oil pan had RTV on it so someone had been in there and removed the large chunks.

Bought another jug off eBay to get honed along with new rings on the pistons. Now I'm getting the jitters because its looking like there was a broken rod in this bike's history (how else could that sleeve be damaged like that). I'm 90% to tearing down the motor to the crank. I should get there tonight to check out the rod.

Its probably a safe bet that this motor is garbage, right? Stop where I'm at and part this thing out?
 

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Discussion Starter #20
If it was only that easy to stop :smiley_drinkcoffee:
That's where I'm at. The motor isn't all that complicated. I really didn't want to have to get this deep into the motor, but whatever. I don't mind honing the cylinders and putting in new rings. Fine. But what guarantee do I have if this motor did have a broken rod?

Which is another weird thing. There is the mid gear that has four TORX bolts that are peened into place. From what I can tell, these bolts are factory. It is impossible to replace a rod without splitting the case. It is impossible to split the case without the removal of these TORX bolts. I just don't see how else this sleeve could have broken though.
 
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