Is this cylinder jug okay?

Hello all,
I am missing riding my 82 xj650 big time! I recently replaced the headgasket but found that I had a pretty bad oil leak after putting it back together. It looked like it was coming from the jug and my friends and I concluded it was cracked, so I bought one from ebay. Over the weekend I disassembled, promptly realized that I didn't have all the gaskets I would need, let loose a string of really bad words, sulked for a little while, and then spent some time examining, measuring and checking the plane of the cylinder jug I'd just bought. So here are my questions:
The cylinders all measure just less than 63 milimeters - ranging from 62.79 to 62.9. Or at least they did. #4 had a sort of a scar deep inside and so I began trying to clean it up with a hone. Now that cylinder measures 63.05. Is that okay that it's different than the others and is it okay that it slightly exceeds the limit? Or did I ruin it?
I also discovered that the original jug wasn't really cracked - it's kind of warped. It's slightly higher in the center, and I think that's why it didn't torque properly. If I can't use the one I bought from eBay, can I get the old one planed at a machine shop? Or does that fact that the jug is aluminum and the sleeves are steel make that impossible? What about sleeving the cylinders? Can that be done on these things? Maybe I could just have the new one resleeved? If I'm at an impasse with all this I guess I need to buy another jug. And, if I have to I have to. I want my bike back on the road!
thanks,
Scott

 

The max. standard bore dim. is 63.10mm. Are you measuring each bore in three places top to bottom then measuring again in the same manner but 90* perpendicular to the first measurements? Imo take both of them to a machine shop and ask them to scale/look at them. Others may chime in with other solutions.

Gary H.

 

Hi Gary,
Thanks for that info, that's a big help. I was wondering about how to measure in other spots than the top of the cylinder. I'll definitely feel more confident getting a pro to check it out for me. By the way, do you mean the maximum bore diameter is 63.10? Do you know the range that's workable? And how much of a difference can there be between the cylinders without it being a problem?
thanks again,
Scott

 

I edited my post. Yes, max. bore dim. is 63.10mm. Haynes says standard bore dim. is 63mm. I don't have a FSM. If you're asking if the 63.05mm jug is worth using i can't answer that. i would think yes if the ovality (how oval the jug is) and taper (the jug tapers from top to bottom) limits check out and there's no major damage to the bore. Again take it to a ms and let them scale/inspect it. Difference between jugs does not matter as long as each jug is within service limits. Fwiw all the jugs in the e-bay head should be gently honed and cleaned prior to assembly. This will give the piston rings a fresh slate.

Gary H.

 

Thanks Gary - really helps.

 

Actually, max bore is 64.00mm (= what Yamaha calls 4th oversize, +1.00mm).

63.10mm is barely broken in.......1st oversize is +0.25mm (= 63.25mm).

 

Ah, that's music to my ears Len! So if I'm only at 63.05 on one cylinder and less than 63 on all others, it sounds like I'm probably okay to put it together - no?

 

So long as none of them are egg shaped...

 

Well, it's hard to image it being LESS than 63.00mm, as 63mm is the stock/standard bore.

Be that as it may, I would still follow roc's advice and take the jugs to a machine shop and have them check the bore, taper, out-of-round. They have the tools to make accurate measurements. Realistically, you should also take the pistons to them and have them measured to make sure the piston-to-cylinder wall clearance will be in-spec, too. Don't want any evil one-eyed blow-by happening............

Here are the specs:

Standard bore: 63.00mm
Wear limit: 63.10mm (= + 0.10mm) THIS IS THE SIZE, ABOVE WHICH, YOU NEED TO RE-BORE THE CYLINDERS TO THE NEXT OVERSIZE.
Taper limit: 0.05mm
Out of round limit: 0.01mm
Piston clearance: 0.030 - 0.050mm standard
Piston clearance: 0.10mm max. allowed
NOTE: piston size should be measured at a point 7.5mm above the bottom edge of the piston, and at right angle to the piston pin bore.
Piston weight (including rings, pins, and clips: 213 grams

 

Great information. I measured the bore before honing any of the cylinders except for the one - so the measurement I got included the ridge from combustion. That would explain it being slightly less I guess. In any case - off to the machine shop!
Thank you.

 

Great info. Thanks km and chacal for the help. i told him i didn't know if the 63.05 should be used because it's so close to the 63.10 wear limit which would require a 1st oversize (as chacal stated). Roughly how long (i know riding conditions are a factor) before he will need to one-up the bore? Thanks again.

Gary H.

 

About as many miles as the bike has on it now. Can you contact the seller to ask the mileage of the machine that the cylinders came from?

 

Good stuff, why I love this site!