'81 Engine rebuild question

[dmschuler]

'81 XS650. blew a hole in one of the pistons. I have new jugs & pistons. I'm sending the jugs & head to the shop for decking & a valve job.

Today when I removed the oil filter I found the other pieces of the piston. Am I throwing good money after bad if I don't rebuild the lower end? I wonder how much damage was done to the bearings after the piston went.

So, should I take the plunge and do an entire rebuild?

Thanks!

 

[littlebill31]

Honestly, if you have that in the filter, it means it went all through the case. If you are going to put money into it, without doing the bottom end, then you are, in my opinion, throwing it away. Those little pieces go everywhere!!! Do it all, do it right, do it once. It really sucks doing all this work and either, 1) wondering if it's gonna blow due to other things you didn't check. or 2) it blowing because of things you didn't check. Piece of mind is worth the money.

 

[member3480]

If the motor has more than 10,000 miles on it do the bottom end . Do it right the first time. You can have a piece down there somewhere that you can't see and you could do more damage. If you want to chance it pull the sump and put it into a cleaning tank and flush it good. But me i would rebuild it.

 

[dmschuler]

Full rebuild it is. I don't want to chance it.

It's amazing how many little pieces there are floating around in there. The fact the the filter had a tear in it didn't help matters either.

 

[gggGary]

The filter always has a tear in it. Unless you bought the bike from me... I'd craigslist for an engine, see what comes up. You should be able to find an engine for 150 or less that has never fragged a piston. I'm not close to you but have 4 or five engines on the bench right now that would be better rebuild candidates than what you have. Unless you are going super stock numbers matching doesn't matter. I have one fragged piston engine, it is going to be my mock up engine (no guts) less weight to handle.

OK after all that I reread the first post holing a piston is not ha same as fragging it. Still used engines aren't that rare in the North. Specially in tough title states like New York.

 

[dmschuler]

So are the filters just cheap, or is it that they don't normally get changed for 20+ years, or is it the piston pieces that ripped the filter?

I've been watching craigslist. There have been a few, but they go quick!

 

[gggGary]

I think there is an oil jet that sprays on and tears the filter. I weld a sheet metal cover over that part of the filter clean it and reinstall it. there are several different ways to cover up the section that tears. For the engine, try posting a "Yamaha XS650 engine needed" ad in motorcycles. That type ad has worked for me many times.

 

[5twins]

There's a guy in our area buying up all the 650s and 650 stuff. That's probably why you're having a hard time snagging a motor. Look in the classifieds here for a guy called Motrhedd. Check the Buffalo Craigslist as well. He usually has a 650 parts ad running. He bought over 20 in the last few months so I'm sure he has a motor to sell.

Technically, the filter doesn't blow out, it blows in. The feed hole going to the oil pump is located at that end near the spot that tears. Pressure or suction is greatest there. The screen isn't pleated in this spot so it's weaker. The new "improved" filters suffer from weakness in the same area. They have a perforated steel sheet backing up the screen everywhere except in the spot that tears. They're improved everywhere but where they need it most.

 

[member3480]

I buy from him his a nice guy with good prices. There are a lot up in that area and he buys to sell. I know of another guy up that way too who buys but he just throws the stuff outside on his farm and it turns to junk in 6 months. I went there and he had a 1969 Honda CB 750 cast bike that is worth over $10,000 sitting in the weeds. If you sell you need to research what you are buying. But Motor head is a good guy. He is always looking for frames for me.