Can anyone give me some advise/help on big bore kit?

[dekline34]

Howdy I'm new to the site. Just wondering if anyone can help me? I have an 81 xs650, I let a guy try and fix it and he screwed it up. While he was fixing it one of the valve springs came off and the valve shot down and shattered the piston. So the the top end is scratched up and pretty much useless now. The crank is still in good shape. I purchased a 82 xs650 special cylinder head off ebay that's in very good shape.I'm planning on ordering a big bore kit, cam chain and gasket set off mikesxs. My question is will all these parts I have work together and do I need to do/order anything else (parts) to complete this project? Any advice would help.

 

[petesxs]

No, that should do it, though you probably need new valves because your ends are probably mushroomed. You might want to get the oil seal kit while you're at it. Installation is straightforward. If I were doing it again, I'd buy the new cylinder/big bore piston set. It's a good deal.

 

[XSLeo]

Yes, all your parts will fit together.
The 750 kit is a straight forward swap. You pull off your head, cylinders and pistons. Install the new pistons, rings, cylinders, put the head back on.
New gaskets and such off course. Tearing your head down and lapping the valves and new valve seals is a good idea.
The head you bought, did you get it as a set, both the head and rocker box? or just a head? At the factory they machined the rocker box and head together and match numbered them. It's bets to use them as the numbered set. The cam bearing seats are line bored, the points and advancer housing seat are machined to gether, the same with the valve adjuster covers. If your lucky mismatching may work. It can cause oil leaks and possible cam bearing binding.

 

[dekline34]

Thanks for the input! Yes it's the whole top end head and rocker box. Just got it in the mail today and it's in good shape. I'm a novice to working on these bikes, learning as I go. A friend that works on bikes is helping me out with the project. I emailed mikesxs a question and they never responded maybe you can help me with this. When I go to install the new cam chain do I need that special tool that mikesxs has?

 

[XSLeo]

For peening the cam chain? I don't use one. I put the link together, use a large set of Vise grips to swell the pins enough so they side plate stays on while I back up the link with a 3 lb hammer and peen the pins with a 23 oz ball peen hammer.

 

[XSLeo]

Do you have a repair manual? If not you can download one from biker.net I like a hard copy version of the factory books. I have them that cover from 70 to 80, as wellas a Clymers book.
Any of them will be a good guideline. Any questions just ask.

 

[dekline34]

Yeah I have a Haynes manual. The original cam chain has been taken apart but is still in the crank. My friend that's helping said I needed a new one (cam chain) so he was wondering if I also need a special tool to put it on. I'm learning as I go so I'm asking alot of rookie questions. Thanks for the input!