compression 110-0-0-0

[tcoop]

Looks like I need to rebuild my top end. I believe that I have three bent valves.

If I am pulling the head should I pull the jugs off and replace teh rings also or can I just leave them aloan and Just repair the valves?

I've cracked the case open on two XJ750 but this will be my first top end rebuild. Any advice would be appriciated.

[bikerphil]

New rings are $$$ so that's your call. How many miles on the motor?

[tcoop]

There is about 32000 on the motor. I am trying to do this on the cheap side. What would I look for to know that I definitely need to change them?

[bikerphil]

32K you're probably fine. Unless there was a lot of oil consumption, no way of really knowing until you take it apart and check clearances. Normal compression is 142 + - 10% with throttle wide open. You're 110 reading could be low if the engine has been sitting for some time, but it will probably normal out after running some. If you do tear it down to do the rings, beware that the jugs can be a real bear to remove sometimes, the base gasket won't give loose. If it was my engine, I'd leave the rings alone. For sure change all your valve seals when the head is off.

[dbeardslee]

What would I look for to know that I definitely need to change them?

You have to pull the head first anyway, so it makes sense to check that first. If you put each valve in a drill press, and spin it very slowly, you'll see immediately if they're bent - even a little bit. You can also turn the head upside down with the cams out (being careful that the buckets and shims don't fall out - they can be secured with a piece of coat hanger wound around the cam shaft cap studs, and routed over the top of each shim/bucket), and pour gas into the top of each cylinder. If you see the gas disappear rapidly on 2,3, and 4 that would be a pretty clear indication it's the valves. It's a lot more likely than rings suddenly going bad on three cylinders. If it jumped the timing at some point, it would almost certainly bend a bunch. Put me down for a +1 on leave the jugs alone.

[tcoop]

thanks for the replies.I think I will leave the jugs and the rings alone. where a good place to get valve seals and valves?

[Elevener]

http://www.xs11.com/forum/showthread.php?t=26876

Might try andreashweiss for used ones.

[dbeardslee]

Partsnmore or georgefix have gasket kits with the stem seals in them. There are more gaskets in the kits than you need, but it's still the cheapest way to go. You'll need a head gasket (in the kit), stem seals (in the kit), and possibly a new valve cover gasket (also in the kit). Might check how much adjustment is left in your cam chain tensioner as it's an opportune time to replace the cam chain as well. You'll also need a cam chain breaking/riveting tool whether you replace the chain or not. You might be able to slide the cams out and get the head off without one, but it's a whole lot easier with the tool. Probably want to get some lapping sticks and some valve lapping compound too so you can lap the new valves in.

[79XS11F]

Before you take the head off the engine .. have you confirmed proper valve clearance adjustment. It would be a shame to pull the head only to discover that the PO had the valve clearances set wrong.
Rob