Update from Las Vegas

Hi everybody, I have been making some progress with my project, to restore my 82 Maxim 750. When I took the head and cylinder block off, I found the rings on #4 piston solidly stuck in their grooves, tonight I may have found out why... As I was removing the exhaust valves from the head, I found that on #4 there was a broken valve guide and no seal was found, at least not the rubber part or spring, so it's my theory is that some idiot broke it somehow, probably while trying to install the valve seal and just put it back together without telling anyone. In other news, I have purchased a media blasting rig from Harbor Freight but I don't yet have a compressor. I borrowed a friends, but it was just too small but I did find out that the rig works. Can anyone give me an idea as to what a machine shop might charge me to replace the valve guide? I don't suppose it could be that expensive.
Anyway, that's it for now, tomorrow I'll pull the intake valves. One last request, how does one remove the old valve seals?

 

Once you have the valves out. The valve seals should come out easily with a dental pic, or other sharp pointed object. Very similar to pulling the throttle shaft seals out of the carbs.

I have seen valve guide service postings on ebay in the $125-$150 range. Maybe check with MiCarl for what he would charge if you shipped the head to him.

Ghost

 

A broken valve guide with no oil seal would make the engine use oil and since it was an exhaust valve there would be pressure on the valve side of the guide making oil not run down the guide into the exhaust as easy as an intake valve. This would not have anything to do with stuck rings.
Stuck rings can happen from excessive carbon build up or corrosion from sitting too long or more than likely an overheated piston from running lean.
It's good you found these issues so they can be corrected. The valve guide is just press fit into the head. The only thing a machine shop would do to replace it would be to drive the old one out and reinstall the new one by driving it back in. They most likely would warm the head up when this was done so the metal would expand and they might freeze the guide with dry ice to have it shrink as much as possible when they drive it into the head. They also should clean and bead blast it and check to see if every thing else is good. A good shop would recommend a valve job and maybe mill a few thousands off to give you a nice flat surface for the head gasket to seal on.

 

Hi Guys, Ghost, what I found with the valve seals is not as simple as you think, the valve seals rubber part is bonded to a metal collar that fits over the valve guide, and it appears to be a press fit. I'll try a little heat from my mini torch and see if that loosens the grip. Thanks for the input Ghost, I suppose that price is for replacing all the guides. Howdy MN-Maxims! I used to reside in the twin cities, it's a pretty place, but I like Vegas much better. When I bought the bike from the PO he told me there was very bad blow-by, which means to me that the rings were already stuck when he acquired the bike. I'm not sure to what extent the lack of a valve seal contributed to the blow-by issue, but to confirm your suspicions, that cylinder was running lean.

 

Be sure to check your ring groove-to-ring "side" gaps; if the cylinder was running hot enough it may have distorted the piston itself and caused the ring grooves to close up. You may end up needing a new piston for that cylinder.

 

Good point Fitz, I had not thought of that, so I will check.

 

I attempted to remove a valve seal by using a pair of long reach needle-nose pliers, the attempt failed. No matter how I twisted and turned, it would not pull off the end of the valve guide. Anyone have any suggestions?

 

If you are going to have the guides done, Let the shop remove them when they do the guides. It should be part of the process.

Otherwise the 83 750 K service manual states to heat the head to 100*C (212*F) in an oven, and use a shouldered punch (yamaha special tool) to remove the valve seal.

Shadetree economy approach: use a propane, or butane torch to heat the seal. Then use the long reach pliers, or punch.

Ghost

 

Howdy Ghost, I thank you for your input, but you were mistaken about using a shouldered punch to drive out the valve seal, it's used to drive out the valve guide. But here's what I found out... the valve seal is held in place by a "ring bulge" of rubber that's inside of the metal band that is part of the seal, and it's this "bulge" that fits into a groove cut into the end of the valve guide. So as this rubber is now very firm from the heat and oil and the long time it's been in the engine, that's why they won't come out very easy. I have to modify my deep reach needle nose pliers so I can get a hold of the metal band. Then it's just a matter of prying the darn things off.