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Oil burner engine rebuild help

motogtp

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I have '78 SS with 6,100 miles. After cussing at the carbs I found out it was burning oil (see pictures). Before I put it back together I would like to get input from the forum. There is some black smudge on the pistons but it is coming off pretty easily with carb cleaner and plastic putty knife (#21). Little bit at the top of the cylinders as well. Can I use emery cloth to remove any stubborn smudges at the top of the cylinder or do I need to hone the cylinders?

Rings are clean and seem to be in good shape (#26). I see no evidence of any blow by so I am not planning on replacing them. Cylinders are in good shape, you can still faintly see the honing cross hatch marks (#18). Valves appear to be in good shape and tightly closed. I don't have the valve springs off yet but I am betting that the seals are what was leaking. I am guessing this thing sat for a long time and they dried out and/or cracked. Does the darker discoloration on the valves tell me anything (#19)?

One last question. Do I replace the valve guides while I am at this point? Even if there is no excessive valve stem play? I don't want to spend a ton on this bike but I also don't want to rebuild it again in another 6,000 miles. Thanks.
 

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I would hone and put new rings in it. Do you really want to be this far apart and put it back together with old rings??? I would bet the rings are low on tension from being overheated....looks like a scuff spot on the piston skirt? As far as the guides you need to check the valve stem play once you get the springs off and go from there. Exhaust is by far the worst for wear. If they are tight and in spec dont replace them as then you will have to do a valve job after the guides are replaced.
 
I agree with digger, I would never put old rings back into a engine thats torn down. You should also think about replaceing the cam chain roller yours looks pretty rough.
 
Since you taking the valve springs out, wouldn't hurt to lap the valves. It's pretty easy and cheap, plus you can check if you have a good seal. New valve guide seals too if your gasket kit didn't come with them.

Like everyone said, I'f you've gone this far, might as well put it back together right.
 
All great advice guys. I will get rings and a gasket kit (I think it has valve seals in the kit) on the way from CycleX. Once I have the valves out and spec'd I will decide whether to order the CycleX valve/guide/spring kit. I assume that once I put in new valves I will have to get the valve seats machined to match? Or just lap them? A friend gave me the number of a mechanic that does cycle motor mechanics on the side. I am going to call him tomorrow to see if he can help me get it back together clean, right, and tight.
 
Yup I mentioned above you have to do a valve job after guide replacement. Guide replacement is not really a do it your self type of thing unless you have done it before. It is easy to ruin the head if you dont R&R the guides correctly. You might want to consider sending you head off to APE or Cycle X. There prices may seem high but believe me by the time you order the parts and run around having the machine work etc done you would be money ahead having them do it. $700 gets you a perfect rebuilt head from APE and they do the best job in the business and specialize in the F2 head. If your local guy doesn't normally do the older Japanese bikes I would stay away...these are not just a Harley motor...the guides are picky and the seat cutting needs to be very close or you will have issues. IMO If you were closer I would consider doing the head for you as I just did my F2 head with my new tools but I am not confident enough in my technique yet to consider doing someone elses head. Plus I wouldn't have time to get to it until the snow starts to fly again LOL You can PM me if you have any motor questions you may have.
 
Thanks DD. I did a valve leak test this PM. No leakage. So I am hoping the guides are good, that would make things easier. The local guy primarily does BMW's but has done a bunch of Japanese fours. At this point it looks like: hone, clean, rings, valve seals, a new chain tensioner, and then put it back together. I will make a final plan once the valve springs are out.
 
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