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    Rebuild needed?

    Hey everyone, earlier this summer I picked up a '78 Gs550. It was blowing white smoke out of the cylinder 1&2 pipe. This was due to a broken fuel needle tip. First thing I did was a compression test, all the cylinders got ~125 psi. I put a new needle in it and cleaned up the carbs. It ran, but not super well. It wouldn't rev out very well and struggled to go up hill. I then adjusted the air screw, changed my valve shims, and synced the carbs. It still doesn't run properly. It revs out better, but still struggles up hills. And now it blows blue smoke out the 3&4 pipe when decelerating and burns more oil than it should. I pulled the spark plugs this morning, they were a brown color. Not golden brown, but not dark black. What should I do?

    Edit: While taking the spark plugs out, I looked in cylinders 1&2 ( I didn't think to look in 3&4... not sure why) both piston tops were relatively clean for having 27,000 miles.
    Last edited by Mr.Vroom; 08-21-2023, 04:12 PM.
    1980 Gs250T- Passed from father to son, also my first build.

    #2
    You might have bad intake exhaust stem seals, that's sucking oil in and giving you the blue smoke. With the compression you quoted, there isn't much else it could be. You adjusted the valves, now change all the valve stem seals, and see what happens. This seems like it may be a new development. Oil won't come from the carbs, though the other problems you mentioned could be carb related. The oil cab only be a few things, and since you have strong compression, that leaves the valve train. IMHO

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