I was wondering if anyone could shed any light on my latest quandary:
I've recently rebuilt the engine in this 79'GS550 (oversized pistons/bored out cylinders (not by me) /serviced cam chain tensioner / reseated valves, adjusted shims), and it's been running well, but I've only done around 20-30 miles since rebuilding it.
One of the remaining problems was I had a spark plug that had gone in threaded and wouldn't come back out. So I asked in my local and very helpful bike shop, and he said the guy that did my cylinder boring could get the plug out without taking the engine apart. He's a machinist who works with bits of older car and motorcycle engines, and came recommended by a few people.
So I took the bike round to him, and he said he could get the plug out, so he had a go at it. Using a breaker bar the plug snapped. So he said he was going to drill it out. I was concerned about what would happen to the debris and he said that he would blow it out with his pressure blower. So he did that. And installed a new insert and blew it out and put a new plug in, whilst I went to get some lunch.
When I returned he got me to start it up. The bike started and ran, but there was a little tinking sort of noise that sounded a lot like a bit of debris in the chamber. So he stopped it and took the plug off and put an endoscope in there and couldn't see anything. He then started turning the engine manually by the kickstart (I'm not sure why) and after a few turns it got jammed. It wasn't completely jammed, it would go forward or back about a 1/4 turn at the big nut. The pistons all moved this amount, and he said 1 & 4 were turning from just before to just past TDC, which indicated they weren't hitting anything.
He couldn't figure out what was up with it and was proposing to get a mechanic in who deals more with whole vehicles in the morning.
I'm wondering if anyone here has any ideas about what might be causing the seizure?
Thanks in advance.
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