SOHC.co.uk Forums > CB500/550
spark plug screwed up / problem
saxby:
have had the bike running on all 4 cylinders after i got it . but no on the re build i can see a problem ...
the spark plug in the first cylinder is in at a slight angle and not screwed in all the way .. i take it out and can see its been put in at a fu**ed up angle . and has crossed the threads . it was only in about 25% of the threading on the spark plug .. i have tryed to screw it back in on what looks straight tightening up a half turn and a quarter back trying to bore back on the original threads .its as tight as i dare go. but only in about 60% - 70% still .. and my worry is that small alloy filings are now siting in the cylinder ...
any ideas ?
*should i just keep an eye out on ebay for a top end ,and do a top end re build?
* or just fire it up and ignore it
SteveD CB500K0:
If the spark plug has been x-threaded, there's no alternative to a helicoil I'm afraid. The internal pressure will blow out any bodged fitting (and you may be correct about swarf in the cylinder).
So, head off I'm afraid.
You can try a used one but how can you be sure that what you're getting is going to be any good?
Best bet is a local breaker or someone on here who has a spare head.
GeoffT in the Orkneys was looking for a 550 head recently. I have a complete 550 engine but shipping it up there would be prohibitive.
saxby:
--- Quote from: SteveD CB500F on March 09, 2008, 04:00:12 PM ---If the spark plug has been x-threaded, there's no alternative to a helicoil I'm afraid. The internal pressure will blow out any bodged fitting (and you may be correct about swarf in the cylinder).
So, head off I'm afraid.
You can try a used one but how can you be sure that what you're getting is going to be any good?
Best bet is a local breaker or someone on here who has a spare head.
GeoffT in the Orkneys was looking for a 550 head recently. I have a complete 550 engine but shipping it up there would be prohibitive.
--- End quote ---
seen one on ebay item no 110231895640
says it needs work but will cost 20 inc shiping
dont realy know about this sort of thing ..
dont know what a helicoil is . im guesing that i will need to take it in some were ..
as for your engine . i live in cardiff at the moment . but do trips back home to hull and manchester a lot . the bike is never going to be a show winner and has been altered in a lot of ways so i am looking at the cheapest option ..
SteveD CB500K0:
I've been talking to the guy on eBay. He's in S Wales. I wanted some gearbox bits but the postage was just too much (
SteveD CB500K0:
A helicoil is a threaded insert. It has to be done by an engineering company but is the only way to fix buggered threads on spark plugs.
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