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]

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.

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.

[saxby]

 thought about it over night . and i had anouthere go at trying to re bore the threads the right way.
as long as i didnt lock the spark plug in there  i had nothing to louse as  the outhere 2 options were to get a new head or  send it away ..
after takeing my time back and forth using oil and  cleaning the plug and the hole up i have it all the way in and squire . my onley woury is that the  tiney aloy bits in there might do some damage . im hopeing that when i fire it up they will just get spat out  and not damage any thing . what do you think.?

[matthewmosse]

Had a friend with the same problem, He used a vacume cleaner to suck out any bits before giving his luck a go. I think it paid off.
Good luck!