sparkplug

Well, make sure its the right plug (obvious, I know, but its gotta be said). Then, if it is the proper plug, check the threads on both the plug AND the cylinder head. If the plug threads are a little off, try a new plug. If the problem persists, check the threads on the cylinder head VERY closely. If they are indeed stripped, dont sweat it. Its an easy fix. A helicoil is a cheap solution that will fix you right up. Also, another easy, but more expensive option, is a new cylinder head. A helicoil will usually do the trick though.

Good luck!

Oh, and I meant to add, if you ride a LONG time, but dont pull your plug very often, the pressure can throw your threads out of whack. Pretty common

A helicoil is an insert that makes it possible for you to re thread a spark plug. Its pretty simple actually, you just retap the hole and isert the helicoil insert (sort of).

Here is an article that explains the whole process. This article is about one done on a car spark plug, but the procedure is identical.

http://www.popularmechanics.com/automotive/how_to/4212608.html

Before you go the helicoil route you might want to try just "chasing" the threads. They are essentially a tap but intended for cleaning up threads rather than cutting new so they are not as robust. They are also a lot cheaper than a full fledged tap, you should be able to find one for about $10. Apply oil to the chaser to any metal shavings stick to the oil and you can get away with doing it on the bike.

After you have chased the threads the result is a bit weaker than it was before. If the threads weren't too bad it will probably be fine but if the threads were badly mangled then you might not have enough material to hold the plug and it might blow out.

The Helicoil, which is a much better fix, you can do yourself if you have the basic tools and skill set. You will need to drill a hole the right size, so you may have to buy a drill bit. You can buy the Helicoil kit that will come with everything else you need, but the kit has some expense to it. Basically, you drill the hole out to larger size, then tap it. The helicoil is a thin cylinder that has a larger thread on the outside and the desired thread on the inside. The outer threads get coated with Locktite so it won't just come out next time you pull the plug.

I always like to invest in tools as I may need them again some day. As a result I have a lot of tools laying around for some day. Occasionally I do use one, however.

If you are looking at just this one occurrence you might be better off taking it to a shop. You should be able to call a shop and get a price quote. You will want to take the cylinder head off, however. While you have the top end half torn down you might as well pull the cylinder and do the top end.


Rod

I agree, I would just do the top end since you have it apart anyway. You should have no trouble doing it yourself. Its a pretty simple procedure.

will0203 said:

is bad for me to leave the spark plug out of my bike for a couple weeks

Click to expand...

No, not at all. As long as its stored inside, or somewhere warm and dry. Plug the hole though, with a rag or something, just to make sure nothing falls into the cylinder.

Are you sure the threads are damaged? Other than you are having trouble getting it started. Was the new plug damaged, does the old plug go back in? What kind of bike?

Then dont bother re-doing it. Another idea, is to just bring the cylinder head into a shop and just ask them to tell you if the threads need work. Im sure they wont charge for an opinion!

Did you try the old plug?