Topic: cm250c (rebel) with a stripped spark plug hole...

[cbr-eric]

I have the spark plug hole and it is now mostly smooth... now it has tiny plugs in it now, wondering what anyone would do in this situation... It is actually too small a plug to get a heli-coil, already tried that route.  so I am now thinking that maybe I can get a plug with the same depth and heat range and maybe just a physically bigger plug, then drill and tap for the increased size?  anyone have any better ideas, or maybe you have tried the same thing with sucess?? any help or ideas would be great, thanks guys!  Eric

[Tim.]

Have you done a valve job recently?  Might be the time to find a donor head and freshen up the valves while you're at it

[cbr-eric]

it has like 9k miles on it and runs great, or it did...

[fuzzybutt]

heli-coil, i did one on a friends escort when the plug hole stripped years ago. it's still together.

[RRRToolSolutions]

Jeff is 100% - have those threads replaced with a helicoil. You can do a google search and find video showing the process. They make kits just for the sparkplug threads.

Regards,
Gordon

[fuzzybutt]

very easy to do too, goop the drill and tap up real good with lots of grease to keep shavings out of the cylinder and you might not have to even pull the head. worked out ok for the job i did.

[cbr-eric]

I know they work great, but they actually dont make a heli coil for the size and thread pitch of these plugs, went to fastenall and checked. the guy even called all his distributors. any other ideas?

[cbr-eric]

here aer the specs on the plugs it has now..
http://sparkplugs.com/more_info.asp?otherMotiveID=225032&pid=3259

[cbr-eric]

now I am thinking they were wrong...  anyone know if this kit would work?
http://www.tooldiscounter.com/ItemDisplay.cfm?lookup=HEL5523-10
is the plug I have a 10mmx1.0?  or is the only way to check to take it to my local hardware store and have them check it for me?  thanks guys, really want to get the wifes bike back on the road!

[cbr-eric]

anyone? bueller??

[Frankenkit]

As long as the diameter and thread pitch are right, I don't see how it wouldn't work.

[mark]

Spark plug thread is 10X1.0mm

I would not recommend trying to tap the hole with the head on. All it takes is one little chip or nugget of carbon to really chew up a piston... and/or cylinder. There isn't much room in there.... having the piston down for tap clearance may open a valve..... tap may hit open valve and bend it. seen it happen.

best of luck.

[cbr-eric]

thanks on both points!

[Frankenkit]

Oh, and I agree 100% with Mark. Some people will tell you it can be done with enough grease. This is probably true, if you do it REALLY slowly and clean out EVERY little bit as you go, but then... you'll never really know if you got them all.

...and you'll keep thinking about it at 3am...

anyway, it's not worth the self-induced paranoia.