Stripped plug hole

[Mello]

I collected a reasonable looking, if a little tatty / dirty, bike last week. She hadn't run in a while but we got her started and I rode her home. Thankfully all on the highway so not much braking was required (luckily all easily fixed). The bike hadn't been serviced in around 5 years but had only be ridden a handful of times. First task was checking the stoppers and a basic service prior to giving the carbs a go.

Plug number 3 was a bit of a battle to get out (I found taking the tank off makes this much easier!). The threads had seized by the looks of things and bits of metal came out with the plug. I tried to ignore what I'd seen and hoped the new plug would go in ok. Well, it did but would not tighten and I didn't want to make it worse. The rest went in ok.

I rode the bike the next morning (Friday) and stopped by a local bike shop that had been recommended by a mate. They specialise on old Japanese bikes and had done a good job with the carbs on his CB750. Left the bike there and asked them to see what they thought about the plug issue and to sort the carbs out.

The question is this: what is the recommended / satisfactory way to fix the stripped threads? The bike guy reckons helicoils are not the way to go and that welding the hole up and retapping is the way to go. Expensive and will take quite a while as the head would need to be removed. I found a thread here where helicoils were used with
The engine in situ and it seemed to be ok?

Pic of the offending plug attached.

Cheers,
Mike

[tevan]

Helicoil it. I have done it several times. Did you try to retap it first with grease on the tap to get the metal shavings?? I would try rethread first.

[Mello]

I didn't try tap it but perhaps that is the way to go. I was worried about the filings but the grease is a good tip. I'm loathe to have the head taken off as it means a long time before I get the bike back.

[EMS]

I am not sure, if it is available where you are, but there are special thread reapair inserts for spark plug holes. I used one of them on my 1970 Mercedes 280SL quite a few years ago. They also require tapping and I did use grease to make sure the chips would not go into the combustion chamber. Removing the head is the safer way to go and actually not THAT much of a deal.
The inserts are solid steel sleeves with an outside and inside thread and a small collar to make them sit against the top face of the plug hole.

Welcome at the ICOA forum, Mello!

[Jeff Bennetts]

TimeSert's are a great and permeant repair.

http://www.timesert.com/html/sparkplug.html

[NobleHops]

TimeSert's are a great and permeant repair.

http://www.timesert.com/html/sparkplug.html

I used a Timesert to repair an oil drain thread in the sump of my V Strom. The kits aren't cheap but once you use one you will never worry about that repair again. As I think of it I also used one on top left upper engine mount on the CBX when some asshole* stripped it because he over-torqued it.

Timeserts FTW, but there is a lot of drilling involved with installing one, and I wouldn't chance it with the head on. Following that link though they say it can be done that way.




(*me)

[steve murdoch icoa #5322]

Nils, that same asshole worked on my top, left, upper engine mount as well.
He does get around.

[kbart1]

I had the same problem on my '81, same cylinder as well. I used a metric "thread chaser" with some grease loaded up on it as well, to try and catch any cuttings. plug tightens down firm now but I wouldn't put too much torque to it. so far so good. I tried one of those "expanding" thread repair tools and it was a complete piece of crap! save your money! actually got out for a little ride on both sat and sun last weekend on the X! pray for warmer weather

thanks!
kent

[NobleHops]

Nils, that same asshole worked on my top, left, upper engine mount as well.
He does get around.

HAHAHAHA!

That guy's a dick!

[Mello]

TimeSert's are a great and permeant repair.

http://www.timesert.com/html/sparkplug.html

Well, would you believe that my brother in law distributes this product here? Just found that out. Anyway, he recommends helicoils and doing it with engine in situ, so will go with that. Will let you guys know how it turns out.

[Mello]

The hole has been "Helicoiled". Thanks for the advice. The BIL suggested I go with the Helicoil and recomended a mobile fitment guy. I wasn't there when he did the job but sounds like he knew what he was doing.

Now for the carbs. Hopefully she will be ticking over sweetly by the weekend.

Then the other bits and cosmetics can get attention.

[steve murdoch icoa #5322]

Glad to hear it got sorted, Mello.

Did i read this right? Your bil sells Timesert but recommended the Helicoil.
I am surprised, did he give the reason?

[Mello]

Sorry Steve, he actually does both but suggested the Helicoil as he supplies the guy who inserted the coil in my bike and knows the quality of his work. Both the helicoil and timeserts are relatively cheap but the tools to cut and insert are expensive, particularly for a one off job. I will ask him but assume that the helicoils are more well known here.