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1000 cc Honda..9mm headbolts? helicoil....

M

moonlight machine

Diamond
Joined
Nov 19, 2007
Location
marysville ohio
A friend road races this thing, 1000cc Honda MC. he had the head off for whatever. when he put it back on it leaked coolant. So he changed the gasket and it leaked again. then he brought it to me thinking the head was warped, can I machine it? The straight edge says it is flat so I look a bit closer. it has helicoils in the head bolt holes. The helicoils are all balled up on the bottom of some of the holes. The head bolts are hitting this mess before they tighten against the head. I guess when He torqued the head the helicoil turned in the head instead of the bolt turning in the helicoil. A bit of anti seize on the headbolts would probably solve this problem. I got 1 helicoil out, not much fun as they are about 1" below the deck. Now here's the problem, where do you get 9x1.25 helicoils? not from McMaster Carr. They must be available somewhere. Does Honda offer them as a repair for stripped headbolt holes? My local dealer is closed till Mon., I guess I'll check with them then. Does anyone know?
 
That's a really oddball size, for sure. Did you measure the O.D. of the bolts to come up with that? If you're right, I think you're probably going to have to source the inserts from Honda.
 
PixMan said:
That's a really oddball size, for sure. Did you measure the O.D. of the bolts to come up with that? If you're right, I think you're probably going to have to source the inserts from Honda.
Click to expand...

I pretty much know how to measure a bolt after doing this sort of thing for 35 years. just to make sure I was not temporarily insane I tried a 8 mm die......no go.......10mm die.....loose as hell.....I know the size does not exist.... it is still 9 mmx1.25.....
 
Thanks Limy, I had a Re Coil kit, 1/4 20. I got it when I was racing in Australia. I did an Internet search for that brand of insert about 2 minutes before I saw your post and found "Newman Tools" is also a distributor in the U.S. I will check on Monday, I hope one or the other has that odd size in stock.
 
My pleasure moonlight ,.......... depending on your shall we say ''point of view'' on such matters;) - stripped 9mm will helicoil at 3/8 unc or unf nicely,............. if you go unf 2xD inserts work nicely in aluminum.
 
Japanese manufacturers seem to like 9mm bolts.... I have a 3 cylinder Kubota diesel motor..It has 9mm head bolts...One snapped off, and they are only available from Kubota...

I piece of 4140 turned to size worked well...
 
moonlight machine said:
The helicoils are all balled up on the bottom of some of the holes. The head bolts are hitting this mess before they tighten against the head. I guess when He torqued the head the helicoil turned in the head instead of the bolt turning in the helicoil.
Click to expand...

I have come across this problem before, at first I could not figure out why the bolt had grabbed the helicoil until I removed the damaged insert & ran a helicoil tap down to clean the thread, some arse had managed to tap the thread at an angle :rolleyes5:.....only solution was to set the crank case up on the mill, tap square to larger size & make up a bronze insert.

regards

Brian

Edited to add:
M9 x 1.25 is indeed quite common on Japanese motorcycles for both cylinder head & main bearing bolts. M7 x 1.00 is another "unusual" size that turns up quite regularly.

The Timesert kits that Don mentioned are very good but considerably more expensive than Helicoil / Recoil kits & inserts, being a solid insert they are probably a little more "foolproof".
They are not always suitable for counterbored threads however as the insert is shouldered.
 
pistonskirt said:
more expensive than Helicoil / Recoil kits & inserts, being a solid insert they are probably a little more "foolproof".
They are not always suitable for counterbored threads however as the insert is shouldered.
Click to expand...


I'm not sure what you mean... but the shoulder is recessed flush (or deeper if desired) by the reamer that comes with the kit. I use timeserts for many engine aluminum/ magnesium repairs - nothing beats them. They were orginal developed for repairs to structural components in helicopters.
 
Lakeside53 said:
I'm not sure what you mean... but the shoulder is recessed flush (or deeper if desired) by the reamer that comes with the kit. I use timeserts for many engine aluminum/ magnesium repairs - nothing beats them. They were orginal developed for repairs to structural components in helicopters.
Click to expand...

They are indeed excellent, I have been using them since Wurth first introduced them over here probably 20 odd years ago, I have them in most sizes commonly found in my work but hold the same size range in Helicoils.
Where a threaded hole in a casting is counterbored for a thin walled locating dowel the shoulder on the Timesert is often larger diameter than the dowel, so one would have to turn down the Timeserts shoulder & not use the recessing tool (without turning that down as well) which then makes it very difficult to hold the Timesert at required fitted depth when the locking/form tap is used. A Helicoil can usually be fitted without compromising the dowels counterbore.

regards

Brian
 
Why not just drill them out to 10.8mm and fit M12 x 1.25 bolts? You'll benefit from fresh threads and increased clamping on the race engine.
 
i have uced keenserts like a solid helicoil with great succes on aluminum engines also might want to consider studding if the motor is torn down often to refresh ARP bolts can make or may have something that will work if you fill out there measurement sheet very they're reasonable and work with small order promptly
 
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