Threaded inserts for cylinder head bolts?
 

Hello,

I have put excessive torque on the long M8 bolts of the cylinder head of a 1989 (1VJ) and the thread of the holes in the cylinder is damaged.
I planned to repair with a helicoil solution, but on the German XT 600 forum I read this is not a good solution.
An alternative would be to use threaded insert with een external M12 thread and internal M8. But there is such a small amount of material around the hole that I doubt this is a good solution.

Any experience with this problem and the solution is very welcome.

Guy

I take it you have stripped the thread in the barrel....

Your only solution is to remove the barrel from the bike... and unless you are a decent mechanic/engineer yourself, take it down to an engineers workshop or engine specialist and have them drill out and insert a "TIMESERT" into the barrel.

Helicoils work but they are not 100% reliable on something as important as those big M8's holding your topend together.

Don't stress though, it shouldnt cost too much.. Maybe £20-£30

If there is not enough metal in the barrel then you will need to replace it... simples !

I can do that!
 

Easy!

YouTube - Time-Sert thread repair

XT Girls on YouTube
 

are you sure?..... I've seen your mechanical exploits on You Tube.......

There is nothing wrong in using Helicoil for this type of application. Just use long ones preferably two in each stud hole.

Pawlie

Thanks for the rplies and advice.

On the German XT 600 forum several people have put messages that helicoils are not a good solution for this application. I don't know if this is from experience or engineering judgement. Do some of you have experience using helicoils to repair the treated holes for the cilinder head bolts .

A 12 mm insert would be the strongest solution but I fear there is not enough material around the holes.

Guy

It does work....
 

I've done a couple of sets of barrels studs for ther 1VJ and a helicoil style insert does work (personally, i use recoils, but they're very similar in principle).

The stud hole needs to ber bored and threaded to full depth - a standard recoil insert gives (from memory) about 8 turns, which isn't nearly enough. I use long inserts, and 2 per hole, so it's threaded all the way down.

I also use some thread lock on the threads, as the german forum is of the opinion that the studs can loosen off if they've been coiled.

I had a similar problem on my XR600 Honda and had the holes helicoiled (by a reputable engineering co in Kegworth). All six of them subsequently stripped again. Eventually I had them redone by another company with custom made inserts similar to Time-Serts and that seems to have worked.

Thanks for all advise.
There seem to be different kind of experiences with a helicoil type repair.
After many measurements I still fear holes for 12 mm inserts would leave too little material.
So I decides to make studs with M10 at one end and M8 at the other. I will have to install them before mounting the cilinder head. This must be a good solution, ... I think.
If anyone discovers I overlooked a possible problem please tell me ASAP.

Guy

Stripped Threads on 1VJ Barrel
 

Revisiting an old issue here: my old 1VJ motor had several stripped threads on the head when I got it including at least one of the M8 cylinder head bolts. I stripped out the top end and helicoiled the lot, including double length ones on the 2 right hand (not cam chain side!) M8 bolts.
The front one has now stripped and pulled the whole helicoil out - down to my heavy hand I guess!!

So what is the best way forward? This old thread rightly identifies the lack of meat around that hole and I worry that a Timesert type repair will not have sufficient material to properly support it.

Something like this needs an 11.4mm hole drilling.
Uni-Thread. Thread Repair. Baerfix. Metric. Boxed Kits

Has anyone successfully used an insert to effect this repair? If yes, what type and what OD was the insert? And if not, what?

PS - I know that fitting a 3AJ motor/top end is the full solution, but I'd quite like to save these parts if poss!

there's a much simpler way.... hint? the 660 uses M9 and M10 studs.....

just go with a bigger bolt, you might save it with just the right sized tap. dont use coarse thread though. That's what we semi old timers used to do back in the days when helicoils were high tech.

Saved plenty of seemingly "no way out" situations with them.

but for god's sake, people! use a torque wrench too!

agreed. done this couple times when I had to pay for some overtorquing sins of previous owner of my bike.
2 upper bolts on oil filter cap (some extra welding was involved here iot strengthen walls) and some more on valve cover. used M8 instead stripped M6 both times.

:mchappy: