TOPIC:

Ok

Picture this after months of getting stuffed around with machining and parts getting lost in the mail and then realising i have some wrong parts i am finally bolting my engine together, i torque all the head studs in order and then go onto the two bots that are at the front and back of the head in the cam chain gallery when the unthinkable happens. the front hole strips clean out (no i didnt over tighten it i was using a torque wrench).

Now i really dont want to take the head back off so i can helicoil the hole as i dont like the chances of finding another new 810 head gasket in Australia and even if i did, paying a reasonable price (bike shops over here are theives)

what im thinking is take the bottom of the hole off in the barrels so that is is a straight through.

Then geta bolt long enough, 2 copper washers and a domed nut(for asthetics) and bolt it all down with maybe a bit of sealant on the washers for good measure. only problem i can forsee is that the standard bolt has a narrow section on it, why is this?

can anyone see any problems with my idea

i would be interested to hear your thoughts.

Post edited by: Jay_G, at: 2006/11/28 03:09

g,day jay from another ossie on this site
what model are we talking mate ? and yeah bike shops are rougues all right

Gt750 (Kz750-P1)

pretty much has a shaft drive gpz motor in it and i have put a wiseco 810 kit in it.

Hi Jay,
an English guy (machinist by trade) living in California here. Depending on whether you have clearance between the top of your head and any upper frame tubes, you might consider making a guide block for a helicoil tap. This would simply be a block that would sit flat on the surface you want to tap. It has a hole through it that just barely clears the tap major diameter. You would have to hold the guide block down flat on the surface to keep the tap going in nice and square. If you don't have clearance, you are going to have to remove the head to have it helicoiled(if I'm following where the stripped thread is.)
Best of luck mate!
Grant.

Personally, I'd take the head back off and helicoil the hole in the block, then assembled it with the same head gasket.

g'day Jay,

which end of Oz are you from, I live side closest to Madagascar and have a couple of P3's. I'll have a look at a stripped engine (got 2 of 'em, can never have enough) but I am sure the shoulder relief on those two bolts do not accommodate oilways. Safest way around it is to get a longer high tensile bolt and machine the waist at the appropriate spot, then do what you first suggested and open the hole out squaring off the exit point to a flat, use a dowty seal under the nut to ensure a seal.

cheers

Popeye

Wow, interesting fix going on here! If you haven't run the engine since you installed the head gasket, I think it will be just fine, if you want to take the head off for a helicoil.
OTOH, I used to be a machinist at a Navy shipyard, and did all kinds of stuff like this, and I think your idea would work. But if you machine a narrow section into a hardened bolt, it will be weaker. I'm not familiar with the insides of these engines or where the oil galleries are, but I am familiar with aircraft engines, and they have a lot of bolts with narrowed sections, but they're not for oil passages. It has more to do with thermal expansion. The aluminum heads and cylinders swell up when it's heated. This causes the holes in the aluminum to swell tighter. The narrowed sections of the bolts allow for this expansion. Plus steel holds heat much longer than aluminum. The aluminum would have to work a lot harder at dispelling engine heat if there was that much contact with the steel bolts.
Instead of machining down a a hardened bolt, consider just using a smaller diameter (high tensile) bolt and nut, and maybe easing off of the torque wrench a bit.

Good luck!

Post edited by: riverroad, at: 2006/11/28 09:57