Need Some Exhaust Fabrication Suggestions

The previous owner had stripped out all of the exhaust studs, so he heli-coiled every hole. The problem is, he drilled and heli-coiled at the wrong angle so the heat sink (light blue) doesn't press against the keepers (red) that keep the exhaust pipe (green) against the exhaust port (gray).

The arrows in purple are the angle which the holes were supposed to be drilled :dry:

Any suggestions on how I could fix this? I would say that I could possible just shim the "low" side, but these holes are also not even centered on the port so that the shims do not line up with the bevel in the heat sink.

Pic...

If you know the exact angle needed you could machine some soft aluminum spacers at the right angle to mate up to the head and then the pipes mate to the spacers.

Might be cheaper (and easier) just to get a new (used) head on ebay (unless your current head is "special" ).

Assuming this is a 900 head from your avatar...
You may be able to use the larger 8mm hole heatsinks from a 1000. The 900's had 6mm studs. It's hard to tell from your drawing, but if the distance between the blue line and purple line is 1mm or less, measured at the thickness of the heatsink, it might work. The studs will be crooked and off center in the heatsink, but it's a cheap solution.

This might be a stupid suggestion as I am not an engineer and I am only looking it from a laymans point of view...

but...

Could you get an engineer to make up some new studs bend at the right angle. Screw them into the head and leave them so they are all facing down at the correct angle.

Just tell me if I am stupid. I can take it!!!

Fergie wrote:

This might be a stupid suggestion as I am not an engineer and I am only looking it from a laymans point of view...

but...

Could you get an engineer to make up some new studs bend at the right angle. Screw them into the head and leave them so they are all facing down at the correct angle.

Just tell me if I am stupid. I can take it!!!

Your not stupid. :laugh:

Its possible, but I would just weld ne studs in place and attach my exhaust as if it were stock.

Super easy.

Could have a machine shop remove the heli-coils, aluminum weld-fill the holes, re-drill at correct angle and depth, and tap for 6mm or 8mm studs.

Or, before tossing the head, might try this zany idea, which likely violates a plethora of metallurgy rules:

Remove heli-coils with heli-coil extraction tool.
(Allows later re-drill and tap without having to cut through steel)

Install brass bolts where the heli-coils were located.
Cut bolts flush with head.

Re-drill at correct angle and depth, and tap for 6mm or 8mm studs.

Good Fortune!

Skyman wrote:

Might be cheaper (and easier) just to get a new (used) head on ebay (unless your current head is "special" ).

I was amazed when a dismantler quoted about $200 for a good used head for my KZ750 including valves, cams, valve covers, lifters, etc.

Patton wrote:

Could have a machine shop remove the heli-coils, aluminum weld-fill the holes, re-drill at correct angle and depth, and tap for 6mm or 8mm studs.

Or, before tossing the head, might try this zany idea, which likely violates a plethora of metallurgy rules:

Remove heli-coils with heli-coil extraction tool.
(Allows later re-drill and tap without having to cut through steel)

Install brass bolts where the heli-coils were located.
Cut bolts flush with head.

Re-drill at correct angle and depth, and tap for 6mm or 8mm studs.

Good Fortune!

You know, as crazy as it sounds, there is no reason it would not work.

Pull the inserts, thread aluminum rod (NOT BRASS) to fill in taped holes, make a jig for a drill press to hold things at the right angle ,re drill and tap.

Something to think about if you have time and a drill press.

It sounds like the head is NOT doing you any good the way it is, so why not play with it.