Super Jet Coffman 650 manifold on 61x cylinder

[kawa js550]

I know that you have to port match the maifold to the cylinder, but I also heard that you might have to drill the bolt holes bigger on the manifold because the 701 cylinders use bigger manifold bolts. Is that true for the 61x cylinder and the 62t cylinder, or just the 62t cylinder?

 

[Quinc]

62t and 64x use M10 bolts. 61x uses M8.

You can either drill out the manifold bolts or put m8x1.25 heli-coils in. Do the heli-coils, you will need them in the two top bolt holes anyway.

 

[Storbeck]

If you're putting a 650 manifold on a 61x cylinder you won't have the issue with bolt size, they're both m8. I don't know if the book pattern is the same (I think it is but I'm not sure) and the shape of the port is definitely different. I'm not sure if you can just "port" the manifold to match. Be careful to make sure you have enough surface area for the gasket to seal. Leaky exhaust gaskets are no fun.

 

[john zigler]

The exhaust runners are smaller are smaller on a 650 manifold. I would NOT just port match it, as it is not enough.

They are rare, and I am sure you could get good money for it. I would sell it and get the correct 701 manifold. You will make more power.