CDH polygon head

[Spare_Parts]

I thought I remembered you going quite large with it, but after taking forever to find on page 111 32.9mm is dead on the money for a max size elliptical exhaust port. Did you stretch it out to look like a football? Not being a wise guy, just don't want to see any dents in the chamber of that new head.

It's more squared off with flay sides and a taper at the top. Also has a decent radius going from the sides to the bottom. Also radius from the port to the cylinder wall. It doesn't look that way in any pictures though. That shape has been working better for me as far as performance goes. The first broken ring was at the transfer port and never did find the cause. IIRC that was also a stock ring. Been getting pistons from MZ for a while now and can't help but wonder if there is a defect in the rings or if they are insalled incorrectly. Not blaming them just wonder if any of that could be the culprit.

 

[gary55]

It's more squared off with flay sides and a taper at the top. Also has a decent radius going from the sides to the bottom. Also radius from the port to the cylinder wall. It doesn't look that way in any pictures though. That shape has been working better for me as far as performance goes. The first broken ring was at the transfer port and never did find the cause. IIRC that was also a stock ring. Been getting pistons from MZ for a while now and can't help but wonder if there is a defect in the rings or if they are insalled incorrectly. Not blaming them just wonder if any of that could be the culprit.

I know the feeling. We do everything we can think of or read about trying to make everything work right, but sometimes s**t just happens. Could be a defective ring. Could be that damned Murphy. I have never tried it, but I don't think you would be able to get the piston in if the rings were installed wrong. I think the entended ends that go under the locating pins would hit the pins and make it like a fat man in a little coat.

 

[Spare_Parts]

I know the feeling. We do everything we can think of or read about trying to make everything work right, but sometimes sh*t just happens. Could be a defective ring. Could be that damned Murphy. I have never tried it, but I don't think you would be able to get the piston in if the rings were installed wrong. I think the entended ends that go under the locating pins would hit the pins and make it like a fat man in a little coat.

I meant maybe they used ring pliers and opened them up to much or twisted them lol.

 

[Spare_Parts]

First post updated.

Use NGK BxS. Fill in the x with 5,6 or 7. This head takes a 3/8 reach plug.