Originally Posted by GearNut
Yes. Almost every motorcycle I have worked on that had a flange mount (bolt on) carburetor and manifold, with the exception of the Honda CT70, had a brown or black heat insulator in between the cylinder and intake manifold.
It is there to help prevent heat transfer from the cylinder to the carburetor.
An intake gasket by itself will not block the heat transfer, soooo.....
I am thinking of making one for my little beastie.
I was thinking the same thing, but something like ceramic.
I am also wondering if using the NGK BPR7
HIX Iridium IX plug might be the cause. It has the most heat transfer from the cylinder to the head I could find, which seemed to make sense considering my extreme heat riding conditions this time of year and usually always running the motor (via gears) in the top 1/3 of the RPM power band.
Then again maybe I am running too lean now, I'll pull the plug and check it, then just pop in a stock LD Z8C and Z4JC plugs and see how it runs.
Don't you hate it when more than one condition has changed when a problem occurs?
In my case a different plug heat rating, a different oil and gas/oil mix, and the ambient temperature is ridiculously hot to start with.
One thing is for sure, it sure as heck performs like a full race motor until it gets hot.
0-30 in a heratbeat, and much faster than I typically want to ride.