chuffing at idle?

[focus frenzy]

working on the 80 1100E project bike and steadily fixing issues.

I got it back together and running and at idle there is a very clear and loud enough "chuffing" noise coming from the intake side of #2 cylinder.

my first thought was a leak in the intake boot but the carb cleaner test had no effect on RPM or running so no leak there.

I pulled the cam cover to check for stuck valve and could find nothing wrong, a couple valves were slightly below spec. but none stuck open and a adjustment of all valves has no effect on the chuffing.

this is where it gets confusing.

with cover off and engine cranking over, ignition disabled. the "chuff" noise happens at the point the #2 cylinder intake is coming off the lobe.

first thought is twisted crank but the noise is only coming from #2

???????????

[Steve]

Have you done a compression check? Almost sounds like a burnt valve.

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[focus frenzy]

Have you done a compression check? Almost sounds like a burnt valve.

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I was leaning that way but the fact that the noise happens as the intake valves are closing and it stops when it comes off the lobe throws that off.

[Steve]

Well, if you think about it, "when the intake valve is closing" is when the piston is on its way up, compressing the mixture.
There might be a small burned area that happens to get sealed when the valve is completely closed.

Hate to say it, but it might be worth it to pull the head. 8-[

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