Topic: Popping at idle

[6adan]

  I have a popping on my 750 after warm up, 4 into 1, K and N air filter in stock airbox. This seems to have started or gotten more notesable after going from 91 to 87 Oct gas. Any ideas ? Thanks Dannie

[TwoTired]

Is the poping from intake or exhaust (or knees) ?

Lower octane fuel burns a bit hotter, more aggressively (ignites at a lower temperature, faster flame front travel) than the higher octane.

When was your last complete tune up?

Has the jetting been changed since the 4 into 1 change?  What carb set up are you running?

Cheers,

[6adan]

 Popping from exhaust( knees pop also but different sound)

  New plugs about 500 mi. timing and valves about 1000.

  Jetting is stock for 1970 750.

  Needles had been set at second from top, I moved to center but that did not seem to help

 If you think a tune up would do it ,I will do it. Thanks again Dannie

[TwoTired]

Ok, Exhaust poping...

Is this on Decelleration?

Are your pipe-to-head gaskets leaking?  Or, any leaks in the exhaust that would let in oxygen to ignite a fuel rich environment in the pipes?

What do the deposits look like on the plugs?  Compare yours to:
http://www.dansmc.com/Spark_Plugs/Spark_Plugs_catalog.html

Let us know...

Cheers,