Hi Guys,


Has anyone ever identified induction bias on a v-twin where one cylinder always gets more fuel than the other? I have experienced it on old BSA vertical twins that I have restored. They actually make a gasket to balance the flow with a small diverter piece on it.


I have been chasing a lean condition on my front cylinder. I fixed a small leak at the manifold and have checked the VOES hose and switch for leakage (the manifold fitting is biased to the front). I have checked all of the other items identified in other posts.


The issue is a light pinging in the front cylinder under even moderate acceleration. I am running with the timing retarded a little and on premium fuel. The plug shows a very small "blister" at the tip of the ceramic. Bore scoping shows nothing out of the ordinary. Leak down and compression tests were great! I did find a "crack?" in the intake tract from one of the intake manifold threaded mounting points down into the head intake tract. Is that just a casting parting line? Couldn't get a good picture of it.


I did install an EV-27 cam, 190 main jet and 48 slow speed jet. A 195 main was too big. The 190 is a little rich under WOT. The adjustable needle had already been set to compensate for the screaming eagle exhaust and K&N air filter by the P.O.. The pinging started after my previously mentioned mods.


I guess the next move is the needle to get a richer mid-range. I have read some bad opinions on the adjustable needle. The needle for a 1988 Sportster is identified as a good replacement?


Sorry for taking everyone down this well traveled road.......


Seabee

 

The front plug always looks lighter than the rear plug.

 

The rear cylinder on a carbed v-twin always runs a tad richer and a tad hotter than the front...being little richer is actually good since the cylinder is hotter...not enough difference to cause a problem...definitely not the root cause of your pinging.