I've posted this query on some bike forums, but haven't met any satisfactory responses. So I thought I'd try the intelligencia of BC.
It's a very simple problem, I just want to know where to start looking for the cause... basically I have a desmodromic V-twin engined FI bike which is backfiring into the airbox sometimes when the engine is up to temp. when I blip the throttle for downshifts and moving away from stationary. It's not causing any other problems but is rather annoying and I would like to get the engine running properly again.
I'm pretty sure it's only 1 cylinder that's acting up, my thoughts on what it could be are:
1. Dodgy mixture in 1 cylinder - possible causes:
- TPS needs adjusting
- Throttle bodies need balancing
- One of the ECU sensors misbehaving
- Sticky injector
2. Dodgy inlet valve clearance in 1 cylinder
3. I think that although 1 cylinder is right out in the airstream, and the other is tucked away between my legs, they both use exactly the same map, which, therefore must be an approximation. Could the backfire here just be the result of one cylinder being much cooler than the other?
Any suggestions about what could be causing this problem, and/or how to test out these hypotheses is much appreciated...
Edited by - charlie_pank on 27 Aug 2004 13:01:47