Hi All,
Having an issue with my 89 FXRP swingarm chop.
It was playing up a few months ago and it was the VOES hose to manifold that had come off.
I am running an Eliminator II SU Carby
The hose was refitted and all seemed fine but was getting a very occasional miss.
As this was getting worse and the plugs were showing it was running lean even with the mix screw adjusted almost fully.
Put a larger jet in and in all but the same throttle/RPM range it seems to be running better but now the miss and backfire appear worse.

My thoughts:

1. Not a problem at Idle
2. Not a problem when not under load (Higher RPM in neutral)
3. Only an issue in a small rev/throttle range. ie: At 95Kph (In Top) its fine just low Rpm,
   At around 98 Kph to about 105 Rpm its terrible, missing and backfiring, after that fine again.
   I rode it over 2000 Klm's like this by watching my Rpm in each gear and it got me home fine.
4. Not a fuel starvation issue, Petcock flows fine and no difference if cap loosened.
5. At time it smells like its running rich to mates behind me.
6. Running stock ignition.

I am thinking it's got to be Timing and/or VOES issues but I am no mechanic so was wondering if anyone has had similar before and what was needed to fix it.

 

I doubt that it is Ignition related...But... Maybe not getting to Full Advance...Maybe..More likely Carburetion.. tho, If Drag Pipes..We have Found yer Problem!!!

 

Running cocktail shakers on stock style header (no crossover)
SU Carby and have gone up a needle/jet size as seemed to be running lean. No real change. Still playing up in same Rev range.

 

I guess you need to start at Vacuum leaks..then, Maybe Ignition system...But...No Way I troubleshoot with That Carb... I do Not know enough about them, except to Avoid it For me.. I am more likely to make the Stock Ka-sneeze work properly.. But.. I never warmed up to them British carbs!! Even on My MG...
What Ignition are you Running??? Stock??