Can't get rid of the "pop"

Not open for further replies.
Jan 8, 2006
Hi All

I wonder if anyone has any ideas about what may be the issue with my 850, it will accelerate without hesitation and generally runs well. The issue I have is that at fixed throttle constant speed, say 100 kph, the bike occasionally "pops" or hesitates very briefly every 2 seconds or so.

Any help appreciated.
Kill switch need some cleaning? Ignition power interrupted by bad ground or bad point wire. If I knew you had a Boyer I would be saying check the connection of the wires down were they hook on to the plate that replaced your points. It's all guessing till you elaborate on your battery condition, Carb and ignition type,state of the wiring and so on. A coil, switch, or a frayed wire could be the problem.If your running a stock harness you may just have the first of many broken female bullet connectors.
If it's doing it every two seconds, that's not a pop it's a bloody misfire Mate ! :D

The cause is probably leanness. Are the carbs standard ? If nothing's been changed and there are no external air leaks then the favourite has to be wear in the carbs.

Does the problem only occur on a constant throttle opening and not on a 'rising' throttle ?
Thx for the replies, Yes only at constant throttle, any other time no probs. Bike has done 26K miles, would carbs be an issue that quickly?

All standard gear including boxy air filter, checked all connections etc and all looks good.
Can't get rid of the pop

Assuming your carbs are the original Mk1 Concentrics I'd say that they've done very well to last 26K - many 'dip-out' at around 10K.
Since it is happening at steady throttle opening, check that you haven't lost a needle clip or bent a needle. That will definitely cause the symptoms you describe. DAMHIK!

As the other posts suggest, this is symptomatic of wear induced leaness.

One way to see if it is, is to up the carby needles so that the clip is on the LOWEST of the 3 grooves. This lifts the needle up a bit higher in the needle jet and may compensate for the slide / body wear.

Run the bike up the Tulla for a good few miles on a quite day preferably before the weather gets any warmer and see if the popping is better.

Bloody amazing your Amals have done 26K, I'd be ready for the 3rd set after inserting new needles and jets in the 2nd set!

I tried everything including pulling carbs to bits and still no response. After pulling plug leads at 3000 revs I noticed the miss seemed to be in the left cylinder so thought I would swap the slides and needles to the opposite carb and see if the problem migrated with the change, ie, the miss moved to the right.

Well, the miss went away completely, I took the bike for a run ...........PERFECT! no miss at all, running like a charm.

It's running well so I aint touching it, as the yanks would say ...Go Figure?........

Thanks for the replies guys, fixed by default!
Not open for further replies.