TOPIC:

Hi. Yes Ive stripped the carbs loads of times, I normaly spray brake cleaner through all the air and petrol ways then blow the cleaner fluid out with compressed air. Mind you some of the channels are so narrow its not suprising they get blocked.
I also notice with a closed throttle on the over run, it give like a popping or more uneven sound from the left side ( Ive got 3 into 1exhaust either side.
Will keep trying till its sorted.
Thanks again, Pete.

Pete

Popping on over-run can happen for a few reasons.

Mixture too rich (unburned fuel in exhaust).

Ignition timing out slightly (late spark).

Air getting into system around carb inlet rubbers.

Problem with the fuel recycling system (US models).

Hi Pete Ive just checked all the plugs and number 1 is running rich , guess what Im doing next weekend,,,
Cheers Pete.

Pete,

You definitely have 5 running well judging by the photo.!!
What is interesting is that only 1 plug is not ok.

As its only 1 cylinder it MUST be a problem with the following on that cylinder only.

Plug.
Plug Lead.
Compression on that cylinder (valves or rings).
Mixture screw issue on cylinder 1 0nly.

As it shares a carb with cylinder 2 & the carb only has 1 main jet, a fuel problem would affect both cylinders, not just 1 as it feeds them both equal quantities of fuel.
Maybe a good idea is to turn the mixture screw IN on that cylinder by 1/2 a turn & try from there.

My 6 mixture screws vary from 3.5 to 4.5 turns OUT once set up with a Gunsons Colourtune Plug so it maybe just fine adjustment you need.?

Pete F

Some other possibilities:


Weak spark?
Did a compression test/ leak-down test?

Ditto on what Strate6 states above on 3.5 to 4.5 turns out on the mixture screws.

Hi,
Yes Ive done a compression test and number 1cyl has about 145 psi which should be ok ( I think )
As for the spark, Ive swapped plugs/ leads/ and coils over still the same.
Will have a go at the mixture settings this weekend.
You can notice a lumpy sound, not a full on misfire though.

Cheers Pete.