Spitting and popping

[bazit]

Hi
I have recently purchased a GS 850 G (1980) which someone has replaced the standard igniter box with an after market (Boyer Bransden) ignition system and the bike will run fairly well on tick over but suffers when the revs rise and spits and pops .
Should I dump this kit and try to return it back to original?
Now before we go any further I should tell you that yes I have balanced the carbs yes I have checked the plugs are sparking and the gap is correct yes I have checked the compression and its 120 psi on all 4 cylinders,there are no air leaks on the inlet ,the carbs have been cleaned and float levels checked the exhaust is in good condition .
Basically I have checked everything that could be checked so I suspect the ignition /coil pack is becoming faulty at higher revs .
If any of you out there have this system installed on your bike let me know your thoughts .If any one has any other ideas I look forward to those answers.
Thanks
Barry

[tom203]

Probably would be more appropriate to have this problem in the "technical" forums. Consider deleting here and moving it.
Anyhow, how does the wiring look on this bike, especially the ignition circuit? A misfiring condition as revs go up can be challenging to find culprit. Sometimes the charging system voltage falls off as revs rise, making for poor ignition. Have you done the Quick Test in thise link ?

http://www.thegsresources.com/_forum/showthread.php?164993-Charging-System-QUICK-TEST/page2&p=1272192#post1272192

[bazit]

Hi
At the moment I have the clutch in bits (rattly) but will perform that test after I sort the clutch .With the lights on when you rev the bike they get a little bit brighter so if that's an indication to whether its charging or not is unclear but as soon as the clutch is done I will check out the charging.
Thanks
Barry

[busa1300]

If its the charging system, a helpful test to try would be to hook up a battery charger while it's running.
If you can adjust the rate of charge, bump it up if it still spits and pops...I found that the engine cleared out and ran perfectly fine on one of my projects this way, telling me it was electrical instead of carburetion.

[bazit]

popping Gs

If its the charging system, a helpful test to try would be to hook up a battery charger while it's running.
If you can adjust the rate of charge, bump it up if it still spits and pops...I found that the engine cleared out and ran perfectly fine on one of my projects this way, telling me it was electrical instead of carburetion.

Will try that after my rattle clutch cure.
Thanks