Recently joined this forum after using lots of the great materials to help restore my 1977 Suzuki GS750DB, UK model, with double front disks. Quite pleased with the results, see attached photo, although I can't get the bike to run properly, and am not sure where to go next!
When I bought the bike, the engine ran OK, although I could not run it on the road to test it for any length of time. The engine has had the following done to it:-
- rebored, new pistons and rings, so compression OK
- carbs cleaned and restored by local bike restoration company
- fitted Dyna electronic ignition
- running standard airbox and filter, standard exhausts
- using original coils and leads, as seem in good condition
- fitted new genuine Suzuki fuel petcock
Once reassembled, the bike started easily and ran OK, if a little lumpy. I have since:-
- static timed the ignition (yet to do this with a timing light)
- adjusted float heights and checked jets (fuel was overflowing)
- fitted two sets of B8ES plugs
- checked for spark. Is good on all cylinders when tested with new plugs
- set pilot air screws to 1 turn out
But the engine won't run properly!
- When plugs are new, it starts on choke OK, and comes off choke after about 1 minute.
- With a new set of plugs, it seemed to run and idle quite sweetly for a short while.
- Plugs seem to get fouled after a while (black carbon, not wet fuel) and bike starts to misfire
- Get's so bad, bike won't run properly, or start properly. Have done about 3-4 miles on the road with new plugs before the symptoms become too bad to ride.
- It doesn't appear to affect specific cylinders, they are all much the same
It seems like the bike is running rich, but not sure why. Was thinking of trying it withour air filter element, and also stripping carbs to adjust pilot fuel jets. Don't think it's running suffering any air leaks, but hard to prove that. But not sure what else it could be....
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