Suzuki bandit 1200 W reg missing under load, will rev freely on its stand,I'm getting sooted plugs, tried new plugs,new air filter, carbs balanced, jets to lean.Also had petrol in the oil on 01 occasion.

When a engine is cold the revs should be higher ( choke on ) but nit going up and down. If you release the accelerator and the engine still rev's up maybe the accelerator cables are not properly installed on the carbs. Also a air leak is possible. Check the cables and air leaks at manifold including the holes from manifold where vacuum gauges should insert when carb calibration is necessary. Those holes should have some caps on.

did you change the carb jets to match the k&n's and exhaust, do the k&n's get wet, restricting air flow

Check Diaphragms in carbs and inlet manifolds for leaks. More likely to be manifolds. Good luck, I hope this helps.

Ride the bike 20 or so miles on open road. Stop and remove plug to inspect. 'Are they black or white ?


Black =rich white=lean

What about your carb, fuel filter and air filter?

A chance of plugs may solve this problem or a new air cleaner .

yes this is the problem i had the same thing withe the bandit i had

hi buddy on my bike i had this problem when you rev it it will rev down gradually so it changed the jets and ir worked so try this buddy then get back to me give me a good rating

as you have replaced carbs you will need to retune for fuel intake also check its getting enough air ie.. air filter has been changed or is clogged

Sounds the pilot passages and or the needl jet air passages are blocked on the carb for that cylinder that is not fireing. The carb should be removed from the bike and disassembled and dipped in carb cleaner. What I think works best for cleaning carb is Yamaha's Carb Dip I mix it 50/50 with warm water. All the rubber parts must be removed as they will be swell and be damaged by the dip. After you dip the carb will need to verify all passages with spray carb clean to make sure the fluid will make it through the intended passage.