OK, I have a 93 evo that Idles perfectly.

Anything above idle it coughs and farts and backfires from both the exhaust and carb. Im at my wits end. These are the things ive checked:

-new plugs and leads

-checked voltage from rotor and stator 14.8v above idle with brand new battery

-checked for manifold leaks with aero start

-checked the coil, tried another spare I had too

-checked wiring

-swapped ignition switch

-swapped circuit breaker

It has a daytona twintec ignition, im just about ready to rip it all out and get some points fort it haha

any help at all will be appreiciated cheers

Carbie problem would be my guess. Something sticking or getting jammed when you're trying to rev.

Blocked main jet.

Hey Bruss, does your carb piston rise when increasing the revs (presuming original cv carb still fitted), most likely carb related like the guys have said. If the pistons moves up and down when changing revs (bike in neutral, carefull of eyebrows if bike backfires ) drop the carb float bowl and give the jets a squirt of air, or remove carby and remove and clean jets and passages with compressed air. If the piston isn't really moving up and down with revs you most likely have a hole in the piston diaphragm and need to replace the piston assembly.

cheers
DocGreen

I recently had similar problems with my evo, dyna ig, S@S carby, earth on VOES was loose.

 

Seeing you've checked the manifold for leaks with aero start I would say your voes hose is good seeing it's in That area and if you had a leak the engine would have sniffed the aerostat forshore And shouldn't affect free rev that much
Under load yes there just a on off switch at certain hg vacuum but cover your self put a blanking plug on the manifold and disconnect the wire and try it thinking carb also

By the way do a intro before some one says  who the fuck are you lol  or the forum police get you ??

Thanks fellas,

Ill check out the Voes and the carby in the morning (its an S&S E series) I suppose it could be the diaphragm in the voes too? I clamped the hose the other day for the voes and I don't remember a huge difference in revs

sounds like ign unit, but i would clean out da fuel tank &cock & fuel bowl check fuel level & back blow jets esp da idle , before you look anywere , then change ign system for a check , i just thro a set of pionts in & time it & see what happens one step @ a time

Sorry for the late feedback fellas, I checked the voes, all good. Cleaned the carb, changed the jets, checked float level and orings. 

BASTARD STILL DID IT !!! I swore a bit and caught my breath (kick start only) and grabbed a set of old shovel points I had, threw a good points coil on it and timed it.............. Fired it up. STILL DID IT!!! 

Gonna run a wire from the battery next to bypass the ignition harness. But if that fails I'll probably self harm 

Nothing more "fun" than a bike problem that could be multiple things... We've all been there, so don't give up.

accelerator pump on S@S can bind up and cause similar symptoms.

Yeah I checked that too, when I had the bowl off, I operated the pushrod and it was squirting pretty good 

Mate, have you drained the tank and got fresh fuel? You may have got a shit batch of fuel.

Good you kick start!

I don't think excellerator  pump as i ran and older S&S kick start only that never came with excellerator pump  flew did standing Quarter in 11.6 & road everywhere & interstate  have you got circut breakers or fuses? also excellerator pump just masks a lean  spot but the S&S not designed to open up quick you roll throtle CV you can open up quick.