2tg maxing out at 4000 revs

[vlas]

2tg with 40mm dellortos. when im driving and put my foot to the floor the engine only revs till 4000 then stays there and struggles to move up to 5000.

[river]

Hi,

How high can it rev in neutral?

seeyuzz
river

[w810sc]

Have had this problem on numerous occasions all being a different fault at the time, all sounds like it's miss firing.
- aggressive cam timing causing the valves to just hit the pistons, not enough to bend them though. It would rev fine neutral but once you start to load up the motor it wouldn't rev past 4krpm.
- ignition coil/igniter faulty and wrong ignition timing.
- carby sucked Ramflo type sponge air filter in one of the runners.
- fuel pressure.

[vlas]

in neutral it goes past with easy it only seams to happen when i am driving it i advanced the timing a slight bit and it seems to help it slightly. i have noticed that when i put my foot 3/4 of the way down the pedal it goes over 4k with easy. only seems to happen when foot is flat to the floor. im thinking that it may be my vacuum advance isnt working when i am driving.

2tg is stock and fuel pressure is set at 2.5psi

[w810sc]

compare the angle of the butterflies when your on 3/4 throttle to when you pedal is flat to the floor. When your foot is flat to the floor you could be pulling the butterflies past it's horizontal position and closing it.

[AAAAGZE]

loose main jet in carby possibly.

Sounds identical to what was happening in my 2tg with twin solex. tightened jet, problem gone.

loosened again a few hundred kays later, loctite =win