Won't rev all the way

[Pomp1]

As per title..
bike picks up fine and strong, get's to a good 4K and then just stop climbing. Checked the Kokusan (Cheers Dirty) I get a good spark and carburation is (only) a bit on the rich side. Any suggestions?

[Rally]

We were talking on this subject tonight about my bike. It will hit the rev limiter in the first five gears, but not 6th. I need the extra speed on the way over the mountain! :D

[Pomp1]

Oh zip it Alun or that Termi may get filled with [fill in blank]:Furious:;)

[manwithredbike]

restriction in the air filter or main jets. last time i had those symptoms, it was restriction in the exhaust, -- a clogged baffle. (not the monster but a single cylinder trials bike.)

[Pomp1]

Main jets are new as are the carbs. No baffles on the Conti. Filter is on a heavy drilled lid. Cheers for the suggestions, keep 'em coming guys

[Rally]

Max, I had those symptoms on a bike many years ago and after chasing everywhere possible, it turned to be a faulty coil that didn't perform the same at higher revs. It wasn't a Duke, but it may be worth swopping with another just in case?

As said on a previous post, maybe its my pipe causing my issue as one is partially blocked. Thank you.

[Nickj]

So it might be ignition related, but if you are being pedantic first you ought to check the carb float height. I'd probably not bother.

Then onto the coils and then the ignition units.
One of the coils might have failed so swapping them out won't do much to help. If you can borrow another to try out it will rule out these as a problem.
Which brings us to the ignition units, these are pretty dumb objects that just step the ignition timing as revs rise. From experience with an electronic rev counter they also seem to change the pulse width at about 4K which might be a significant point.
If one has failed then at 4k one pot will be running a bit retarded, the other normal. This could well make it hard for the motor to rev out.
If it is this then it would be worth looking at replacing with a more sophisticated unit like ignition tec rather than standard.

[Sirc]

it's worth checking the fuel tank air breather just to cross it off the list.

[Pomp1]

So it might be ignition related, but if you are being pedantic first you ought to check the carb float height. I'd probably not bother.

Then onto the coils and then the ignition units.
One of the coils might have failed so swapping them out won't do much to help. If you can borrow another to try out it will rule out these as a problem.
Which brings us to the ignition units, these are pretty dumb objects that just step the ignition timing as revs rise. From experience with an electronic rev counter they also seem to change the pulse width at about 4K which might be a significant point.
If one has failed then at 4k one pot will be running a bit retarded, the other normal. This could well make it hard for the motor to rev out.
If it is this then it would be worth looking at replacing with a more sophisticated unit like ignition tec rather than standard.

CDI units have been swapped for sound ones, this are not solving. I'm considering however a ignitech.
Coils seem to give a healthy spark, will try swap them..
What about the pick ups? in my experience this would show a backfire when failing, which I haven't..

[Pomp1]

it's worth checking the fuel tank air breather just to cross it off the list.

will try, but I've blown the lines recently..

[DrD]

What about the pick ups? in my experience this would show a backfire when failing, which I haven't..
The ones on my M900 failed a year or so ago...checked out fine when cold.
Failed to rev once hot...confirmed by taking the multimeter out on a ride!

[gary tompkins]

If you are sure the fuelling is ok then my money would be on something HT related

Does it backfire or stutter at all when it hits 4k?

[Pomp1]

The ones on my M900 failed a year or so ago...checked out fine when cold.
Failed to rev once hot...confirmed by taking the multimeter out on a ride!

And what were the symptoms please?

[Pomp1]

If you are sure the fuelling is ok then my money would be on something HT related

Does it backfire or stutter at all when it hits 4k?

No backfiring, but yes, judders and stutters. You can tell she wants to rev but something stops her..

[gary tompkins]

My suggestion would be to substitute all ignition related parts (coils. igniters, pickups) for known good spares to try to isolate fault.

It could even be something as simple as a spark plug, cap or lead breaking down under load.

What jets sizes are you running for the 944 kit?

[Pomp1]

My suggestion would be to substitute all ignition related parts (coils. igniters, pickups) for known good spares to try to isolate fault.

It could even be something as simple as a spark plug, cap or lead breaking down under load.

What jets sizes are you running for the 944 kit?

Yep, that would next step.
I have 175 Mikunis mains which equate to 185 dynojet, 42.5 pilots and needle on 5th from top

[S4Rs MacK]

Max. My suggestion is to man up and twist the throttle properly to the stop. Use some muscles man. Hahaha.

[Saint aka ML]

If you have transparent fuel filter observe fuel level if it drops to dry.

Check pickups I think it was 180ohms? Does it rev at idle over 4k or not at all?

When you swapped the ignition did you accidentally swap cables coming from pickups?

[Dirty]

Did you get to the bottom of this yet?

[Pomp1]

Did you get to the bottom of this yet?

Getting there, will post up details once I've finalised them. Swapped coils and pickups to no avail but reducing main jet size helped a bit, but now sounds like wanting more, so maybe need an in-between size. On the lookout for a AF gauge at the moment..

[urbanfireblade]

If it revs up ok on idle i'd look at ignition-plugs, leads and coils. Check the connecting wires on the coils are good and ht leads are wound in tight to the coil and cap. Is it lumpy at idle? Mine ran on 1 cylinder and rev counter stopped working and it refused to rev after a dismantle to adjust carb needle heights, turned out i knocked off the single wire connector off the bottom of a coil.
Is it possible belt(s) could be 1 tooth out? Do the pulley marks line up or there abouts?

[gary tompkins]

I did ask Paul Critcher what his High comp 944 was running on Sunday.

The bike was set up on a dyno by Protwins when conversion was done, so he has no idea what jets it runs unless he strips carbs down.

[Pomp1]

Timing is fine and as said all ignition parts have been swapped/checked. I'm leaning more toward fuelling, but with an engine that isn't strictly standard is trial and error stuff. Will get there in the end and I'll have learned a lot in the mean time :)

[Pomp1]

I did ask Paul Critcher what his High comp 944 was running on Sunday.

The bike was set up on a dyno by Protwins when conversion was done, so he has no idea what jets it runs unless he strips carbs down.

1 hour and I'll have all done ;)