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Discussion Starter · #1 ·
I will write the full story here, if you don't wanna read it go to the bottom where I list my problems.

When i bought this bike It ran well apart from an annoyingly high idle. I did a lot of work on it to sort it but didn't get anywhere. A while ago I bought a carb balancing kit and balanceed the carbs. Now it ran perfect. Everything worked fine except for a slight stutter at 7000, nothing big. I looked over things and found that one EXUp wire was frayed so I renewed them.
The bike now ran fine for a few weeks then suddenly my battery died. I exchanged it for a new one and things worked well except I had no rear light. I looked for the fault and found a wire had been snapped when I mounted my carbs. Don't ask me how cause I dont really know.
I fixed the wire and rode the bike. Ran perfect for 20 km then all of a sudden it refused to rev over 4000 rpm. Since I had heard about this I went home and adjusted the EXUP. Still 4000. Adjusted again, 4000. Screamed very loud while looking angrily at the EXUP, ran well for ten minutes, then 4000.
This annoyed me a lot so I removed the wires and tested the servo but found no fault with it. But when I rev the bike the valve only moves about 20 degrees, not the full 90 degrees it should. The valve moves fine, I have lubed it and can move it with my fingers. The wires move smoothly and the EXUP valve centers itself as it shall on ignition. I have also tried switching the wires over just to check but it doesnt make any difference.
Now I have removed the wires and fixed the Valve open thinking this will fix the problem but now I have a new one. The bike Bogs down at 7000 rpm. It runs great from bottom up til 7000 then totally loses grunt and barely continues to rev. Past 8000 it howls nicely.
I have tried changing out the fuel line, put new plugs in and cleaned all electrical contacts but no difference.
I'm gonna put another set of carbs on and see if theres any difference as i have a spare set but I really dont think that will do anything.
Need help.

Summary:

With EXUP valve connected will only rev to 4000 rpm.

Without EXUP connected will run into a wall at 7000 rpm.
 

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sorry for my bad English, but he is translating the computer.
if you disconnect the valve EXUP gives you heror the cdi, and not go to 7000 laps.
you have to disconnect the wires from the valve.
but the valve, you have to leave open the butt, because otherwise the bike will drown.:thumbup
 

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Discussion Starter · #3 ·
I have disconnected the Exup wires but not the servo itself so it is not the error code problem. I have had it before so i know its not that.
But thanks anyways.
 

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The problem with it running into a wall sounds exactly the same as my GPX600/Zephyr project. I ran that with pod filters and rejetted it, but it was running really rich in the midrange.

I would rev to about 6500 revs then it would bog down. Change down a gear to get the revs to 7500 and she would fly again.

If the needles have been fiddled with, try leaning them off 1 notch on the needle and see if that makes any difference.

As I said my experience was with a kwak not a yam so if anyone knows differently then feel free to correct me.
 

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Discussion Starter · #5 ·
I haven't touched the carbs after the balancing which resulted in it running really well. But it sure feels like a carb problem when I ride it.
I did however empty the tank and then refill it since the diaphragm in the fuel tap had decided to not work any more. Maybe some dirt has been caught in the carbs?
 

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Discussion Starter · #6 ·
I think I found the problem. When i pulled the carbs apart in a fit of rage I noticed that there were lots of small white debris in all the float chambers. I cleaned them out and blew everything clean with an air jet and now it runs smoothly.
Gonna try it proper tomorrow unless it rains, again.
I think the debris came from my Quick-connector. Hope there's no more.
 

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Discussion Starter · #7 ·
Still runs like shit at 6500-8000. I am getting pretty annoyed as I have to go down two gears to get some drive when passing slow drivers.

I noticed the diaphragm in the fuel tap doesn't stop gas from flowing when the engine is off. Will this affect engine performance? I hardly think so but still. I can just remove the diaphragm ans its seating if that would solve the issue.
 
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