high rpm miss

[edgo]

I've got a breakup at high rpms in all gears, I'm guessing at 6k and above rpms, my tach sucks. It starts with a little choke and it idles fine and chugs around at 2K rpms very smoothly. The pilot circuit seems good. It revs freely in neutral all the way to redline. When it's on the road in 5th gear in gets rough at 70mph. It will slowly climb but is very sluggish and rough like it is running out of gas. My carbs are stock 79sf and I went to 140 mains with pod filters and 4 into 2 Jardens. It did this with 137.5 mains too. Float height is 25mm.

What do I check next?

Thanks,
Ed

[Ken Talbot]

Pull the plugs and tell us what you see....

[GNEPIG]

.. hello Ed, have you tried removing the pod filters and going for a ride to see what happens?.. also you might want to check the fuel filters on your fuel valves, on these old bikes sometimes stuff can plug them up and cause a low fuel flow.. there are also little fuel screens on top of the needles and seats in the float bowl, i just remove those and put in in line fuel filters

[petejw]

If the break down is occurring under load,
check out ur spark plug leads.


pete

[edgo]

I cleaned the carbs but didn't clean those screens. I'll do that next and I have a spare set of coils with new wires installed. So I guess I'm on the right track, I just need yet another weekend.

Thanks,
Ed

[chevy45412001]

filters

i had the same prob. turned out being fuel filters were pretty dirty. Or not able to flow enough fuel to supply the higher rpm's.Just a thought.

[edgo]

Thanks. My first thought when it did this was that it was starving for fuel. I'll check it out.

Ed

[pggg]

Mmmm... restricted fuel filters.. heh heh.. say no more..

[edgo]

My wife wants to know why would I need the bike to go over 80mph.

Ed

[Ken Talbot]

Tell her need has nothing to do with it!

[jimboreeno]

Tell her, "It's to enhance my safe riding. In case I am next to a semi and it begins to merge into my lane, and there is another semi right behind me so I can't slow quickly."
We must be able to make sure we are safe when we ride...musn't we??

[xj11john]

jimboreeno

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Tell her, "It's to enhance my safe riding. In case I am next to a semi and it begins to merge into my lane, and there is another semi right behind me so I can't slow quickly."
We must be able to make sure we are safe when we ride...musn't we??
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Hmmm. good one I'll have to store that one in the deep dark recesses of my cranium

[cueball]

By asking the question, she is already letting you know that she would not understand the answer.

[xj11john]

Edgo,

Heres a tech tip that may help.

http://www.xs11.com/forum/showthread...=&threadid=145

Here one part that several have had happen concering the gas cap. #3.

1. Try moving the pet-cocks to the reserve and prime positions.
2. Try experimenting with the carb enricher (choke) lever.
3. Try opening your gas tank (if the vent gets plugged you will experience gas starvation)

[edgo]

I put the new coils with new wires in it and the miss was still there. I then raised up the floats to richen it up and I took off the pod filters. The miss comes and goes now as I play with the petcocks so I think it is still starving for fuel.

I like the pod filters and don't want to put the airbox back on. Where can I get some that won't choke the bike?

When it gets fuel it really gets up and goes. My floats are at about one inch now whick is a little over 26mm. I don't have a metric caliper. Should I go up a bit more on the floats or go to 142 main jets?

Ed