Ok Folks I have a Carb problem.

I was doing a carb synch and the bike ran out of Petrol. No biggie as I just didn't have enough in my little tank.

I synched the carbs to all within about 5mm of each other. idles well.

But ever since when the throttle is between 1700rpm and 3000rpm is stutters like it is running out of fuel!

Got me stuffed what I could have done or bumped even.

Spark - Fine. Even replaced the plugs just in case.
Vacuum Leaks - Did the spray test around all the joints and no problems.
Can't be a blockage as I recently overhauled the carbs and cleaned out the petrol tank.
Tried running a bit of Toluene through just in case and no different.
Valve Timing is fine.

At all other revs the bike is fine at full throttle or coasting. It only when coasting at 1700-3000 like in carparks that there is the problem. Problem wasn't there before I did the carb Synch.

I'm lost for ideas.

 

Are all four rubber hats where you measured vacum in place and no one is broken?

 

Whats the spray test?

 

Spray Carb Cleaner or any other flamable solvent around any likely leak spots. If there is a leak you will hear the revs change as it gets burnt in the engine..

 

Could there have been some crap in your "little tank" which ran out of fuel during carb sync? Just a thought..
Dave.

 

Nah. Brand New all clean

 

well i'm no expert at these things but given the circumstances and all the things which are not wrong it seems to me there is air trapped in the system. How to get it out (if that's it) is another matter. I might go with running the carbs dry or draining the float bowls. Or any other thing along those lines you can think of.

 

Hi Rob,

Just been looking at your little problem. I Know that you've probably been thorough in rebuilding the carbs, but assuming that after you had rebuilt the carbs you were running the system on say 1700rpm when you were syncing the carbs, would it be possible that the throttle link arm is out of line. The reason why I bring this up is that when on idle it is in the rest position and when you throttle up it rises up. Now you already stated that it is fine in high revs, so with the arm being out of line then the fuel going into the carbs between 1700 to 3500rpm would throw the ballance out. I hope you can see where I'm going with this and that it helps. Let me know how you get on. All the best and good luck



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Problem solved folks.

Breather tube pinched,

 

Would you credit it, something as simple as that. Congrats on solving this problem. I bet that you spent some time backtracking on what it was. All the best



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