I have a 2003 superhawk. It was working fine at the end of a ride, sitting for 3 days, then began acting up at the start of the next ride.

It starts fine, idles Ok, and revs up with no problems. In 2nd, and 3rd I can take it up to 8500rpm with no noticeable issues. It is only when I am in 4th,5th, or 6th and cruising at a speed of 120 to 130kpm (4000-4500rpm) that it begins to hiccup when I crack the throttle. If I turn the throttle slowly I can increase speed with no notice effect until i reach full throttle. then at full throttle in 4th I notice the same problems. A lack of power with some lurching when crack the throttle. It has also started to stall out when traveling at highway speed when I pull in teh clutch and roll back the trottle.

Prior to noticing these problems I went for a trouble free ride, then filled the gas, and parked it. It was a heavy rain for 2 days. Next trip out it began with these issues. I though maybe some bad gas or wet. I ran two tanks of carb cleaner through it. It impoved somewhat (not stalling so much) but still not right. I took it to the shop and had a tune up done (plugs, oil, filter,etc...). The mechanic couldn't find anything wrong...but he did not take it for a highway ride.

Any suggestion where I might look next to source the root cause of this issue?

 

carbs could need cleaning. sounds like it might be running a little rich or perhaps something is sticking in the carbs that you wont notice until your under load in a higher gear. could just need to be tuned. what did the plugs look like that came out of the motor?

 

I don't think so Uchi - I think it's fuel starvation.

 

hard to tell without checking the plugs. i know whwn we were tuning my turbo car in the lower gears you could get away with a sloppy fuel map but in the higher gears where the motor spends more time under load at those rms is where the maps had to be tight. almost seems like the same thing. i know my predator does something simliar to whats mentioned above and it runs rich.

pull the plug after a ride and see what its showing

 

a wild hair, but just to be sure: check for PVLIR