at low end, 45-50 mph, every thing is fine. When i get up to speed, 55-65 and ride a couple miles, it feels like its running out of gas. I can pull in the clutch, rev it up, and its fine for a couple miles, then it starts again. As long as im driving slow, no problem. New Mikuni carb on a 99 model evo, new gas caps, just had Pingel fuel valve rebuilt. New gas, drained tanks while fuel valve was at Pingel. Thats why I had it rebuilt, it felt like it was running out of gas. When Id turn the valve off, it would die immediately. Now valve is in place, filled tanks at store, and it started again. I took one cap loose while riding, in case it wasnt venting, no joy. If the rubber gasket between intake and carb is bad, would it do this?

 

Gas filter? Under load loosing power classic sign of fuel starvation. You took out the valve had it rebuilt was the tank off the bike so you could shake the tank to listen for loose matter ?

I'd go and take a 1gallon plastic fuel can and rig it up to piggy back on the tank and feed the bike from that. Take her out on the highway and either rule in or out the fuel tank.

 

Gas filter was my first thought, piggy back gas tank, can you say moving target any lowder?

 

oh, new fuel filter, just ordered new one when I sent the petcock in, ebay, $11 for chrome cleanable filter, inline filter. So, Ive taken it off, put on new fuel line, even drained bowl on carb in case any trash was in there, going to drain the tank, take it off, put some fuel in it a few times, shake it and drain it, hopefully if theres any trash sloshing around, that should clean it. I'll keep you posted. Im not real sure about that gas can tied to the tank, to much opportunity for self destruction there. I see the point, but, I'll make sure the tank is clean first.

 

Just a thought - what about the carb float level. You said that that it runs fine at low end and at high end if you pull in the clutch its fine again for a wile. Perhaps at higher R.P.M. if the float is set too low it is causing the bowl to run too low a fuel level and starving the carb.

 

Thought about this too; what about the plugs? Do they show signs of rich or lean? Would indicate float/jet issues.

 

I meant tie the side gas can to your helmet! Not to your tank silly....

 

Seriously though the float setting does sound like next step. I thought the reason you installed the new carb, caps etc is that you had this issue before but now you still have it even with the new carb, caps etc. ?

Or did all this start with the new carb?

 

no, didnt have this issue til I removed the tank and put it back on. Ive the tank, changed the gas line, took out the plug on the bottom of the carb, shot carb cleaner in it, took the gas line loose, sprayed carb cleaner in there, took the inlet off, sprayed more carb cleaner in there, then back into bottom of bowl and sprayed upward inside carb again. Took the bike out, rode about 20 miles, no problem, then, on the way home, it started again. I can pull out the choke, it makes it run fine, also I can turn in the long idle screw, which starve it for air, and it runs ok. I also sprayed carb cleaner on intake while it was running, all 3 junctions before I took it out,with the bike idling, no change in idle. When i got back, I sprayed WD40 in intake with it running, no change in idle. When its happening, if I just hold the throttle still, it'll die, then fire back up, like its running out of gas. Is there a primary and a secondary jet in there? When Im taking off, no problem, just when I get to speed and barely have the throttle twisted. I caught the fuel when I drained the bowl the second time, it was clean, no specs of dirt that I could see.

 

OHHHHHHHH, I had about 3400 miles on the carb and engine, no problems til I removed the tank, ran fine, no problems, the tank was only off for about 3 days .