2000 M750 dies at high speeds.

[toreadorxlt]

Hey,

I purchased a used 2000 M750 that had sat for 5 years with aftermarket pipes on it. I took my chances, knowing I would have issues with how long it has sat. Being ignorant and anxious, I never replaced the fuel filter.

Initially riding it around, it was lean, and breaking up in mid-high RPM range. I figured it needed to be rejetted but decided to run some sea-foam through it to see if it helped. It didn't... One day I was riding it home on the highway doing above the posted speed limit and it just died on me... Felt like it wasn't getting fuel. On the side of the highway, I could get it to sputter with the choke on and nothing else. I flipped the tank up, tapped the fuel filter, and waited 5 or so minutes. Bike fired up and drove 100 miles home no issues. I decided it was time to re-jet.

Fast forward to today... I just picked the bike up from the dealer after getting a Dynojet Stage 1 kit put it and it runs like a totally new bike. No more hesitation, tons of power I didnt know about... everything feels great. I take it for a quick spin, pushing it pretty hard and holding it at a high speed, and it dies... again. Just like the first time... Acts like it has no fuel. This time it recovered way easier and I was able to keep the bike sputtering almost the whole time while fiddling with the choke. after 15 seconds it just came back to life like nothing ever happened.

I had the dealer replace the fuel filter, and adjust/tune/clean the carbs.

Any ideas on what could be causing this?

[toreadorxlt]

Just pushed it inside and closed the garage door. I could hear the fuel cap whistling so i opened it. Upon opening it there was a louder than normal vacuum rush type sound. Seems like the tanks not venting like it should. Could this be causing fuel starvation?

[1010ths]

....you have a clogged vent hole in the gas cap. Open the gas cap, see that little pin-sized hole? Take a compressed air nozzle and blow out that hole. That will fix the problem.

I had the same thing on my '97 M750.

Cheers.

[Myocean4vr]

I just had the same problem over the weekend, was hearing the same hissing sound from my gas tank. Cleaned the gas cap vent with compressed air and took it for a spin, it acted totally regular like nothing happened. I also found that when I lifted the gas tank few days back, that the vent hose going down from the bottom of the tank, got mangled between the tank and the frame which was another reason for lack of ventilation and hence the fuel starvation symptom. Thanks for the advice !