350r weird problem????

[norcalduner]

i recently took the quad out on the dunes and experienced something wierd. everytime i hit 3/4 to full throttle climbing up steep hills, the SOUND of the motor changes significantly from lo pitch to high pitch (bah, bah, bah) and i can almost feel a subtle vibration within the fuel tank.

my ct350 has a 195 main jet, 60 pilot, DGH needle at middle clip running an esr airbox eliminator kit, elevation at sea level with an 38 a/s.

can anyone explain what is happening please.

[kustomfab2003]

You might need to go to a larger carb. I know alot of people running 38's with a 295-330cc cylinder. The sand might be just enough of a load to allow it to not breathe enough and messing with the mixture.

[wilkin250r]

It's tough to diagnose without hearing it in person.

Is it possible you have a slight engine knock? It would fit with climbing uphill at WOT, max engine load is when you're most prone to detonation. You might try higher octane.

Otherwise, I don't know what it could be. I can't see it being the carb and messing with your mixture. Ordinarily, high RPM will result in a RICH mixture with these 2-stroke engines (which is why they have Powerjet carbs on the dirtbikes). A rich mixture would generally result in low-pitch gurgle, not high-pitch.

[zedicus00]

could be fuel starved, high RPM 350cc could suck the bowl dry faster then the line to the tank can keep it fed.

especially on an incline.

[norcalduner]

i also have noticed the pitch change on a flat surface for as long as i hit the 3/4 to WOT range. could it be that im hitting the rev limiter ? and even as i hit this condition the bike still pulls hard and does not skip a beat. i do use a 50/50 mix of 91 pump and 112 sunoco. does the stock cdi on these even have rev limiters? could it be also due to the fact that im not using an airbox and that the velocity of air into the carb is altered ?