Odd jetting question/yoshi pipe

[kineo3]

Ok, I have read about every jetting thread created so I think I have a pretty solid idea of what I am doing. So here's the thing... I put a new full yoshi tri oval pipe on this winter. I have the full HRC kit with the stock air filter. It ran dead on in the cold weather, which if memory serves me correct should be a leaner condition then warm weather. Now comes my odd question. Now that the weather is warmer the thing starts to stutter at wide open throttle. This leads me to believe I need to drop the main jet down a little, but this does not make sense with a full pipe does it? I currently have a 185 main jet (what came with the HRC) Any ideas???

[dtzalba450r]

I have the same exact set up with the exception of a knn filter. I'm running a 190mj, 50p and 2 1/2 turns out. I'm at about 250 feet. You may have to play with the fuel screw or jet up a little bit.

[asdf450r]

i believe its the other way around;

cooler air temp = more rich
warmer air temp = more lean

because colder air is more dense than warm air, thus needing more fuel to compensate for the greater density of the air and produce more efficient combustion, and vice versa.

can anyone varify this?

[Sinsai]

You are correct, colder air does required richer jetting. I have the same pipe and filter setup, no lid. I have found that with this pipe it likes to hit the rev limiter quickly depending on the main jet size. If nothing has changed on your quad and it ran great before, just the temp changed, I would lean the main.

[d3ktrix]

Yeah you need to lean your main for the warmer weather.
The stuttering at WOT is another sign that its too rich.

Try a 180

I have the HRC kit and a sparks pipe with the stock air filter.
600ft elv

185 stuttered at 3/4 - WOT
180 had no top end power and stuttered a tinny bit
175 is balls out power

I'm going to try a 178 next, like to stay as rich as I can.