HMF + Quiet Insert = Bogging & Sputtering

[quadman21]

First, I have had my HMF for my 05 TRX450 for well over a year and raced all last year with it. It's awesome and the power hits hard. So now I installed the quiet core due to new series db demands and it runs like crap. So I need help to bring it back to life (or as close to it) using the quiet insert. before the quiet insert I was running a 180 or 184 (not sure) main jet. With the quiet insert the quad boggs down on take off and fells sluggish. I also noticed some sputtering but it was rainy and wet today. So does anyone have any advice or answers on what to do or change to correct this? Thanks in advance!!

[Iliketogofast]

One size or one half-size down on the main.

Originally posted by Iliketogofast
One size or one half-size down on the main.

how do you go a half size down on the main?

[Iliketogofast]

Sometimes they make half sizes like 140.5. Basically get two main jets - The very next size smaller and the very next size smaller than that one.

Try the closest one first and then move to the full size or the next size or whatever.

[quadman21]

Thanks. I actually took my main out and it's a 180. So I'll pick up a 179 and a 178 and see what happens. Going back to the sputtering end of my trouble I realized what the sputtering was from my vent hosed being blocked off. The steering stem on my 05 does not have any weep holes near the bottom. The same day I tried the quiet core it was rainy and wet. My stem filled with water to a level which blocked my vent hose. Weird huh? I'm gonna fix that!

[Iliketogofast]

Good that you found your sputtering problem. I'm pretty confident that you will be able to fix your bogging problem by jetting down.

When you decrease the out flow, you need to decrease the in flow as well. Sometimes the smallest things that most people wouldn't expect to make a difference can make a big change in jetting.

[bwamos]

If it's a Keihin.. you're probably only going to find a 178 and a 175. ;)