I have installed an FMF Megamax silencer,
K&N filter and Dynojet kit on my 400 EX.
I like the top end gain but the engine
boggs in the low end of the power curve
when I gas it under a load. Should I try
to adjust the pilot screw or go up a size
on the slow jet. If i change the main jet
up or down it does not seem to help the
low end throttle response.

 

Meven, I just did the same thing yesterday with exception of the dynojet. According to a plug reading and expert advice from Honda and fmf tech support, I'm running the stock jet and it screams through all gears and rpm levels. Fmf suggested running all discs that come with the pipe and no quiet core insert. The chance of a lean mixture was said to cause bogging in the upper rpm's. Maybee you should start over to the stock jet and test it first before moving on to the next size.

------------------
Steve Small, 00' 400ex, 00' 325 Trail Boss for the Mrs.

 

The main jet only handles the top 1/4 of throttle. The slow jet handles the idle, and the needle jet handles the rest. I would recommend that you go to the White Bros. site and download any of the documents from the technical papers section. For example download the Warrior technical paper. It has a full page dedicated to jetting diagnosis and resolution.

Good luck.

 

The main jet only handles the top 1/4 of throttle. The slow jet handles the idle, and the needle jet handles the rest. I would recommend that you go to the White Bros. site and download any of the documents from the technical papers section. For example download the Warrior technical paper. It has a full page dedicated to jetting diagnosis and resolution.

Good luck.

 

ive the same setup, but only run about 5 discs and the quietcore, because of DNR. (am trailrider only) and have to point one major thing out. the pipe we bought is engineered for mid and low range torque/power, so if you are gaining on top, is a minor amount. your big gains are mid and low, for racing/trail riding. try dialing in your jetting, im at a 155, and 5 discs, or around there, and plug color is perfect. good luck.

------------------
'99 400 ex, K&N, Dynojet, Megamax, Baja guards, IMS Tank.

 

as far as the pilot screw goes, trust the printed material that came with the dynojet kit, for elevation and pilot screw, is it 2.5 or 3 turns? is on there.



Ride Hard.

------------------
'99 400 ex, K&N, Dynojet, Megamax, Baja guards, IMS Tank.

 

Has anybody drilled holes in their air box to gain more flow?To adjust for a higher exaust flow?

LRD is sugesting me to run with the air box lid off,To acomidate for their pipes much larger flow.But I do have water conserns.

Arlen said, I will definitly need to rejet to maintain the ballence of air and fuel.

Still waiting on UPS.

 

Yup, got holes in my airbox cover, well one of them anyways. pick up an extra-depending on your climate. they are probably the cheapest thing on the bike- $5.00. i got an extra, kept one closed(stock) adn one open for riding like i like to. helped my plug color balance better, and keep the stocker for rainy day riding. one hint though, drill alot of them, and put in the k&n or uni airbox filters- they are little round filters that you can drill into your airbox cover and get lots of air, yet be a little safer than running an open airbox. i put 12 in the lid, and works fine. if its going to be muddy, i drop the stocker on, and the bike runs a little richer, but is still a lighter brown, not black. good luck.

------------------
'99 400 ex, K&N, Dynojet, Megamax, Baja guards, IMS Tank.