426EX Not Running Right

[HondaRacing23]

I Just recently put a 426 Kit 11:1 with a hot cam stage 1 in my bike. I am getting beat by a stock z400 and stock artic cat. That shouldnt be. I have an HMF FULL SYSTEM on this bike. I am running a 42 Pilot with a 155Main. Stock Jets. *NO jet kit* The plug is black no matter what jetting i do. The bike runs pretty good i think but it cant be running at top performance in my opinion. I need some ideas on what to do to see what my problem may be if i even have one. Thanks guys...:confused: :confused: :confused:

[HondaRacing23]

Just some more info to help You out....

I have a K&N Air Filter with the air box lid on. thought someone may ask that...

[cals400ex]

what needle clip position?? what fuel skrew positon??

i have a really good feeling your not rich on the mainjet. you might even want to go one size bigger.

there is no reason why you are getting beat by those two bikes. what gearing and tire sizes you running? is your throttle lever adjusted properly?

11:1 piston huh


What octane gas you running:confused:

And also I'd say your jetting is off..:cool:

[UglyMotha™]

cal, ya got me curious cause you post alot about jetting, and you always say skrew, you do know that it's spelt screw right, just curious :confused: :p

[HondaRacing23]

clip is on the 3rd and i beleive its 3 1/2 out on the screw. everyone on here(exriders) tod m that a 6160 main sound way to high its run pretty good with the 155 but it dont seem likeits giving all its got in top end...

[cals400ex]

Originally posted by UglyMotha™
cal, ya got me curious cause you post alot about jetting, and you always say skrew, you do know that it's spelt screw right, just curious :confused: :p


yeah yeah yeah. sorry mr perfection. :p

i just don't know how to spell i guess.

[hawiianpwr]

I agree with Rico. If your already running premium in it I'd trying running and mix of race gas in it and see how it runs. What is your elevation up where you live?

[HondaRacing23]

Im pretty sure its like Below 5000 but i could be wrong

[nakomis0]

I'd just start with basic jetting.. keep the fuel air and all them other screws in the stock position messing with them could get you in a worse situation.

Open the carb, get the needle in the middle position, then drop the main 1 jet size.

Do plug chops with the throttle 75-100%, check the plug. Keep dropping the jet size till it turns more brown. Actually ride the bike around for a few hours, just pay attention to how it runs witht he throttle wide open.

Once you get the feeling the main jet (full throttle) is good, then do the same for the needle to get your mid throttle good.

If you get down, to a 148 main, and your not seeing any improvement..then i don't know what to tell ya. I just wouldn't drop the main much farther than 148.

[Foxnake42]

try a 165 maybe 170 main keep the 42 pilot, needle in the middle pos., 3 turns out and go from there

[norcalatver]

Take the air box lid off and keep the 155 main jet. You're choking the dang thing to death. Especially if your above 5,000ft. elevation. Give it some air so it can breathe!

[tinner]

That sounds very lean. I just bought an HMF full pipe and did a little home work. HMF will recommend a 180-190 main, raise the needle one notch and adjust the air screw out to around 3-3 1/2 turns. Mine is a stock bore with 10.5:1,porting, cam, HMF,and a UNI filter. I just got the bike together yesterday and found that the 180 was too much for mine....but I run a lid, am currently running a UNI,and have the stock bore. I worked my way down to a 172, but figured I'd hold off until my quiet core comes in and decide which filter I want to run. Let me tell you...that HMF made a huge difference.:devil: I had a FMF Hi-flo header and comparing it to the HMF header made the Hi-flo look like it was a stocker. Back to the subject...I would start at the 180, you will see a big difference. That should put you in the Ball park.

[HondaRacing23]

180 170 and a 165are all to high. I wont run for crap with them in it besides the 155 I have in it now. I will try and take the air screw to 3 turns instead of 3 1/2. I think a 148 is going to be to low. I think the main jet is just fine its just has something to do with the Needle or air screw....I dont want to take my air box lid off because I do a lot of water riding and mud riding. If i lived near DUNES I would prolly take it off(maybe) but not here in little ole boring OHIO...

[Foxnake42]

don't believe HMF . I have the HMF full system running 42 pilot and 170 main. trust me you don't need a main the size of washington.

Take the air box lid off and keep the 155 main jet. You're choking the dang thing to death. Especially if your above 5,000ft. elevation. Give it some air so it can breathe!


I agree with norcalatv. Take your airbox lid off and try it! You ask for everyone's advice and then you refuse to use it to help. At 5000 feet my bike has a significant loss of power. If I want to counter that loss, I just reduce the size of the mainjet and increase the air any way I can. You need to take off your airbox and see if it fixes the problem. If it does, there are many aftermarket airbox lids that protect as well as breathe.:rolleyes:

What octane gas you running:confused: :confused:

You might be rejetting for nothing if your runnin 87 octane in it..:eek2:

[HondaRacing23]

I want to use VP racing fuels but none of my local shops carry it and all the gas stations dont have any racing fuel till mid spring. I am running 93 octane now i was going to use a booster aditive but i heard that not good on the bike...

[400exracer26]

It sounds like the bikes not getting enough air take the lid off or install a prefilter lid. Black is RICH, WHITE OR brown LEAN

[cals400ex]

Originally posted by 400exracer26
It sounds like the bikes not getting enough air take the lid off or install a prefilter lid. Black is RICH, WHITE OR brown LEAN


i don't consider brown lean??

[UglyMotha™]

Originally posted by 400exracer26
It sounds like the bikes not getting enough air take the lid off or install a prefilter lid. Black is RICH, WHITE OR brown LEAN


coco is sexy :o :p


to me that is the ideal color


so since you pretty much summed it up there i'm curious as to what you would consider the ideal plug color, possibly blue or green

[HondaRacing23]

IM NOT TAKING THE LID OFF.. THERE ARE WAYS TO GET MORE AIR OTHER THAN TAKING THE LID OFF. ILL FIND A WAY THANKS FOR THE HELP...

Originally posted by HondaRacing23
IM NOT TAKING THE LID OFF.. THERE ARE WAYS TO GET MORE AIR OTHER THAN TAKING THE LID OFF. ILL FIND A WAY THANKS FOR THE HELP...

Get you one of these from GT thunder. It looks small and useless but it will help a heck of a lot more than you think...;)

http://ricoracing.netfirms.com/images/airtube.jpg

[400exracer26]

Ok sorry I mean white instead of brown