HMF Full system JETTING

[IanCFitz]

Just got my full system today (thank you UPS man)

Got it all installed, including the single jet they shipped (a 165 kehein) and i just checked HMF's website and they recommend a 180-200 for a basline. WTF???

Who makes a worthwhile jet kit or what would be the ideal jets I would need.

Just fast trail riding, more than likely I will leave my airbox lid on.

Also, I'm seriously considering getting the quiet core for the HMF.

thanks,
Ian

[Old Head]

I like the dyno kit. It has 5 or 6 main jets and a new needle and clip. The instructions are easy to folllow also

[Chino]

Originally posted by IanCFitz
Just got my full system today (thank you UPS man)

Got it all installed, including the single jet they shipped (a 165 kehein) and i just checked HMF's website and they recommend a 180-200 for a basline. WTF???

Who makes a worthwhile jet kit or what would be the ideal jets I would need.

Just fast trail riding, more than likely I will leave my airbox lid on.

Also, I'm seriously considering getting the quiet core for the HMF.

thanks,
Ian

Run a 158 or 160 main and a 42 pilot jet you will be perfect. The jetting they recommend is way off and your bike will run like crap. You are only 45 minutes away from me, I have the same exhaust, i'm running a 42 pilot, and a 158 main with no problems. Get a 160 and a 158 main and a 42 pilot I gurantee you that setup will work.


IMO, Jet kits are a waste of money when you can pick up the individual jets you need for a few bucks. No need in spending all that money on a kit that you will never use 95% of the jets they give you. You buy the 3 jets i listed above you will have zero problems, i promise.

[meanyellow03ex]

I only have a slip on and vented airbox lid and run a 170 main and stock pilot. It was run on a dyno to get it tuned in. It was way lean with a 155 main. They jumped it up to a 170, and it was perfect. The airbox lid makes the most difference with the jetting. If you run the stock lid, a 165 may be right. And these are keihin jets too.

[Chino]

Originally posted by meanyellow03ex
I only have a slip on and vented airbox lid and run a 170 main and stock pilot. It was run on a dyno to get it tuned in. It was way lean with a 155 main. They jumped it up to a 170, and it was perfect. The airbox lid makes the most difference with the jetting. If you run the stock lid, a 165 may be right. And these are keihin jets too.


take into consideration your in Wisconsin elevation is different. I'm guessing he still has the airbox lid on. I put money on a 158 main or 160 and a 42 pilot jet. 20 dolla says she will run like a red-headed step-child!

[meanyellow03ex]

Whats the elevation in WV?

[IanCFitz]

Where I live it is around 1100 feet, but can go up around 3000 or so in places.

Also, is the stock needle decent or are there any better options there.

I haven't decided what to do about the airbox, for the most part I won't see much water or mud, but I'm still kinda leery of running without the lid.

[Chino]

Originally posted by IanCFitz
Where I live it is around 1100 feet, but can go up around 3000 or so in places.

Also, is the stock needle decent or are there any better options there.

I haven't decided what to do about the airbox, for the most part I won't see much water or mud, but I'm still kinda leery of running without the lid.


Stock needle is fine.

[IanCFitz]

Hey Chino do you get much popping and backfire on deceleration with the 42 and 158 jets?

i still have the stock 38 and now the 165 and it still loads up quite a bit on decelleration. Even with the spark arrester I'm blowing some 4-5" flames out the back sometimes.

Also, do you have the quiet core? or are you running with the canister open?

[Chino]

Originally posted by IanCFitz
Hey Chino do you get much popping and backfire on deceleration with the 42 and 158 jets?

i still have the stock 38 and now the 165 and it still loads up quite a bit on decelleration. Even with the spark arrester I'm blowing some 4-5" flames out the back sometimes.

Also, do you have the quiet core? or are you running with the canister open?

no quiet core just the spark arrestor and the turned down tip. I do get some backfire and popping on deceleration nothing that could not be tweaked out. I have never gotten any flames to shoot out. Try the 42 pilot jet and a 160 main jet, that seems to be what everyone has the best luck with around here. I didn't have a 160 on hand so i used the 158 and it seems to be working fine although im sure the 160 would help it.

[IanCFitz]

I picked up a 42 pilot today, but never got a chance to mess with it.

I might try the 165 with the 42 and see how that goes.

I've noticed that when I'm idling and start to take off, there is some hesitation. Feels like its not getting enough fuel for that first split second. The engine has actually stalled out a couple times from it. I'm guessing the 42 should take care of that low end.

Top end seems ok, just acts like it is still kinda lean even with the 165. I need to get the queit core and see how that does because I'm thinking as soon as I get it running good, then I go throw the quiet core in it will throw everything off again.

[Chino]

Originally posted by IanCFitz
I picked up a 42 pilot today, but never got a chance to mess with it.

I might try the 165 with the 42 and see how that goes.

I've noticed that when I'm idling and start to take off, there is some hesitation. Feels like its not getting enough fuel for that first split second. The engine has actually stalled out a couple times from it. I'm guessing the 42 should take care of that low end.

Top end seems ok, just acts like it is still kinda lean even with the 165. I need to get the queit core and see how that does because I'm thinking as soon as I get it running good, then I go throw the quiet core in it will throw everything off again.


quiet core should not effect anything other than sound.

[400exstud]

I run a 155K with my full HMF, airbok like ON, quiet core, and K&N filter. It runs great. Way more power than the 160K that I had in it.

[Chino]

Originally posted by 400exstud
I run a 155K with my full HMF, airbok like ON, quiet core, and K&N filter. It runs great. Way more power than the 160K that I had in it.

I agree, it's going to be different for him though, the only reason i replied to this thread is because we are in the same elevation and region. Your elevation in Wisconsin is going to be way out of wack compared to what we are in, in West Virginia. So what may work for you will not work for him.

[IanCFitz]

Tinkered around today and have it set up like this:

165 main
42 pilot
Choke removed

With airbox lid on and quietcore its running pretty damn good.

I experimented with no lid and no quiet core, and it was a bit different. something must have been wrong with the front wheels because they just didn't want to stay on the ground much.

:D

I still had a little rumble on deceleration, but not nearly as much as when I still had the 38 pilot.

Only thing I noticed is that headers are tuning purple where they connect to the head. I forget what that is a sign of. maybe too rich??

[400EXride]

Some of those recommendations sound rich but then again I am in Alabama. I have a hmf slip on, running with the air box lid on, K&N filter, quiet core inserted.

-42 pilot
-152 main

The quad runs great, no hesitation or popping. Spark plug check looked fine.

05' 400EX

[coryatver]

The 04 and up have different carbs so the jetting will be different