simple jetting question

[biggyb12]

2008 gonna get a hmf slip on what should my jetting be i'm around 2000ft and its usually 50-80 when i ride. Also will i need a jet kit or just buy the jets seperate somewhere? Stock everything just putting an exhaust on at the moment.

[dave07ex]

You should probably buy separate jets. I got mine from rockymountainatv.com. You should get pilots and mains. I would suggest 40 and 42 pilots and a few mains, probably between 148 and 160. Consider an aftermarket air filter since the shipping cost for the jets will be as much as the jets. 40 pilot and 150 main would be a good starting point. Definitely read the stickies on how to properly tune the carb. It's really not that hard once get the carb apart and see what you're dealing with.

[jake"08"400]

I would do as dave said, get ya a uni are k&n which ever you are comfortable with itl help a lot ( I have both and like the uni better personally) with that hmf cause that's what's on mine. I have a 155 main and 42 pilot 2.5 out on f/a screw and I'm right arounf 1000 feet elevation. Also I have uni filter elements in my airbox.

[jake"08"400]

O I forgot jets r us is a good site id go ahead and get the kit from them comes with 150 threw 170 are so just in case you ever decide to do any more mods. If not id get a 150 - 160 and a 42 pilot.

[jake"08"400]

Also youl need a d shaped tool to adjust your f/a screw thay have them on jets r us are you could get a 99-04 carb rebuild kit take out the stock f/a screw with a set of needle nose tweezer's and put in the new one with the kit its a flat head screw head. Are you might find a f/a screw off a 99-04 at your local shop but no tellin what they ask for it lol

[CJM]

I like jets r us jets, I bought quite a few from them and a rebuild kit and was impressed with the packing, service an shipping time. I also know the jets are keihin or equivalents and trust them b/c they have an excellent rep.

The only jets so far I wouldnt recommend are dynojets. They work in some bikes, but hondas just dont like them to much. I ran them in mine for awhile cause I didnt know about jetsrus and no matter what they made me have a lowend bog. Thier numbering system is also very odd compared to OEM keihin.

No idea about the rocky mtn jets, not to many have used them from what I know.

[slightlybent47]

If you’re at 155 now I recommend just change the main jet up to 158 and leave everything else alone. Just a slip on pipe and air filter doesn’t change much on a stock motor, so you don’t need to change much on the jetting. Only when you add the full pipe and do porting and head work and cam do the real gains begin.


You can change the main jet without even taking the carb off. I can change mine in 5 minuets.
Turn the fuel off and use a 17mm end wrench to take the screw from the bottom of the bowl. Some fuel will leak out, and take the bowl off. You’ll see the float hanging down and just in front of that is the main jet. I think it’s a 1/4 end wench for the jet, remove it and replace with the new one. Be careful not to cross thread the jet when you put it in. it should screw most of the way in by hand, that way you know it threaded rite. Replace the bowl and turn on the gas make sure it is not leaking. And that’s it, you’re done. It just takes a few minuets and all you need is one jet at $6.00. A cheap fix.

[dave07ex]

Good call about the D shaped tool. Totally slipped my mind. I happen to have if you need one, biggyb.

[biggyb12]

thanks for the info guys should be able to get it up and running good once the exhaust gets here. Thanks for the offer Dave but my buddy works at the local dealership so I should be all set.

[kt1148]

I bought a Works Connection replacement f/a screw to replace the d-shaped one. It sticks down from the carb about 2 inches and can be turned by hand for adjustment. cost was around $20