HMF pipe and jet question..

[Jersey450R]

hey, i'm looking to buy the red HMF slip on for my 450r and was wondering what jets to use if i'm gonna keep the airbox lid on. its very dusty around here and feel more comfortable with the lid on. i heard of using a 180 but thats with no box lid so helpful tips wouldd be greatly appreciated, ty.

[Pappy]

ill tell you before you get slammed with "use the search button jackass" posts...



stock lid on you can run stock jetting.

[Jersey450R]

ok thanks dude, what about if i cut the lid or take it off completely? prob a 180-190 right?

[Pappy]

yup

[r450rr]

id say stock jetting would be way to lean, u could fatten it up a little an still leave the lid on like a one twenty something.. but it might be way lean u u pipe it and leave the lid on and not do anything to the jets.. but just check your plug and see to be safe

[Pappy]

Originally posted by r450rr
id say stock jetting would be way to lean,

myself and many many others run this and havent had problem 1

[red2004 TRX450R]

http://www.hmfengineering.com/hondtrx450r.html

S/O jet = 124

[Pappy]

ive tried hmf's 124 and it was close but still rich. i too would like a margin of safety but stock is working just fine:D

[xsr_racing28c]

i actually went with a 135 jet and i am starting to have problems with fouled plugs... i think i might move down to a 125 or 120....let me know if this sounds correct or what i should do

[Motoman440]

I run a full HMF system with the air box lid closed and I run a 125. Since your not opening up the header pipe your air flow is still ristricted, for the most part. Stock jetting should work fine for yours with the slip on. Ride it for awhile and check your plug. If its dry and brownish move up slightly but you will not need to go anymore than a 125. HMF has a great website that tells you exactly what to do as well.

[Punk'd]

Originally posted by Pappy
ive tried hmf's 124 and it was close but still rich. i too would like a margin of safety but stock is working just fine:D

So you run your Hmf full with stock jetting? Would that work?

[Jersey450R]

Wow, this thread was reborn. Anyway, When i was running a closed box with my HMF slip on, i had a 125 main and i thought it was running perfect. Now i cut the back of my airbox out and i'm running a 175. I may go down to a 165 and see if that works better.

[spincr4hire]

I have an HMF Ballance slip-on, running the 185 main (with HRC kit) and it seems to be running pretty good.

[schulte_85]

I am running a full system HMF with HRC Kit, 185 main jet runs awesome.

[450r's r sexy]

hmf invented a website for these kinds of questions and they say with just the pipe only slip on a 124 mainjet with open lid i put a 182

[cady#1]

:ermm:

If the Hmf is more bottom-mid pipe, then you should fatten up the slow jet and needle, right?

[Punk'd]

and yet I still have no clue how to rejet:p

[frogdaddy]

i got the full system with a k&n filter and no lid and run a 180 seems to run fine to me, i went by the specs off the HMF website. but i think i may be just a tad rich