Just installed HMF Slip-on and K&N on 300ex, Jetting ??'s

[DamnRock]

Well, I just installed the HMF exhaust and k&N filter on my wifes 300ex... man getting that slip-on to slide onto the stock header was a *****... but I got it on there.

SO, the stock jet is a 122... the HMF came with 125. I've read on HMF's forum that they used a 125 main jet and 2.5 turns on the fuel screw but didn't change the needle. Does anyone think this will work? It just seems like not enough. Granted, it'll be running with the lid on... but still.

Getting to the carb is a ***** so I'd like to get the jet right the first time, or at least really close. Also, is it required to take the tank off to change jets? I just don't see any other way to do it. I long for the days of my kfx400 where I could just twist the carb and go to work and not disassemble anything. The hmf only came with the 125 main... so I'm gonna have to order any other jets... I was thinking if a 125 didn't do it a 128 definitely would.

Well, at least my new 700r is fuel injected!

also, does cold weather create a lean situation? So if I ran a 125 and was slightly lean, then runnin in the cold would make it MORE lean right? So if I had a choice, running rich with a 128 would be better than running lean with a 125 if the weather were going to be colder for the next month or so?

Rock

[TarheelRedRider]

Yeah it works fine. It sounds too easy but it works.

[ChubbyEXby300]

yah i put the 125 jet in my 300ex ran good. but then i noticed it would smoke a very little when i stared and then the smoke would stop. i just took the carb apart and adjusted the pilot jet and it ran perfect. i am so pleased with the HMF people they are the best.

[DamnRock]

what do you mean "adjusted the pilot jet" ??? you mean your eplaced the pilot jet? if so, to what?

I installed the main jet 125 today and tried it out, started at 2.5 turns on the fuel screw, stock pilot jet... once ti got warm it seemed like it reved through the range smoothly but I won't truly know till I get ti somewhere I can open ti up.

I'm thinking I'm gonna see if my local shop has a 128 main and the pilot jet that is one size larger than stock... not sure what that is yet though.

Rock

[bwamos]

If you are running with the airbox lid on and unpunched, 125 main should be jsut about right (you're sucking all of the air through the (2) 1" square frame tubes. If you take the air box lid off, you will need to rejet to a 132 for a starting point.

[DamnRock]

sounds good... I'm gonna leave the lid on for now and see how she likes it... if she wants more power later I'll remove the lid and get the higher jets...

I have the 125 installed right now and just need to set the fuel screw to the optimum position. I also have a 128 main jet just in case but in my preliminary testing it seemed ok.

Rock

[big_saxy]

I've got an hmf slip on on my 300ex as well. I'm running with the lid off, and i'm running a 128 main, one size bigger pilot and i moved the needle up one. Runs perfect. The one size larger pilot made it start so much easier in the cold weather. Barley even need the choke now! The problem i had when i just put a 125 main in and left everything the same was on deceleration my quad would backfire like crazy. The bigger pilot jet and adjusting the air fuel screw fixed that right up. Hope this helps.

[TarheelRedRider]

Hell, just buy you a quilksilver carb like me and be done with it. No more jet guessing. It is the simplist way to adjust for any mod and you dont even have to pull the carb off to adjust it. I love mine, I thought it cost too much at first but it is worth every penny now to me.

[drifterx]

Originally posted by TarheelRedRider
Hell, just buy you a quilksilver carb like me and be done with it. No more jet guessing. It is the simplist way to adjust for any mod and you dont even have to pull the carb off to adjust it. I love mine, I thought it cost too much at first but it is worth every penny now to me.

Is that en edelbrock or what? Or is it like a Lectron? My buddy's dad runs a Lectron on his Kawasaki drag bike (must work good, he's pretty fast in the quarter)

And my HMF i got used, so i just jetted with what Dynojet said in the instructions i got with the kit, and its spot on. My buddy did what HMF said in their instructions, and it was too rich because Dynojet jets are bigger, and he didn't know that. He got it now though. But with normal jets, jet what HMF says, and you'll be good. :macho

[TarheelRedRider]

1993-06 TRX300EX
Carb kit is designed for mildly modified engines (cam, higher compression piston) and competition exhaust.
Bore: 32x34mm oval
Thumb Kit #3007
Twist Kit #3106
Horsepower and RPM Chart

[TarheelRedRider]

1999-06 TRX400
Carb kit is designed for stock to mild engines with competition exhaust.
Bore: 34x38mm oval
Thumb Kit #3004
Twist Kit #3105
Horsepower and RPM Chart

This is the one Im running.

[TarheelRedRider]

Heres another look at how it works.

[drifterx]

How much did that run you?

[TarheelRedRider]

I watched and watched on ebay for one for about three months and cought one on a good day and paid 165.00 shipped so not too bad. New they cost 400.00. You can use one for a 400ex but have to mod the boot a little to get it to fit. Also you will need a pipe and header and just tune the carb down to get it to work on the stock 300ex motor. But man what a big top end gain with it and the 300ex motor will get loud if your not running a spark arester or a quiet core. I have a friend that has a 660 raptor with the lrd pipe and when I changed to this carb and my hmf pipe my 300 was just as loud if not louder then his 660. Talk about mean sounding. I have to keep my quiet core with me when we go ridding incase people complain about the sound. I cant amagin how much louder it will be now when I get the motor back together, I just poked and stroked it to a 396 with 12:1 compression.:devil: Cant wait!