What jet kit to buy? 350x with 400ex carb

[k00leo]

Alrighty then. I bought this carburetor from ebay for my 350x. It is a brand new 400ex carb.

http://cgi.ebay.com/ebaymotors/Carburetor-Carb-Honda-ATC350-ATC350X-85-86-NEW-_W0QQcmdZViewItemQQhashZitem5ade9246feQQitemZ39028 1185022QQptZMotorsQ5fATVQ5fPartsQ5fAccessories

Specs:
Main Jet #148
Pilot Jet #38
Needle Set #V284
Air Jet #110

I love it.

The 350x seems to backfire when decelerating and gets VERY hot. So hot, that it burned a hole in my JT team Paintball pants that i was wearing. I figure that the 350x is running lean. The fuel/air screw seems to have no effect.

My question is, what jet kit should i buy for the 400ex carb? What do you recommend? And how many sizes should i jump up too? The only performance upgrade to the bike is the 400ex carburetor.

I'm guessing i should jump the main jet to around 160?

[bugler30]

the main jet doesn't really kick in till about 3/4+ throttle so I would think your pilot jet is causing the leanness. Have you tried backing out the PJ screw? I'd try about 1/4 turn at a time and see if it helps. I'm no expert on tuning carbs though just going off what i've read and the little experience I have on trying to tune a 200x motor. But hopefully I'm not talking out my trailpro

[Dirtcrasher]

First off, it's a fake knock off, just like this (http://cgi.ebay.com/ebaymotors/Honda-ATC-350X-350-Three-Wheeler-Gas-FUEL-PETCOCK-NEW-_W0QQcmdZViewItemQQhashZitem519706a787QQitemZ35042 6146695QQptZMotorsQ5fATVQ5fPartsQ5fAccessories) which usually makes finding jets that much harder. There are no OEM carbs on EBAY, the patents expired and people made their own.

Your gonna have to spend 50-100$ in jets. You'll always have them and they MAY fit something else, IDK...

There is no one jet that can be suggested, you may go up 4 sizes on the main and 2 on the pilot, who knows. Jetting suks..........

I don't understand why they are even selling it as a 3 wheeler carb, did the 400EX become LESS popular than a 400EX??

Your pilot is most likely too lean, the screw will tell you that if you've read some threads on that. And you may be able to bump up the main or it may be too much for an engine with no other mods.

Whats the plug look like?

[oscarmayer]

polite is way too small for that size engine. my 200cc runs a #38 pilot. you shoudl eb running a #44-#48 pilot.
if your stock, any reason your messing with a larger carb? in my expirences, unless you open the exhaust up and run a decent cam, there is no point in getting different than stock carb. you can get a stocker to run so much better for a stocker motor than a bigger one.

[k00leo]

Thanks for the help everyone.

I think i will try to get a larger Pilot jet.



Dirtcrasher,

Thanks for the help.

It does seem odd they are selling the 400ex carb as a 3 wheeler carb, but from what i have read the 400ex carb is an upgrade for the 350x, so maybe that is why?


Oscar,

Thanks for the help.

Its kind of complicated write down...

When i bought the 350x it was having carb issues and i didn't know how to kick it over yet to actually start it and figure it out. I thought a 400ex carb would not only give it a performance increase (as i have read that it does), but make it easy to start. I was basically trying to narrow down why i couldn't start it. Which turned out to be not knowing how to kick over a 350.

Anyway, i threw the 350x carb on the 250sx to fix the cold start problems and give it a performance increase as well.

[k00leo]

Where do you guys buy your pilot and main jets? I see that ebay and amazon has main jet kits, but i do not see any where to purchase pilot jets.

[oscarmayer]

http://www.psep.biz/store/fuelintake.htm

[Dirtcrasher]

Where do you guys buy your pilot and main jets? I see that ebay and amazon has main jet kits, but i do not see any where to purchase pilot jets.

I have used MRCycles, their Parts Unlimited book has every odd and normal jet imaginable.