I hope that I can find some help here. I have a 96 Foreman 400. I just bought it a few months ago and really have only had 4 good rides on it. Just trail riden. I have searched for this issue and some have had it but none really post what they did to fix it, or I have already done that and still have the issue.

It will start and run fine, as long as the choke is on. I first noticed an issue when I was just running down the street on it. It just got a little higher pitch then normal. So I parked it for a week till I had time to work on it. I have pulled the carb and cleaned it 3 times now. adjusted the valvles, replaced the o-ring from the boot from the carb to the head. I have 110psi on the piston compression. I have good spark, tested the coil, stater, pulse gen, all within spec. I am getting good fuel flow to the carb. I verified that the timing was correct. Tested the wiring. Cleaned and reoiled the air filter. changed the fuel in the tank. replaced the spark plug. I have sprayed carb cleaner all around the carb, and engine and not once did the engine speed change or even sound different. It still will only run with the choke on. I can hold my hand over the intake tube and feel the vaccum, and let it die and the vac does hold pretty good. I can also make it run be regulating how much air gets in with my hand.

If I turn the choke off, it will try and idle for about 1-3 sec miss alot and just die. If I throttle it up and turn off the choke it will start back firing bad. I think it is running lean, but as to WHY? That I can not figure out. I hope one of you can.

 

This is classic for one of two possible conditions: A clogged pilot jet, or an air leak somewhere in the intake system.

Current fuel formulations make the fuel dry up into a nasty scum, which easily cloggs up the pilot. Just "spraying some cleaner aound" isn't going to clean a clogged up pilot. They are cheap, so just replace it rather than try to clean it, then readjust the fuel screw.

To diagnose an intake leak, remove the air filter and place your hand over the opening. With the kill switch on, crank the starter a few times and you should feel the vacume against your hand. It should hold for a while if there is no leak.

 

check your main jet good it sound like there is still something in it or it is too small the stock size jet for a 400 is a #130

you can try to run a small piece of wire or a tip cleaner for a cutting torch through it im pretty sure that is your problem i pulled one down that was doing that and it actually had a small spider stuck in it. also if one sits for a period of time varnish will build up aroud the inside of that jet and carbcleaner alone will not get it out youll have to run that tip cleaner through it

 

also it should still run with the pilot stopped up when you pull the carb down the pilot will have a very small hole in it and you can only see dim light through it but check both the main and the pilot a rebuild kit may be what you need Moose make a good kit that is a lot cheaper than honda

 

Thank you both for the very quick responses. I just ordered a Moose rebuild kit. WOW they are alot cheaper then Honda.

I just wanted to clarify, when I was spraying the engine are with carb cleaner, I was aiming at different points, like the intake boot, head gasket, areas that I thought that can leak, hoping that the if the engine reved up little, from sucking in the carb cleaner, I can pinpoint a leak. When I did pull the carb, I soaked the jets in carb cleaner and sprayed them down. I did use pipe cleaners too, they do look somewhat varnished though.

When I get home tonight I will be pulling the air filter and trying that test that way. Thanks again for the advice, man I hope I get this thing running right, I already miss riding!

 

Well, I got home and tried that leak test. At first it held the vaccum pretty good, .....then it started leaking down from the vent tube from the carb. Not to mention that when I pulled my hand back about a CUP of gas came out of the carb into the air box. Then I tried to start it, it did start up, only with the choke, and there was just a spray of gas going out the tail pipe! I shut it down as quickly as I could and still got a nice 3 foot long flame shoot out the back. What just happened???????

 

Well, my carb rebuild kit came in today. It's sitting at my door now. So tonight I will be pulling the carb and rebuilding it. Is the anything that I should really look for as for as what is causing that gas to be pushed out? Hopefully its not that air cut off valve, cause I haven't been able to find that part for less then $60. For such a little plastic part, thats not that cheap. If this doesn't work I'll end up Ebaying a carb and just using the rebuild kit on it.

 

clean your pilot jet like reconranger said and mabe see if your needle is makeing good contact with the main jet.

its not much help, but its something, good luck