[pigdog]

Here is the story:

97 Foreman 400, less than 500 miles on it. I bought it back when I was young and single to take with me to colorado for elk hunting. then I got married. Now it gets a mile or two on it every year, mainly around deer season. About three years ago, I had some bad gas in it, completly gummed up the works. The carb was rebuilt, and it ran ok, but never as good as it had. Very cold natured, and didn't like to idle.

So last week I went to get it running. Pulled the carb, cleaned the jets, put fresh gas and Seafoam in it. Started on the first pull Battery was dead). Ran fine for about a half hour. Idled fine, went most of the way around my dad's farm. No problems.

Just about back to the barn and it started to buck then died. At first I thought it might have overheated. My leg WAS getting rather warm, and I don't remember the fan ever coming on. So I let it cool down for about a half an hour. Pulled the battery out of the lawn tractor so I wouldn't have to pull on it, and tried again.

It didn't want to start, and when it did, it wouldn't idle for crap, and kept dying, like it was staved for fuel. AND, it kept backfiring through the exhaust, multiple times.

Since then, I've made sure the jets were still clean, drained the fuel, made sure the petcock wasn't blocked, fresh gas again, new battery, looked at the plug (dark tan), and put the air mix screw at the factory setting.

so yesterday as I quit, it would start (usually) still backfires through the exhaust (both trying to start and when it dies), and if I get it started, if i turn up the idle screw, it will run at a very fast idle, but when I try adjusting it back down, the speed seems to stay high, and then suddenly falls off to the point that the bike will die.

Any suggestions??

By the way, stock jets, stock air filter, stock exhaust.

 

[Helmut]

Welcome to the forums. Sounds like you still have some debris in the idle circuit of the carb. When you cleaned the carb, did you remove all the jets (main jet, slow jet, and starter jet) and the pilot screw and blow out the passageways in the carb body with an air hose?

 

[pigdog]

Pulled them out but didn't blow them through. I'll try that next.

 

[pigdog]

Update

Let's see, carb has been cleaned three times now, including blowing through every orifice with my handy Russian tire pump, new battery, etc. and what does it do, same old thing.

If I turn the idle screw in so that it will run fast, it runs. When I try adjusting it down, it acts like it is running out of gas and dies; and yes, I did check to make sure there was still gas in the float bowl.

At this point I said enough, I admit defeat and I'll take it to a dealer. Loaded it up on the trailer and...




No brake lights on the trailer. Seems my truck has burned through another brake controller or wiring harness.

While I was trying to find enough parts to get the lights working, I ended up buying a new spark plug for the thing. And installed it when I made it out to my dad's (I promised I would have the trailer back to him by today). Started it up. Still wants to run fast, and not idle. At least at first.

Put the thing in the barn, and turned off the petcock so I could burn off the gas in the bowl. As it started to run low, it sputtered and seemed to idle. Turned the gas back on, and while it is idling a bit high, it is running better. But I ran out of time to see if I could get it adjusted just right.

Maybe Friday, before I have to head up to Chicago...

 

[Whitehorse]

The Honda trx400 foreman is known for backfiring after you let off the throttle. Honda claims the air mixture screw tip gets carboned up along with the orfice it goes in. The best fix i've found is to drill the low speed (pilot jet) out 10%. I can't remember what size drill bit that is, it is around a #77 or #78 bit. Better yet, put in a Dyno Jet kit for that model and it should run better than it has ever run.

 

[shadetree]

The Honda trx400 foreman is known for backfiring after you let off the throttle. Honda claims the air mixture screw tip gets carboned up along with the orfice it goes in. The best fix i've found is to drill the low speed (pilot jet) out 10%. I can't remember what size drill bit that is, it is around a #77 or #78 bit. Better yet, put in a Dyno Jet kit for that model and it should run better than it has ever run.

drilling the pilot jet ( idle jet )..is the worst thing you can do..it will never run right if he does that..at least it never has worked from what i know of...ask anyone on here..i think they will agree with me.

 

[pigdog]

Update

Well the last time I was out at my Dad's, it started and ran fine. There was one instance where the idle mysteriously picked up, just as I was going to shut her down to put air in the tires. When I started her back up, it ran just fine.

I will not be drilling out any pilot jets. If I thought that was the problem, I would rather just replace the one that is in there with a bigger one. Then I can always go back.

One thing I did notice was that while I was having problems, there seemed to be no free play with the throttle. I wonder that when I took the carb apart the last time, I freed up whatever was sticking in there, because now there is free play at the throttle.

I dunno know.

As to the backfiring thing, It never backfired before all this happened.

 

[ostrx250]

welcome to the forum pigdog