Honda Fourtrax 300 wont idle

[RollingsFarms]

M having trouble with my honda not wanting to idle. It will idle fine for a few seconds and then gradually die, acts like it starts starving for fuel. It'll do this when I crank it up and even when I've ridden it for awhile. I've replaced the carb last year, new petcock, took the carb apart and it didn't appear to be gunked up...neither did the old petcock but went ahead and replaced it anyways. I've even messed around with the idle screw but that doesn't help with the problem. Should I try some carb cleaner just incase a jet is clogged up? Never had an issue like this that was so hard to resolve!

 

[Fasttalker]

Try changing your spark plug. This will usually clear up rough idle problems on my old '91 300.

 

[RollingsFarms]

Try changing your spark plug. This will usually clear up rough idle problems on my old '91 300.

Did that today matter of fact! Forgot to mention that. I've done everything I can think of short of just taking off the new carb and tossing it for another one. Sad thing is I didn't buy one of those cheep Chinese knockoff carbs, it was a legit Honda one.

 

[RandyT]

Make sure the valves are adjusted properly.

 

[RollingsFarms]

Make sure the valves are adjusted properly.

Is that hard to do on a Fourtrax or should I just take it to a dealer you think? It did have a top end rebuild few years back I think.

 

[Fasttalker]

Try checking the rubber vent tubes coming off the carb, I don't recall having problems with the Honda but a dirt dauber caused me to spend a lot of time, money and headaches on a 350 Yamaha. It had plugged up the carb vent tube and it was acting just like your Honda. Don't know if the little suckers are a problem where you are, but around here they build their nests in every little hole they can find. Hope it's something simple like this. Good Luck!

 

[Fasttalker]

You have probably already checked the tank vent on the fuel cap, but that will starve the carb for fuel if it's plugged.

 

[RollingsFarms]

Try checking the rubber vent tubes coming off the carb, I don't recall having problems with the Honda but a dirt dauber caused me to spend a lot of time, money and headaches on a 350 Yamaha. It had plugged up the carb vent tube and it was acting just like your Honda. Don't know if the little suckers are a problem where you are, but around here they build their nests in every little hole they can find. Hope it's something simple like this. Good Luck!

You know I bet that might be what it is! Those things are a major pain around here every single year, I have no idea what attracts them either but for some reason around my farm they are terrible! I will check that first thing tomorrow morning.

 

[moriboy]

If you have used ethanol gas, and let it sit in the carb for as little as a few months, I would almost guarantee you've got a clogged idle circuit/jet. It doesn't matter if the carb doesn't seem gunked up, the hole in the idle circuit is tiny so it doesn't take much at all to clog it up. The no idle condition you are describing is exactly what happens, and this a very common problem, and has kept small engine guys busy since the introduction of ethanol.

Also, check for a vacuum leak. The boot from the carb to the motor could be the culprit.

 

[RandyT]

Normally when dirt daubers clog the carb vent tubes, it will cause a rich run situation with fuel siphoning in some cases. Idle jet could be partially clogged, plugged tank vent should effect all running not just idle.

Adjusting the valves isn't all that hard, what is hard is removing all the stuff to get to the valve covers. In some cases requires removing the plastic around and over the fuel tank, removing the fuel tank, the plastic plate under the fuel tank, etc.