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Discussion Starter #1
Hello All,
New to the forum but happy to have found it.
Just purchased a 2000 Honda Foreman 450es and trying to determine why it won't stay running. Previous owner said the problem began when he pull started due to a dead battery and proceeded to use the quad to haul firewood putting it under a pretty heavy load.
Now it will run for a few minutes at idle, sputter and backfire if you try to give it gas and eventually quit. Wait a few minutes and it will start again.
Carb is clean and vent tube is clear.
I suspect I may have a bad CDI (or ECM as they are called in the manual). Maybe from a voltage spike?
Just wanted to check in here with the experts before I buy parts I may not need. Anything else I should be looking for?
Thanks in advance for any helpful information.
 

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I think you are spot on in your evaluation. I think if you see the charge output in the 12 range you are good but spikes above that would be an excess. Rough idle and conk out are all symptoms. Try turning the high beams on or anything that would create a drain on power output and see if idle smooths out. Suzuki is famous for rectifier going bad. Good luck
 

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Discussion Starter #4
Thanks so much for the reply. I do have a good battery in it now and ill check the charging voltage. Great suggestions!
 

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Discussion Starter #5
Update on the troubleshooting: I checked the charging voltage and found it was a steady 14.5 volts. I'm guessing this is not good?
Just to be clear on the condition I'm seeing - when it's cold it starts and idles fine, when you give it some throttle it breaks up a bit and occasionally backfires. Then eventually it warms up and dies.
Could this be the symptoms of a bad rectifier? Or is it the CDI box?
Again thank you for any helpful information in getting this thing running right again.
 

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So I just assumed you had already ruled carb out but air mixture screw could be out of whack which would cause a hard start or back fire when on the gas. Air is more dense when it’s cold so the fact that it’s running better when it’s cold says let’s rethink. Air mixture screw is big brass flat head screw. I was told to turn the screw all the way in and then back out 1 3/4 to to full rotations for factory set but that proved to be so wrong on mine. I wound up turning all the way in and backing it out at small increments while running till I got it right. Also you said carb was clear but are you sure. Did you pull jets not just the bowl and clean good. Is it leaking air around primer is vaccum diaphragm in good shape. When you pull carb visually inspect but then blow air through to see if it is functioning good. Now pull fuel line make sure it’s not dry rotted and fuel is flowing is pet **** working. Most of all is the gas good is there crap in the tank. Bad gas has caused me more heartache than I know. If all seems good on these most basic things air, fuel, spark then move on to the on to charging system. I immediately thought that was it running a atv with a battery in a low state of charge causes this so makes sense right. But you’re not seeing any spikes so I’m not sure maybe someone else with the manufacture specs will see this and help. When there bad they usually roll all over as high as 16 sometimes. I think you can download service manuals for free on google and that would end the guessing. Get her right don’t want to miss the snow I’m sure it’s coming
 

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You got me thinking tonight before you turn one screw or start taking stuff apart try turning the peacock to the reserve position and give it a few minutes to run. If it’s clogged would explain everything. Fuel trickles down to bowl while sitting enough to start and once it’s used supply doesn’t keep up engine starves starts popping and cuts out which would also make sense when you hit throttle not enough fuel. This is a 20 year old machine a bad petcock would not be unusual
 

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Discussion Starter #9
Jake and Dad,
Thanks again for your time and suggestions. I'm fairly certain I eliminated any fuel related issues. I have two carbs. One is brand new and the machine exhibits the same symptoms with either of them installed. The screen filter in the tank is clean and the petcock is flowing on both reserve and on. Also have a portable fuel tank I use for testing that I know was flowing fresh gas to the carb.
Pretty sure I'm dealing with an electrical or possibly timing issue which is why I'm leaning towards the cdi box.

Trout Brook Rider,
I'll check out atvhonda.com. Thanks for the suggestion.
 

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I don’t think the 14.5 is a fore sure bad charging system. Mine runs just below 13. Yours might just be in good shape and mine is getting old. The big giveaway is inconsistent and yours is running a constant not jumping around. He ran the thing with a low/dead battery which would cause a rectifier to go bad but before you buy unnecessary parts be sure it’s not fuel related. Let me know what the outcome is good luck
 

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Discussion Starter #12
Jake and Dad,
Didn't do the high beam test but I did get another piece of information from the previous owner. For some reason he hard wired the fan to run because he said it wasn't kicking on when he thought it should.
Trying to determine how that relates to the machine shutting down as soon as it warms up (if at all).
Again, I think I eliminated the fuel system as an issue. It shuts down like clockwork when it warms up. Let it cool down and it starts back up.
 

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I have heard of a lot of people hard wiring fans on these bikes . Usually to a toggle switch probably not a problem unless he really hacked up the wiring harnesses doing it. My fan spins for ten seconds when key first turns on so I know it works but I can’t remember when it’s ever come on while riding. I think there just cold natured motors. Old big bears are same way. So I don’t know a 100% answer on this one. Once it dies do you have to wait a while for it to cool down before it restarts? If you want to go ahead with a gamble on a part replacement I would try rectifier/ regulator. There’s only one it’s up under year fender on right side I think. Should be able to grab one for 20$. It sounds like you have done everything you can on fuel system so this would be next step. I have seen a lot of people complaining of same problem but get mixed answers on for sure cure. A lot of people say as simple as clogged vent tubes can cause this. But you have run off an auxiliary tank so should be eliminated. Man I hate electrical the fixes are never obvious
 

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Jaycee beware of trout brook he chimes into every convo and redirects to another site. Don’t know what his angle on this one is but I’m sure money is involved. Click on his name and check his replies you’ll see what I mean. Can’t trust anyone real shame
 

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Check some of these other posts on bad rectifier lots of info give it a read one guy says he unhooked his and although there was no charge now bike ran perfect. Might be worth a try takes two seconds
 

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Discussion Starter #19
Hey Jake, Thanks so much for all your advice and suggestions. I will give that last one a shot and let you know what happens.
 

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Jaycee beware of trout brook he chimes into every convo and redirects to another site. Don’t know what his angle on this one is but I’m sure money is involved. Click on his name and check his replies you’ll see what I mean. Can’t trust anyone real shame
This comming from someone who just joined her 2 weeks ago....
I'm only trying to get people the right help.
You must be with virtual scope.
 
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