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Discussion Starter #1
So I recently picked up a 96 Honda Foreman, test drive at the guys house and everything ran good. Loaded on the truck, stopped to the car wash to give the machine a bath, got home and ran it around the yard and now its stalling out.

The wheeler will start right up and you can ride it around for approximately 5 minutes and then it'll stall out. When you try starting it back up immediately it'll back fire and WON'T start. You let it sit again for awhile and it'll start back up again but stall out after riding a few minutes.

Just got the wheeler yesterday and plan to take the tank and carb apart tonight but has anyone else experienced these same issues? I am hoping its not electrical but any suggestions would be helpful.

Thanks
 

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it's posb you got water on a connector ?, never wash atvs with a pressure washer around the electrical connectors, bad idea !..lol. anyway, check to make sure there is plenty of fuel in the tank ?,and its on ??..lol. other wise, yeah, a good tank cleaning/carb rebuild might be in order ? :).
 

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Yup a pressure washer is what it was... anything I can do about the water now or just let it air dry?

It looks like a new Carburetor was recently installed, I'll want to check if its OEM. I'll report back on what I find.
 

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Yup a pressure washer is what it was... anything I can do about the water now or just let it air dry?

It looks like a new Carburetor was recently installed, I'll want to check if its OEM. I'll report back on what I find.
lol, might be a china knock-off carb ?..lol. let it air dry.
 

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You could pull the plugs and blow them out, might take ages to dry if one is full of water. Hope your carb is OEM, that’s gonna suck if it’s a China special.
 

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Could be water on anything esp plug wires. Did the PO seem like he knew a lot about the machine?

Download the service manual below and walk your way thru the periodic inspections.

Backfiring is typically a lean condition. Could be carb not set right, boots not tight. Jets gummed.

Try some fresh gas and a bit of seafoam cleaner. While the tank is empty, peer in to see if the petcock screen in dirty. I’ve found a rubber glove and a screwdriver in my last tank
 

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Discussion Starter #7
Appreciate all the replies guys!

So I don't think its an issue with the carb although it is an aftermarket one. Something Keikhin made in Japan... When the machine quits, it doesn't sputter or nothing, just shuts off. Thinking its eltrical

I found the spark plug to be cracked but after replaced I'm continuing to have the same issue. I noticed after the machine is running for 5 minutes at max, just idling the engine will get extremely hot AND the fan doesn't turn on.

Is there a sensor which would shut off the machine if it gets too hot?

I put some seafoam in the tank but no luck.
 

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Yes check the manual ignition troubleshooting guide. Your fan control might be bad; I found the power wire disconnected on one atv after connecting work perfectly. On my present project the fan control doesn’t work and so I hooked the fan to a switched power source
 

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Discussion Starter #9
Update...

I cleaned the gas tank and carburetor, changed the speak plug(tip looks good), tested the fan(NOT WORKING) and ran a compression test... continuing to have the same issues. Waiting on a coil to be delivered to get that replaced.

The compression test read 70PSI, does that seem low?

I'm also noticing a small knock near the valve cover, valves need adjusting?
 

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Update...

I cleaned the gas tank and carburetor, changed the speak plug(tip looks good), tested the fan(NOT WORKING) and ran a compression test... continuing to have the same issues. Waiting on a coil to be delivered to get that replaced.

The compression test read 70PSI, does that seem low?

I'm also noticing a small knock near the valve cover, valves need adjusting?
either you did the compression test wrong ?, or your rings are worn ?. 70 psi is low. knock at valve top could be anything.
 

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For the compression test... I had the carburetor, tank, and air filter disconnected but I don't think this would affect the compression.

Connected compression tester to spark plug input, held the throttle all the way in, and turned over the engine until the compression gauge stopped moving. Anything I'm doing wrong and could this cause the bike to stop running after 5 minutes?
 

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For the compression test... I had the carburetor, tank, and air filter disconnected but I don't think this would affect the compression.

Connected compression tester to spark plug input, held the throttle all the way in, and turned over the engine until the compression gauge stopped moving. Anything I'm doing wrong and could this cause the bike to stop running after 5 minutes?
your not suppose to remove the carb from the intake, leave the carb on, push the throttle wide open, crank it over, a few secs cranking over will show you your compression.
 

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Update...

I cleaned the gas tank and carburetor, changed the speak plug(tip looks good), tested the fan(NOT WORKING) and ran a compression test... continuing to have the same issues. Waiting on a coil to be delivered to get that replaced.

The compression test read 70PSI, does that seem low?

I'm also noticing a small knock near the valve cover, valves need adjusting?
You did the compression test right if you held the throttle wide open while cranking the motor over with the starter. 70 PSI is not a terrible reading either, considering that many testers are not accurate. The 400 Foreman motor has a decompressor, so the normal cranking RPM compression spec on a warm motor is 78-121 PSI. 70 is close enough at this point in troubleshooting... it should run fine with that.

I would adjust the valves next though. Get a copy of the service manual and follow the procedure.

You'll have to replace the china carb with an OEM too, if thats what you have on it now. But first make sure the mechanical condition of the motor is sound, that you have good spark, the choke is not stuck open and that it isn't overheating.

And have fun...
 

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Keihin should be the stock carb check the Parts numbers of the carb, jet numbers, everything. Backfire is a lean condition sounds like starving for fuel is your issue
 

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Discussion Starter #15
Oh I'm have fun alright!!

Ran the compression test again with the carburetor attached. Same result, also ran a wet test and the compression jumped to 110. Plan on checking the valves next to see if they need adjusting and re-test compression. I pulled the valve cover off today as I wanted to make sure oil was circulating in the top end which it appeared to be.

Received my replacement coil today but this didn't resolve the issue as hoped. The bike is no longer backfiring, think this was resolved by cleaning the carburetor.

Could there be an issue in the top end with the compression jumping so much been the dry and wet test?
 

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I was pretty sure a dirty or malfunctioning carb was involved. You may also have a valve sticking open after it warms up, which could also cause some noise.
Check the slack in the decompression lever that could also cause top end knocking
 

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I was pretty sure a dirty or malfunctioning carb was involved. You may also have a valve sticking open after it warms up, which could also cause some noise.
Check the slack in the decompression lever that could also cause top end knocking
there is no decompression lever to check on his model, it's built into the cam, they are not like the trx300's that have the decompression lever :).
 
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Discussion Starter #18
Back again...

Bike seems to idle good now after a thorough carb cleaning and valve adjustment. I tried running the bike around the house after idling seemed good and the bike stalled.

When on the gas(only when in gear)I hear a clunk, the bike losses throttle response and then dies. Any ideas?
 

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Back again...

Bike seems to idle good now after a thorough carb cleaning and valve adjustment. I tried running the bike around the house after idling seemed good and the bike stalled.

When on the gas(only when in gear)I hear a clunk, the bike losses throttle response and then dies. Any ideas?
check your timing !!!. what I mean is, check the timing by removing the sight cap, flywheel in top dead center. only prob I see is ?, is the front cover has to be removed in order to see if the cam chain is lining up with the index inside the case. I have a feeling your cam chain is stretched ?.
 
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