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2008 Foremen 500 only revs up with choke on

2K views 6 replies 3 participants last post by  TannerPennell 
#1 ·
Hi everyone, I have an ‘08 foreman that I bought for a project. I was told the timing chain snapped so they installed a new one with a new tensioner, but when they put it back in the quad, he told me that it would only backfire. I found the timing was 180° (ish) out. So I set the timing to the correct markings. Installed it, and she fired right up. But the next problem was the exhaust got red hot within a few minutes. Turned out to be the quad was running entirely too lean. Now since I’m the 3rd person who is attempting to get this thing back together, I have no idea what has been done with the carb. So I ordered and installed a new carb. Direct replacement supposedly already pre set. I put the new carb on and primed it a few times, and she fired right up and sounded great. But, once I go to give it throttle, it boggs down and will die if I keep trying to give it throttle. I don’t see any adjustment screws other than the idle screw. Was wondering if anyone had any ideas? I have installed a new spark plug, fresh oil, new carb, clean air filter. And the guy before me who took it apart and set timing wrong also installed a new top end. Supposedly 100% factory specs. No larger piston. Any help would be appreciated!


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#2 ·
i would make sure the timing chain is set right with the camshaft and flywheel marks, ( make sure it is not one tooth off) also check compression and set valves.Not knowing how it was rebuilt anything could be wrong, all parts should have been checked, measured and made sure they were within the shop manual specs.
 
#3 ·
The timing is correct. I set that when I bought the bike, all timing marks are aligned and in spec. As for the valves, that’s another thing I’m going to do, but have to wait till I get back to work on Monday to get my feeler gauges, and compression gauge


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#4 ·
Hi everyone, I have an ‘08 foreman that I bought for a project. I was told the timing chain snapped so they installed a new one with a new tensioner, but when they put it back in the quad, he told me that it would only backfire. I found the timing was 180° (ish) out. So I set the timing to the correct markings. Installed it, and she fired right up. But the next problem was the exhaust got red hot within a few minutes. Turned out to be the quad was running entirely too lean. Now since I’m the 3rd person who is attempting to get this thing back together, I have no idea what has been done with the carb. So I ordered and installed a new carb. Direct replacement supposedly already pre set. I put the new carb on and primed it a few times, and she fired right up and sounded great. But, once I go to give it throttle, it boggs down and will die if I keep trying to give it throttle. I don’t see any adjustment screws other than the idle screw. Was wondering if anyone had any ideas? I have installed a new spark plug, fresh oil, new carb, clean air filter. And the guy before me who took it apart and set timing wrong also installed a new top end. Supposedly 100% factory specs. No larger piston. Any help would be appreciated!


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You buy an OEM carb or aftermarket Chinese junk?
 
#6 ·
Aftermarket carbs are hit or miss, mostly miss.


If I'm taking the time to troubleshoot something that isn't working right the last thing I want to do is replace a potentially faulty part with another faulty part, which leaves me chasing after other solutions when that same component has and continues to be the problem. I've used cheap china carbs on small stuff, but I've seen too many ATV's that would never run right but were miraculously running perfect with a good OEM carb installed.


You can download a free factory service manual here. https://www.hondaatvforums.net/foru...nual-help/50817-service-manual-downloads.html


There should be an adjustment screw on the bottom right behind the bowl. #6 in this schematic.
https://www.partzilla.com/catalog/honda/atv/2008/trx500fm-2a-fourtrax-foreman-4x4/carburetor






If it were me, I'd clean that factory carb. What jets were in the factory carb? Should have numbers stamped on them. A factory is 62 IIRC.
 
#7 ·
Jeepwm69,

I agree, I don’t like not using OEM parts on anything. But I have had good luck with the carbs from the company I bought his replacement from, called “Karby”-I think. But the four wheeler was not running right before hand. It was running way too lean, causing the exhaust to get red hot. And like I mentioned in the original post, I’m the 3rd person to try n get this bike running haha. So far I’m also the only one to have it actually run. But I will try those links you sent, because I’m doing this without a service Manuel, just going off what I can find online in my spare time. I should be able to work on it this weekend I hope


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