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Discussion Starter #1
Please Help!!!!

Hi. I am new to the forum I’ve read a lot of post on here but now I got a question of my own.. I’ve got a 2006 Honda foreman trx500fm is was running really rough when I bought it so I decided to rebuild the top end.. After getting it back together it started right up and ran fine! I took it for a 5 minute ride it ran fine at first and then it started to act up and slowly got worse and worse until it Quit.. I just put a brand new carb on it thinking it was a carb problem still nothing I can get it to fire up only when I continually press the prime on the carb.. or if I hold my hand over the back of the carb and let it build vacuum and only then will it start and idle as long as I only let a curtain amount of air in but as soon as I remove my hand it dies... it will start for just a bit with the choke on... I’m really stumped on this one it seems to have good compression but just not a ton of vacuum.. I would really appreciate and help from you guys!!!
 

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Sounds like a bad carb or the motor is out of time..

Is the carb OEM Honda or a China knock off from eBay or Amazon?
 

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Discussion Starter #3
The carb is a brand new oem carb made sure it wasn’t a cheap junk one!... I was thinking maybe timing to but it will idle smooth when I have my hand on the carb...?
 

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If you have your hand on the carb it would suggest to me to much air and not enough fuel.. Check the timing.

I assume you adjusted the pilot (air/fuel) screw on the carb?
 

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Discussion Starter #5
Ok. No I didn’t touch the fuel/air screw! I’m pretty sure the are pre set from the factory.
Thanks for the quick replies!
 

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Ok. No I didn’t touch the fuel/air screw! I’m pretty sure the are pre set from the factory.
Thanks for the quick replies!
No I wouldn’t think they are preset you should still have to perform throttle cable synchronization, adjust the pilot screw and idle screw
It sounds like the carb is not clean—like there’s an obstruction in the enrichment or idle circuit—stumbling like that i think it’s starving for fuel. Especially after it was running well I would remove it and blow out the jets
 

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Discussion Starter #7
I was adjusting the idle screw but on these carbs you need a special tool to adjust the air/fuel screw! I’m thinking it’s either timing, spark plug although I just put a new one in it it isn’t a nice blue spark anymore.. and I might try re adjusting the valves.?
 

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Leave the valves, check the timing. If timing is fine it's a carb issue. Clean, clean and clean again.. If it looks clean it probably isn't! It needs to be surgically clean..!!
 

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Discussion Starter #9
ok I will see if I can check the timing sometime soon.. do I need a new gasket before taking off the front cover?
 

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Discussion Starter #10
I took the carb off everything looks very clean I blow out the jet stuck it back on and no different.. I might have to check the timing..
 
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