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Discussion Starter · #1 ·
hello all, just joined am in need of help badly. i have a 2003 honda foreman 450es.
last year it started loosing power greatly on acceleration, and then the worst happend...the valves snapped and one went into the piston and one went into the head.
replaced head and piston, honed cylinder, changed oil, set valves and it started up and seemed to work great around the yard.
i took it for a drive to the trail today and didnt even make it all the way to the trail (bout 2km away or roughly a mile) and it started loosing power and speed, i stopped and let it idle while i tried to think what it could be, tried reving the engine and it would start to spit and sputter wanting to stall, again it would idle just fine no problems. turned it off checked the air filter seemed fine. started the bike back up and limped it half way home, stopped again and played with the choke and found that if i put the choke on half way to full it seemed to get better, after a min or 2 of playing around on the side of the road i went on my way again and it seemed to be working just fine again, then a quarter mile from home it started again and limped it the rest of the way home again.
any ideas what could be causing this? its interminitent and seems to be more when it gets hot and drives high speeds. im wondering if the plug and carb could have something to do with it, i put a new plug in but it was just a cheap champion plug.
any help would be greatly appreciated, its been a year since ive got to do a good ride and im eager to get riding again

thanks
 

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If it seems to run better with the choke on, then I would start with taking the carb off and cleaning it good.
 

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Discussion Starter · #3 ·
i forgot to mention every time it starts happening is when driving at high speeds (max speed actually)
do you think i should try the high speed plug as well?
 

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You could try a new NGK brand spark plug, but after rereading your post, I don't know if it would be the carb or not. Are you sure you got it in time right and are you sure you adjusted the valves right?
 

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Discussion Starter · #5 ·
im sure the valves are right, i set them both for .006 gap as the specs in the manual say. and never touched the timing, i only did the top end of the motor. i think it was an overly rich condition that killed the bike before, there was a small heat hole burned in the hold piston head wich i beleive lead to the breaking valves. which is one of the reasons im leaning towards a higher speed plug and carb as the problem. also like i said for the most part it will run great with no problems, and then all of a sudden after driving at 77kmh for over 4 or 5 mins is when it starts. let it sit for a while and its fine again.
 

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maybe your filter is broke off in your tank my was doing that and i pulled out mine to check it out and it was broken replace that and it's working fine now. hmm
 

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Just a quick question have you checked your air filter and carb boots?
 

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Discussion Starter · #8 ·
maybe your filter is broke off in your tank my was doing that and i pulled out mine to check it out and it was broken replace that and it's working fine now. hmm
actualy i took the filter out because it was broken, couldnt get a hold of one so put a inline clear filter in. wonder if that might be the problem
 

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im sure the valves are right, i set them both for .006 gap as the specs in the manual say. and never touched the timing, i only did the top end of the motor. i think it was an overly rich condition that killed the bike before, there was a small heat hole burned in the hold piston head wich i beleive lead to the breaking valves. which is one of the reasons im leaning towards a higher speed plug and carb as the problem. also like i said for the most part it will run great with no problems, and then all of a sudden after driving at 77kmh for over 4 or 5 mins is when it starts. let it sit for a while and its fine again.
Yeah, I forgot, those don't have an overhead cam. It sounds to me like it might be running lean.
 

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Discussion Starter · #10 ·
woo hoo[/B

problem solved. removed the inline fuel filter and installed a new fuel line today. no more bogging out and loosing power at high speeds. i had suspicions that it wasnt flowing enough when it started acting up, when i looked at the clear inline filter it was only half full, but when i started it up today it was completely full so it really made me wonder if it was starving for fuel at high speeds because it just wasnt flowing fast enough and sure enough i removed the filter and tried blowing thru it and could feel the restriction of flow.


thanks everyone
 

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Great. Glad you got it fixed and it was something simple.
 

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Discussion Starter · #12 ·
me 2, now i just gotta get my brakes working, back brake i cant get at all and just replaced the shoes last year, but no matter how much i try to adjust i start to get a lil brake and then loose it all together. and for the front i always have to pump them about 5-8 times every time i stop to get brake
 

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Does it have drum brakes? If it does, the front probably needs to be adjusted up. If that don't fix them, then they will need to be bled. If it has discs on the front, check to make sure the pads aren't worn out. If they aren't, then they probably need to be bled, because discs don't have an adjustment.

If the back are drums, you might need to check them and see if they are worn out. I know you said you replaced them last year, but those drum brakes on the rear usually don't last too long, especially if mud and water gets into them.
 

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Discussion Starter · #14 ·
thanks, already ahead of you on the front, adjusted them up after i posted that and i got front brakes at least right now, prob wont last long tho because there is very little left on the shoes.
the rear shoes have only got about 3 months maybe on them, and even after i replaced them it wasnt long mayb 2 weeks before i started loosing the rear brakes again, im thinking the brake cam might be worn out. ive got a little over 6000km on the bike and thats the first time i changed the shoes since i bought it 4 years ago, the old ones even had a little bit of linning left to them even, if it were a car they still would have passed a safety inspection even.
i adjust the rear till the wheels almost wont move by hand in the air, but as soon as i pull the lever i loose all tension on the rear brake and i can push the brake arm even in pretty far, further then i could when first adjusting the rear, i could push it only a quarter inch and then the rear wheels wouldnt move by hand, after pulling the lever i can move the arm 2 inches and still the wheels spin free

oh and its drums all the way around :(
 

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I don't know then. You might just have to take the rear brakes apart and see what it looks like in there to determine the problem.
 
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