Honda Foreman Forums banner

2003 Foreman 450 running hot

1 reading
21K views 24 replies 6 participants last post by  SSpeckerwood  
#1 · (Edited)
I bought a 2003 4x4 Honda foreman 450s that had a blown up motor.It was setting outside for about 10 months. We tore the atv down to where the only thing that was on the frame was the wiring harness and everything on the front(diff, shocks, brakes). We ended up buying another motor. It was a 2002 Honda foreman 450s 4x4 motor. It was shipped to us so it was tossed around and when we opened the box the motor did have oil on it.so we cleaned the motor some and put it in. We put the carb, gas tank, exhaust, and air box on. We also replaced the oil and oil filter. We got it running but at first it was backfiring out of the carb and wouldn't idle. We found out that problem was the carb. We bought the carb that was on the motor that we bought and ended up having to clean it.That fixed the backfiring problem problem but it still doesn't idle and now its running hot.We found that the main jet was clogged and that fixed the running hot problem, or a least we thought. We were able to ride it it went through all 5 gears and it wasn't running hot. Later we started it to adjust the idle screw and it was running hot again. We put a carb kit in and cleaned the gas tank. We were able to ride it again and it want through all 5 gears and it wasn't running hot but still wont idle. We adjusted the valves because they were ticking really loud and when we started it the motor ran quietly but was running hot again.

I don't know why it's running hot but want to get it fixed before we tear the motor up. Any help will be appreciated.
 
#2 ·
is the machine running lean? does it have good compression?(blown head gasket) where was the oil u were talking about, on the motor?
 
#3 ·
did you clean the oil cooler lines out ? since it sat outside for 10 months . we got a big problem with mudd wasps around here and thay will plug just about any hole (like you sspeckerhead lol). also check the boot on the carb for cracks or splits (will cause a lean pbroblem and run hot ).......rich
 
#4 ·
x2 on everything rich just said. lol
 
#5 ·
to revise the original post. its not so much the motor is getting hot its that the header will get cherry red within thirty to 45 seconds of starting it. this is why people have told us it is running lean. also i have read on other posts that it could be timing or the valves but since we adjusted the valves and the motor still runs okay when we have rode it i don't think it is the timing.
 
#6 ·
you asked me where the oil was. it was on the outside of the motor. we think it may have been shipped upside down for a little while.
 
#7 ·
i'm betting ur running lean
 
#9 ·
yes and no. do u know the altitude the machine came from? if it came from higher altitude ur putting more air than gas in there. if thats the case u may need to re-jet it
 
#11 ·
thats a good idea, see i knew rich was good for something...
 
#12 ·
to answer you sspeckerwood on the altitude the carb and motor came from St Charles, IL and when we put the carb kit in it looked like it had been jetted and we didn't replace the jets so it should still be jetted
to answer rich another problem is wont idle right. it will but it either idles high or it shut off there is no in between
 
#14 ·
i dont have the atv at my house, so i might be able to get some one to do it but i dont know when.
Before when we had this same problem(header getting hot) the plug was white there was no black on it.
 
#17 ·
then he must not know what he's talking about. ur exhaust wouldn't get hot if ur motor wasn't getting hot. ya know what i mean?
 
#18 ·
grab a manual for the bike, reset the carb to factory specs IE: jets AF mixture etc.
Retest, then jet as needed, if there is no work done to bike and no airleaks you should be gtg or **** close.
 
#19 ·
All the solution you guys are giving me are good but what i want to know is how come sometimes the ATV runs hot and sometimes it doesn't. Like we got it running and rode it down the road and rode through all 5 gears and it didn't get hot. The next day we started it and it was running hot again. I didn't do any thing to it it just sat in my garage over night and it started running hot again.
Also I wanted to make clear that it is the top end(head,cylinder)of the motor that is getting hot. The header is also glowing red. But the motor it self isn't getting hot. When we run it long enough for the header to get hot i can still touch and hold my hand to the motor.
 
#20 ·
thats because ur most friction is up in the cylinder. have u happened to check ur oil flow. maybe ur not getting enough oil to the topend and having it get hot. its all a process of eliminations. u gotta narrow everything down. some intermittent stuff will come and go. dont be discouraged
 
#21 ·
carb

hey man i had same problem with a foreman and if the header gets cherry in 30 sec and doesnt like to idle and pops threw carb its running lean and your problem is 99% in your carb i dont know where the problem is "if you figure it out let me know please" cause we cleaned our old carb a half dozen times reset everything to factory specs and still had the problem we ended up buying a new carb of ebay $175 fixed the problem we own 3 foremans so we took a carb off of a known good running quad and placed it on the quad that was running lean and it fixed it so we knew that was the problem hope this helps
 
#22 ·
u might of had a crack somewhere in the carb allowing a air leak.

op- have u sprayed carb cleaner around ur carb to see if its sucking air anywhere. it may not be ur carb but even a cracked intake manifold or a bad seal somewhere in that region
 
#23 ·
I realize the problem is in the carb and that the motor is getting to much air but what i don't understand is how sometimes the motor runs hot and sometimes it doesn't
 
#24 ·
Jeremy, the advice rich and sspeckerwood have given is sound, I wouldn't focus so much on the overheating other than knowing that you have that condition and then try to identify what is wrong with the fuel mixture and addressing that, address the fuel mixture you'll most likely address the overheating. If there is a speck of dirt in the carb or a loose piece of dirt or dirty jet, it could cause the overheating problem intermittently, thus making it more frustrating to diagnose. To add, it would explain high, low and no idle conditions.
 
  • Like
Reactions: 1armhottie
#25 ·
my dad's 450 had a spec of dirt in the carb. it would come and go and would make his bike run like ****. cleaned the carb, never had another trouble