[dirtrider67]

i just bought an 04 crf450 that only runs with the choke on and it overheats. i tore the carb apart and cleaned the jets and that didn't help. the motor sounds good and powerfull but pops and pisses when the choke is turned off. any advice would be greatly appreciated.

[124]

I assume it ran good before...

If yes, sounds like an air leak. Check the intake tract to make srue the carb didn't slip out of the boot. Check all the clamps, etc, etc...

Check the exhaust flange bolts.

If all checks out OK, check compression.

[nedirtbikr]

Is where it came from and where it is a significant change in elevation?

[dirtrider67]

i bought the bike in this condition thinking it only had clogged jets. the guy i bought it from was up front about it running bad. so the first thing i did was clean the carb. that did nothing for it.

yes, same elevation and it has a 165 main.

[Mr Smith]

You have an extreme lean condition of some sort or possible head gasket leak. Check your carb again, and check for water in the oil or oil in the water. How long does it run before boiling over?

[dirtrider67]

it spews antifreeze out in less than a minute. not a lot, but i shut it off immediately.

[Mr Smith]

This is an R correct? Your sig says X. Im assuming its an R because you say its an '04. My R will overheat sitting at idle in about five minutes. The rads arent big enough to support sitting at idle for very long. Does it run ok above idle or crappy all over?

[dirtrider67]

when i take the choke off, it dies. i rode it down the street with the choke on and it seems to have plenty of power. turn the choke off, it dies. it does sure a little with the choke on.

i just got this 450R for my son. my ride is a 450x.

thanks for your help

[Mr Smith]

I just caught on to you saying its got a 165. The R comes stock with a 170 main. Did you get a manual with it? In the back shows the stock jetting the R comes with and the correct needle settings. I would take the carb to those specs exactly and tear out the backfire screen in the air filter if its still got one. Put the fuel screw at 1 1/4 and you should be good to go if theres no mechanical problems. I also run Engine ice in my R...Helps the overheating issues 150%

[dirtrider67]

thanks for the advice. i have a 172 main so i'll try throwing that in and see what happens.

thanks for your help.

[nedirtbikr]

I just caught on to you saying its got a 165. The R comes stock with a 170 main. Did you get a manual with it? In the back shows the stock jetting the R comes with and the correct needle settings. I would take the carb to those specs exactly and tear out the backfire screen in the air filter if its still got one. Put the fuel screw at 1 1/4 and you should be good to go if theres no mechanical problems. I also run Engine ice in my R...Helps the overheating issues 150%

Just for comparison, I run the following:
- Twin Air PowerFlow (backfire screen gone)
- JD Kit 180 main
- 48 Pilot
- Fuel Screw 1 1/8 out
- Engine Ice
- Nebraska riding (about a 1000' ASL)

Good luck!

[dirtrider67]

i just realized that the coolant is comming from the water pump weep hole. could this have anything to do with the way it's running?

[Mr Smith]

If its overheating yes....You check your fluid level in the rads lately?

You will need to replace that water pump seal. Real easy to do.

[nedirtbikr]

i just realized that the coolant is comming from the water pump weep hole. could this have anything to do with the way it's running?

Well, you definately need a new pump seal there. Fluid from the weep hole shouldn't really have anything to do with your "choke on/off" related running problems. Make sure your rads aren't REALLY low on coolant.

[dirtrider67]

thanks guys. i'll replace the waterpump seal immediately. my owners manual says that the stock main jet is 165. i'l still change it to a 172 since i have an extra.

do you think maybe it might need a new top end? it seems to have plenty of power. maybe a valve adjustment? i'll check the valves this weekend.

once again, thanks for all the help.