08 crf250r head pipe glowing red after idling 30 seconds

I acquired a 2008 crf250r that supposedly had been rebuilt, but didn't have spark. Well I replaced Cdi box and got fire. Could not kick bike for nothing. Bump started on second try and ran like crap, popping and sputtering. The head pipe was also glowing red after 30 seconds of run time. Could it be valve adjustment or maybe a tooth off? Gonna take it apart Monday. Anyone have this problem before?

Pilot jet could be clogged. Check clean carb. Especially if it sat for a long time with gas in it

5 minutes ago, tom02cr250 said:

Pilot jet could be clogged. Check clean carb. Especially if it sat for a long time with gas in it

That's what I was thinking since it was popping when running. Thanks for the input!

We're you in a not so great lighted area??? 

Edited by DEMI
4 minutes ago, DEMI said:

We're you in a not so great lighted area??? 

It was a little cloudy and rainy out but not in dark. 

Those conditions amplify the intense heat, lots of those bikes do that... my yz400 did that in a garage and I thought it was going to burn up!! If you were outside, sun, you wouldn't have noticed. 

"Normal"... others will say the same.

Normal for a header to do that.

Buy a new pilot jet. When you pull the cap off the bottom of the carb, if it is not near spotless, the carb should be properly cleaned.

Confirm valve clearances, recheck them in 10 hours or less to confirm they are sound.

IMO be methodical and sort the starting issue out first. Could be the valves and if your are taking it apart, check them first.

Then the 3 things.

Spark - Do you have the correct CDI and the correct new plug and is the timing correct?

Gas - Is there good gas, is the fuel filter clean, is the carb clean and set correctly?

Air - Is the air filter clean etc?

 

44 minutes ago, William1 said:

Normal for a header to do that.

Buy a new pilot jet. When you pull the cap off the bottom of the carb, if it is not near spotless, the carb should be properly cleaned.

Confirm valve clearances, recheck them in 10 hours or less to confirm they are sound.

Thanks for the reply! Does the carb have to be removed on this model? I hope my repair manual arrives by Monday... 

Edited by Tim Allen Elvington
51 minutes ago, filterx said:

IMO be methodical and sort the starting issue out first. Could be the valves and if your are taking it apart, check them first.

Then the 3 things.

Spark - Do you have the correct CDI and the correct new plug and is the timing correct?

Gas - Is there good gas, is the fuel filter clean, is the carb clean and set correctly?

Air - Is the air filter clean etc?

 

That's my plan on Monday. I'm gonna check those valves and pull the carb bowl and clean the jets for safe measure. Thanks for the input!

44 minutes ago, Tim Allen Elvington said:

Thanks for the reply! Does the carb have to be removed on this model? I hope my repair manual arrives by Monday... 

Well... depends. If you have the tools and know what you are doing, no, it does not. I can swap a pilot jet in three minutes tops. But I ahve done it more often than most change underwear. I also have the specialized tools that make it easy.

First thing, (fuel petcock 'off') is remove teh cap on thje bottom of the carb (17mm wrench) is there junk in the bottom? If so, then the carb has to come off and get cleaned. If it is clean and after you have looked at some pictures, identify the pilot jet (use a mirror) A narrow straight blade short screw driver takes it out. When putting it back, just snug, do not crank down on it. Be sure teh driver you use fits and does not have to be forced in., you will break the carb. It is a fragile, precision instrument and very expensive.

1 hour ago, William1 said:

Well... depends. If you have the tools and know what you are doing, no, it does not. I can swap a pilot jet in three minutes tops. But I ahve done it more often than most change underwear. I also have the specialized tools that make it easy.

First thing, (fuel petcock 'off') is remove teh cap on thje bottom of the carb (17mm wrench) is there junk in the bottom? If so, then the carb has to come off and get cleaned. If it is clean and after you have looked at some pictures, identify the pilot jet (use a mirror) A narrow straight blade short screw driver takes it out. When putting it back, just snug, do not crank down on it. Be sure teh driver you use fits and does not have to be forced in., you will break the carb. It is a fragile, precision instrument and very expensive.

Fortunately I have the tools needed. I am a master tech in my day job. Just recently been bit by the dirt bike bug. Lol thanks a ton for the help!

19 hours ago, Tim Allen Elvington said:

Fortunately I have the tools needed. I am a master tech in my day job. Just recently been bit by the dirt bike bug. Lol thanks a ton for the help!

Where roughly do you live and ride?

The reason I'm asking is that for example, I live and ride generally at sea level but can get to say 5000ft elevation pretty quick in temps from say -4C to 35C. When you have the manual there is a spec for float hight and a table for carb settings which IMO I would start with stock (which I have for my set-up an med works for) unless your continentally riding at say for example high elevations and high air temps.

I also use an aftermarket pilot screw in case I do want to adjust on the trail cus the OEM one is a bitch to get without rotating the carb.

7 hours ago, filterx said:

Where roughly do you live and ride?

The reason I'm asking is that for example, I live and ride generally at sea level but can get to say 5000ft elevation pretty quick in temps from say -4C to 35C. When you have the manual there is a spec for float hight and a table for carb settings which IMO I would start with stock (which I have for my set-up an med works for) unless your continentally riding at say for example high elevations and high air temps.

I also use an aftermarket pilot screw in case I do want to adjust on the trail cus the OEM one is a bitch to get without rotating the carb.

I live and ride in West Tennessee mostly. Typically around 500 to 1000 ft. elevation. Definitely going on to get one of those aftermarket pilot screw as well. 

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now