Glowing red header pipe

**03rm250** · 14th April 2010, 18:43

Hi guys.

Tryed starting my crf today for the first time in two weeks and it was a b*#ch to start and finially when i got it going after about 5mins of idling the header pipe was glowing red hot.

Surley this can't be right, Last time i rode the bike it was perfectly fine.

Bike is a 09 crf250r dune 100hrs.

Any help would be great.

Cheers Daniel

**bogan** · 14th April 2010, 18:45

exhaust valve knackerd would be my guess.

edit, so check the compression to find out

**03rm250** · 14th April 2010, 18:47

if i checked the clearences would i be able to tell??

**steve_t** · 14th April 2010, 18:48

Not running lean?

**03rm250** · 14th April 2010, 18:52

im not 100% sure lol, bike run mint as last time i rode it.
oh and also while trying to start it some of the time it would backfire real loud.

Originally Posted by steve_t

Not running lean?

**Crasherfromwayback** · 14th April 2010, 18:54

Originally Posted by 03rm250

if i checked the clearences would i be able to tell??

If exhaust valve is tight...it could cause the exhaust pipe to get pretty hot. It'll also burn the exhaust valve and fuck it in no time too. Do a com test as Bogan says...AND do the valve clearances.

**CHAPLIN** · 14th April 2010, 19:00

If you leave the choke on for to long this will happen

**kevfromcoro** · 14th April 2010, 19:10

Originally Posted by CHAPLIN

If you leave the choke on for to long this will happen

does it... wouldnt of thought so....
mayebe you are right......
i know timing will do it.
interesting thread

**Crasherfromwayback** · 14th April 2010, 19:47

Originally Posted by CHAPLIN

If you leave the choke on for to long this will happen

I'm not so sure a rich mixture will heat the header pipe that badly that quicly.

**vifferman** · 14th April 2010, 19:48

With the exhaust being really hot, and the backfiring, it sounds like it's really lean - possibly an air leak.

**03rm250** · 14th April 2010, 20:29

right.. have checked the clearences if sitting on bike.

exhuast; left is .005. right is .005.
intake; left is .003 right is .004.

acording to this website
http://crfsonly.com/howto/crf250x/cr...adjustment.php

the exhaust should be .011 and intake should be .005.

would this be the cause, or do these seam ok

**pete376403** · 14th April 2010, 20:32

The header pipe on my KLR will glow red hot if it's left on a fast idle for about ten minutes. Nothing wrong, it's just a combination of a bit of heat and the air injection system that puts fresh air in the exhaust port to burn any excess hydrocarbons in the exhaust gas. It's only making the pipe glow because there's no cooling airflow.