My new 05 CRF 450

[fnengineer]

question on my new 05 CRF 450

I picked up my first 4 stroke today and I have a couple of questions.

I haven't ridden it yet but when I rev it up a bit it backfires pretty bad, small flames out the exhaust. Is this normal?
If not what could the problem be?

Second if I try to rev it real quick it will usually die or sometimes backfire.

Any suggestions?

 

[BEEF706]

A question for you did you let it warm up with the choke on for a bit before you revved it? mine pops a bit especially when cold, but not like you describe, I am at altittude so mine should be a little rich but so far so good with stock jetting BTW you are gonna love this ride it rips :ride:

 

[Revlimiter Racing]

Yeah - I have an 04 which I just gave to my son and I just picked up the '05. I dont have this problem though. I would say your jetting is off. Sounds like your air/fuel mixture needs some work in the very least. Where do you live? Are you at sea level or up in the mountains? My '04 used to feel like it was going to die when it was warming it up and I revved it....it would bog. I rejetted it and the problems totally disappeared!
-Shane

 

[jimt_yz400]

This usually reflects a lean condition on the pilot or fuel mixture area.
Try turning your fuel mixture screw out 1/4 turn at a time to see if lessens the popping.
You could also be lean on the main jet though you can try the fuel screw 1st to see if affects the popping.
Cheers!

 

[fnengineer]

I will try the air screw first and see what happens.
I let the bike warm up for a few minutes first.
I am in Utah at about 5000 feet in elevation. My dealer changed the main jet but not sure what they put in yet.
Thanks

 

[02crf450]

I live in utah also. Where did you get yours I may be getting one in the next few weeks.

 

[fnengineer]

I purchased mine from Honda Suzuki of Salt Lake.

Update on backfire. I adjusted the air screw out to sea level 1 7/8 and the back fire during the rev seems to be much better.

 

[02crf450]

If you dont mind me asking what was the OTD price.