CRF 450 carb question 2

[C41Xracer]

i need some jetting and needle recomendations for my hybrid crf450.My main jet is a 170 and clip on needle is in the middle.Here is my problem pipe gets hot fast and starts to glow red and back fires alot and blows a flame out the pipe.It sounds like its way fat but could be wrong.Also is hard to start

[ZRider400]

check your plug and see what color it is.

[BSTURDIVANT]

Check your hot start cable to seee if you have enough slack. My be staying open!

[C41Xracer]

plug is a little black on the electrode and the rest is clean.I also checked my hot start and its fine.Here is when i noticed the problem, this motor would run 100% fine with the stock CRF exhaust, then i put a TC slip on silencer.It ran fine for a few times then started giving me problems.

[protrax]

put in a 50 pilot jet and a 165 main. leave the needle in the middle, that should clean it up

[C41Xracer]

ok ill try it

[joe1l]

Sounds to me that you are running lean, especially since the problems started happening after you put on the slip on. I would definately go up on the main jet to a 180 and go from there.

The main jet has nothing to do with the problem you are talking about. Backfiring and pipe being red at idle are all signs of a too lean Pilot jet. Take it out and see if the pilot is clogged. If it is, clean it and put it back in. If still the same symptoms turn your fuel screw out 1 turn. Still have problems, go up 1 size on pilot and raise your needle 1 position. Only the YFZ's glow on the headpipes.

[C41Xracer]

here' the deal now.................185 main and 50 pilot, no back firing any more but the motor still gets hot and head pipe starts to glow.Whats the deal still to lean????

[BSTURDIVANT]

Raise the needle 1 clip abd see what happens- we had a crf450 and it glowed at the headpipe at part throttle. Titanium headpipe is thin!
Ride the Quad and re-check plug, if not showing lean, run it hard!!

[C41Xracer]

the clip is on the 3rd position from bottom and is glowing at an idle

[C41Xracer]

Here is the fianl result........170 main, 50 pilot, needle on 2nd position from bottom and idle mixture screw(on bottom)4 3/8 turns out.This thing run awsome now and thanks for all your input

[joe1l]

Only the YFZ's glow on the headpipes.
The trx450r headpipe glows if you let idle too long right from the factory. This has been discussed before, and has been agreed that it is a normal behavior.

[jgfarmsracer]

Is all that with a stock piston, air cleaner

[C41Xracer]

yeah it all stock internalls, LSR air box and TC slip on w/stock Ti head pipe