CRF's Only Forums

Hi, Firstly i am new to this forum but have been reading many of your threads over the past few weeks. great info everywhere you look!

I have very recently purchased a used 2005 450x road registered pretty new to the 4 stroke dirt bike scene, have road sport bikes and 2 strokes many years ago.

the crf is a pig to start when cold and warm. really struggling with it, it has been stood for a good while and battery has next to no life for electric start.

i have noticed when cold the bike is much easier to start when choke is off.

when it is running after only a very short time of ticking over the exhaust header is glowing bright red, i have read some things on this but only a little and have seen mixed opinions, What i would say is.. mine GLOWS very red.

The bike also back fires ALOT. big flames and pops and bangs like crazy on deceleration.

as far as i can see airbox is standard (not cut open) and has a full FMF system with power bomb.

also, i have no hot start cable, lever is there but no cable. could this cause any of the above problems????

any one advise me on what jetting set up just for full exhaust system? (i am at sea level)

could valve clearances cause all these issues?

any advice will be massively appreciated and my apologies for my lack of knowledge

Welcome to the site !!

You could have a few things going on , I am guessing you just bought this bike ?? , and are unsure of the prior owners maintenance , correct ??

First thing is , if it has been sitting for a few months , then its highly likely the pilot jet is clogged , it is much easier and better to just replace it as it is fairly inexpensive (about $6) for Sea Level you should be 45/165 , if it is stock it will probably be 42/142 , which is way too lean

I would also suggest looking at the valve lash (not sure of your mechanical ability/knowledge , or if you have either the Owners Manual or Factory Honda Service Manual , to help with doing any service , or if you will be referring your needed work to a shop) , but jetting AND valves being tight can cause the popping , as can a loose exhaust clamp , so you need to at least inspect this stuff to confirm or eliminate it from causing your issue

You can get away without a Hot Start Cable , as long as you have the alternative Hot Start Plunger , which is basically the same as your Choke pull knob on the carb , but i would not recommend running without one of the 2 , so your best bet would be to remove the carb , or at least tilt it so you can get to where the cable goes , and inspect that it does in fact have the plunger assembly still intact , or if its gone completely , if its gone , then this would also explain a lot of lean condition symptoms , so you will need to either replace the stock components , or get the alternative plunger setup

Not sure why it would start better cold without the choke , unless its over jetted , but if its backfiring and popping , this would mean a lean condition (or the valves or loose exhaust or Hot Start assembly missing or stuck in a closed or open position)

Also these bikes will glow at the header when running/idling for more than a minute or more , especially when viewing it in the dark or low light conditions , as the header temp is usually around 1500 degrees F , so it will glow to a point , but excessive glowing is usually a indication of exhaust leak or lean condition , so you will have to check things over to exclude them before moving to the next item............