CRF450X thread.....

[zzlejeune]

Originally Posted by BikePilot

Red hot is actually quite normal for a thin-wall header - most modern 4-strokes actually do this. It won't usually be red when you are riding due to the airflow I guess, but at a fast idle it'll glow. No worries (and definitely don't go and try to jet the bike based on header temp). If you mess with jetting just jet it so that it runs the way you want it to run. Also, you needn't worry about hurting the top end with jetting - it isn't really possible (note how most all non-MX bikes come lean from the factory, but virtually none cook themselves?). I think back way before I was born motors were poorly made and had to add extra fuel for cooling - they weren't able to run at an optimal mixture (which generally would yeild peak EGT). Technically, a lean mixture will actually reduce temp, but most folks are rich so leaning might increase EGTs, but you needn't worry. Again, just jet it so it runs well.

If you care, the first thing to go from high EGTs will be the exhaust valves. The head gasket doesn't give a crap what EGTs you like (though sitting around for 10 minutes without moving might be pushing your luck with coolant temps). It is normal for it to overheat when stopped. Unlike street bikes and cages its cooling system only works when the bike is moving (no fan). It isn't made for being stopped and running.

The CRF is a fantastic, high performance bike, have fun with it and don't worry so much (but also don't treat it like a cage and leave it idling forever!).

Thanks for the advice and info........the header did look normal under riding conditions, and the bike performed well under throttle, it just doesn't like to stop for long... It definitely is set lean, so I'm looking forward to getting it properly jetted and running well. Plus the jet kit will come in handy once I'm up in Colorado for our trip, since I'm about 26' above sea level here....

[Sturgell]

For engine longevity I would jet it rich to help keep it cool since it doesn't have a fan and every little bit helps.

[Jono777]

Definitely jet the bike properly. It makes a big difference in how the bike runs. I too have a CRF450X, and love it. I'm in Southern California (0-6000 ft), and have a mostly stock bike (stock exhaust, stock motor) and am running a 165 main, and 45 pilot; but I did take the "snorkel" off the top of the airbox underneath the seat. Also, if you don't have one already, get an adjustable fuel screw. I run Engine Ice coolant, and it seems to help keep the bike cool. Enjoy your new ride...

[zzlejeune]

Originally Posted by Jono777

Definitely jet the bike properly. It makes a big difference in how the bike runs. I too have a CRF450X, and love it. I'm in Southern California (0-6000 ft), and have a mostly stock bike (stock exhaust, stock motor) and am running a 165 main, and 45 pilot; but I did take the "snorkel" off the top of the airbox underneath the seat. Also, if you don't have one already, get an adjustable fuel screw. I run Engine Ice coolant, and it seems to help keep the bike cool. Enjoy your new ride...

I did purchase a Flex-Jet also, and still waiting on my JD jet kit. The stock jet (142) is what is in the bike now, the PO had a couple of extra jets that he had tried, a 145 and 148, but judging from everyone else's settings (good setup info on CRF's Only), I'm probably looking at needing a 160 or close to it. It still has stock exhaust and header and I'm going to do the airbox mod this week, plus draining the coolant and replacing with Engine Ice, so hopefully by the time I get the jet kit in and installed, she'll be ready to fire up!!

Unfortunately I've only ridden the bike twice, due to the poor jetting....

[markjenn]

Originally Posted by zzlejeune

I did try to not let it sit long without getting some airflow across the radiators, I would probably say around the 8-10 min range, so I was probably pushing my luck, and even then it would die out once I turned the choke off, I had to constantly play with the idle screw.

So you're letting the bike sit for 8-10 min on enrichner, bumping the idle screw so it will run without throttle? This is a sure-fire recipe for glowing headers and an overheated bike.

I suspect there is absolutely nothing wrong with your bike. You need to start it up and as soon as it will take throttle, start riding gently. Get it off the enrichner ASAP.

- Mark

[zzlejeune]

Originally Posted by markjenn

So you're letting the bike sit for 8-10 min on enrichner, bumping the idle screw so it will run without throttle? This is a sure-fire recipe for glowing headers and an overheated bike.

I suspect there is absolutely nothing wrong with your bike. You need to start it up and as soon as it will take throttle, start riding gently. Get it off the enrichner ASAP.

- Mark

Well, there's more to it than just that, it will not idle off of choke within the first 3 - 5 mins of warm up, and it constantly back-fires at high idle, and even when under way after warm up, it will back fire everytime coming off of throttle, after about 10 mins of actual riding, it starts to act a little better.

Guys, For what it is worth, I have a 2006 CRF 450X and I have not had any problems with it. And it is for sale! I am replacing it with a KTM 525 EXC. Time will tell if it was the right thing to do.

[Larry Ferguson]

Originally Posted by zzlejeune

It is backfiring some after it idles down, which takes forever, ....

That just screams leak in the intake. Check the intake boot for leaks before you do anything.

[Jono777]

Originally Posted by zzlejeune

I did purchase a Flex-Jet also, and still waiting on my JD jet kit. The stock jet (142) is what is in the bike now, the PO had a couple of extra jets that he had tried, a 145 and 148, but judging from everyone else's settings (good setup info on CRF's Only), I'm probably looking at needing a 160 or close to it. It still has stock exhaust and header and I'm going to do the airbox mod this week, plus draining the coolant and replacing with Engine Ice, so hopefully by the time I get the jet kit in and installed, she'll be ready to fire up!!

Unfortunately I've only ridden the bike twice, due to the poor jetting....

Install the JD jet kit, and your flex-jet fuel screw...adjust the fuel screw properly. Then report back...I'm certain this will take care of the issues you have described.

Checking the air boot described above is also good to do, just to rule it out and make sure it won't be an issue after you do your mods.

[zzlejeune]

Finally got a chance to work on the bike.....

Installed JD jet kit (165 main jet with red needle on 4th clip)
Changed engine oil
Changed tranny oil (Running 1 full quart)
Replaced antifreeze with Engine Ice
Airbox Mod
Installed new Racelite battery
Wrapped header
Installed Flex Jet screw

As soon as the carb primed up, it started right away, idled like a champ, and came off of choke within 1 minute with no stumble, and revved with no backfiring!!!!

Took it for a quick run down the road, WOW, it has a nice mid-range grunt that it didnt have before, and it took some effort to keep the front end down under acceleration. It's like a new bike....

Thanks everyone for the tips and advice, can't wait to put it through its paces and fine tune the carb, if it even needs it....... Thanks again!

[Richie Mc]

Just sold my XR650R (pretty sad about it) and got brand new X set up with TRX piston and SS valves, the whole bit. Going in an 500km enduro race in a few weeks and now have to go thru the drawn out task of setting up suspension from square one.

Have standard springs at this point, I weigh 100kgs, don't suspose anyone knows if standard will be heavy enough?

[wrk2surf]

Its time for a new thread..

I have looked around and there seems to be no 450x thread.. I have a new (to me) 05 450 x with 80ish hrs and some mods... seems like this needs doin.. if you have mods please put em in here or link old mods to this one... Will do a oil change tomorrow and will start with that...

Mike

[wrk2surf]

Going over some things beside the normal air box, smog block, pink wire. There are some new radiators with oil cooler built in(= more oil) made by PWR a ozzie outfit offered by Chris Blais here.... http://blaisracingservices.com/Honda.../prod_596.html

When doing a oil and tranny change today I ran into this same issue.. http://www.thumpertalk.com/forum/arc.../t-667390.html
and may have a long tap in my future...

I was also informed the 05's have a 3rd gear issue and maybe should be replaced by a 06 or 07 slightly different machined gear..

also was told that using 1ltr in the tranny as opposed to .74 will help a bit...

Now to test it again tommorow!

[wrk2surf]

During high-load operation at extremely low
rpm, the crankshaft may experience instanta-
neous reverse rotation that momentarily
extends the decompressor plunger. The
extended decompressor plunger can collide
with the rocker arm with enough force to pos-
sibly damage the actuation pin on the decom-
pressor shaft. If the decompressor actuation
pin is bent or broken the engine will not start.
The UPDATE PROCEDURE outlined in this
Service Bulletin will replace the decompres-
sor shaft and plunger on 2008-2009 CRF450X
models with more durable components.


link to pdf bulletin... via crfs only dot com

http://www.crfsonly.com/forum/images...__r36__web.pdf

[trailrider383]

Interesting. I guess I must have the "more durable components" in my 2005 model.