CRF's Only Forums

New to forum, need some advice, no good with carbs, so I've done some reading and still can't get this thing lined out...
I am at sea level and riding a "plated" '04 CRF450R around town and to work. It sees 5th gear for about 3miles on the way to work and RPM ranges from 4800-5400...(45-50mph). The rest of the route is in town...stop and go traffic. I have one "fire road" excursion to finish my trip to work.
Problem..Seems to be leaned out..plug is more gray than tan...
Surging when throttle is held at 1/4 throttle (mostly during highway trip...4800-5400RPM range in any gear)
Deacceleration Pop...
Surge goes away when choke is pulled, or if throttle is whacked open...instant wheelie.
Bike will not Idle when choke is off
Haven't found any air leaks
Hot Start is seating closed with a snap
Throttle Stop screw turns, but hose is slipping. Is there an aftermarket solution to this design.

Modifications and current settings....

Uni Filter
Yoshimura slip on
5oz. over stock flywheel
Trail tech lighting stator
NGK IFR9H11 plug
Pilot screw....1.5 turns out
Slow jet...45
Main...165
Clip is in 4th position down from top/blunt end.

I removed and cleaned slow jet, and put clip in 5th position from top on needle. Installed 175 main. Deacceleration pop is worse, hard to start and bike still will not idle. I'm going to put everything back to baseline and wait for some advice...

Any help will be much appreciated...

Has the carb been taken apart? Slide ever been removed?

[quote]Has the carb been taken apart? Slide ever been removed?

*I don't think so.

It idled fine when purchased, but has always surged a little as mentioned. It just started giving me trouble (deacceleration pop, no idle w/o choke) a few days ago and I decided it needed to be fattened up so I bought a step colder plug (was running an IFR8H11...went to a 9), and lowered clip to 5th position and installed 175 main.

While setting main and air back to baseline I discovered two things...

Throttle stop screw has cable under it...works fine

Bike will idle while carb is turned too access air screw. I can adjust air, set idle, and whack throttle...no pops and it settles right back down to an 1800 RPM idle.

As soon as I turn the carb the way it is supposed to be it dies. I can keep it started by opening throttle, but the backfire/pop comes back and it will not idle without choke.

What is this telling me???

Could be the rubber boot between the carb and head is messed up.

Could be the float level is wrong...should be 8.0mm.

I'll remove carb and check boot/float level. Haven't checked valves...Should I have went there first? This is my first CRF. Last bike was XR...two totally different animals.

Any links for checking/adjusting float level on the FCR carb?

I checked my valve clearance..

R Intake is 0.20mm or 0.008in
L Intake is 0.15mm or 0.006
L& R Exhaust is 0.35mm or .014in
Decomp is 0.30 or .012in...so when combined with R. exhaust is (0.65mm or 0.26in)

I have no idea about current shim size as I haven't taken it down yet. Do these measurements suggest I go ahead and pull the camshaft assy to check shims? Don't know how to do that yet...

Any suggestions for the new guy?

Floating Valve - Hole was on top
Bike started - No deaceleration pop
I can adjust fuel screw and achieve 1800 RPM idle speed, but now the bike shoots to 4000+RPM when I straighten the carb up... It's got to be something simple, but I've not found it yet.

Any input on those valves?

Check the freeplay on your throttle. It sounds like you rotate it and the throttle cables are free. Rotate it back and it stretches the cable and is holding the throttle open. Adjust the cables so there is some freeplay in the throttle tube.

mpdddiesel wrote:Floating Valve - Hole was on top

That's your issue...hole goes to the bottom...

bambamsc wrote:Check the freeplay on your throttle. It sounds like you rotate it and the throttle cables are free. Rotate it back and it stretches the cable and is holding the throttle open. Adjust the cables so there is some freeplay in the throttle tube.

Man what a learning experience this has been.
The Throttle stop was completely bottomed out in the carb and stuck. I was told by previous owner that dealership had replaced everything from the crank up including a thorough cleaning of the carb. I'm guessing the cable is broke inside. I manually turned it back down and missed the mark so now its idled too low. I'm going back in...

Can I get the following parts at CRF's only?

*Throttle stop screw/cable assembly
*Remotely adjustable Fuel screw
*14mm cap that covers the ignition side timing marks. Yes I hamfisted it and broke the cap

Used needle nose pliers to adjust the throttle-stop until bike idled...Took it out for a ride and seems to be running much better. Ordered replacement throttle stop and adj. fuel screw.

Sea level
Main is 175
Fuel is 2.0 turns out
Clip is in 5th position
Pilot is 45
Floating valve - Hole is on BOTTOM

Thanks for all the input. Great forum.

yes we can get you anything you need. for OEM parts go to our OEM parts website, www.yeltrik.com for aftermarket go to www.crfsonly.com. for anything you don't see on these two websites PM me.

ken

Im having the same issue with the engine not idling and is constantly at high idle and not returning to low proper idling speed, in your post you mention floating valve hole on bottom, can you let me know what that is as I am unsure or provide a foto.

any enlightment on why my throttle is not returning to proper idle speed would be gravely appreciated

Leak 70
Main 152
Pilot 42
Leak 58
Altitude 150 feet

This should help brother.

http://crfsonly.com/howto/keihin-fcr-ca ... rf450r.php