CRF's Only Forums

Hey whats shakin guys,
Ive been trying to figure this idle out, its running high with the choke not on.

Im not sure if adjusting the throttle cable at the carb did it. My throttle was a little sticky and still holds open when i crack the throttle. So i adjjsted the throttle cable at the carb. It fixed the throttle sticking.

It idles high when hot, i can hit the decomp lever and it bring it back down for 5 to 10 secs then idles high again.
Good luck adjusting the pilot screw fml.

Any ideas?

Thanks so much

Was it doing this before ???

The Hot Start (not a Decompression Lever , these are Hot Start Levers) , it leans the mixture so it is easier to start when hot or after a tip over when you usually flood the engine ... why can't you adjust the fuel screw ?? , is it the D shaped one ?? , you can get the tool for it at any bike shop , or just remove the carb or twist it sideways by loosening the clamps , so you can get a clear shot at the screw , and remove the screw with needle nose or something , or remove the bowl so you can grab onto the screw easier , and replace it with a R&D Flex Jet , or a aftermarket fuel screw , the issue with the X (I have a 06) is with the starter there , it is harder to get at the fuel screw , so I personally use the R&D Flex Jet , as it makes life so much simpler when needing to adjust the screw , you can even adjust it while you are riding with that screw

The idle can be your cable adjustment still , what I would do is loosen the adjusters at the carb again , the one with the nut should be just about bottomed out , the other should be bottomed out as well , then the throttle should snap back , then , any fine tuning can be done on the cable at the throttle housing , it should have some slop to it , it should not be tight , and you should be able to turn the bars lock to lock and hit the throttle and it should snap back at each lockout point , if not , then readjust , or , you have the cable bound up under the tank , lift the tank and see if it frees up , it is easy to place the cable over the valve cover instead of besides it , then when you install the tank it pushes down on it ,and your throttle sticks ... ask me how I know this ...

So check that stuff and make sure it is how I said .... Also , if you are using a aftermarket cable , I have seen issues with them having too thick a sleeve and it pinches it as well when the tank is installed , I quit using aftermarket cables , and went back to OEM , they always work right and are always the correct length ..

Also , if you fell on the throttle side , it may be jammed into the bar , so loosen the clamp and slide the throttle housing out about 1/4 inch , then make sure you have end to end play , so the throttle tube should slop in/out to the end of the bar , if it is all the way in , it will bind ..

Yo Jim thanks for the quick reply, the bike wasent running when i got it. It needed a valve shimmed. So this is the first time ive heard it running.
Funny you mention about running the cables along the top of the motor, cause thats exactly what i did lol. The throttle kept getting hung open so thats why i re ran the cables. Now the throttle shuts but the bike runs fast when it warms up.

Im going to re run these two cables, adjust them at the carb to where they were. Im also going to get that pilot screw to move.
The pilot screw is behind one of the screws that keeps the carb together right ?
Its an 05

Ill write back and let you know what happens

Im looking into getting that pilot knob too

The fuel screw is at the center front(to the front of the bike) underside of the carb , these are from my 450X Factory Service Manual



In the 2nd pic the Slow Jet is the Pilot Jet


The Needle Jet is the long tube the Main Jet screws into and what the Slide Needle goes into to close off or open up the Main Jet for fuel delivery when opening or closing the throttle


When messing with the carb , unless absolutely necessary , do not remove or try to adjust the Throttle Position Sensor , which is the black part with the wire at the top of the carb , it is very sensitive to adjustment and you need a Ohm meter to set it

So I ended up adjusting back the throttle cable at the carb like you said, also routed the throttle cables properly and zip tied them. It seems to have made a big difference, it reved a little high but it would go back down quickly. And not often

Gonna test some more later this week.

Thanks jim

Good to hear ... Also check your fuel screw adjustment , if it is off , it could cause the slow return ..

Try to set it to these specs


And make sure that it snaps back turning the bars lock to lock , just to make sure there is no cable bind or adjustment still ..

So back to this idle issue..... i ran the cables the throttle snaps back great now.

The bike is stock, no exhaust, no jetting as far as i can tell. It has the oem skid plate lol
2005 crf450x
The bike idles well after warm up but after ive been riding for 15 minutes and the bike warms up fully the revs go up when im stopped. If i put the bike into first gear and let the clutch out the revs drop and the bike idles fine, but goes back up a few seconds later.

Im not sure whats causing this? The hot start lever also bring the revs down but the bike back fires and proceeds to idle high again.

I havent messed with the idle screw, mostly cause its an 05

Thanks for any input

It could be a hanging idle, or some version of one.

A slightly plugged pilot jet or passage is letting enough fuel through it to run, in a less than ideal air/fuel mixture. That can be made better by taking the pilot out, changing it or trying to clean it, and blowing out the passage that the pilot screws into with air.

The idling could be the Needle Jet is worn out (that is the long brass tube that the main jet and the needle go into) when it wears , the needle will bounce around and cause inconsistent idle .... The Hot Start making the idle come down tells you that there is a rich condition that is making the RPM go up , (reference back to the needle jet worn allowing extra fuel from the main jet because it is not closed off all the time due to oval nature of the worn hole that used to be round and would seal when the throttle was closed , now it allows fuel to bypass what otherwise would be blocked)

So due to your explanation , that is what I would do is go to the Honda Dealer and get a Needle Jet , and a needle and replace them both , and you should be good to go ....

EDIT: , just noticed Leardriver posted while I was typing .... so do what he says first as he is the carb guru here , so he is usually right , then refer to the Needle Jet ...

Thanks for the good info, i took the bottom plug out again and sprayed carb cleaner in while twisting the throttle i had a little bit of something in the bottom of that plug

I also let it get to operating temp and adjust the screw on the side i turned it a half turn right and it brought my idle down to perfect while hot.

I have to test ot again im gonna let the bike cool first.
I have one more issuse where it sounds lile my coolant ia bubbling in the rad after its been running.is this normal ?

If i didnt solve the issue im gonna remove the carb and do a rebuild. Its too hard to work on with it attached to the boots still

To clean the pilot jet and passage:

Loosen the boots, twist the bottom of the carb towards the left, remove the 17 mm plug, turn off the gas, and lay the bike on it's right side. You may have to drain the tank a little with a long funnel into a gas can from the petcock hose.

You can now see the jets clearly. Remove the pilot. You can't clean it with just carb cleaner and a quick spray unless it is barely dirty.

Spray up into the hole that the jet came out of. I even use a metal dental pick to gently wiggle around up in that passage, in case a chunk of ethanol pudding is blocking things. Air compressor spray nozzle up in there.

Do all of this 2-3 times. It will take 10 minutes.

I replace my pilot jet at least yearly. A 10 pack of them online is less than $12, and saves a lot of guessing.

I had it twisted and sprayed in the hole, i didnt remove the pilot as i didnt want to damage anything....but i will. I may have fixed it. What is that flat head screw driver knob on the choke side of the carb ? I turned that a half tob3/4 turn wjen itbwas hot and it dropped my idle perfectly. Im gonna start it from cold this morning and see if its fixed if not the pilot jets coming out

The flat blade screw is the Idle adjustment .... I am guessing your fuel screw is the D shaped one , you can get a tool for it .. any of your local bike shops should be able to get one , or should have one in stock .... (EPA thing so you don't mess with the mixture) until you get a replacement ....

As shown in my prior post above , this shows the flat screw (Throttle Stop Screw/Idle Adjustment)





And yes it is normal for it to boil if you are running it for more than a minute or 2 without riding ... the bike is "Air Cooled" (as well as water cooled) , which means if air is not flowing thru the radiators (just like a car) it will get hot (your car has a fan to keep cool air flowing over the radiator core , on your bike , riding does this) , you can install a fan kit on it (I have one on my 06 450X) , or while working on it , just put a box fan in front of the radiators and turn it up to keep airflow going to help cool it down , it is not a fix , but it will help

Here is a guide Leardriver made to tell you where you need to be with jetting , you should be jetted like this chart and have your fuel screw adjusted as shown above in the manual page I posted earlier ... it should be around 1-1/4 to 2-3/4 out from lightly seated , you adjust it till the idle raises slightly , then go the other way till it drops , and go in the middle of that and you should be good , which will probably be around 2 - 2-1/14 turns out

Jetting Guide for Main Jet:(pilot 45) CRF450R/X

Sea level....165
2000 ft.......162
4000 ft.......160
6000 ft.......158
8000 ft.......155


Temperature/Elevation:
One main jet size (up/down) for every 2,000 feet or 25 degrees in temp.