[dodemans]

Hey all!
I have a CRF250 04 , it has been running 100 hours since rebuild but since i bought the bike like a year ago it would never idle low.
I need to get the Idle to about 3000 for it to not die on me , Wich is all fine on a track but its a road bike for me(Has the crf R engine , not the X) .
It never liked to idle below 3000 and it keeps jumping a bit , i have replaced the spark plug , it has new intake valves (and intake+exhaust are on point). It has a brand new ignition and i tried two different carburators (both orginal), Carburators were clean.


What's normal for a CRF to run? 3000 seems a bit high for me.
Ofc my airfilter and fuel are clean also

Thank you!

[JimDirt]

Manual says 1,700 rpm +/-100 rpm

What is the jetting ??? , what is your fuel screw set to ?? , what elevation are you at ??

Also , have you tried setting the carb to stock specs ??? (I know you have tried several carbs , but if they were not set to your elevation and jetted accordingly , they can all have the same issue) , have you taken each of those carbs apart , and when you did , was the slide removed ??? , if so is the hole in the floating slide plate at the bottom or top ?? , if you are cleaning the carb (all of them) and put that plate upside down , you will have all sorts of issues ... ..... one last one , what are you using to determine the rpm's ???

[dodemans]

Manual says 1,700 rpm +/-100 rpm

What is the jetting ??? , what is your fuel screw set to ?? , what elevation are you at ??

Also , have you tried setting the carb to stock specs ??? (I know you have tried several carbs , but if they were not set to your elevation and jetted accordingly , they can all have the same issue) , have you taken each of those carbs apart , and when you did , was the slide removed ??? , if so is the hole in the floating slide plate at the bottom or top ?? , if you are cleaning the carb (all of them) and put that plate upside down , you will have all sorts of issues ... ..... one last one , what are you using to determine the rpm's ???

Hey jimdirt! thank you for your reply!
I'm not sure what you mean with what elevation?
The hold in the floating slide plate is Down , i got a 162 main jet in it and also tried a 168 i had laying around , wiht both jets same problem. The carb i got on Right now i never opened , it came of a running crf250 and i just threw it on to see if anything was different but nope... same problem.
I didn't touch the Fuel/Air screw at the bottom.


I make a mistake above about the 3000 PRM. its actually 4000.
I'm using a Koso RPM meter , its attached with a wire to the spark plug , and i believe it as it really is idling very high.
Problem is , the bike drives amazing.. so im not thinking about flooding or anything like that , just the idle is not going lower then 4000 without problems , when i set it to 3000 it jumps and just shuts off sometimes (engine doesnt sound like its heavy running as broken bearrings or bad rod or anything btw)

[dodemans]

Looks like the pictures aint showing

https://ibb.co/4fSKBYL
https://ibb.co/PgLB2gR
https://ibb.co/W25tN0R

[JimDirt]

Elevation is the altitude where you live/ride , like sea level , 800 ft , 4,000 ft , etc , like if you live in California on the coast it would be sea level or close to it , if you live in the mountains of Colorado you would be around 5,000 ft above sea level , your elevation is critical to jetting correctly , the 162 or 168 main jets wont help if you are not at the correct elevation to run that size jet , and will make tuning almost impossible .... for example if you bought a bike from someone that lived in Colorado , and you live in the Arizona desert , the bike most likely will have severe jetting issues and either won't run , or will run poorly or have issues idling , or starting .... follow ??

[dodemans]

Ah got ya
Accorting to the internet we'r (in holland) are 22Ft Below sealevel.
I bought the bike from a dealer in holland but i don't know where it came from before him

[Leardriver]

The pilot jet affects the idle. The main jet doesn't affect idle at all. Either the needle clip is way off, or the pilot circuit is plugged. Does it idle down when you pull the choke on?

[JimDirt]

This guy (above) is the carb expert here , so whatever he says , is what you should look into ....

[dodemans]

Thank you both!
When i turn the choke on the RPM's will go Higher (cold start) i will try with warm engine in about a hr , its too early over here
The Clip of the needle is on the Second Lowest.
I bought a ''Moose Racing revision set'' with all the stock jets for over here, gonna start it soon and let you know if it fixed the problem.
It had all the Jets , needle and sealers.

[dodemans]

The crf drives way better and seems to have more power with the rebuild kit.
but the idle still won't work , If i put it on about 4000 RPM It works but anything below it's jumping too much and eventually cut off.
Its just way too high idle to be in traffic.
Also warm engine +Choke is Higher RPM.

I also Disconnected the cable from the carb to see if that did anything but didn't seem to impact much

[JimDirt]

OK , jumping too much , you mean when you leave a stop light/sign , and try to take off it blubbers ?? , or it lugs like you are starting out in 4th gear ??? , if it is the latter , then you might need to regear for street riding by going up 1 or 2 teeth on the rear sprocket , or 1 tooth on the front (1 tooth front equals about 3 teeth for the rear) ... OR , your clutch may be the issue ... a worn clutch basket will make it real "grabby/jerky" when taking off from a stop , and can make is stall easy

If you lay the bike on its left side , propped up by the handlebar on a crate or 5 gallon bucket or something about 1 foot high , then remove the 6 bolts from the round clutch cover ..... pull the 6 screws holding the springs , pull the springs ,pull the plate and pull out the clutch disk/plates , look at the basket , if it looks like the one in the picture below , then that might be your issue and you can either file the grooves out (a temporary repair) , or replace the basket

If it has grooves like this it is worn:

[Aussiecrf230]

Hi dodemans,
If you have a high idle and pulling the choke on makes it go faster I would tend to think you have an air leak.
Could be on carby boot or the hot start is not seated or is stuck letting air in.

[dodemans]

Hey both!

No the clutch is all brand new and just about 10 hours old , The driving of the crf is amazing no issues at all even on highways just amazing.

The only problem the bike has is the Idle.
I keeps jumping or higher or lower without me even touching the bike
This video is after a 30min Normal Road use ride, it jumps without reason higher untill i touch the throttle for a sec higher.
https://youtu.be/nSaBbBBD4vA
Yes if i put the choke on (hot engine) the rpm's go higher

The engine has been fully rebuilded 100 hours ago , even with a entire new clutch and crankshaft , so i really think the problem isnt in the engine itself but in the carburator.
Also the stator is brand new.
The carburator is now fully rebuilded but the idle is still a problem (this has been a problem since i bought the bike even before the rebuild)

Note: The bike has a Radiator fan (so it shouldnt be a overheating problem)

[bosshaug1]

I watched/listened to your video.

My guess is your slow air jet is plugged. My logic is that it is only in play when idling, so when you first get to idle after riding, there is enough air/fuel to keep engine running. Then, as it continues to idle, it becomes more rich, due to not enough air coming through the slow air jet. This is like being choked and thus RPMs rise. If you snap the throttle, a new charge of fresh air/fuel through the main circuit will allow you to continue idling. If you don't snap the throttle, then eventually the idle circuit will be starved of air and die.

Disclaimer: I am NOT a carb expert, just thinking out loud.

[dodemans]

I watched/listened to your video.

My guess is your slow air jet is plugged. My logic is that it is only in play when idling, so when you first get to idle after riding, there is enough air/fuel to keep engine running. Then, as it continues to idle, it becomes more rich, due to not enough air coming through the slow air jet. This is like being choked and thus RPMs rise. If you snap the throttle, a new charge of fresh air/fuel through the main circuit will allow you to continue idling. If you don't snap the throttle, then eventually the idle circuit will be starved of air and die.

Disclaimer: I am NOT a carb expert, just thinking out loud.

heyhey thank you!
Shouldn't be plugged as all of the jets are replaced , the crf had this problem before already and even on different carbs i tried.
The bike works amazing but if i dont let it adle at about 4000 it just jeeps jumping.

Its killing me as i really can't find the solution to this