CR jetting issues

[scotty dog]

Im running 98 octane

[SachsGS]

Has your CR run better in the past? What's running through the back of my mind is that I recall Motocross Action doing a test on your bike and having problems similar to what you described.I also remember them becoming quite frustrated in their attempts to rectify these "driveability"
issues.I'm trying to figure out if your jetting problems are just that, jetting problems,or if you are up against something more that is a result of Honda releasing a motorcycle that was (maybe) not quite right.The CRF450 was brought out just after this model (if my memory is correct) and your case reed,electronic power valved CR suffered as a result.

[scotty dog]

Could it be very sensitive to temperature/weather conditions etc?
The reason i ask is yesterday the thing ran perfect!
It didnt reslly choke up at all, only a slight sputter when i would go back on the track.
Last week was wet n miserable and about 19 degrees C
Yesterday was perfect about 25 C. The best day for riding.
Now that you mention it Sachs it has its moments.
I might still get a leaner pilot just to clean up the bottom.
Thanks for the input :-)

[xandyx]

i think the best way to get a proper jetting to a cr is to forget about the mikuni tmx and go for a keihin carb.

i'm about to do that on my cr 125..

[scotty dog]

I thought getting a new carb too........maybe one thats attached to a new bike :-)

[oldermxr]

Scotty I see you are still having some problems with your CR250 I would still try going 1 number smaller on the pilot jet there not that expensive. And something else I was wondering how old or how many times have you rode your bike with the spark plug you have in it now? Plugs for a 2t don't actually last a real long time maybe your plug is in need of being replaced. And how fresh is your pre-mix your useing?

[eprovenzano]

Could it be very sensitive to temperature/weather conditions etc?
The reason i ask is yesterday the thing ran perfect!
It didnt reslly choke up at all, only a slight sputter when i would go back on the track.
Last week was wet n miserable and about 19 degrees C
Yesterday was perfect about 25 C. The best day for riding.
Now that you mention it Sachs it has its moments.
I might still get a leaner pilot just to clean up the bottom.
Thanks for the input :-)

I can't answer about your CR, but my KTm is very sensitive to weather conditions.  Currently I've jetted it for summer conditions, but I will be adjusting as it gets colder. Sometimes its just an air screw adj, but when it gets colder, I'll be adjusting the clip position, and then the needle too.

[oldermxr]

Scotty how many races/rides do you have on the present spark plug in your CR250? your bike isn't going to be tempermental to only a 6 degree tempurature change.#1 It could very well be that your spark plug needs to be replaced #2 did you mix up a new batch of pre-mix and you got new gas? You could have got ahold of some bad gas too that does occationally happen.

[scotty dog]

Oldermxr, im not too sure how old the plug is, i know its not too old but i think it might have been fouled and cleaned so im gunna get a new one and a smaller pilot, i didnt get a chance last week due to work, my premix is always new, i put what i dont use in the car.
Thanks fellas :-)

[oldermxr]

Scotty your plug could very well be part of your problem that I last read about specially if it's been fouled before and cleaned. If you are doing alot of racing and play rideing I would replace your plug every 8 races/rides. And glad to see your going to go with 1 number smaller on your pilot jet. A new plug and smaller pilot jet you should be good to go.

[scotty dog]

Will let ya know how it goes,
thanks Scotty

[throttle violence]

Im not happy with the way my 05CR 250 is running at the moment.

It fouls up easily if im just riding slow even for a short distance and it never has been very crisp.
On the weekend even just sitting on the start gate for 2 minutes it would choke up even though i had just cleared it out. Although i have issues with it pinging. I dropped the needle one clip position but then it pinged worse so i lifted the needle 2 positions and it stopped it pinging and seemed to run ok on the track.
Its doing my head in not really knowing what to do and i know it will perform a whole lot better once its sorted.
I checked out the FMF jetting guide and they reccomended,
Pilot-35
Main-410
Needle-12-82 second clip position
Air screw- 1.5

At the moment it has
Pilot-40
Main-430
Needle-26-65.......(im guessing you go by the last four numbers on it)
Clip- 4th position....(down from the top)
Air screw- 1.5

I dont know what the standard jets are but have been told that it is one bigger than stock on the main and they go up in tens.
I think its stock apart from the FMF Pipe and shorty and i run 98 octane.

Any help or suggestions would be greatly appreciated if i haven't confused you all

Cheers Scotty

[throttle violence]

maybe get rid of the mikuni carb and put a keihin

[oldermxr]

Scotty I looked at the test that Motocross Action Magazine did on your 05 Honda CR250 and they said going up one on the main jet made it burble on going down one made it ping so they left the stock 420 main in. Your clip possition on your needle should be 3rd from the top. Your air screw should be 2 turns out from all the way in with useing the stock pilot jet wich is a #40. Also try your pre-mix ratio at 40:1 instead of 32:1  that will make a big differance also. Your running too rich so you need to lean it out put the stock 420 main jet in try 1 smaller on the pilot and mix up your pre-mix at 40:1 Turn air screw all the way in and back it out 1/4 turn and start the engine start blipping the throttle and turn the air screw out 1/4 turn at a time till you get clean crisp throttle responce also put a number #8 spark plug in it.