CFMOTO 244cc Idle Issue By sinister008 (Read 1,935 times)

[sinister008]

Hello all.

My scoot seems to be possessed.

I can tune the throttle (cable) adjustment to the right RPMs and then the next time I start the bike, it needs re-adjusted because it's either much too high,
or way too low (usually too low, but not always).
I haven't tried tinkering with the carb just yet, because I wanted to check to see if that was the most sensible course of action.

I have a Jonway YY250T with the CFMOTO motor, and I'm assuming that the "Carb Tuning Illustrated" PDF in the tech library will be close enough for me to follow
if all I'm doing is turning the Idle Mixture Adjustment Screw.

She barely has 100 miles on her.
So I don't want to go adjusting the valves just yet, do I?

It runs great when the throttle is tuned just right...nice and smooth, but having to adjust it so often just isn't practical. Haha...
As soon as I correct this problem, I have to figure out why my left headlight NEVER comes on (Hi or Low beam).

Any advice, or words of wisdom?

[richardthescooter3]

Your Air/fuel mixture may need adjusted

[sinister008]

Thanks for confirming my suspicions.

My main question was regarding a good illustration or picture I could go by, and whether or not the "Help_Carb_Tuning_Illustrated.pdf"
(located in the tech files section) would be a good enough one to use?

TIA

[kz1000st]

Intake manifold issues aren't uncommon on CN-250 motors either. A slight crack in just the right spot would have you pulling your hair out.

[cruiser]

The CfMoto engine is fairly tolerant of tight valve settings. This can make it difficult to set a good idle speed even when the engine seems to run good. After checking for leaks at the intake manifold like kz said, I would adjust the valves before going any further. Both my valve adjusters moved 2 notches for the best adjustment. This also improved starting and idling.

The headlight problem could be a bad bulb, but I think it's either a bad connection or the bulb was improperly installed to start with.

[sinister008]

Aug 3, 2012 21:44:57 GMT -6 cruiser said:

The CfMoto engine is fairly tolerant of tight valve settings. This can make it difficult to set a good idle speed even when the engine seems to run good. After checking for leaks at the intake manifold like kz said, I would adjust the valves before going any further. Both my valve adjusters moved 2 notches for the best adjustment. This also improved starting and idling.

Okay. I was hoping I could just adjust the idle on the carb (because it sounds easier).
I don't really know why...but I had it in my head that I shouldn't adjust the valves before I'd put on 200-300 miles
and since the scoot only has 100 or so, I guess I thought I'd be "upsetting the break-in process".
I get a bit silly sometimes.

Aug 3, 2012 21:44:57 GMT -6 cruiser said:

The headlight problem could be a bad bulb, but I think it's either a bad connection or the bulb was improperly installed to start with.

You're probably right on that one. too. I'm leaning toward a bad or improperly seated bulb.
I checked, and if I reach under the front and swap the headlight plugs, the right side works on either plug, but the left...not so much.

The thing that bothers me is that I just finished putting the scoot back together again yesterday, and now I'm taking her apart again.

It's kinda' exhausting. Hahaha.
I guess I'll go get started.

[scootaway]

I would go with the advice given sinister. It is probably air/fuel too lean and or valves need an adjustment. Was a pds (pre-delivery service) done, they might have done it wrong. I would suggests you follow the old rule of adjusting one thing at a time and test to see if the problem is fixed

[nulldevice]

Do not use the cable adjustment to set the idle. Use the screw on the throttle shaft (the circular plate the cable connects to).

Use the cable adjustment to give you just a little slack when the throttle is fully closed.

Check the cable adjustment by turning the handlebars from lock to lock and make sure the idle speed doesn't change.