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View Full Version : the idle knob is maxed out on my 85 250r, What to do



EastWest
03-15-2011, 06:41 PM
When I bought the trike several years ago it would idle good with the knob barely up,but slowly I have been having to turn up the idle knob on the carb to keep the trike running. Now that it is maxed out I rekon it is time to address the problem. Who knows, maybe I have overlooked a simple adjustment, i just dont get much time to play with it these days. The motor has been ported and who knows what else complete with a re domed head that leaked when I got it. Only thing i have replaced is the reed assembly which is a v force. The old assembly had a stuffer and was grinded on in different places. I have taken the carb apart and attempted to make sure everything was clean. There was some gunk inside the idle knob, but I cleaned it with no real noticeable difference. The head is fixed and It seems to be running good besides the idle issues. A set of rings would probably make it run even better and maybe that is the problem. I did bring the trike out to Oregon, so the atmosphere & elevation have changed, I rekon by about 2000 feet, perhaps less, but the problem began long before i moved the trike.
Any help will be greatly appreciated, Thanks!

coolpool
03-15-2011, 06:43 PM
Is it possible that the idle screw is worn down? Or that a groove has worn into the slide?

EastWest
03-15-2011, 06:54 PM
I don't know about the screw, but the slide seems pretty snug in it's housing. I was reading about timing on another idle based thread, could a jump in timing cause a crummy idle, can these motors jump time without quitting all together or burning up? I wish I know where my manual was. . .

coolpool
03-15-2011, 07:07 PM
Not sure about the timing but I can't see it being an issue with a two stroke. What I meant about the slide is that there is a groove in the side of the slide machined like a ramp that the idle screw rides in. If a groove starts the slide will drop lower into the carb body slowing the engine speed down.

MonroeMike
03-15-2011, 08:25 PM
There's a pdf manual here.
http://72.52.143.80/~trikes/atc250r_85-86_servicemanual.pdf

Dirtcrasher
03-15-2011, 08:35 PM
If your slide is grooved up, get a new slide.

Other wise, try jumping up one size on the pilot jet...........

cr480r
03-16-2011, 03:21 AM
is it still using a stock carb? if a keihin pj has been swapped on you may need to replace the choke plunger

RubberSalt
03-16-2011, 03:33 AM
I'd make life easy and get a carb kit. The jets might have a partial clog, but a carb kit can fix it all back up.

EastWest
03-17-2011, 01:52 AM
I am not sure what model the carb is, tomorrow I will find out.

RubberSalt
03-17-2011, 04:13 AM
In that case, a carb kit wont work - youll nee to get new jets for the trike + the kit, odds are that the kit wont come with the jets needed.

EastWest
03-17-2011, 03:34 PM
The carb is a Keihin PJ. the main is a 145 that I have suspicions of being drilled out. I forget the pilot size, but Il find out later. .