Shim the needles?

[Bill + Karen]

I know not GS related, but bear with me please. My CX500C has a lean stumble 4 to 5 grand not there every time, mostly when hot. I can move on by it using the accelerater pump. It has a Mac 2 to 1, finally opened up do to getting some muffler packing. 1st question, what do you use for needle shims? 2nd question, what would be a good starting lift, 1/16th inch, 1/32nd, any W.A. guesses would be greatly appreciated. Thanks and Safe Riding, Bill

 

[Jeff Tate]

Hi There, The shims I have in my carbs came with the jet kit and are approximatley 4-5 mm in diameter and have an inside diameter just big enough for the thickest part of the needles. Their thickness is probably about 1mm. You can probably find something that will work at Home Depot or such. I can't be sure of what type carbs you have on your CX, but for about 89cents it would be worth a try.
Here's a link to a site that explains basic carb tuning that may be helpful.
http://www.factorypro.com/tech/carbtun.html
Just copy and paste. Good luck.

 

[TheNose]

Jeff, that site was really helpful. I have been having trouble setting my floats and it gave me some good insight on setting them correctly. Thanks for the link. Lots of good information there.

Terry

 

[Anonymous]

mixture screws

mixture screws

Here's what I read on the above mentioned site:

"The fuel screws also, secondarily, affect part throttle / cruise - as in 2nd gear / 3,000 rpm, steady state operation - meaning that, if you think that you might need a larger pilot jet to correct a lean 3,000 rpm cruise, you could open up the fuel screws an extra amount (disregarding idle quality for the moment) and see if that helps the cruise.
Then, as long as you end up with best idle quality somewhere 1.5x to 3x turns out, you can enlarge the pilot jet size."

Am I correct in assuming the small screws on top and on the engine side of carbs are these screws? (32mm Mikunis) They are at 2? turns now. I might try turning them out more because it is definitely a lean condition. Running with the choke part way out makes the flatness disappear.

 

[Jeff Tate]

Yep! Those are the ones. If yours are at 2.5 turns out now, you still have have some room to experiment.If you find you have to go 4 turns out or more something else needs "fiddling" with . And believe me when I say I am an expert fiddler! Not to mention a Journyman "Tinkerer" Older bikes like ours came jetted very lean in this portion of the carbueration range from the factory, so I wouldn't hesitate to try a size larger pilot jets even on a stock bike. It's reletively inexpensive and might just give you a pleasant surprise... mine did.
Words to live by: Tighten it down till it breaks... then back it off a quarter.

 

[Anonymous]

screws

screws

Jeff, I tried the screws. Seems they are not affecting the range I am having trouble with. It made no difference in the stubling problem. It did affect my idle so I put them back to 2? turns. Using the choke in that problem spot does smooth it out. I am going to try shimming the needles up a little with thin washers then try jets.

Where can I get jets online? I assume we are only talking about main jets, right? Any ideas on sizes to get? My mains have a 115 stamped on them. Mikuni 32 mm. Thanks

I'm getting closer to a solution every day. (fingers crossed)