Yet Another Rejetting Q

[applecrew]

I do a lot of cold weather riding at temps less than 40 degrees F, sometimes in the single digits (*Brrrrrrrrr*) here in winter in PA, and have frequently experienced lean stumbling at freeway speeds to the point of feeling that the lack of power was becoming a significant safety issue - I had one instance (it was 23 degrees on a clear, dry, cold morning where the air is very dense) where I was at WOT and could not accelerate past 60. I also have a lean misfire at just off idle when cold.

My ride is an '07 with 63,000 miles and I have taken reasonably good care of her... valve clearances checked & maintained regularly. Stock air filter & exhaust). I run a lot of fuel through her, so tank is spotless and she's never sat more than 2 weeks without a fresh tank of fuel to have to worry about varnish & gum buildup. I do not have any issues when temps are over 45 degrees F and she runs very well at that point and warmer.

I cleaned and rejetted carbs over the christmas holiday, going +1 size on pilot & main (20 and 132.5, respectively) and am 3 turns out on the mixture, and for the most part am pleased with the results  - the lean misfire at idle is gone, and when I open the throttle and get on the main jets, the bike really runs well and have no problems accelerating, even on the coldest morning.

Unfortunately, she is still pretty lumpy (lean surging) in the midrange and wanted to get opinions on addressing it. My two options are to either add washers to the needle or go +1 on the mid-range jets to 62.5. Does anyone have any info they would like to share?

Thanks & a safe & Happy New Year to all!

[jestercinti]

Try 2 washers (or 1 o-ring) under the needle -or- +1 on the mid-range jet.  You can also go an additional size on the Main if you want to 135.  That's the ideal jetting size for the stock config.  Set mixture screws to 3 turns out and adjust from there.

But, the mid-range is giving you the most problems, so focus on that for now.

In winter, you need to run richer than summer.  All else fails, run some Seafoam through it.  You may have picked up some bad gas or a speck of dirt got in the carb.

[Calpantera]

I would go ahead and add a washer to each and see what happens. You don't even have to pulls the carbs to do it and would know right away, heck if you have extra long fuel lines like mine you can even leave the tank connected. But remember if it does not help to switch back to one washer if you the change the jets..

[motopumps]

We currently have two GS500E's, one a 1995 and one a 1999.  Both had mid-range sags, the 1995 being huge.  I had previously cleaned the carbs, replaced the intake boots, orings, etc.  Finally I shimmed the needles up with three very small washers I had for RC Aircraft bolts.  That was the solution for both bikes.  The run better all around.

Shim the needles!!!

Rob