do I need to change jetting when adding a flywheel weight?

[triffecpa]

I've been careful to make only one change at a time so that I can determine the impact of each change.  Tonight, I repacked the silencer, added a new rear tire and threw on a 14oz flywheel weight.  I didn't think of the new tire as a "change", nor the silencer repacking.  However, after getting the bike back together and taking it for a quick spin down the arroyo behind the house.  I found that the low end jetting seems to be kind of soggy.  I did end up shortening the silencer by about an inch (Answer silencer/spark arrestor).  Could shortening the silncer by that small amount have changed the jetting, or does the flywheel weight have an impact on jetting?  I've taken the KX5 out four or fine times before the installation of the weight.  I did like the powerband prior to adding the weight.  Not sure if I dislike the change because of the jetting issues (or percieved jetting issues) or if I just dislike it.  Any comments?

[Paul]

Welcome to the world of flywheel weights, I hate 'em myself but Rick loves them. No, you don't need to re-jet it's just the extra weight "slowing" the crank down.

[triffecpa]

well, at least it's easily reversable  

[Rick]

Yup, I take my weight off and on periodically depending upon event.  For trail riding, I almost always run a weight to slow wheel spin.  It also makes a tractor out of the 500 , so getting up any tight knarly switchback/sidehill trail is a cinch, without any clutch work.  

It also helps when riding my daughter or wife.  We recently spent 9 days camping in Idaho City where the June ISDE was held.  I had been told that this years ISDE was really technical, but since I was just coming off my broker collar bone and my son's broker arm, we had to miss.  We were looking forward to getting a chance to ride the coarse while camping...daughter on the special rear seat.  To my surprise, while the ISDE was technical, I was able to ride Rebecca on all but a couple of miles of trail (she actually rode with me for a total of 20 hours, so covered a lot of ground), most certainly benefited by the flywheel weight.  When I didn't have a passenger, the weight kept the power on the ground, and the wheel tracking straight.  

The only time I don't like the weight is in the wide open desert races, but those are really only in California anymore.

A suggestion:  Now that you have a weight, you can run a little larger sprocket on the rear without getting wheel spin.  Top speed will remain over 80 MPH, but no clutch work in the tight and technical.

Good luck.

Rick

[Sharc]

Amen....Just rode Kennedy Meadows - Super technical, lots of rocks and roots, 14x49 gears with a 10oz. flywheel weight and the K5 worked GREAT. Stills feels like a freight train, but nothing can touch it corner-to-corner....rolls over the rocks, tracks straight, and climbs anything...Blows peoples minds to see you come crashing through the woods on a 500 2-stroke. Plus kept my 4,000ft jetting and it was fine as high as 9,000ft...! My buddy's KTM 300 jetting was a mess...K5's rule.