KX100 too smooth???

[OldTimer]

I just got my son a used 2008 KX100 for his twelfth birthday.
He's coming off a 2005 KX85, so the change isn't a huge step. In fact the bikes are a lot closer than I would have liked.
Anyhow, he's only taken it for a short spin around the yard, but his first impression was that the power is better except there's no hit or over rev(well, less anyway). His next comment was, "Dad could you take the flywheel weight off please?"
Well... I didn't know if it even had one so to took the cover off to look and discovered that the newer models have what appears to be a really heavy stock flywheel. The new fw definately looks a lot different, but are they in fact heavier? Could I swap it for the fw off the '05 85?
The bike has an FMF SST pipe with a Shorty silencer and I haven't wrung out the jetting, just wondering what's up with the flywheel????

 

[Vic]

I would try it, but that's just me.

You could weigh them both first before you swap them.

 

[SteveinSpringHill]

In 2007 Kawasaki started using a lighter flywheel, one of the very few changes on this bike. I'd try a pipe and jetting change.

 

[Kawi4life]

I had a 95 KX100 and it was a rocket ship! It would easily beat most 125's in a drag race... Heck I owned it after owning two YZ125's and was never disappointing with the power and pull, lol.

 

[gwcrim]

I put a pretty heavy weight on our 2003 KX100. It sure tamed out what I thought was a hard hit.

I would expect the 100 to be a bit more mellow than an 85.

 

[SAPPER]

You said it was used. if it doesn't run harder faster, and hit harder than an 85, then something is seriously wrong. My son has a 100 and has ridden many other 85's to include the kx. His pulls much harder. Being used these are the problems you may be facing:
The KIPS shaft may be out of line (good chance if someone had the r/s case off)
Some of these bikes are known for breaking the powervalve. I fixed 4 already. 1 ours and 3 others.
Topend is worn and just so you know, the factory Nikasil plating isn't great. It does well but not great.