Highly recommend 125,42 jets in carbs
 

If you have stock jets in your bike, I can assure you
That replacing with 125,42. That's a stage 2 jet kit.

It's like riding a different bike.

It had a 122,40, and wow what a difference.

Ryan

Good 2 know!
What other mods do you have?

Just a hi. Flo air filter and 4 into 1 pipe. But bought it like that.

Got plans down the road, 4 more, need $$$. First

And......2 1/2 turns out on the pilots.

I plan on doing the same this winter then. I know the bike will never be super human fast like some the newer ones, but it's worth it for me to get a couple extra hp by just going through the carbs and bigger jets

Surprisingly 10.5 is doable in 1/4 mile, there is plenty of bike, old or new that don't run that fast.
Top end, sure alot. More out there can go faster. But really, around town. This bike is still a good contender, and price for a used one, for that speed, and fastness. Is much better then a $10,000 plus bike.

That's my take

Agreed.
10.5 in the quarter is definitely no slouch. I haven't looked into sprocket changing yet for these bikes. Something else to start reading up on.

I fitted a standard 43 tooth rear sprocket from an 87/88 SC21 to my 89 SC24 which has a 42 as standard. The only mod to fit the early sprocket was to drill the 5x holes out from 10 to 12mm. Easier than trying to source a +1 rear.

Check out Gearing Commander: Motorcycle Speed, RPM, Chain & Sprockets Calculator for acceleration speeds and top end etc.

Will changing gearing affect my speedometer at all?

Not sure where the speedo takes the drive from sorry.