My easy to start, reliable, 100% stocker KLX is lacking power, but what to do. The default choice is $500+ for jets and pipe. Then it's the carb, on and off, on and off, on and off until the settings are correct.

Instead, I thought I'd first try gearing. I spent $10 for a front sprocket, dropping it from the stock 14t to 13t. That's it, EZPZ.

And now it wheelies (up and over technical terrain; curbs, logs, rocks, etc). It's hardly going to flip-out, but it has enough to pop it easy. In fact, from a dead stop, pop it in first, and stay on the gas and it pops it in second. A fun zippy bike, what I thought it always should have been. Did I mention it cost $10?

So what did I lose on the top end? I know you're already thinking this. So today on my 20 mile freeway commute to work, it topped out at about 78, taking into account the 8mph deficit these bikes are rigged with. The RPMs at this speed is the same as it was with the old sprocket, but believe it or not, it's now smoother. It feels more stable, a solid buzz if you will.

I'm very happy with this simple mod and am now anxious to go off-road to see how it helps.

 

There is no on/off, on/off. Header+muffler+pull lid+144/1N. Done.

No offense this is not possible. You will be ~400rpm difference

 

The tach isn't the most accurate in terms of reading it. You're right, it may be slightly higher, a "notch" or two more? Yes, maybe it was.

HOWEVER; top speed, 6th gear WOT leaves you at the same point, no? Rev limiter is the same as well.

 

All else being equal, if you were hitting the rev limiter with the 14t, doing the same with the 13t would be at roughly 93% of the previous top speed.

There's no free lunch with a sprocket change. The increased torque comes at the cost of top speed (or higher RPM while cruising).

 

Most of the time the klx is not able to hit rev limiter in 6th gear with the 14T, so in reality you don't loose anything on the top end with a 13T.
In fact you even gain a little going uphill (and/or with a passenger) thanks to the extra torque.

 

Exactly right. Unless you lay down on the bike, tuck in, the air resistance is what makes the top speed pretty much equal. The smaller the bike the more noticeable it is. On a Honda MB5 50cc 7hp bike the difference between tucked in and upright is around 5 mph.

I think the best bang for the buck has to be the Marcelino Cam Mod, getting more mid-range punch for $0 investment, only the time to do the work.

I'd love to see the OP's box stock easy starting bike. I didn't know Kawasaki made a KLX250 that actually started cold without having to spin over for 15 seconds and run choke on for ten minutes.

Of course doing the MCM has the tank off so that lays things bare to do the jetting changes which, for all but the totally driven who are trying to wring the last tenth of a horsepower out, are pretty well established and "plug and play". So for about $100 you can pick up better useable power and near ideal jetting for the bike, but probably not legal in CA.

If doing the Kawasaki parts I have the KLX250 cheap hop ups link in my signature that is a collection of information on the work done using Kawasaki KLX300/Kiehin parts. If going Dyno Jet get the information from KLXter. It is relatively easy to gain some smoke and start easier with a one-time change in the carb, the jetting is pretty down pat.

If pursuing perfect air/fuel mixture to go for the max power on a dyno or racing, or just wants to do it, sure the carb's gonna be off and on. But I know of two 250s that essentially had a one time off for jetting adequately for the average Joe who wants to ride. Neither my brother nor I have had to dink with the carb. He runs a 300 pipe and I am stock at the moment. I'm betting others here have done the one-time jetting on their bikes too.

So if you are spending money, it would be the FREE MCM job and jetting. I bet the bike will start even easier, for about $100. The pipe will add, but is not the best bang alone... unless you mean bang from the bike.

 

More miles racked up since my original post, still so pleased. Haven't gone off road, but with about 80 miles street riding thus far, I'm thrilled. I can't even say I'm noticing top end loss at all.

I have noticed a few red to green light wheelies that were ugly. "in my head, it looked so cool"

 

Weighing in again, many more street miles logged with this set-up. Worth mentioning is something of a surprise, granted it just may be my lack of knowledge on the subject. Aside from the gained initial "pull" the 13t provides, it also has a noticeable "thrust increase" just prior to reaching 8,000rpm. Keeping the throttle on, pulling through 8k, the bike picks up it's speed gain; great fun!

I'm still able to ride to 80mph in top gear; with a tuck, it can pull a bit faster and touch the rev-limiter. I believe 80mph is fast enough for this particular bike, riding on the freeway.

Again, so very pleased with this upgrade, really makes riding this bike noticeably more fun.

 

I would not recommend cruising this motor at 8k+ rpm for any length of time. Power is falling off that high with *most* setups, its pointless to spin that high, all you are doing is trashing things faster.

 

YIKES! I seriously have hundreds, maybe a thousand miles at over 8k! I ride 20 freeway miles each way to work, WOT. I need to stay off the freeway, and stick to dirt paths.