1999 suzuki rm250 how to make it faster

Add a flywheel weight.

Change your final drive gearing ratio.

Paw Paw

What color power band are you running?

There’s a grip that rotates - usually on the RHS.
Turn it against the light spring you feel. (Top of grip towards the rear of bike.)

Bike should get louder/faster.

If that thing is tuned up, It should already be too fast.

OK, I'll be the dick here - why all the smart ass answers and downvotes? Dude asked a legit, albiet vaguely phrased, question. Y'all never had to learn? Do you think he's just trolling or something?

Colin - you might get a little more direct help in the tech section or you could start doing some
of your own searching around on two stroke tuning basics.

You could always go with a smaller rear sprocket for more top speed. You’ll lose some on bottom though.

Alright, bad joke. In all honesty, your bike is known for being a mid range engine. I would give Tom Morgan a call and see what your options are in regards to porting and head work to get the results your looking for.
I had a 95 RM 250. It was a problematic bike for me. More of a gun and run type of bike that fell flat on top. Your 99 is a much better platform.

Sounds like 99 was supposed to be a good year:

https://motocrossactionmag.com/amp/two-stroke-tuesday-1999-suzuki-rm250/

We have traditionally had jetting problems with Suzukis and ‘99 was no different. It was rich. Here is what we ran in our bike for SoCal’s sea level tracks. Stock setting in parentheses:
Mainjet: 152 (158 stock)
Pilot jet: 42 (45 stock)
Power Jet: 55
Needle: N1EG
Slide: 6.0
Air screw: 1 1/2 turns
Clip: Groove number 2
Note: The RM250 is very rich. The first step to getting it to run clean is to drop the main from 158 to 152. We also lowered the pilot, but some conditions may not require this (turning the air screw out to two turns could clean up the very bottom).

99 rm250 is a great bike all stock. You can win 250 a at red Bud night track. Then race the national. That rod going threw the cases for the clutch. Smooth the ends better, but don,t loose that ball bearing. Like MC ,s mechanic then you loose the clutch in a race.

So OP, are you asking how to get more top end HP or are you looking for more MPH.

Fix your jetting.

Fix the jetting like they said and if u want a higher top speed put a 14 tooth sprocket on the front and or a 48-49 in rear
I found in some years the pc pipe and the dep pipe made better topend on the rm250s.