How does a power valve work?

The power valve is a movable flap located on the cylinder exhaust port of a two-stroke engine – where burnt gasses are flushed out of the cylinder. At low RPM, the flap is held partially closed to make the exhaust port smaller. This helps the engine generate torque at low speeds.

Is a YZ 125 fast?

Paradoxically, while not as powerful or as fast, the YZ125 is a blast to ride. The added dose of power down low makes it easy to get the blue bike up to speed with nary a touch of the clutch. And while it may not match the KTM’s numbers at high rpm, it does rev to 11,700 rpm before falling off the pipe.

How often should you clean power valves?

I’d recommend cleaning after the first season; then either once a year or every 3000 miles or so. While in most cases you can get away with neglecting that, there are possible issues in doing so.

What do you clean power valves with?

Some valves only install a certain way so jot down notes and/or take photos as you remove and disassemble. Once removed, scrape off any carbon build-up using steel wool or a stiff toothbrush then apply contact cleaner or other similar solvent (brake cleaner, gasoline) to finish the job.

How long does a YZ 125 bottom end last?

Eric Gorr says the 125 two strokes need new bottom ends every 80 hours.

How fast can a 2020 YZ 125 go?

So, with that out of the way, a stock 125cc two stroke shouldn’t have a problem getting up to 60-65 mph, maybe a little more or less. Fast enough to scare you in the rough stuff, that’s for sure.

How fast is a 125 4 stroke?

125cc dirt bikes have an average top speed of 45mph. The highest speed recorded was more than 100mph. Manufacturers advertise around 45 miles per hour, but some consumers find they can push the limits to over 60mph.

What can you do with a Yamaha YZ125?

If you do nothing else but a pipe/silencer and a V-Force you will be almost on a level playing field with the KTM 125SX. The V-Force3 system gives the Yamaha increased power, throttle response and also allows the Yamaha to rev farther than that of the stock reed cage system.

How old is Aden on a Yamaha YZ125?

My 14 year old son Aden has been going back and forth between two different colored 125’s, but has seemed to take a liking to the YZ125 the most lately. I decided see which simple mods could help this Yamaha YZ125 two stroke the most in order to get him some extra ponies.

Which is better FMF or stock on a Yamaha YZ125?

The FMF set up doesn’t provide more over-rev over stock, but you will notice a healthier second and third gear pull down the straights. The YZ125 runs much cleaner with the FMF pipe/silencer (compared to stock) and looks stealthy as the silencer is hidden behind the number plate.

What kind of engine does the Yamaha YZ85 have?

A newly-designed 85cc liquid-cooled 2-stroke engine featuring a case reed-valve intake and a mechanical Yamaha Power Valve System (YPVS) lies at the heart of the 2019 YZ85.