PX200 low 4th gear

Probably the millionth time this question has been asked…but here goes anyway!

I have a PX 200 with some mild porting and a 1mm plate under the barrel. Also a Sito plus. Mid range is much better then standard (not difficult!), and it revs really well also - except in 4th (surprise!). Goes nearly to 60mph in 3rd, then 4th needs downhill or a long run before it will pick up well. Once it does, it will get to 75. Hills or headwinds will kill it again. If I go for a T5 top gear, will the engine stand the higher revs? Just how bulletproof are PX engines?

Would a different pipe help, or is that likely to move the power high up the rev range?

I use the scoot for work, and A and B road runs, plus long trips at weekends. I only rarely use dual carriageways, never motorways (hate them - even in a car).

Next stop will be a kit, I suppose, but I dont want a tiring, revvy screamer, I much prefer mid-range power for the riding I do.

Any advice and guidance?

Cheers. Nick

I _[:bounce:]


Thanks for the reply. I will try the T5 top gear this month and see how it goes. I am planning to get the additional work done in Feb next year (after the worst of the weather!), so I think I might go for the Pinasco. I notice on the SIP site, they recommend going with a „long stroke“ conversion with the Pinasco kit - any thoughts? If that is the way to go, what parts would I need for the whole job?

As you can probably see I am a bit wary about tuning - past experiences with a Yoshimura Honda 460 many years ago (sky high revs, and nothing below 7,000) and various other expensive disasters! Remember 3 into 1 pipes for Suzuki triples??? Great noise, dreadful performance!

Thanks, Nick


as stringy said for your pinking retard not advance.

For the longstroke matter: I did it with pinasco kit it works really well and no problem in the long run, or if problem, equivalent to standard.
-But get a worb 5 fine balanced crank, if not you will have more vibration.-
Also a person that I know has this kind of tuning and expirienced the same satisfaction.

Malossi kit it is also a very good reliable kit for px200.
Not to use with longstroke tough since the altering in port timing will make you loose performance.

So at the end: either malossi standard, or Pinasco with longstroke, both good choices. [:roll:]

…as far as regard your future kit, for your need I will go for a Pinasco with the Sito plus.[:roll:]

hello viperboy,

I have somebody that will bring his PX with this kit next month, beginning of january, he is waiting because still doesn’t have enough money for the complete tuning. I will keep you updated.


no for exhaust change. It will make things worse.
T5 4th will make things much better even though won’t solve 100% the problem.
The engine can take this no problem.


If your engine pinks at high revs you may want to retard the ignition timing slightly. What grade spark plug are you using?

The Pinasco kit is basically a copy of the standard barrel in Aluminium with slightly bigger ports and bigger piston cut outs.

The performance is better than standard but not as high as the Malossi, makes a good touring kit, it runs really cool as the Aluminium dissipates the heat better.

Built my engine myself, just had the head re-profiled and skimmed, will let you know how it goes.


Thanks Curare and Stringy for all your advice - great help!

Cheers, Nick

The top end of a PX200 has two main faults, one is that the ports are partly covered when the piston is at BDC and that you could drive a bus through the squish clearance at TDC.

Packing your barrel up will increase performance as it will allow the ports to flow more as there is more area at BDC and raising the barrel will also slightly advance the port timing.

The downside is that it will lower the compression and increase the squish clearance. It may pay you to measure this and maybe have either the head skimmed or material removed from the top of the barrel to remedy this problem.

This may give you an increase in performance allowing you to pull 4th gear better.

I have found the same fault on my Pinasco 213 kit, I have had it machined and am in the process of rebuilding it.



Thanks for the info - the head has already been skimmed, but what you say about the timing is interesting. When my engine is hot (after 30-40 miles maybe) I sometimes get some slight pinking going from high revs in 3rd into 4th. Which would be explained by the port timing issue. I will try advancing my timing.

How have you found your Pinasco kit? Where did you get it built, or did you do it yourself? Important question, as I am a technical smurf! Even after 30-odd years on almost as many bikes - love riding, have trouble changing a headlight bulb! Oh well…!

Cheers, Nick

Did anyone had any experience with the Zirri 230 kit?