I have a weird idea for an old cylinder...

I've been reading up in the last couple of days about port maps and I have the urge to tinker.

I have an old air cooled 50cc cylinder here from my TKR in good nick that I am tempted to try and uprate a bit, by changing the port timing slightly. I don't intend to go totally OTT, just a mild tune to the transfer and exhaust ports to give it a bit more 'edge'.

There are plenty of port maps posted on the various scooter forums and am going to study these and try to come up with some suggested 'mild' tweaks to this cylinder and see what effect it has on the performance.

I know that some aftermarket uprated cylinders are cast iron (e.g. Malossi), but which make and model would you recommend that I use as a pattern to work with for adjusting the port heights, etc. as a 'softer' tune?

I'm still on the original crank with a 10mm top end, so I can't go mad and too far up the rev range for fear of blowing the crank.

 

have read up of the pdf on scubabikers post on the front page..well up your street all the valve timings,port transfers,all that in it.

 

I must be getting old, can you post a link to it please as I can't find it?

[/old fart]

 

I have had some good results with ovetto cylinders just raising the height of the exhaust port by a mm or so and making it a bit more square ar the top corners. You need to chamfer them afterwards, and you need to lighten the rollers and put at least a Yas Z - or preferably a yas R on there. But the results are not subtle.

 

Thanks for that. My fiendishly cunning plan is to try and match the stock barrel up with the nearest cast iron sports barrel then try and take my barrel towards that spec in terms of port area and timing. I accept that there will be compromises and even if I only change the squish slightly and the port timing by 0.5mm and adjust the port areas, I am prepared to tinker to see what I can get as a 'mild' tune on the Peugeot barrel.

 

I'm tempted to turn a stock barrel into a Top perf 50! But cast iron is such a chore........

 

Who dares wins, Turbovetto...

 

Sf rider is the one with the tuning pdf link..merlin.
ibe had a read of one and its piss easy to follow..dunno what its like doing it but easy to grasp.