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pw 50

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ive been reading all of the pw posts to get more power, checked all the parts sites found one that sells a shim that goes between the base and cylinder just wondering if any one knows how thick it is also has anyone tried a cdi box, need to get more top end speed my daughter 5 years old races flat track on a 1/4mile and an 1/8 mile need the speed for the 1/4 if you want to see her go to google type in livvies racing videos

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Sorry I can't be of any help on your PW, but I did google your video. Your girl is fast!!! Good job to her. The one I watched she wasted the competition. Awesome...

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Any reason you're locked into the pee-dub? There are several other 50's with more speed potential that your daughter should fit on.

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yes there is its a class on its own and we only started racing halfway through the season so we want to run a full season before we go to a ktm or cobra or ?

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You can stack base gaskets, it'll probably be cheaper. In your situation I would highly recommend talking to a porting expert (i.e. Eric Gorr or his Canuck equivalent) as simply raising the ports and decking the cylinder is a start, but a handicapped start.

I've done a huge amount of research and have been guided by a friend who is big time into go karts who is guiding me. I can't recommend someone simply buy the tools and try it as it will likely be frustrating, fruitless and expensive. It would be cheaper to pay someone who knows what they're doing rather than trying to learn. Esp. on a small cylinder.

Also, it will be easier and cheaper to send him the whole motor rather than trying to measure everything for him.

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You can stack base gaskets, it'll probably be cheaper. In your situation I would highly recommend talking to a porting expert (i.e. Eric Gorr or his Canuck equivalent) as simply raising the ports and decking the cylinder is a start, but a handicapped start.

I've done a huge amount of research and have been guided by a friend who is big time into go karts who is guiding me. I can't recommend someone simply buy the tools and try it as it will likely be frustrating, fruitless and expensive. It would be cheaper to pay someone who knows what they're doing rather than trying to learn. Esp. on a small cylinder.

Also, it will be easier and cheaper to send him the whole motor rather than trying to measure everything for him.

For basics, this sounds as if you are talking about squish band dimensions and squish clearance.

For some general basics, on a small engine like the 50 with intentions ofr flat track only, I would suggest a squish clearance of .5mm, stick with 50 / 50 squish band to bowl ratio.

I am not sure how many cc's the head is stock, but it is quite possible that after the head is prepped the cc's will be less and this will bump up the compression ratio.

PK

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Yes and no. You stack several base gaskets to raise the ports. The more advanced the exhaust port opens, typically the bike will make more power, but also at a higher RPM (good for this type of racing, not so good for trail riding), but since you're raising the transfers at the same rate, depending on the existing porting, you're reducing the blowdown degrees which may be good or it may be detrimental. It's possible that one, or maybe even two base gaskets extra will leave the blowdown time untouched, but more than that will almost certainly alter this.

Also, if the PW50 is as choked up as the PW80 is (my suspicions), the exhaust port is too small to evacuate the cylinder at higher RPM which means the bike will attempt to reburn combustion gasses which means less power.

This of course is all speculation since I've never had my hands on a PW50 cylinder, this is just my experience with the PW80.

Also, look at the Minarelli and Maglietti?/Morini?cylinders found on the Yamaha Zuma/Jog and Honda Dio and clone motors. The clone cylinders are cheap and I'm betting these can be adapted to the PW50 cylinders quite easily (would require some epoxying and expanding the existing cases to move the transfers). These scooters can make 9 hp so it would be worth looking into.

They're not a straight bolt on but with a small amount of machine shop time and carefully selected parts (some use 10mm wrist pins, some use 12mm) I truely think it can be done and would be a much better start than the PW50 cylinder while maintaining the same displacement.

Compare this to your existing base gasket (Yamaha Zuma):

zuma_yamaha.jpg

PW50 base gasket:

pw50.png

I apologize for the lack of squareness on the scans, these weren't intended to be physically measured. I scanned them so I can use digital tools to take the measurements, even though I could tell just by holding them that they wouldn't work for my current projects.

If you've got dividers (looks like a paper compass for drawing arcs and circles), you can probably still take easy measurements, otherwise just print out the large copies below and cut the ruler out of the printout to measure.

Zuma 50

PW50

As far as squish goes, it's probably got a huge combustion chamber and simply decking the cylinder or milling the head a few mm off will be a cheap and easy experiment.

Speaking of experimenting, I'd suggest checking out the GSF software dyno as the seat of the pants dyno is highly inaccurate.

Edited by Smacaroni

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