PK

[T5-190]

Hi fellas, so I treated myself to a late Christmas present. I have been after a PK 125 for a long time to do a winter project on. A PK 50S came up for a little over £500 running and it quite good nick. One owner from new etc.So I have a few questions for you smallframe guys on here (jonny and Wayne etc). I have desided to go down the QUATTRINI 51x60 route along with their own cases and the crank that matches. So my questions are....

1. Is there anything inside the PK50 engine that is useable
2. Am I better off opening up the opening in the cases to use a reedvalve and use a normal type cylinder kit ( pic one ) or leave it closed and use a cylinder mounted reedvalve ( pic 2 )
Pic 1

Pic 2

Cases


Crank

[shilloboxer]

Hi mate ive used the quattrini caseings and although expensive they are very good quality and running W Force H2O which is the reed valve to cylinder. Regarding whats in the PK theres nothing of much use really

[T5-190]

Thank for the info shilloboxer, I thought it would be better to use the propper crankcases as new PK 125 casings are over £300 and with welding and re-maching it would be about £500 anyway.

[Wayne Miller]

Should be good fun

You can use your rear wheel set up and driveshaft as well as your gearbox but youd be better to get yourself a DRT runner xmas tree (Small gear cogs) as this will give you a shorter forth gear. Dont worry your not going to go slower in forth as you will need to upgrade your primaries too 27/69 is the natural choice for that set up. You'll need a stronger DRT Gear selector and an uprated spring too. Full set of bearings, oils seals and gaskets. You crank may come with bearings, Im not sure you'll have to check but I know falc cranks come with bearings (Most dont) You'll need a decent clutch too Hartz4 comes with its own primary basket but does require a spacer, you may want to go with a falc clutch and basket if you dont fancy a spacer. If you want to go 3.50x10 tyre instead of 3.00x10 then you may not be able to use a hartz4 again though saying that you will have to check or I can let you know as Im getting some quattrini casing in stock soon so I'll have a play with one when it gets here You'll need some new cylinder studs to as the 50cc studs are shorter. You'll also need a decent ignition, carb and pipe. plus theres woodruff keys, nuts and washers too. Oh you should be able to use your kickstart quadrant if its not worn, that goes for yor loose gears too, if there worn replace them If you get stuck when you put it all together pop over to the smallframe forum as you'll get lots of help there with your motor.

As regards as to what to do with the casings. The easiest thing to do is by a kit with direct induction but everybody buys these Id open up the case reed and buy a crankcase inducted cyclinder just to be different. Have you thought about going with a falc cylinder? they're the usual weapon of choice. I know that with falc stuff that I sell theres usually about £180 to £200 difference between direct and case induction cylinders. Mind you saying that the money that you would save buying a case induction cylinder you would spend opening up the case reed and buying a vforce reed. I guess it just a matter of preference really.

[Juan]

I'm not convinced at all by Quattrini's cranks.

Have a look over on smallframes as Wayne says, there's a thread recently where a German bloke is building cranks compatible with the Quattrini cases for up to 60mm stroke. You'd really need a bespoke Falc topend to run with the longer strokes though.

[Wayne Miller]

Lauro is making 51mm, 54mm, 54.5mm & 56mm cranks for Quattrini casings. I'll have them in stock in February when he's finished making them