P K GOES BOOM

pk50 · Post by **pk50** » Sun Jun 21, 2009 4:58 pm

After dismantling the flux capacitor i see that the rings are stuck in the piston , seised is my guess . it has a polini kit , not to sure what size it is . the only markings are inside the piston ASSO-W + 2610 can any one can translate this into CC s ? I think i need to get the new piston +rings before i hone the cylinder ? Thanks Graham

coyoteran · Post by **coyoteran** » Sun Jun 21, 2009 7:35 pm

That designator is for an Asso Werkes 26,10 piston. Which, without knowing the stroke, you can't reasonably determine the displacement. It also doesn't help if you don't know if the rings are stock or oversize due to previous engine work.

The dudes at American Scooter Center carry asso pistons. They might be able to help.

jbcollier · Post by **jbcollier** » Sun Jun 21, 2009 9:23 pm

The stock 50 has a bore/stroke of 38.4 mm/43 mm. The smallest Polini kit is a 70 cc. If you could swing by my work with the cylinder or the piston, we could measure it up. Mind, I think tomorrow is going to be my last day for the summer.

jbcollier · Post by **jbcollier** » Sun Jun 21, 2009 9:25 pm

Does the connecting rod small end (where the piston attaches) have a bushing or a needle bearing? If it has a bushing, then it is a 43 mm stroke crank for sure.

jbcollier · Post by **jbcollier** » Sun Jun 21, 2009 9:35 pm

Polini 75 has a 47 mm piston with a single oversize of 47.4 mm.

Polini 102 has a 55 mm piston.

Polini 115 has a 57.5 mm piston.

pk50 · Post by **pk50** » Sun Jun 21, 2009 10:05 pm

it seems to be 55 mm with a tape-measure and it does have needle bearings thanks for the info guys. call me if it works for you tomorrow john .298-7540 Graham

jbcollier · Post by **jbcollier** » Sun Jun 21, 2009 10:13 pm

Hi Graham,

Pop by tomorrow between 9:30 and 3:30 and I'll be there.

A needle bearing should mean it has a long stroke crank!

pk50 · Post by **pk50** » Mon Jun 22, 2009 10:00 pm

John i took a look at the gears the small one has 16 teeth not 15 , i looked at the sip site to find new primary gears but i have a hard time finding anything . was it on scouter help you found them ? Graham

jbcollier · Post by **jbcollier** » Mon Jun 22, 2009 11:17 pm

Yup, scooterhelp.com

16t crank gear means it has 16/68 primary gear set which gives a 4.25:1 ratio. With a 110 kit, the 90/100 primaries (22/63 or 2.86:1) would work best.

You would probably be safe ordering engine parts for a V50. I would get a seal set, gasket set and the crank bearings in addition to the 55.4 piston and the 22/63 primaries.

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You know the piston is going to set you back $60ish and the machining is $100+, you might be able to buy a new 102 kit for similar or less. Check with vespa motor sports on that.

Other thought is that we should measure up the piston pin. I have never heard of a 50 having a needle bearing small end before. Mention that when you talk to VMS as that may mean it needs a different piston/kit.

Hope this makes sense as it's late!