Modern Vespa

Hi guys need some help before spending or wasting money. can get a set of lml new cases with reed valve sip part 78201000 but not sure if all my parts will fit. my present standard engine is totally worn out. So intend to bring it up to date with reed valve and polini 177 block, cheap px engines are none existent so this is the only way to go any ideas

You'll need a p125/150 crank, fly side bearing, fly side seal, and a p125 flywheel. You'll also need a different fan shroud. the wiring on your old stator wont be long enough to make it to the junction box, so that will need to be extended. You'll have to figure out how to attach your coil which isn't that big of a deal. there may be some differences in rear axle bearing or seals, but all your expensive parts should fit except the crank.

P.S. is it the cases that are worn out, or the parts in the case? sloppy tolerances will follow you from case to case, so if your gears are worn, drive shaft, and primary are jacked, it will be cheaper to buy a complete engine. even buying a brand new engine is cheaper than building one.

Hi that's great. Yes I will be replacing crank and ignition (still on 6v) crank bearings have end to end play, compression is 25lbs instead of 120 (down to piston rings end gap .9mm (should be .2/.4) But still it runs and starts easily. A new engine will be about £700 and still only a standard engine. This will probably be my last project so it has to be special without wasting money .

The flywheel end of the shaft that carries the xmas tree gear is something like 11mm on the Sprint and 13 or so in the LML case. So you'll need to replace that shaft with the later type... the new shaft should fit with no issues into your xmas tree, but it's worth cross-referencing bearing sizes.

hi all, took bike out for hard run yesterday after resetting timing to try and improve top speed but no different. put up on ramp and on top of other problems the cases are leaking, so am taking plunge and ordering new cases ie lml reed valve. so now looking for best crank either bell or full circle any suggestions

Personally I like the flowed cranks.