Modern Vespa

Hi guys, I'm rebuilding my sprint v engine and I've noticed a chip on the driveshaft. I can't see it fowling on anything but I'm not sure if I need to replace it. I've attached a picture and would appreciate any suggestions. Cheers in advance.

If you want to repair it the only way is to replace it. On the other side on my friend's PK shaft looks much worse with lot of similar damages but for few years it works without any problems. Need to notice that he have only DR 102cc engine and calm riding style.

Probably more important are the conditions of the spines, if the shaft is straight and the wear on the shaft where the bearing goes.

If a new bearing slides on by hand, the shaft is trash.

I wouldn't worry about that chip. There's nothing that can catch on it.

+1

Now if your driveshaft looked like *this* on the other hand...

Duct tape'll do that up right, no problem.

Going back to the OP, are there any hard edges that could catch a spinning gear? If so, I 'd hit it with a file to smooth out any edges and run it. If you hear a tick tick tick tick sound from the gearbox at idle, I'd remove and replace immediately.

+1 to MJ's advice. I'd dress it with a file and then assemble the gears on there and give a spin to see if I could hear anything untoward.

I might even go as far as to spin the gearbox up in the cases with a drill to assess.

it's a low power application, but if you get a good stress riser there that could chip off some more which may get lodged somewhere and lock the whole thing up tighter than a bull's ass at fly time, and that usually happens at speed.

Cheers guys, I'm gonna dress it, check it for snags. Should be good to go… 👍🛵

Just don't forget to proper shim loose gears.