Modern Vespa

I've wanting to rebuild this sprint 1968 engine for a few summer already and finally it is in the front of the line.


A buddy asked to document it but it's quite terrible. Lost some of first few snaps of disassemble, cleaning, remove old bearings, putting new bearings and missing some steps during the process.


Choice between Indian or Japanese bearing.

seal / gasket set. Have to buy the cylinder gasket separately since it's 3 ports instead of 2

original Piaggio pistons. One of them is 0Step

some special tools

got the bearings in.

got primary gears in.



testing crank.

installed crank

puller pulled crank in place.

replaced cross, keep the gears as they are still in great condition. Assembled cross, & gear

installed shaft

looking good.

old kickstart gear looks worn

new piaggio is ready to use.

reinstall kickstart quadrant

put on gasket and assemble the case.


Last edited by ph0ngvu on Fri, 21 Sep 2018 18:01:52 +0000; edited 2 times

Your engine stand is brilliant!

I need to head over to Home Depot anyway, but I'll definitely by stopping by the plumbing department while I'm there.

Wow, excellent pics PV! I'm glad you posted them. And yes, the engine stand looks fantastic. That's some serious engine rebuilding. Good job!

That engine stand has got me thinking about diy stands that aren't welded. Hmmm...

Nice job! How did you come to have all those pistons?

I hope you removed the cover/seal from the clutch side bearing? Seeing it has the proper seal on the other side you want some lubrication to get in there.

Oh, how I love seeing battered old motors being lovingly coaxed back to life. You are doing it first class w/ all quality new bearings etc.



I've always wondered about those yellow inserts in the main crank bores. I always thought they were brass and yours look to be, but I scrapped a motor that had plated iron inserts. They weren't dimpled all around in the case like yours, seemed original and I've seen enough of them to think they are maybe factory items in some motors?

Anybody know?


I have a magnet stuck to one half here
and the two brake posts w/ anchor pins
all are from a dead motor half that I melted

you can see the gray color and I think it's iron rather than steel because it's brittle & seeing the grain structure

I thought the point of a sealed bearing was that it didn't need external lubrication.

These are not sealed bearings. They're polyamide ball caged bearings (instead of steel caged). They're supposed to be quieter, stiffer and more flexible...

The dimples are not standard; someone has done this to stop the bearing from moving in the brass sleeve. I often see this on Asian bikes; this area is worn out. The right way to resolve this issue is to machine new brass sleeves and install. The early bikes had brass sleeves and later went to steel. Hope all that helps.

So wouldn't you want the 'open' side towards the lubrication?

I got it now. In the 7th photo of the original post, it looks like there is a gap between the black cage bit and the outer bearing race. So oil can get past that.

What's the point of even keeping the black seal on, when it's on the inside facing the gears? Why not just take it out?

It's not a seal. See the picture SaFiS posted. It looks like it's a carrier for the ball bearings. We're seeing the back of it installed in the engine.

Sorry, didn't realize that. I wonder if that would restrict lubrication.

Yea, I just want to have something that can be disassembled to smaller pieces and put away. With the same base and different pipe setup, it also can hold those Motobecane, Mobylette engines.

Last edited by ph0ngvu on Mon, 27 Aug 2018 16:57:16 +0000; edited 1 time

My current stand is one that I hacked together out of some random lumber. I worry it's going to collapse every time I kick a bike over on it.

I'll definitely going with the piping on a proper base route before my next rebuild.

I went to Europe in April and was able to visit a couple scoot "swapmeet". Still lot of NOS parts being sold there. There was one guy with a full trunk of NOS pistons. You are right. I was wondering why as well. Unfortunately, I did not know you can remove the bearing seal. Should I worry about the bearing not have enough lubrication? I see your point. I'm not original owner of this engine until 5 summers ago. It has 40+ years of unknown history.

some more porn.

Last edited by ph0ngvu on Mon, 27 Aug 2018 20:46:15 +0000; edited 3 times

I have to ask... how do you test a crank by putting it on a can ?

I didn't really test it on the can. Gotta put it on something to take picture. What I did prior to that was to make sure the connecting rod doesn't slide side to side and everything else looks good visually.

weird, last post images were out of order.


install cylinder styds

get the engine bolts on. I reused most of original bolt and screws. Some people are against it and use new one but why not reuse when they are in great shape.

clutch time! replace corks, plates

all good to go

change out worn part of clutch lever.

clutch in, bend the tab

clutch cover on

original factory 3 ports and header. A Piaggio NOS 57.8 piston go with it.

mount the piston and rings.

gasket in place, piston ring compressed, sliding cylinder over.

looking good, arrow down.

header in place. Did not clean as it should be.

original flywheel & stator next.

looks like flywheel magnetizing is still very good.

install stator

put on woodruff key

install NOS coil without any thinking

then realizing original stator is messed up and needs some new parts. Replaced with NOS condensor, coils and point

all set

preadjust timing a little and temporary screw in flywheel.

more and more


Selector looks to be ok just need clean up and not rebuild.

gasket

slide it in

and done

Carb time

stock carburetor looks great

rebuilding time. Taken apart.

all clean and assemble time with new parts from Dellorto kit.

on board

considering on a 40+ yrs old engine, stock filter is still in great shape. A quick clean and assemble

almost there. Time for the drum hub.

rubber seal on, installed circlip.

new brake pad or NOS or the one came with the engine?

installed

right torque? humm no idea :D Repaint? I think old patina looks great.

forgot to order castle nut pin. ScootMercato sold for .50c each + $3 shipping. Found a bunch at Home Depot around 49c for 3 :D

temporary installed exhaust to test the engine later

had to stole wifey baking "equipment" to inject oil =)

oil is in and letting it sits overnight to see any leakage.

After using the motor for a week, dump that gear oil and get yourself some GL4 rated... GL5 has additives that attack the brass bits (in the clutch).

Engine started for the first time in years which is not bad for one with bunch of original parts.




repaint the exhaust with high heat resistant.

only found high heat resistant up to 750c. Hope this will last.

put it back on the frame, connect fuel lines, clutch, throttle cables ...

engine started after a few kicks.

redo the wiring.

Old parts but nice and neat along with ring wire connector from HomeDepot.

Are you sure about that gear selector rod in the photo under the one with the gaskets? It looks pretty mangled to me, unless it's my eye sight that's bad.

Very Nice - I love following along - thanks for posting the pics!

Really, I did not know this.

To be honest I have no idea how long it takes to do damage, but you may as well use the right stuff.

... like this one?

https://pbs.twimg.com/profile_images/849075007984734208/l3NlQtFM_400x400.jpg