Modern Vespa

Since I never did a writeup on the original build in 2006 I figured I'd do one now as I prepare for a rebuild.

We'll start with a glimpse of the finish before stepping back through the build. Here's the bike after fulfilling its intended purpose in the 2006 Scooter Cannonball Run.

Here's the first dry build. The frame has already had the seams welded, brace braised in, and nuts welded in to hold the cowls on. The PK fork in is but as you can see the headset sits way too high. The floor is cut out for rearsets I haven't come up with a plan for mounting them yet. Also, the dummy tank is cut out and mounted at this point.

It was about this time that I heard about the Scooter Cannonball Run and decided I would be entering with this bike.

The p98 headset has a lip on the inside that rests on top of headset bearing lock nut. The lip was cut down to lower the headset.

Here's one of the final dry builds on the body. Flat head M6 stainless bolts are used everywhere they can and the sheet metal deformed so they sit flush. Second picture shows the mounting for the rearsets.

Good start, please keep them coming. I like how you did the floor, simple. What was your range with all fuel tanks full?

How did you mount the older mudguard on the PK fork? Yours looks real straight, better than mine. I ran into interference on the top shock mount flanged bracket and had to grind off just a little from the outside edge to get the mudguard on straight as I could.


ground back next to that nut

Fitting the fender mostly just needed trimming the mounting plate for the top of the shock. I put the fork in a vice with the wheel vertical and then lined up the fender as best I could and marked the holes. Everything fit fine till I fitted the RS24 shock. Then I found I needed a bulge to clear the shock, the day before it needed to go to the paint shop.

I don't have any pictures of the cylinder but it's a mostly stock Malossi 133. I did cut out the lower section of the cylinder skirt by the transfer ports and connected the boost ports to the reed intake.

Due to the long range tank I need a fuel pump and needed a connection from the crank to drive the pump. Since I'm using direct induction on the cylinder, this allowed me to use the stock rotary port to drive the pump.

Things are a bit tight but it does all clear.


Removing the lower cylinder skirt allows for a smoother feed to the transfer ports.

This will be a fun one!

Saw you there at Pacific City in your black full leathers. On that scooter, cool!

Great idea using the intake cover plate for a fuel pump pull.. and your triming of the onside of the headset to lower it was also really good! I'm glad you're doing this thread... It makes me wanna start chopping mine whole it's still apart... good stuff Oops.

You know what else I like, is that P headset fits really nicely... doesn't look wrong at all.

are those kangaroo whistles on the front mudguard

now ya talking .... summat cool to watch again

The bike almost had to skip the paint as I was running short on time. Went with a cheap earl scheib, no clear. In the meantime I finished putting the front end together.




back from paint

Starts to come together

Wiring harness done and in the frame, next it's lots of detail connections.

The wires were all left long on the harness so each needed to be trimmed to length, connectors crimped, soldered, and insulated with shrink wrap.

The fuel lines were all secured with safety wire.

Almost ready for the engine

Engine completed.

I saw him, too! Heh. My fave sighting was when he flew by Noe and me in some dusty western burg whilst riding sidesaddle. Seriously, the unstealth is amazing. It's really cool to finally see the original build documented.

I love it, your attention to details and the craftsmanship is awesome..!!!

Almost done, but done just gets you to the point of knowing what works as expected and what needs rethinking.


Engine in

Testing fuel gauge

Done

The first thing that didn't go as planed was the fuel pump. I use to have an ultralight that used the same pump and as I remembered it there was no return line. But as soon as it started it would overflow the float bowl.

I had bungs installed on the tops of both tanks for the vent line but what was really needed was another for a return line. Since there was no time for this I just looped the return back to the input side of the pump. This worked but it's kind of a mess. The feed to the carb is from a tee at the very top of the frame and gravity feed down from there.

Issues to be lived with:
Because of the recirculating fuel the gauge shows lower than normal under full throttle. Rolling off the throttle to check the fuel gives a more accurate reading.
The lower tank has a "one way" vented cap but if you top up both tanks the lower cap leaks a lot.
I had hoped to be able to just fill one tank and have it flow to the other. This turned out to be unrealistic with 1/4" fuel line so I have to measure out the oil for each tank and fill each one.

I was gonna ask if you used the stock tank too. seems like the Aux tank would be sufficient as a stand alone and convenient not to have to deal with the stock tank. But then I never tried a 3000 mile run either. Either way it improves weight distribution no doubt, eh?

Here's some diagrams of my initial intent on the aux tank and the quick fix done given the need for a return line.

The stock tank is only 1.25gal IIR and the aux was 3.5. I was expecting to get 50 mpg (wishful thinking) but only ended up with about 35 mpg. The I misjudged the first day and ran out of fuel late in the day. I also found that I needed to run 1-2 main jet sizes larger to keep the temps on target.

While I could stretch it and make 150 miles on full tanks, I found I started looking for fuel after 100 miles just to be safe.

The weight distribution is great , but the front tank does need foam added to it. On high speed corners the fuel can start to slosh and the rear of the bike starts to wag a bit.


plan A

plan B

Oops, did you look at electric pump options at all? I'd like to do one that fills the main tank but don't want it to run all the time.

Looks like it was a fun project!

I did an electric pump on the SYM. Write up here: Cannonball Fuel Tank

One nice thing about the way I ran it on the unstealth is that I really don't ever have to turn off the fuel, and it never floods. Also, recirculating the fuel assures a good mix of the fuel and oil.

Thanks... more planning required I think.
I did see somewhere an NZ guy had fiberglassed the inside of his glovebox cowl, then used tank sealer to seal it. Not sure how you would attach a cap to fiberglass though.

Beautiful project!

This is a GREAT bike Patrick.. really great.. I'm glad you resurrected it's beginnings for us!


What size Raceman is on the rear? and did you have to grind your swingarm at all to fit it?

This looks awesome!

That fuel guage, YES!

Yup. My ultralight had a fuel gauge like that and back when you could get away with fiberglass tanks they often left a clear patch (rickman, ducati).

Much easier to take a quick look down and know how much you have left. I've always intended to make 1/2 gal markings so I know how much I can fit in at fill up.

Dropped the engine last night to start the rebuild.

Here's the reason for the rebuild. Really pains me as the rest of the engine is in really good shape.

Top end is in really great shape.

Shows a 4 corner seise from when I let the EGT go way to high, trying to nurse it up a mountain at 1/2 throttle with a burnt clutch.




No carbon buildup on the underside of the piston

Listen to your EGT!

35MPG hey? I actually think that's pretty good!
Here's me thinking that I would only get 10 or 11km/L (about 25MPG), and I would blow the thing up after only 2 weeks by sitting on a steady 65mph.

Now that I know the fuel economy is likely to be quite acceptable, and yours took (for my annual travel anyway) about 2 years before rebuild time, the idea of a little manual old-school hotrod is planted firmly in front of my thinking again.
Thanks for that!
(I'll keep your address hidden from my long-suffering wife).

Nothing to stop me now apart from the usual lack of ability, blind ignorance of 2-smokes and a frightening ability to get in over my head.........

For the record, most of those miles were just sitting on a steady 65-75mph. Max power is at 68mph and jetted right it will do that all day long.

Thanks again.
Oh, and in case you want to sit on 135kph or so on an X8 250ie, they only last about 15secs.

Nice ride man.
8)

Cases are split, gears look really good still.

Something I should have had done long ago but didn't was to deck the cases down to get a better gasket face.

Had an extra set of cases done as well.

The cases had been ported to match the Malossi cylinder but for the next build I'll be using the Parmakit. Came out well, better than the malossi. The ports of the parmakit angle out at the gasket surface so the cases needed to match in both size and angle.


Ports roughed in



Cases done

And cylinder to match.