Modern Vespa

very nice, mr. owens.

any additional barrel work or pretty much stock out of the box?

is that additional material i see welded to the cases before the clean up decking?

-g

No welding on the cases at all, never saw a need. Just decked to get enough gasket face. Enough is as good as a feast.

Mostly leaving the barrel as is other than where the ports met the case. I will be doing some work on the piston to help flow near BDC.

Also need to cc the head and piston crown to dial in the squish gap. I'm aiming for ~17m/s squish velocity at 8000rpm.

Do you have a formula or calculator for that? And what guidelines do you use?

I have a spreadsheet for the squish. It's in Apple Numbers, I can post it if it's useful.

Here's a thread where I outlined the process and the sheet.

Squish gap

The plate I made for the line to the fuel pump was not clearing the parmakit. At first I was just hitting it with a file till I decided a better tool was needed. Had to make a small fixture to hold it but after that the process went quickly.

Finished up the plate for the intake, it now clears the cylinder.

A good friend also made me some custom exhaust nuts. Brass, M8 thread, 11mm hex, and drilled for safety wire.

Cleaned up the casting on the intake manifold and matched it to the reed stuffer.

I'm not gonna lie, this thread makes me jealous, and I look at it all the time! Awesome work dude, I really like that scooter. Thanks for the updates and keep posting pics!

Measured the volume of the head today. Found it to come in at 11.83 ml vs 11.09 ml that I had estimated from the dimensions. I calculated the crown of the piston to be 3.20 ml.

With a 1.5mm squish clearance this will give:
Compression Ratio: 11.4:1
Max squish velocity at 8000 rpm: 18.1m/s

Did a dry fit to figure out what size packing plate to use. With a 1mm packing and no gaskets I get 1.345mm clearance giving 20m/s max squish velocity at 8000rpm.

An update! w00t!

Done with all the metal cutting. Trimmed the 0.8, 1.0, and 1.5mm packing plates to fit. Now to clean the bench, clean all the parts, and put it together.

Did the final clean on the cases and started putting the bearings in. Just realized I never ordered seals, need to get those ordered.

I'd missed a few bits when ordering for my v90 build.. it sucked.. moving happily along..

.... part A: check! install .... part B: check! install ...... part C: .... part C? shuffle shuffle shuffle ..... part C? ... ahhh F!




*this is still one of my fav bikes on the forum

Finally making some progress.

Got the cases buttoned up today

finished up the cylinder today, matching the exhaust port to to the manifold.

Then I found that the primary gear fouls on the case, joy!

GAH! that's just the worst! I feel your pain... currently in the midst of a falc build for a client, who insists on using only his machinist for even the tiniest of modifications and clearance issues. i think fed-ex has made more off of him that i have in the labor department!

anyway, looking good man! great work and attention to detail as always!

-g

Disaster averted, thanks to a great machinist.

whoa! that primary looks... uh... big!

did you have to clearance the cover as well? genius idea on locating the piece with a bushing and using a rotary table! are you running a sealed bearing or did you just seal it for the operation?

-g

just popped the seal in to keep the chips out.

tall primary = happy clutch

nicely played, sir. an elegant hack to what could be a problematic situation. pssh. whatever. you know it's all about 3rd gear power wheelies. /s

looking forward to completion and the ride report!

-g

Tool to hold the primary gear, will be here in two weeks printed in aluminum

Some predicted power and selection of gearing, this is in terms of force at the rear wheel. the top curve is ideal if you were able to have infinite gears to keep it at max power all the time. The lower curve is the force from drag. Where those two lines cross is the theoretical top speed. The primary gearing was selected to place the peak force in 4th gear as close to that cross as possible.

does this mean i'm going to have to put the PK back together?

*sighs heavily*

as always, i love the approach to each facet of the project you stud! looking forward to the updates as you complete the project. inspiring to say the least!

-g

Got around to reworking my spreadsheet to do the gearing in terms of power instead of force. This makes for a much more intuitive display (I think) as it allows you to see what can be adjusted to get a higher top speed.

That's nice! If you want to do 140 then you just need 16hp. I like it. I guess that's another spreadsheet you wrote Patrick?

Did some refinement of the gearing spreadsheet. Added in rolling resistance and incline to get a more accurate picture.

Top speed on level ground should be about 82mph. Should be able to pull 4th up to a 4% incline. At 6% 4th will be unreachable, 5% is that no-mans land of over revving in 3rd, but can't quite get to 4th (the reason people use a short 4th). I'd rather close that gap with improvements to the aerodynamics.

This just gets better... Even I can understand the chart easily. Can you tell us anything about this yet? Are you going after the front or the rear or both? I mocked up something on a Cosa frame, I'll have to find pics.

The aero improvements will be some time down the road, but this is the general idea of what I've been thinking.

I spoke to Paul McIntosh at some length regarding aerodynamics. Apart from the area you've identified he mentioned that he had seen some results where carrying a pillion actually helped to fill the void behind the rider and reduce drag. Taking a pillion on the Cannonball is probably (from my back-of-the-envelope calculations) the stupidest idea yet... but what about for instance a back pack filled with bubble wrap or similar? Might be worth a shot. I'm sure he'd be happy to discuss it with you if you'd like.

I like it & you look very competent on there. It seems that it would make a significant if not huge difference. Are you thinking something like 18 ga aluminum riveted on at the edges? Fiberglass?

I found the Cosa pics and it's quite similar plus some attempt to, as Ginch mentioned, '.. help to fill the void behind the rider and reduce drag.' The narrow Chinese seat kicks up at the back and I've blended it to the body. The cowls & frame could be cut @ top of the green tape and cowls narrowed at the rear, perhaps the P cowls in background, pic 2.


looks vaguely like your LX in this view


I'd leave the glove box off to tuck easier & pad the back half of the seat higher to help fill the void even more.




Of course the stock Cosa is already fairly slippery compared to the bricks we usually ride.


Sorry for the jack, back to the regular program now

I made the side skirts on the LX out of .5in foam core art board. The most interesting effect of filling in the space between the legshield and rider is that it was more stable in crosswinds.

This weekend I did a final dry fit of the cylinder, measured the squish, fretted about it for a bit, then decided it was fine, 1.25mm squish clearance.

Also installed the clutch hub. The fancy nut came with a star washer but I opted not to use it. Used loctite 648 on the taper and red on the threads. Still not sure of that call but for now it is done.

Also fretted about the nuts and washer for the head. I think I'm going to order some M7 flange nuts from BMW. They use them on the cam towers on a bunch of engines. If anyone makes a good M7 it will be them, and they are not that expensive (less than $1). Also been thinking of using Nordlock washers.

Got the primary gear holder in from shape ways and I'm pleased to see they hold very tight tolerances. Everything fits as expected.

primary gear holder worked perfect with no drama.

The flats on the outside of the tool could stand to be longer but the teeth held the gear nicely.

File for a patent! very cool project.

Forget the patent, gear holders have been out there for years, just not for this.

Get it from shapeways, admit it's spendy. On that same page I've also made the 3D file downloadable, not that anyone has an Aluminum 3D printer at home...

With 11.4:1 compression, what kind of octane will you have to use? I assume since it's for the Cannonball you'll be using pump gas, so premium?

I'll run the highest I can get from the pumps, typically 91. In theory the squish velocity should suppress detonation enough to make this all work, but I'll not be that surprised if I have to make some small adjustments.

goal for today was to get the exhaust header installed.

found out that the header does not clear the case and can't slip on over the studs. So, out came the grinder, again. Got the studs trimmed to length and installed. fitting the header will have to wait till next weekend.

Manifold surfaced, installed, and safety wired.