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
Sergeant at Arms
![]() Weird 80's Vespas & Cool Vintage Lambrettas
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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 |
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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. ![]() finished fly side port
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Veni, Vidi, Posti
![]() 74 Super, 75 Super, PX project, LML off-roader and '66 Blue Badge Smallframe
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oopsclunkthud wrote: 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. |
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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 |
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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.
![]() Intake port adaptor for fuel pump vacuum line.
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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. ![]() ![]() |
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Rawwwwwwwr!
Cleaned up the casting on the intake manifold and matched it to the reed stuffer.
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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!
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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 ![]() ![]() ![]() |
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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.
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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.
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Did the final clean on the cases and started putting the bearings in. Just realized I never ordered seals, need to get those ordered.
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RIP
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oopsclunkthud wrote: Just realized I never ordered seals, .... 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 |
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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! ![]() |
Sergeant at Arms
![]() Weird 80's Vespas & Cool Vintage Lambrettas
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oopsclunkthud wrote: Then I found that the primary gear fouls on the case, joy! anyway, looking good man! great work and attention to detail as always! -g |
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Disaster averted, thanks to a great machinist.
![]() first step was turning a nice bushing to go in the center of the rotary table to locate the crank, case...
![]() once fixtured in place it was down to picking the right end mill
![]() A 1/2in end mill with a radius ground to the corner
![]() and now everything clears just fine
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Sergeant at Arms
![]() Weird 80's Vespas & Cool Vintage Lambrettas
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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 |
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Sergeant at Arms
![]() Weird 80's Vespas & Cool Vintage Lambrettas
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oopsclunkthud wrote: just popped the seal in to keep the chips out. Quote: tall primary = happy clutch looking forward to completion and the ride report! -g |
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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.
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Sergeant at Arms
![]() Weird 80's Vespas & Cool Vintage Lambrettas
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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 |
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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.
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Veni, Vidi, Posti
![]() 74 Super, 75 Super, PX project, LML off-roader and '66 Blue Badge Smallframe
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oopsclunkthud wrote: 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. |
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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. ![]() |
Style Maven
![]() '74 50s x3 '87 PK125XL '92 PK50XL2 Plurimatic - & - '58 AllState '68 Sprint '66(?) 125 Super '72 DanMotor 150 Super and '04 Bajaj LML hybrid
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This just gets better... Even I can understand the chart easily.
oopsclunkthud wrote: ... I'd rather close that gap with improvements to the aerodynamics. |
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The aero improvements will be some time down the road, but this is the general idea of what I've been thinking.
![]() The transition will need some work but...
![]() Similar tests on the LX were encouraging
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Veni, Vidi, Posti
![]() 74 Super, 75 Super, PX project, LML off-roader and '66 Blue Badge Smallframe
Joined: UTC
Posts: 9195 Location: Ballarat VIC, Australia |
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oopsclunkthud wrote: The aero improvements will be some time down the road, but this is the general idea of what I've been thinking. |
Style Maven
![]() '74 50s x3 '87 PK125XL '92 PK50XL2 Plurimatic - & - '58 AllState '68 Sprint '66(?) 125 Super '72 DanMotor 150 Super and '04 Bajaj LML hybrid
Joined: UTC
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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 |
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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. ![]() dry fit, clearance of vacuum line to cylinder.
![]() Clutch hub with fancy nut and loctite.
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Got the primary gear holder in from shape ways and I'm pleased to see they hold very tight tolerances. Everything fits as expected.
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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. |
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Davetopay wrote: File for a patent! very cool project. 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... |
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oopsclunkthud wrote: 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 |
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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.
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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. ![]() Studs trimmed to length
![]() Case modified to clear header
![]() final dry fit
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