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GT6MK3

Vespa smallframe

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Got to admire your clamp collection!

It is quite hard to believe you need another!

Serious bodywork nearly done now :)

Nick

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Unwanted hole (OE though?) now gone.  Oven to pre-heat casting.  Not quite sure what honking great finger crusher for......

Nick

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Very unwanted hole - not oe - it blew through during hydroblasting, a result of trying to maximise case volume by expanding the crank void to the maximum possible, might have overdone it.  Hopefully filled now.  Oven cost me a sold 10 bucks on ebay!

Neededto cut out and bend a 25mm by 270mm piece of 1.5mm sheet to fill the rear base of the legshield.  Was planning on cutting it out with an angle grinder, and bending it in a vise, but Mat laughed and used his toys to good effect.  Nice to have friends,

Hope you're improving,

C.

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Had a good day in the garage building up a buddy’s motor that’s the fraternal twin to Buffy’s

BDE3121D-4064-41CD-85CF-D65B2FD6053F.jpeg973DB7DA-3D03-4944-8558-427C2B3148E7.jpeg7FF7C18F-7076-463A-80AF-A686784AEEC9.jpeg10DF6E49-CDAF-410F-A95E-F3E8B31BAC66.jpeg

he’s pretty chuffed...

the inside of the crank housing weld cleaned up ok

818FC55C-6721-4890-A171-6690B54798EA.jpeg

Sunday I milled down the massive pimples left after building up the ports for machining

0500A68E-77F2-4BCF-97FF-5CBB4AC642DE.jpeg

and this arvo the base of the leg shield got sealed up

8D749986-1E28-4336-98A9-5B63F78F590B.jpeg609A8999-76BC-4A33-AFA0-DD5A34EFEA74.jpeg

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Went to Alan's headquarters today, and did some measuring.

FC3ACC54-21EC-43F1-97D7-9F2EDC0E5A43.jpeg

We put up the first engine, with the piston at TDC (re-measured with a dial indicator). 

5E736DAF-1081-4053-A0AA-DE0DB0AFFFD7.jpeg

We touched off the face of the cylinder, and established a plane there as a base.

7159C74C-04DA-4FEA-B33B-EC1BC40BD805.jpeg

Next we touched around outside wall of the protruding piston to give us a reference circle to work within.

Finally, we touched off four points as close to the outer edge of the face of the cylinder as possible, two in line with the gudgeon pin and two perpendicular to it.  We may have got some minuscule piston rock on the across touches, so we'll trust the "along" numbers.  Here they all are...

vespa_tdc_1.jpg

Basically, they show that along the gudgeon pin, the piston edges protrude 1.6251mm (averaged), and across it, 1.6118mm.  So lets call it 1.63mm for our purposes.
 
Next the second engiine (Mine!) went up
 
177E88B1-6B8B-4AE2-A1A3-D70793232BE7.jpeg
 
After the TDC procedure, we measured again
 
vespa_tdc_2.jpg
 
Across the pin we'll call mine 1.94mm
 
Next we measured the cylinder itself, including some numbers for future reference in case we want to mill replacements later (Outer holes, combustion chamber sphere etc)
 
DC893E26-6863-46F0-90FF-1B0C2DB9D1E7.jpeg.
 
The squish area of the cylinder head is a sloped ramp, which then meets a short outer cylindrical wall, which then in turn meets the outer mating face.
 
We need to know the height of the cylinder wall, s (a) it will allow us to set our squish, and (b) it will form the hard limit of how far the piston can protrude from the cylinder, lest it mash into the head, rapidly, with great and expensive force...
 
Because the wall meets a sloping face, accurate measurement required some maths and calculation.
 
First, we touched off points on the upper face, and made that a reference plane.
 
Next we carefully touched off points on the inner wall of the cylinder, all at the same height.  (with the software, if you tell it your're measuring the inside of a circle, and touch three points, it can extrapolate the circle.  Touch more points, and you have more accuracy). Once we had the circle, we then had the software expand it into a cylinder, perpendicular to the original top reference plane.
 
To measure the squish ramp, we told the software we were measuring a cone.  By touching off points up, down, and around the ramp, we were able to calculate the ramp. then find (a), where it intersected with our wall cylinder, and (b), how far down from the top reference plane that intersection was.
 
vespahead.jpg
 
Abracadabra, the built in squish headroom for the cylinder is 0.9252mm.  Lets call it .93.
 
So as they stand, we're going to make expensive noises with our 1.63 and 1.94 popups.
 
On to the cylinders.
 
We measured these with a 90 degree probe, trying to get about 0.8mm into the port to beat the roundoff on the edges.
 
B4EA86B6-432B-465F-9B10-7A07CC8C2E43.jpeg
 
Because we have the current popup numbers referenced to the top face of the cylinders, we were able to take these off the engines and measure them stand alone.
 
2444C288-B8F3-4F8C-AD6B-8A7F4545DC18.jpeg
 
Results for #1
 
vespa_cyl_1.jpg
 
and  mine.
 
vespa_cyl_2.jpg
 
Mains on #1 are 38.87 39.01 38.64 and 38.78. (Average of 38.83) Exhaust is 27.46.  So 130.12 and 185.29 with 27.58 and zero deck, and 132.87/187.51/27.32 with 0.5mm popup.
 
Mains on mine are 38.65 39.09 38.58 and 39.23. (Average of 38.89) Exhaust is 27.97  So 129.79 and 183.02 with 26.62 at zero deck, and 132.54/185.25/26.36 with 0.5mm popup.
 
Now I'm off to consult guru's and do maths...
 

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A trip to Alan's shed tonight for some programming.

My buddy Michael had provided this as the basis for the cylinder spacer.

Screen Shot 2018-07-19 at 11.50.39 pm.png

That let me build up this in a mere 24 steps.

IMG_2015.jpg

But I needed to step the ports out 3mm horizontally over the 10mm thickness.

Each arc for example has 13 adjustable variables to be set, with 3 check results.  Then there's lines, blends, depths, and repeats.

IMG_2018.jpg

Which meant lots of maths, educated assumptions, (and a buttload of scientific wild arse guesswork). 

Till I had this

IMG_2019.jpg

It was 4 degrees in the shed, and almost 10pm, so I saved it and naffed off home for a hot toddy.

I'll cut it tomorrow.

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ClampIMG_2024.jpg

 

Cut

 

IMG_2028.jpg

 

Think and program

IMG_2043 (1).jpg

 

Cut more

 

IMG_2042.jpg

 

and moreIMG_2037.jpg

And parts magically appear

IMG_2045.jpg

 

Oh, and re-re-re-cut the top surface...

IMG_2022.jpg

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Yep, it's an awesome toy.  wish I had the garage big enough to house one, and the budget to buy one.  Luckily, Alan lets me use his!

More work I the garage Saturday.  Sadly, I overdid it pressing a bearing holder into a 50 year old engine case and cracked it, which was cause for a large amount of swearing, and will require the opening of my wallet to fix.  Dammit.

My buddy Michael was able to continue his build though, and more port grinding ensued.

IMG_2046.jpg

And, with the arrival a third set of hands and experience, the stuffing of oversize parts into an undersize case began

IMG_2052.jpg

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Buffy hasn't been forgotten, but her powerplant has been taking much longer than I anticipated to put together.  Everything almost fits, and everything that doesn't quite needs careful thought and precise fettling to make right if she's going to be capable of the rev's she'll need.

And then of course, there's my idiot/rookie mistakes.

Today's task was to put together the clutch cover.  Should be simple, but there's aftermarket bits, which precicely almost fit, and I needed to waste hours filing, sanding, twisting, heating, cooling, clamping, swearing and pondering.

Eventually, without breaking too many parts,  this simple assembly was together.

IMG_2157.jpeg

Easy.  I should have left it there.

Instead, I decided to fit it.

 

And dropped a clutch cover bolt (actually a high tensile M6 socket head screw), into the open clutch case.  Sod's law dictated that it (of course), immediately rolled through a tiny gap, into the gearbox.

 

Fair to say I was displeased.

 

Genius that I am, I gently rolled the case over, and tried to gently shake it back out.  Which resulted in a click, a clunk, and then silence.  Yep, I'd got it jammed in the gearbox.

113E6D34-F8FB-46FF-A3EF-0848FA663381.gif

 

A machine screw floating in the gearbox is not ideal.  After a short, blue coloured hiatus, more shaking and swearing (if it was a baby, I'd have been arrested), and some general poking around, I remembered I impulse bought an inspection camera at Aldi a while back.

Oil filler bolt out, camera in, a bit of wiggling, and the little bugger came into view.

IMG_2159.jpeg

Half an hours prodding and probing with a bit of bent mig wire, some more rolling of the case, and I'd got it loose of where it had wedged, and worked it up towards the front of the gearbox.  Now to get it out.

So I glued a rare earth button magnet to a thin screwdriver and went in on an angle past the clutch

IMG_2164.jpeg

I felt like Jack Swigert trying to capture the LEM in Apollo 13, I really didn't want to have to split my pressure tested cases, so it was a delicate operation done juggling the mag stick, the camera probe, and the screen, but before too long I had "Capture", as the bolt jumped onto the magnet.

IMG_2163.jpeg

 

From there it was a twisting and turning in and out see saw to gently twist the bolt out of the gearbox, through the slot, and under the clutch.  Finally though,

 

Success

IMG_2167.jpeg

It reappeared.

 

Good tools,

IMG_2162.jpeg

 

Are their own reward.

 

Craig

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Thats a damn good quality picture on the camera!!

I occasionally have to use a ridiculously expensive FLIR one of those on the ship's, and to say it is awful is an understatement. Several thousand dollars of waste.

Phil

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These things are sent to try you. And do.

"Blue coloured hiatus" Yeah. Maybe some small tools ricochetting of the walls too. Can relate.

Nick

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After a long road, I headed out to the garage last night to prepare Buffy's powerplant for it's first fireup.

Today I headed back to Mat's factory after a work induced hiatus.

Clamped up the first of the underfloor bracing ready for welding (You cant use too many clamps!)

7tRF9sbBTgizEYcpIioQmw.jpg

And made a start on glueing them in

6uSC4wPdRc6z1voi%AtNig.jpg

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Hah!  It runs....... :banana:

 

Did it really start first kick........ or was there some undocumented cussing........ my 2 stroke experiences all involve much cussing!

Frame must be nearly done now?

Nick

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