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Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
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Posts: 4568
Location: London UK
 
Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: UTC
Posts: 4568
Location: London UK
UTC quote
hibbert wrote:
I entered 60.65 for piston height and 88.5 for inlet floor = 148.82 less than the 154 spec. The cutaway goes above the inlet port at TDC. Does the cutaway need to be raised to get the 154?
I get exactly the same. Inlet slightly shorter than spec. However, I'd leave it. 140 is pushing it. See how much blow back there is first. Exhaust might be a bit low too. Can fix in round 2.
OP
@hibbert avatar
UTC

Molto Verboso
Vespa
Joined: UTC
Posts: 1712
Location: California
 
Molto Verboso
@hibbert avatar
Vespa
Joined: UTC
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Location: California
UTC quote
Round 2 say what? Hopefully not if it runs I anticipate it will be better than ever and hopefully good enough for parades. For now I'll leave it.

I kept trying to visualize my previous squish calculations in my mind and things weren't adding up so I made a sketch to give the brain cells a break. Think I made an error and this looks more sense. Think I'll need only 2.7 mm under the head to get to 1.2 space. Look good?
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UTC

Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: UTC
Posts: 4568
Location: London UK
 
Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: UTC
Posts: 4568
Location: London UK
UTC quote
Yeah, I got the same, 2.70. Looks like that's all good. Power will be comfortable to ride. Will putter about at 50mph really solid.
If not quite enough there's always a round 2. See how it goes. Piston port, no reed, is not the best. Piston port with reed is the best. There's going to be blow back. The issue will be if it's too easy to flood on a missed start. Could be great, we'll see. Just having it running will be pretty cool.
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@hibbert avatar
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Molto Verboso
Vespa
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Posts: 1712
Location: California
 
Molto Verboso
@hibbert avatar
Vespa
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Location: California
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Thanks for checking my math Jack! I hope 50 is not top speed I thought stock set up was closer to 60.

I think I'm going to use a 23T on the clutch original is 22/67.
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OP
@hibbert avatar
UTC

Molto Verboso
Vespa
Joined: UTC
Posts: 1712
Location: California
 
Molto Verboso
@hibbert avatar
Vespa
Joined: UTC
Posts: 1712
Location: California
UTC quote
Made some progress on the GS that had me stumped for a few days. Piston seemed to hang up on rotation turned out to be the connecting rod interfering with the cylinder skirt maybe because it's a 60mm crank. There was a cut out on ONE side of the cylinder skirt but not on the other. Finally I separated the cases put crank and cylinder on 1/2 case so I could see what was going on and duh that's the problem. A smile returned to my face just knowing what was wrong.

Took cylinder to machine shop to cut other side of cylinder skirt and to enlarge the original cut wanted more clearance for the rod. The original slot was 6mm wide and the rod was 6mm I wanted an 8mm wide track. Machinist had trouble he started to enlarge the first side and had some of the nikasil chip fortunately it's not on the bore and on the bottom edge of the skirt. He made a quick cut mark on the opposite side but got too nervous and put it on the shelf. Ended up picking it up as is still needing the 2nd slot cut. Spent a few hours cleaning up the damage so the piston could move freely again in the cylinder something happened could not see or feel lots of working with Emory paper rolled on a small steel rod seemed to get it back into shape.

Checked marks again with crank on both sides 1/2 case assembly and went at it with a stone bit in the dremel. Think it's good now after more sanding with the steel dowel.

After finishing the grinding and checking clearance I asked myself why didn't I grind the rod instead? Still can't answer maybe I could do a little to make more room?

Going to start working on exhaust Polini box needs a few changes to fit.
Original Bollag cut
Original Bollag cut
Rod interference
Rod interference
Interference
Interference
Magnified light
Magnified light
Machinists work after some smoothing with Emory paper
Machinists work after some smoothing with Emory paper
Chipped nikasil bottom edge of skirt
Chipped nikasil bottom edge of skirt
My initial cut
My initial cut
My finished cut
My finished cut
Feathering cut with Emory paper rolled onto a steel dowel
Feathering cut with Emory paper rolled onto a steel dowel
OP
@hibbert avatar
UTC

Molto Verboso
Vespa
Joined: UTC
Posts: 1712
Location: California
 
Molto Verboso
@hibbert avatar
Vespa
Joined: UTC
Posts: 1712
Location: California
UTC quote
Waiting on parts to move this along. Had the exhaust modifications made to a Polini box. Bollag offers an optional slip collar with an internal o-ring so the clamp can be eliminated. I added two spring hoops to keep it tight. Removed pipe hangers, captive nut welded both tabs together and re-attached. Removed rear hanger patch so it looks like it was never there. Fits like a glove.

Had the exhaust ceramic coated. Chose burnt bronze to mimic the color on Mauro Pascoli exhausts. Might not be everyone's cup of tea but I'm jazzed.
Forum member supplied image with no explanatory text
Forum member supplied image with no explanatory text
Forum member supplied image with no explanatory text
Forum member supplied image with no explanatory text
Forum member supplied image with no explanatory text
Forum member supplied image with no explanatory text
Mauro Pascoli exhaust
Mauro Pascoli exhaust
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Forum member supplied image with no explanatory text
Forum member supplied image with no explanatory text
@oopsclunkthud avatar
UTC

Banned
3:5
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Posts: 8965
Location: San Francisco
 
Banned
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3:5
Joined: UTC
Posts: 8965
Location: San Francisco
OP
@hibbert avatar
UTC

Molto Verboso
Vespa
Joined: UTC
Posts: 1712
Location: California
 
Molto Verboso
@hibbert avatar
Vespa
Joined: UTC
Posts: 1712
Location: California
UTC quote
Wow ok so this is the carby you mentioned before I still had no idea. Got a little sticker shock when I reviewed the link. If anyone has one laying around please let me know maybe we can work something out. I'm not expecting too much performance increase but I'm not sure what to expect. The bore is actually slightly smaller than original old piston is 57.5mm new piston is 55.9mm. Old stroke is 57mm new stroke is 60mm. Both old and new come in at 147cc's. Expect some advantage with the aluminum cylinder, better piston, ring and wrist pin roller bearing. Looking forward to running 2% oil mix big savings on that. 20 years ago I rode a VS5 with a custom expansion chamber and could not believe how much it improved.
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@bajarob avatar
UTC

Addicted
1961 VS5T, 1981 P200E, Rigid Frame Chopper, 2001 Harley FXDXT
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Posts: 829
Location: Ventura, CA
 
Addicted
@bajarob avatar
1961 VS5T, 1981 P200E, Rigid Frame Chopper, 2001 Harley FXDXT
Joined: UTC
Posts: 829
Location: Ventura, CA
UTC quote
Had the exhaust ceramic coated. Chose burnt bronze to mimic the color on Mauro Pascoli exhausts. Might not be everyone's cup of tea but I'm jazzed.
[/quote]

That pipe should look good on the GS. I like it better than the Pascoli. They did a nice job on the coating.

I've heard that it's not difficult to up the ponies on the GS engine but don't ask me how it's done. After mine is running I'll have you take a spin and you can tell me if it's better than stock. Curious how my newer style pipe performs.
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