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1964 v90, 1970 VBC, lots of dumb twist n go toys
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@thomashsb avatar
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UTC quote
Brain fart I had tonight while pulling my plug...

The issue with running a large kit on an early smallframe is that the sparkplug winds up buried in the cowl, right?

If you disconnect the shock will the engine then drop out of the body enough to get to the plug? I'd be willing to go through the hassle of removing one more fastener to get a better top end.

Hell, I'm the asshole that'd just take a hole saw to the cowl where the plug winds up. It's just steel.
⚠️ Last edited by ThomasHSB on UTC; edited 1 time
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The engine on the small door smallies are different from the other engines. If you run the right engine you can't do much to it. We have a 100 sport head on ours. i am also very adamant about keeping my '64 as original as possible. Now we are going to put s race engine into the 50n which is also a small door but we have to get the frame ready for a little paint and we need to buy a fork. I have heard of someone making a tool for help in removing the plug. We have a large door 50r that we use as our "running in" bike and will probably Plug chop the engine in that frame before we plop the race motor in the small door 50n.
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Hooked
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UTC quote
My engine is already a '74. After my gearbox self destructed that was the most cost effective way for me to get it back on the road.

This engine's crank is broken off on the flywheel end though. There are only two or less theads holding the nut on. The flywheel is in place mostly from habit, lol. I'm planning a springtime rebuild with a new crank and have been pondering how performance oriented I'd like to go.
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ThomasHSB wrote:
have been pondering how performance oriented I'd like to go.
What's your budget? I'm here to spend your money.
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Hooked
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PureDrivenSnow wrote:
ThomasHSB wrote:
have been pondering how performance oriented I'd like to go.
What's your budget? I'm here to spend your money.
Lol, don't know yet. Gonna wait until I sell my Comet. Truck's transmission gets the first shot at that money though.

I know I'd like to go to a 4 speed box while ithe Vespa is apart, so that'll be a chunk in itself.
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Molto Verboso
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Molto Verboso
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well... what do you want the bike to be, besides a vague 'more?'


With anything 125 or greater, while it will fit, it makes it very difficult to remove the spark plug. it's difficult, but not impossible. i've seen it done.

if you want to be in the 'stock primavera' neighborhood, you could run a 100 sport top end; these are a later 3-port and are roughly equivalent to a stock 125 but are based on, and fit in the same shrouds as a stock 90 so they dodge the spark plug issue.

beyond that, there are some short stroke options based on the 50 that keep the spark plug in reach as well; they combine the shorter stroke of the 50 with the bore of the 125+ kits. as they are based on the 50 jugs, they would require a 50 exhaust and cooling shroud. polini's 115 kit is one od these; they claim 9.8 hp at 8200 rpm. for comparison, the standard 135 polini cast iron claims 12.2 hp @ 8100. and a stock primavera claims 5.6 @ 5500.
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I'll probably.just do a four speed gearbox when I do the crank and save top end thoughts for later. Just take care of the stuff that requires splitting cases.

I know I want to get rid of the gap between second and third gear. Makes climbing hills aggravating if I can't hit them at speed.

Are HP numbers really that.low for this stuff? I also.play around with newer stuff and it really doesn't take alot to get close to 10 horses from a horizontal Minarelli or Morini engine. I've been drooling over a 77cc kit that claims 25hp with matched pipe and carb.
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I went from a 3 to a 4 speed box on my '74 v90. It's definitely a boring way to spend money. You end up trading the gap between 2nd/3rd for a new gap between 3rd/4th. That being said top speeds are better and I upgraded a bunch of other stuff so it made sense.
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If you go 4 speed make sure to do the DRT short 4th tree to avoid the dreaded 3-4 gap.
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On a serious note, I would set some sort of budget or make a plan. Let's just say you go short 4th, primaries, loose gears, etc... you just spent $400 on gearing. Are you gonna have enough power to pull that gearing? Now it's top end, carb, exhaust.
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UTC quote
I am not really chasing higher speeds on this bike. 50mph is pretty terrifying for me on it as is. I'd like to do a gear stack that just gives me closer ratios.

For all out speed I've got a Derbi Predator in the works. 13" wheels, front and rear disks, inverted forks, much better suited for building a fast scooter. 50 on it feels like 25 on the smallie.
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ThomasHSB wrote:
I am not really chasing higher speeds on this bike. 50mph is pretty terrifying for me on it as is. I'd like to do a gear stack that just gives me closer ratios.

For all out speed I've got a Derbi Predator in the works. 13" wheels, front and rear disks, inverted forks, much better suited for building a fast scooter. 50 on it feels like 25 on the smallie.
honestly, i'd stay stock-ish then. a standard 4-speed with 90 primaries would give a ridiculous amount of overlap between gears- especially if you go up to a 19 carb and a mild pipe.

if you want further than that, while they aren't cheap, new pk100 top ends are available- these have later revised port timings and are 3-port.
a slightly higher primary and that top end with the 4-speed would work well, or stock primaries if going 3-speed.
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UTC quote
I need to double check. I swear it's already a 19mm carb on there. Maybe not.

I do already have the basic Polini sport pipe, that woke the engine up immensely. And sounds so wonderfully angry.

I'd like to try a pure expansion chamber on here, just because I've seen the difference they've made on my other bikes, but with gears worry the peakier powerband would be less fun for daily riding. Will PK Automatica engine fit in an early smallie?
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Pure expansion chamber, not over 50 mph and convert to PK Automatica. That would definitely be the road less traveled. Maybe Rob can help you sort that out?
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UTC quote
rob hodge wrote:
ThomasHSB wrote:
I am not really chasing higher speeds on this bike. 50mph is pretty terrifying for me on it as is. I'd like to do a gear stack that just gives me closer ratios.

For all out speed I've got a Derbi Predator in the works. 13" wheels, front and rear disks, inverted forks, much better suited for building a fast scooter. 50 on it feels like 25 on the smallie.
honestly, i'd stay stock-ish then. a standard 4-speed with 90 primaries would give a ridiculous amount of overlap between gears- especially if you go up to a 19 carb and a mild pipe.

if you want further than that, while they aren't cheap, new pk100 top ends are available- these have later revised port timings and are 3-port.
a slightly higher primary and that top end with the 4-speed would work well, or stock primaries if going 3-speed.
Done almost EXACTLY this on two bikes that were originally a 50S and a 90. The 50S got a used Primmy crank and both got stock used Primavera 125 2 port top ends matched to the cases*, the 90 got a used 4 speed gear set and the 50S got 90/100 primary gears. Both have decent pipes and are running 3.50 tires on the motor for a slight 'upgear'. One has a 19 carb plus reed valve and the other has a 20L.

Either one would deliver all you are asking for and more with good reliability and reasonable cost. If you go this route, I do like this idea and think you could do it nicely with a little effort & luck.
ThomasHSB wrote:
Hell, I'm the asshole that'd just take a hole saw to the cowl where the plug winds up. It's just steel.
*More here on matching the cylinder to your case where you can see both motors being built: Cannot recommend...
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I put a Pollini 130 in my '64 V90.. it's a bitch to take the spark plug out, but it is do-able. I bought a MB (Mark Broadhurst) spark plug "socket" .. carefully put in on the plug and then use a 13mm wrench to turn the socket and get the plug out..

... it's tight... very tight, but it works.

http://www.lambrettaspares.com/spares/tools/tool,-spark-plug-socket,-mb/mbp0267.html
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Brillant tool.

Here is a link to Automatica conversion...

http://www.scooterhelp.com/restorations/vespa.auto.start.html
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Vader19 wrote:
I put a Pollini 130 in my '64 V90.. it's a bitch to take the spark plug out, but it is do-able. I bought a MB (Mark Broadhurst) spark plug "socket" .. carefully put in on the plug and then use a 13mm wrench to turn the socket and get the plug out..

... it's tight... very tight, but it works.

http://www.lambrettaspares.com/spares/tools/tool,-spark-plug-socket,-mb/mbp0267.html
I have a basic sparkplug socket with the hex on the end that I already usually use that way as it makes it easier. Or use the old school tube that you stick a screwdriver across.

Do you have any pictures of the fit on your bike?
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ThomasHSB wrote:
Do you have any pictures of the fit on your bike?
I'm still dying from the flu, but I'll take a pic for you ASAP.. .
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UTC quote
I've got a 136 stuffed into a small door and i'm getting the socket out with the sparkplug tool with the angled handle. You cant see what youre doing bit it seems to do the job ok
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UTC quote
So honestly top end swap is all based on what things look like when. I disassemble. I can swap jugs without splitting cases.

What is 100% in the plans is a new crank, the end is broken on mine and if I ever got the flywheel off I have no assurance I'd get it back on solidly, so I can't get to the stator for things like points replacement and such right now. And I definitely want to go with a 4 speed gearbox while the cases are split.

Recommendations on a new crank? I plan on keeping rotary valve induction. Lots of options out there, I get overwhelmed and distracted. Actually, overwhelmed and distracted is why most of my questions tend to.be rambling and go off random directions.

Gears. I would need both the gears themselves, including the Christmas tree, and a new output axle shaft?

Clutch. At what point are better than stock clutch components deemed truly necessary? Mine slips so if I'm in there anyway stuffs getting replaced.

I like the idea of going electronic ignition but that doesn't require splitting the cases, so it can wait. Right now I have a 12v stator that works but I've never gotten it to 100℅ match any wiring diagrams I've happened across so I don't know exactly what it is. Something older and aftermarket maybe? I have good ignition and my lights all work so I haven't sweated it that much.

If I do swap topends, and am willing to deal with tight plug access, I like the looks of this kit. http://www.sip-scootershop.com/en/products/racing+cylinder+polini+mono+_14000500

While we're at it and speaking of getting distracted, anyone have a smallie with this kit????? http://www.sip-scootershop.com/en/products/racing+cylinder+quattrini+_15052000. WTF?!? How terrifying is that to ride???
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UTC quote
DRT makes a number of 3 speed trees. Worth a look.

having sheared small taper cranks and hassled with the ETS conversion, a 20/20 crank is my choice from now on. But then you need the corresponding flywheel too.

Haven't had luck with 4 plate clutches. They're a drag. Or maybe I'm not spending enough. Actually just ordered the Crimaz EZ4.

Happy with longer stroke conversion. Added torque makes for less shifting, more rolling on.

And yeah, your 77cc minnerelli will still kick ass on you 130cc Vespa.such is life
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UTC quote
scootermarc69 wrote:
And yeah, your 77cc minnerelli will still kick ass on you 130cc Vespa.such is life
Even on the twist n gos I don't have anything as sensible as a Mina, just follow lots of go fast builds. Two TGBs w/ Morini based engines and a liquid cooled Derbi, with the Derbi/Morini engine. I think my next scoot will be something with a Piaggio LC 2t.
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