1976 Sprint V mechanical rebuild
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Molto Verboso
05 Stella, '62 VBB, 76 Sprint V
Joined: 16 Jun 2011
Posts: 1797
Location: Chicago. Well, Evanston, but that's almost Chicago
Fri Nov 09, 2018 3:27 pm quote
First start, just to see...

The fuel tank was leaking when I first filled it up, so I need to see if the tap is leaking or the fuel line is cracked, as it's basically petrified.

A lot of white smoke at first, but that cleared up after it ran for a few minutes.

I took it for a ride around the block and the ride was just really smooth. Much slower than I'm used to, and I didn't really push it since I only swapped out one tire, but from that two minutes of riding, I like it a lot.

Next will probably be pulling the tank and cleaning out the autolube. I'll swap it over to 12v. It had the wiring harness replaced, but the ignition is still the original points. That will turn into a SIP Variable Timing ignition soon enough, along with the engine rebuild.

Let the fun begin!

Last edited by chandlerman on Tue Nov 20, 2018 6:44 pm; edited 1 time in total
Molto Verboso
05 Stella, '62 VBB, 76 Sprint V
Joined: 16 Jun 2011
Posts: 1797
Location: Chicago. Well, Evanston, but that's almost Chicago
Fri Nov 09, 2018 5:22 pm quote
First parts orders placed. Engine rebuild bits, plus a SIP Road XL and 60mm Mazzi crank. Clauss Mounts for the motor and rear shock. A new 6v battery from Amazon.

I'll use the Polini 177 that's sitting on the shelf for a top end, keep the stock gearing. Maybe swap the clutch out at some point.

No ignition upgrade for the moment, because the SIP Sport Ignition is out of stock and that's an easy swap later. No shocks, rims, or tires, either, because I have a couple of spare Continental Zippy 1's already sitting on rims. I just needed an inner tube for one of them.j

And no front disc, which will probably happen at the same time as I replace the shocks since I'll be going the PK fork route.

And for the moment, I'll probably pull the 24/24 carb off the VBB and install that until I eventually go to a PWK 28 or 30 (again, becauseI have those lying around).

My goal is to get reliably back on the road, then worry about the less intrusive (i.e. cosmetic or no case splitting) upgrades later.
Addicted
2008 GTS 250, 1979 P200E
Joined: 11 Jan 2006
Posts: 838
Location: Florence, OR
Fri Nov 09, 2018 7:56 pm quote
SCORE - It runs! Very nice. Now for the general stuff (fuel line, tires, etc) and at least you'll be rolling. I'll be watching what you do.

BTW, is that a Pinasco tubless split rim on the Stella I saw in the vid? If so, how are you liking them? I'm thinking of getting a set myself...
Molto Verboso
05 Stella, '62 VBB, 76 Sprint V
Joined: 16 Jun 2011
Posts: 1797
Location: Chicago. Well, Evanston, but that's almost Chicago
Sat Nov 10, 2018 4:42 am quote
qascooter wrote:
SCORE - It runs! Very nice. Now for the general stuff (fuel line, tires, etc) and at least you'll be rolling. I'll be watching what you do.
The biggest problem right now is that I don't have enough room in my garage because of the boat project, which is inside the plastic sheeting in all the recent pictures.

It's pretty sad when I've gone from no workshop (I was, literally, a shade tree mechanic for three years before moving into this house) to "oh, my two car garage workshop isn't big enough for all my toys!"

So next up is probably some workspace cleaning, at least getting my workbench cleared off, so I can pull the motor and see what's up inside the cases. I know that the previous owner never rebuilt the motor. He owned it for 25 years and put 7,000 miles on it, but the transmission was super-smooth yesterday, so to me that's a very good sign.

You can see a LOT of white smoke in that video, which might just be crud from sitting for ten years, but given that he originally asked me about help with getting the carb to dial in, I'm guessing leaky clutch side seal. Either way, it's getting replaced once the SIP Fairy arrives.

And I'll be replacing the motor mounts, too, since I'm pretty certain that they and the top rear shock mount are all going to be shot to hell since he also told me that he and his wife used to ride two-up a lot, and he's over six feet.
qascooter wrote:
BTW, is that a Pinasco tubless split rim on the Stella I saw in the vid? If so, how are you liking them? I'm thinking of getting a set myself...
Yes, it is. I bought a pair of them four or five years ago, then had to replace one when it got loose on the hub and damages the mounting holes. The newer generation version goes together a lot better, but is a millimeter too tight for the front hub on the Stella.

All three of them have had a tendency for intermittent slow leaks, I assume along the split.

They have not held up to general wear & tear as much as I would have liked, but they're significantly lighter and noticeably better balanced at higher speeds.

I've been tempted to try the SIP Tubeless rims, especially now that they'll ship them with tires pre-mounted, but that's a fair ways down the scooter budget list right now, what with a couple grand worth of brakes, suspension, ignition, and probably more engine upgrades beyond the long stroke and basic rebuild bits I've already ordered for this current adventure.
Veni, Vidi, Posti
74 Super, 75 Super, PX project, LML off-roader and new to 2018, '66 Blue Badge Smallframe
Joined: 30 Nov 2011
Posts: 6557
Location: Victoria, Australia
Mon Nov 19, 2018 11:32 pm quote
Looks like a great project Chandler! Should be good fun.
Do you have the Clauss mounts on your VBB? I tried them on the Super and had to take them out, waaay too much vibration. But I haven't heard anyone with a P complain about them.

I recently had a Pinasco wheel come off... I had done about 400km since tightening the wheel nuts. But they came loose and eventually fell off altogether. Funny thing was I didn't notice anything strange until suddenly I was skidding along with the wheel jammed up in behind the hub and the scooter simply stopped. The stud holes were all enlarged by this time. I've ordered another one but I'll be looking for another type of nut this time!
Molto Verboso
05 Stella, '62 VBB, 76 Sprint V
Joined: 16 Jun 2011
Posts: 1797
Location: Chicago. Well, Evanston, but that's almost Chicago
Tue Nov 20, 2018 7:10 pm quote
I thought I'd posted a reply this morning, but it seems to have been eaten by The Internet Gods, so...
Ginch wrote:
Looks like a great project Chandler! Should be good fun.
Do you have the Clauss mounts on your VBB? I tried them on the Super and had to take them out, waaay too much vibration. But I haven't heard anyone with a P complain about them.
I have them in my Stella, but not my VBB. I've been pleased with them on the Stella, so I'm going to go with them again.
Ginch wrote:
I recently had a Pinasco wheel come off... I had done about 400km since tightening the wheel nuts. But they came loose and eventually fell off altogether. Funny thing was I didn't notice anything strange until suddenly I was skidding along with the wheel jammed up in behind the hub and the scooter simply stopped. The stud holes were all enlarged by this time. I've ordered another one but I'll be looking for another type of nut this time!
I had a similar issue. It felt like the rear hub nut had come loose, but when I went to check it, several lug nuts were loose and the rim was trashed.

I replaced the rim and the newer version had several engineering changes, most of them related to making bolting the halves together easier, and some that might have been cosmetic, or maybe just simplified manufacturing. It was also a tiny bit tight on the hub, but not so tight it couldn't be persuaded on with a tiny bit of love from a dead blow hammer.

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Trashed :(

Molto Verboso
05 Stella, '62 VBB, 76 Sprint V
Joined: 16 Jun 2011
Posts: 1797
Location: Chicago. Well, Evanston, but that's almost Chicago
Tue Nov 20, 2018 7:39 pm quote
Also, this afternoon I pulled the tank for general cleaning (it has a little loose crud, but not much rust; oil tank just needs cleaning) and to replace the fuel tap with a faster flow.

I also dropped the motor. Crankcase oil was gas-free, which surprised me a little. I guess all the white smoke when I fired it up was just from sitting for ten years.

With the motor out, the frame is amazingly light. I was able to easily hoist it by the tail with one hand after the centerstand slipped and folded up while I was dropping the motor. I think it's even lighter than the VBB, if that's possible.

The fuel line was basically petrified, to the point I couldn't even pull it out and had to cut it when I pulled the tank. The shocks are looking pretty dodgy, so maybe I'll do the rear since I'm replacing the mount, then suck it up on the front until I put the disc brake on.

The rubbing on the clutch cover is from the stick-on whitewalls the PO had which had come un-stuck.

I'm still working around the boat hull painting, but I figure that tomorrow I'll get my workbench cleaned up so I can split the cases and see what I failed to order first time around in the way of rebuild parts. Thus far, the only thing I've realized I forgot is clutch plates and new cables, neither of which are show stoppers for the engine rebuild.

And a guy I work with has a sandblasting cage and powercoating rig, so I'll probably hook up with him to do the wheel rims and hubs. I'm still thinking black for those.

Who knows. I might be rolling before the snow gets too deep yet!

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Definitely not VaderKleen!

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Naked frame

Molto Verboso
05 Stella, '62 VBB, 76 Sprint V
Joined: 16 Jun 2011
Posts: 1797
Location: Chicago. Well, Evanston, but that's almost Chicago
Mon Jan 07, 2019 2:52 pm quote
It begins...
I decided to move my project thread over to, well, my project thread.

Hopefully it won't wind up as long as some build threads .

I started the teardown on Saturday morning and provided my initial update over in Today, I...
chandlerman wrote:
I finally started the teardown on my Sprint's motor yesterday.

First up was scraping off all the crud, which took an hour or two by itself. It still needs more cleaning, but at least it's not a total muddy/greasy mess so I can work on it.

I don't think it had ever been opened up before, but it definitely needed a rebuild. Leaks on every seal, but almost no wear on things like the cruciform or gears. Maybe it's just how I build and ride my bikes, but this thing shows less wear on the gears and cruciform after at least 25 years (PO never rebuilt it) than I get in a year.

Assuming that I don't get pulled into too many other things, today will hopefully see me finishing the tear down and building up the cases around the ports with JB Weld prior to tearing into them with the ol' Dremel.

I also decided after watching The latest (ep 34) of That Scooter Thing that I'd go ahead and get a Vape ignition for it rather than mess with points and 6v. I have a few other things I need to get from SIP anyway (brake shoes? those wear out?), so why not, other than, well, money?
And yesterday's update...
chandlerman wrote:
Finished the teardown this morning, then cleaned the cases and JBWeld'ed around the ports.

I also went a little bit crazy over at SIP.

The build plan is now:
- Polini 177
- 60mm Mazzi cut crank
- 24/24e with the fuel passage drilled out
- Polini Venturi carb adapter
- SIP (Vape) variable timing ignition
- Full DC & 12v conversion
- SIP RoadXL
- Clauss Mounts

I'll keep the autolube and see where all that gets me.
But future updates will live here.

Next up is porting, grinding down the excess of JBWeld that I put around the ports, and then assembly. Maybe not until Friday, but maybe earlier. Now that it's under way, I'm pretty fired to get things rolling.

My biggest challenge is that SIP didn't get my order shipped today, so I could be waiting for parts over the weekend. Luckily, nothing that will keep me from getting the cases buttoned up, though.

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Ready to go!

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Head leak. My personal nemesis.

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Now we're getting somewhere!

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But it still started and ran before I pulled the motor off the bike. Compression was not all it could have been, though...

Addicted
One or two fun scoots....nothing too precious
Joined: 17 Jul 2013
Posts: 928
Location: UK (South East)
Tue Jan 08, 2019 3:37 am quote
Chandlerman, I was surprised to see what looks like a narrow taper crank in a 1976 Sprint V motor. I thought Piaggio had transitioned to the P style crank by then. There's a lot of material around the transfers on those older 3 ports. I doubt you'll need the JB Weld.
Molto Verboso
05 Stella, '62 VBB, 76 Sprint V
Joined: 16 Jun 2011
Posts: 1797
Location: Chicago. Well, Evanston, but that's almost Chicago
Tue Jan 08, 2019 6:15 am quote
swa45 wrote:
Chandlerman, I was surprised to see what looks like a narrow taper crank in a 1976 Sprint V motor. I thought Piaggio had transitioned to the P style crank by then. There's a lot of material around the transfers on those older 3 ports. I doubt you'll need the JB Weld.
To be honest, I hadn't really considered the crank taper. I'll measure it when I get home and confirm. It used the self-extracting flywheel though, which actually worked just fine, a bit to my surprise after having a terrible time with the one on my VBB.

Yes, the JBWeld is overkill (it's *really* overkill), but it's soooo much easier to do it now when the cases are clean and de-greased and then not need it. A lot of it will be getting dremeled off, for sure. I didn't realize how much I'd overkilled it until I put the cylinder on and saw the excess.

I had the Polini on my Stella previously and matched its ports to the Stella cases at the time, so I was kind've beholden to those openings as a result. Looking at what I have, I'm in good shape. A little bit on that upper transfer would have been plenty, but I also don't have to worry about breaking through this way, either.

And in less happy news, the expected delivery date on my SIP order is not until Monday, although it's been known to arrive a day early, or go to the FedEx distribution center, which is about ten minutes from my house. Either way, Meh.

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Look at that beautiful rotary pad!

IMG_20190108_073220-porting.jpg
Big ol' ports

Veni, Vidi, Posti
74 Super, 75 Super, PX project, LML off-roader and new to 2018, '66 Blue Badge Smallframe
Joined: 30 Nov 2011
Posts: 6557
Location: Victoria, Australia
Tue Jan 08, 2019 5:49 pm quote
That pad looks great! Nice motor you got there.

I have 74 and a 75 Super motors (according to the Scooterhelp calculator - although Rob Hodge has said that there is some wiggle room on the dates given) and one has the P type flywheel side bearing and the other doesn't.
Both have the narrow taper though. So looks like there was another step between these late motors and the P.
Molto Verboso
05 Stella, '62 VBB, 76 Sprint V
Joined: 16 Jun 2011
Posts: 1797
Location: Chicago. Well, Evanston, but that's almost Chicago
Sun Jan 13, 2019 6:09 pm quote
Today was Dremel Day.

Spent a few hours in the garage opening up the ports, cutting out the gates in the cylinder, porting and flowing the airbox into the cases for the 24/24, and rounding out a few edges.

I have a couple spots to touch up, then

Naturally, I managed to break through the ports on each side, so I had the pleasure of fixing those spots. I should get a JBWeld endorsement.

I'll clean up the JBWeld, polish it all a little bit, and then it'll be good-to-go.

Almost ready for the re-assembly to begin!

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Before

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After

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I like big ports and I cannot lie

Veni, Vidi, Posti
74 Super, 75 Super, PX project, LML off-roader and new to 2018, '66 Blue Badge Smallframe
Joined: 30 Nov 2011
Posts: 6557
Location: Victoria, Australia
Sun Jan 13, 2019 8:50 pm quote
I do often wonder what the right shape for the base of the transfers is. Thinking about it, I wonder if digging them out with a relatively sharp radius at the bottom is really the best? I imagine the flow would be smoother with a gentler path from case to cylinder.

CYLINDER.jpg

Addicted
One or two fun scoots....nothing too precious
Joined: 17 Jul 2013
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Location: UK (South East)
Mon Jan 14, 2019 12:46 am quote
I would assume that volume is equally important, but only if you have the inlet/crank/carb combo that can create the requisite volume of charge in the first place. Otherwise, flow, as you say would surely be better with the sloping port sides.

The added benefit would be little or no need for JB Weld !!
Addicted
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 958
Location: London UK
Mon Jan 14, 2019 12:57 am quote
Looking like good progress. Shape is not as important as big. There should be no sharp edges or right angles all those parts should be radiused. Round edges create less turbulance.

What port timing you aiming for?
Molto Verboso
05 Stella, '62 VBB, 76 Sprint V
Joined: 16 Jun 2011
Posts: 1797
Location: Chicago. Well, Evanston, but that's almost Chicago
Mon Jan 14, 2019 7:09 am quote
I'm going for a torque-y build, so probably 123-1225 TD, see what that gets me in terms of exhaust duration and blowdown. I'm hoping to get through the metal-shaving-making portion of the show maybe this week

I decided to keep the SI carb and autolube for this build, so I'm going to run a 24/24e with the DRT modifications that just arrived from SIP, along with a Polini venturi on the intake.

I matched the airbox to the carb and flowed the carb opening into the airbox and cases yesterday, too. Still needs to get final sanding, but it's coming along nicely.

This biggest mystery for me at this point is intake timings. I went with the Long Stroke Mazzi Cut Crank, which is timed at 138/6 post TDC, per SIP's product page, but will have to measure actuals. I didn't molest the intake port at all other than to straighten the edges.

As to transfer shape, I'm thinking shallow going forward, if only because I'm tired of breaking through the cases and having to break out the JBWeld.

IMG_20190113_153850-cropped.jpg

Ossessionato
1976 Super (x 2), 1974 Primavera (x 2), 2006 Fly 150
Joined: 26 Sep 2013
Posts: 4284
Location: So Cal
Mon Jan 14, 2019 10:49 am quote
I know what you're saying Ginch ... I'm also wondering if maybe "big" isn't necessarily the most important part of the porting game.

I'm thinking velocity may be equally, or more important ... you want the mix to get sucked in there fast and get swooped around quickly. Opening up a port increases volume, but slows velocity because the area of highest velocity is being spread across a larger area. Think of putting your thumb over a garden hose.

I could be wrong but I think shaping for velocity - if done carefully - might make more usable power than just gouging out giantic ports.
Molto Verboso
05 Stella, '62 VBB, 76 Sprint V
Joined: 16 Jun 2011
Posts: 1797
Location: Chicago. Well, Evanston, but that's almost Chicago
Mon Jan 14, 2019 11:33 am quote
SoCalGuy wrote:
I could be wrong but I think shaping for velocity - if done carefully - might make more usable power than just gouging out giantic ports.
Heresy!
Veni, Vidi, Posti
74 Super, 75 Super, PX project, LML off-roader and new to 2018, '66 Blue Badge Smallframe
Joined: 30 Nov 2011
Posts: 6557
Location: Victoria, Australia
Mon Jan 14, 2019 6:10 pm quote
SoCalGuy wrote:
I know what you're saying Ginch ... I'm also wondering if maybe "big" isn't necessarily the most important part of the porting game.

I'm thinking velocity may be equally, or more important ... you want the mix to get sucked in there fast and get swooped around quickly. Opening up a port increases volume, but slows velocity because the area of highest velocity is being spread across a larger area. Think of putting your thumb over a garden hose.

I could be wrong but I think shaping for velocity - if done carefully - might make more usable power than just gouging out gigantic ports.
Well this is pretty much exactly what I was told. When I had my old Polini cylinder I found a guy to rebore it. His main gig though was making sleeves for 2 stroke racing dirt bikes. His advice - based on a colleague's flow bench testing - was that you don't want to enlarge the transfers so much that what you said happens. He was talking about regular motorcycle transfers however, and not piddly Vespa ones which are clearly a lot smaller.
My recent projects have reeds so volume is easily addressed so I'm not so concerned about finding volume in the transfers. Plus of course what Chandlerman says about breaking through.
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