1976 Sprint V mechanical rebuild
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Molto Verboso
05 Stella, '62 VBB, 76 Sprint V, 63 GL
Joined: 16 Jun 2011
Posts: 1856
Location: Chicago. Well, Evanston, but that's almost Chicago
Sun Feb 03, 2019 5:10 am quote
Yesterday, I spent a lot of time at the kitchen counter with my vernier calipers and the Lambretta Images Port Timing Calculator, followed by some time in the garage and finished up the porting. All is looking good and I'm right at 124TD / 172 ED. Adjusted the bottom of the exhaust to match the piston at TDC, life was good.

Naturally, with everything going so well, it was the perfect time to realize I made a significant mistake in this whole process. I ordered the wrong crank for this motor, not paying proper attention to the fact that some Sprints' cranks had the later PX flywheel cone. Some did not. Mine is the Did Not kind.

Lucky for me, I can spend my way out of the problem, but it's going to cost me $200 (with shipping), a week of time and a lot of self-flagellation.

So assuming no one tells me not to, I'm going to order the Mazzi long stroke crank shaft that has a P series cone for the SIP Ignition, but fits the old seal.

It was a dumb mistake on my part to forget to verify rather than blithely trusting SIP's fit list for the part rather than using my eyes & brain. I don't know that I'll ever build up a P series motor with a rotary on it, or if I do, it'll be a P200, so I'd be willing to let it go relatively cheap to someone so I don't have to look at my mistake on the parts shelf every time I'm in the garage.

In the meantime, assembly of other components continues. Cruciform swapped, axle and drive shaft bearings installed. Crank seals, xmas tree and gear stack will go back in today.

Assuming no more parts ordering failures on my part, short of crank installation and any adjustments that the new crank requires (I'll have to measure stroke again, but I'm not going to bother until I get the new crank), this thing should be ready to seal up.

IMG_20190203_061050.jpg
Original vs. new-but-incorrect, crank shaft.

Doh!

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Sun Feb 03, 2019 6:00 am quote
Maybe check out the DRT seal adapters. I used them with the PX taper conversion crank in my VBC motor. Better seals (Viton) and in theory can be changed much more easily. I used a stock PX stator, flywheel and CDI. All lovely and stronger than with the original narrow taper crank.
Molto Verboso
05 Stella, '62 VBB, 76 Sprint V, 63 GL
Joined: 16 Jun 2011
Posts: 1856
Location: Chicago. Well, Evanston, but that's almost Chicago
Sun Feb 03, 2019 7:05 am quote
Unfortunately, I don't think that's an option.

The adapters are for using old cranks with modern seals. I'm not dead yet, but I think I'm still looking at a new crank.

I MIGHT be able to make it work on the clutch side, but it would require installing the clutch side bearing on the gear box side of the seal, then closing up the lubrication channel in the case. That scares me a little, because I don't feel like I can know if that bearing will get enough lubrication or not in that configuration.

On the fly side, I'd need a 24x32x6 seal to fit the adapter. A little googling led me to a 24x32x7, but that's the closest I could get.

To me, that feels like a lot of engineering for not a lot of cost savings versus just ordering the new crank.

IMG_20190203_083813.jpg

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Sun Feb 03, 2019 8:27 am quote
Sorry I wasn't clear. You need to buy a different crank any how, the adapters are for the narrow taper or hybrid (PX taper) cranks. The seals come with the adapters and are easy to source if/when they fail. My thinking was that while I was in there, I would improve what I could.

Remember to install both bearings on the crank before assembly.
Molto Verboso
05 Stella, '62 VBB, 76 Sprint V, 63 GL
Joined: 16 Jun 2011
Posts: 1856
Location: Chicago. Well, Evanston, but that's almost Chicago
Sun Feb 03, 2019 10:56 am quote
I was over-thinking to make up for my previous under-thinking
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One or two fun scoots....nothing too precious
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Sun Feb 03, 2019 11:18 am quote
Chandlerman, you may find my project thread interesting and helpful in places. It was my first attempt at a pre-P motor. Your Sprint V and my Super had similar motors from the factory, but the Sprint V was given a 3 port cylinder, 10" wheel, gearing to suit, a better SI carb (20/20?) and exhaust. Both will end up as 190cc three porters on 10s.

VBC1M (190 Super) engine build
Molto Verboso
05 Stella, '62 VBB, 76 Sprint V, 63 GL
Joined: 16 Jun 2011
Posts: 1856
Location: Chicago. Well, Evanston, but that's almost Chicago
Sun Feb 03, 2019 11:39 am quote
That thread was a great read, Swa. It was

I'm going back and forth on whether or not to throw the seal adapters in my SIP cart. Eventually, I'm going to need to rebuild my VBB's motor, too, and I could also use them on it, but since it's just sitting on the shelf right now, I haven't been in too much of a hurry since it's only a two port, and the first time I rebuilt it, there was a lot of blood and cursing involved.

Plus, I have a multitude of other projects in front of it, including my boat restoration (which I have committed to have in the water in under four months from now), the GL, and a bunch of work on my house that my wife is getting fairly impatient about...
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2008 GTS 250, 1979 P200E
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Mon Feb 04, 2019 1:03 pm quote
chandlerman wrote:
That thread was a great read, Swa. It was.
I second that! Great read swa. And I'm digging this thread also. I seem to learn something from every post I read so thank you for posting!
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: 6591
Location: Victoria, Australia
Mon Feb 04, 2019 1:43 pm quote
chandlerman wrote:
I MIGHT be able to make it work on the clutch side, but it would require installing the clutch side bearing on the gear box side of the seal, then closing up the lubrication channel in the case. That scares me a little, because I don't feel like I can know if that bearing will get enough lubrication or not in that configuration.

On the fly side, I'd need a 24x32x6 seal to fit the adapter. A little googling led me to a 24x32x7, but that's the closest I could get.
The clutch side bearing would get plenty of lubrication - this is of course how the P motors are set up. But what you would need to do is create a new circlip groove in the case to retain the bearing. Not impossible, but maybe trickier than you wanted. Also that seal you found would be fine... if it stuck out towards the stator another 1mm then it should be no big deal. Plus it's a double lip seal. Bonus.
There was a thread on the old ScooterCentral / even older StellaSpeed forum "So you wanna install a P crank in a Sprint" that went through this... from memory he used a Rally 180 seal on the flyside. He just used bearing retainer on the clutch side, and said it worked fine, but I couldn't live with that.[/url]
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: 6591
Location: Victoria, Australia
Mon Feb 04, 2019 1:48 pm quote
chandlerman wrote:
I MIGHT be able to make it work on the clutch side, but it would require installing the clutch side bearing on the gear box side of the seal, then closing up the lubrication channel in the case. That scares me a little, because I don't feel like I can know if that bearing will get enough lubrication or not in that configuration.

On the fly side, I'd need a 24x32x6 seal to fit the adapter. A little googling led me to a 24x32x7, but that's the closest I could get.
The clutch side bearing would get plenty of lubrication - this is of course how the P motors are set up. But what you would need to do is create a new circlip groove in the case to retain the bearing. Not impossible, but maybe trickier than you wanted. Also that seal you found would be fine... if it stuck out towards the stator another 1mm then it should be no big deal. Plus it's a double lip seal. Bonus.
There was a thread on the old ScooterCentral / even older StellaSpeed forum "So you wanna install a P crank in a Sprint" that went through this... from memory he used a Rally 180 seal on the flyside. He just used bearing retainer on the clutch side, and said it worked fine, but I couldn't live with that.

Aha! Found it!!!
https://web.archive.org/web/20160310065830/http://www.scootercentral.net/forums/viewtopic.php?t=16229
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1976 Super (x 2), 1974 Primavera (x 2), 2006 Fly 150
Joined: 26 Sep 2013
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Mon Feb 04, 2019 3:22 pm quote
I say cut your old crank.
Molto Verboso
05 Stella, '62 VBB, 76 Sprint V, 63 GL
Joined: 16 Jun 2011
Posts: 1856
Location: Chicago. Well, Evanston, but that's almost Chicago
Mon Feb 04, 2019 6:34 pm quote
New crank is already on its way from Deutschland, so that decision is made.

The issue of needing a circlip groove cut on the clutch side of the cases seems to be the biggest obstacle to doing the swap out, but that's more work than I'm going to track down or take on. At this point, I want to get this sucker back on the road so I can focus on other projects for a little bit.

There's also the issue of how much engineering and expense is required versus just going with the correct part for the job. It's kind've an interesting problem, but if I'm going to do a bunch of extra work on something like this, it's going to be to make it faster and/or more reliable. One thing I think we all know is that nothing ever seems to get done to make things cheaper
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Tue Feb 05, 2019 1:09 am quote
Sounds like the operation was a success. Any pictures of the cylinder? And final dimensions?

Unfortunate to have a last minute crank fiasco but seems like all under control. I'm sure the PX Mazz one will sell. Someone here could buy it and stick it in a stock 125 to make an interesting thread.
Molto Verboso
05 Stella, '62 VBB, 76 Sprint V, 63 GL
Joined: 16 Jun 2011
Posts: 1856
Location: Chicago. Well, Evanston, but that's almost Chicago
Tue Feb 05, 2019 6:13 am quote
I'll post some this evening, Jack.

Short version is that everything matched up to what I was aiming for with no mistakes.

I was going to just wait until the new crank arrived, then re-measure everything to make sure it's all still good.
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: 6591
Location: Victoria, Australia
Tue Feb 05, 2019 11:31 pm quote
chandlerman wrote:
...with no mistakes...
Sounds interesting! I'm not familiar with the concept though...
Veni, Vidi, Posti
a herd of easy shifty rats
Joined: 22 Nov 2010
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Location: seattle/athens
Tue Feb 05, 2019 11:34 pm quote
Ginch wrote:
chandlerman wrote:
...with no mistakes...
Sounds interesting! I'm not familiar with the concept though...
It could be quite useful! Hey Chandler, got a link?
Molto Verboso
05 Stella, '62 VBB, 76 Sprint V, 63 GL
Joined: 16 Jun 2011
Posts: 1856
Location: Chicago. Well, Evanston, but that's almost Chicago
Sun Feb 10, 2019 3:30 pm quote
Made some progress today.

Also today, discovered that I lost the old kick start gear spring and forgot to order a new one.

Scooter Mercato, here I come...

IMG_20190210_170741.jpg

Veni, Vidi, Posti
a herd of easy shifty rats
Joined: 22 Nov 2010
Posts: 6678
Location: seattle/athens
Sun Feb 10, 2019 3:46 pm quote
Grrr


... Well that sucks!

PM me your addy & I'll send you this.
Big snowstorms here, but there's a window tomorrow morning & I plan on getting out to the post office if I can.
Wish me luck.

IMG_20190210_153639598.jpg

Molto Verboso
05 Stella, '62 VBB, 76 Sprint V, 63 GL
Joined: 16 Jun 2011
Posts: 1856
Location: Chicago. Well, Evanston, but that's almost Chicago
Sun Feb 10, 2019 7:12 pm quote
That spring I had. It was the one that presses the kickstart gear out of the way.

For some reason, I really struggled to get the quadrant return spring installed today.

I finally made a shim out of a scrap of aluminum sheeting which I put inside the spring and used as both a guide to keep in in line and also drive it around the shaft. Solved the problem about as easy as could be.

139100n.jpg
This one.

IMG_20190210_195827-arrow.jpg
shim it to win it.

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Sun Feb 10, 2019 8:01 pm quote
Hmmm....I think its not lost. In those older engines, do they not have that spring?
Veni, Vidi, Posti
a herd of easy shifty rats
Joined: 22 Nov 2010
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Sun Feb 10, 2019 8:17 pm quote
Yep, you have the riveted on leaf spring. No need for the coil spring.
Molto Verboso
05 Stella, '62 VBB, 76 Sprint V, 63 GL
Joined: 16 Jun 2011
Posts: 1856
Location: Chicago. Well, Evanston, but that's almost Chicago
Mon Feb 11, 2019 4:51 am quote
V oodoo wrote:
Yep, you have the riveted on leaf spring. No need for the coil spring.
Jack221 wrote:
Hmmm....I think its not lost. In those older engines, do they not have that spring?
So it sounds like the only thing I've lost is my mind, and it's been gone for years at this point.
Molto Verboso
05 Stella, '62 VBB, 76 Sprint V, 63 GL
Joined: 16 Jun 2011
Posts: 1856
Location: Chicago. Well, Evanston, but that's almost Chicago
Sat Feb 16, 2019 12:55 pm quote
Actual stroke on it was 60.1mm.

I just buttoned up the motor and just took final port timing measurements with the new crank.

176 ED / 124 TD / 26 BD

with a 1.5mm base gasket.

I'll take that

Top of crown to top of cylinder was only .6mm, though, so the head will need to get milled down for proper squish, but that's relatively secondary and I'll get to that once I confirm that everything else is solid.

Next up, leakdown testing!
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2008 GTS 250, 1979 P200E
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Sat Feb 16, 2019 3:00 pm quote
chandlerman wrote:
Next up, leakdown testing!
Looking good Chandlerman. Could you do me a favor and post a pic of your leakdown mechanism. I'm getting ready to fab something up and I'm particularly curious how you interface with the carb intake.

Thanks man!
Molto Verboso
05 Stella, '62 VBB, 76 Sprint V, 63 GL
Joined: 16 Jun 2011
Posts: 1856
Location: Chicago. Well, Evanston, but that's almost Chicago
Sat Feb 16, 2019 3:27 pm quote
For the carb, I do it with the airbox installed, so I use a piece of innertube that I've cut more-or-less like a gasket, then bolt an old carb body over that.
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2008 GTS 250, 1979 P200E
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Sat Feb 16, 2019 6:41 pm quote
Ahh, got it. Then just blow up the.....exhaust. That just sounds wrong! Thanks, I'll probably do the same...
Ossessionato
1976 Super (x 2), 1974 Primavera (x 2), 2006 Fly 150
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Sat Feb 16, 2019 10:24 pm quote
Blank off the inlet (I use a piece of neoprene from an old wet suit under the carb box), put an expansion plug in the exhaust stub, and pump air in through the spark plug hole.
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Sun Feb 17, 2019 12:25 am quote
chandlerman wrote:
Actual stroke on it was 60.1mm.

I just buttoned up the motor and just took final port timing measurements with the new crank.

176 ED / 124 TD / 26 BD
A little over target. With the 1.5mm packer at least it can be lowered if 4th doesn't pull.

Be prerpared for rpm. Not to strong on the ignition timing. 16 degrees is a good place to start. Make sure that WOT splutters bad, before down jetting. If you only follow one rule, then this is the one.
Molto Verboso
05 Stella, '62 VBB, 76 Sprint V, 63 GL
Joined: 16 Jun 2011
Posts: 1856
Location: Chicago. Well, Evanston, but that's almost Chicago
Sun Feb 17, 2019 8:23 pm quote
It's on!

First kick on the stand
Once I confirmed it was all looking solid, other than that weird little rubbing sounds right after I started it (anyone know what that is? Nothing seems awry other than that), I put it in the bike. What a pain in the butt that always is, even when it goes well.

I completely spaced on checking compression and squish until just now, but it'll be there when I get to it.

Initial jetting is starting from what came in the DRT modified carb, plus the main jet from the Venturi, so 190/BE4/140.

I still need to sort out a better airbox, too, so the venturi isn't just choking from lack of headroom. Maybe I can get one of my 3D printing friends to kick out a spacer for me, or just order one.

It's been snowing all day, so no action shots just yet and the clutch still needs a little bit more adjustment, but as of right now I'm feeling like this is going to be another solid build.

Now, it's time to start looking at the rest of the bike. First thing I noticed was that the throttle tube is extremely stiff. I don't know if it's just frozen up, or actually bent. Either way, it's going to need some love.

I'll replace most of the cables while I have the headset open, too.

I'll have to do some franken-wiring on the electrical system as I swap it over to DC and install LED lights.

The turn signals, while original, are in varying levels of disrepair. Some have duct tape on the stems, some have zip ties holding them on. Some have both. It's going to take some work to sort that out.

I need to get some more of those adjustable mirrors since I put the first one I bought on the Stella.

And last, but by no means least, I'm running the stock clutch. It looks like I could install a modern clutch in it, but I'll need to cut back a flange inside the case which I'm guessing is intended to help guide oil onto the clutch.

IMG_20190217_221732.jpg
Looking good!

IMG_20190217_221757.jpg
Work to do.

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2008 GTS 250, 1979 P200E
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Sun Feb 17, 2019 8:49 pm quote
Damn dude, you are THE MAN! Great job!
Ossessionato
1976 Super (x 2), 1974 Primavera (x 2), 2006 Fly 150
Joined: 26 Sep 2013
Posts: 4319
Location: So Cal
Sun Feb 17, 2019 9:07 pm quote
Sounds nice n crisp... is the flywheel cover rubbing?
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