Modern Vespa

Welcome to project Rosebud

This was going to be my cannonball bike but I opted to ride a SYM HD200 instead.

I decided to post now instead of waiting till it's done as another thread was started asking what would be needed to fit a GT engine in an LX frame.

Here's what I know and have tried so far.

To convert the rear hub to a 10 in wheel you need all three gears from the LX or ET4, the outside case of the rear hub, and the rear rim.

As you can see from the pictures the GT engine case has the castings in place to move the gears from the GT format to the LX.

This same conversion can't be done on the GTS engine as the bearing placement is completely different.

It looks so weird with that tiny little wheel. Do you have one or two shocks mounted?

P.S. It still looks gay.

With the spring removed from the rear shock to check travel the engine can be squeezed in mostly. Everything clears at the bottom of travel but at the top there is issues with the valve cover hitting on the internal support of the frame.

I decided to remove it with plans to replace it with one that clears everything.

The engine mount will need a lot of work so the exhaust clears but the coolant lines enter the frame with no issues at all.

nice work, sir.

let me know if you need that head flowed...

best,
-greasy

Wow, thats really cool. That would def be interesting to ride.

Props my brotha.

Manny

Its going to be very interesting to see what happens, good luck.

Did you get to take "Rosebud" out for a spin ever? I'm wondering if using the different final gears makes a difference in performance, positive or negative. Intuition says it would, but I dunno.

Patrick, that's insanely cool. You da man!

That is fantastic. I can't wait to see where you put the radiators and other cooling system goodies.

I'd love to see someone make or adapt a 4V head (and corresponding piston) for the air cooled LEADER engine. Maybe make the piston fit the 190 kit since that's another likely modification someone swapping cylinder heads might do.

Haven't had it to a state where I could take it for a spin. I've got tooth counts of gears from the LX1215, 150, GT200, and GTS as well as the kits that are out there. There is a promising combination in there. An additional factor that helps is that the power and redline on the GT200 is at a much higher RPM than the LX.

Oopsclunkthud,

I see that you have quite a bit of experience with the internals of the transmissions of the gt and lx models and their gear arrangements. Using one of the configs in the cases would it be possible to install a gt rear disc and wheel setup on an LX? I would like the advantages of the disc brake and larger diameter wheel. Thanks for any advice in advance.

Good luck with Rosebud!

Justin

Meh, why? The brakes on an LX are already fantastic, and the larger wheel in the back is just gonna look/ride funny w/o a larger wheel in front. Is your rear drum dialed in correctly?

I have a 12" MP3 wheel, gt rotor, 4 piston brembo in the front. I would just like to match the wheels (and have 2 - 12" wheels for better handling, etc) and also have rear discs. I am not to fond of the rear drum that's all.

Ah, well then.

Awesome Patrick, keep it up!

To change to a 12" rear wheel would move the axle back by about 2". As a result the tire will not clear the back of the frame. This was the primary reason I went with the 10" rear.

Looks like from your pics that you have the 10" wheel converted GT motor with the LX swingarm bolted into the LX.

You did try fitting it before converting to 10", right? How close is it? Might it work with a 110/70 on the 12" wheel? Swingarm shortened by 1/2"?

I'm researching 12" rear wheel conversion for the S/LX. Figured I'd post in this thread as it has much related information.

Have a question someone may have already answered. Will the GT rear hub fit LX shaft/splines?

To fit the 12 wheel on the leader cases a different gear housing is used. This has the axle aligned with the rear most bearing. This extends the wheel base by about 2 in over the 10 in setup. With the added diameter of the 12 wheel you end up with the rear of the tire being about 3in further back and there's just no room in the LX frame for it.

The splines are also different from the LX to the GT, though the Fly may be the same as the LX. But again you would need the fly gear housing and this would shift the wheel back the 2 in.

Thanks OCT.

So looks like it's not a parts bin project, knew there was a reason it hadn't been done yet. I'm not giving up though.

you got me thinking of two options that may work.

GT gear housing with 11in lx front rim (disk brake)
Fly gear housing with 10in lx rear rim (drum brake)

Both these would move the wheel back by ~2in. could be good for high speed... May just fit under there.

GT gear housing with ET front wheel (10") for the rear disk?

That may work, the rear disk on the GT is 220mm, front disk on the ET is 200mm, The LX rim just fits over a 220 disk so the ET rim may not fit.

Also, the rear disk sits more to the center of the rim than the front one. That may make the 220 not fit in the 11in rim as well. In that case you'd need to modify the hub to take the 200mm disk and also use the LX front caliper at the rear.

All this assumes that the wheel clears with the added 2in in the wheelbase, so that would be the first thing to check.

I'm loving the effort and time you're putting in to this match up, which if works could well be ideal modern Vespa, small light(ish) and powerful.
Awaiting the outcome...

Is this scooter on the road yet? Great modification!!! 8)

Nope, not even close. It's third in line at the moment.

GT/GTS front wheel swap on LX (Post 798833)

I got the motor mount for Rosebud back today. It is a work of art! The point of the new mount was to extend it by 30mm to allow clearance for the exhaust. But as long as this was being done I figured why not get rid of the crappy rubber bushings and use roller bearings as well as gusseting the area where it connects to the motor.

The motor will still be able to pitch up and down relative to the frame but all roll and yaw will be a thing of the past.

Next step, powdercoating.

Interesting theory, of putting bearings in there. I did replace the rubber bushings with Poly bushings from Clause Studio, and that got rid of alot if not all the twist in the swing arm. I am sure we will find out how well it holds up to the vibration and such without the bushings smooting it out a bit. Great project so far, and will look forward to the final bits... !!

Looks good. You did have two made up while you were at it, right?

The GT/GTS use rollerbearings in the motor mount, I've scavenged the section that mounts in the frame of the GT to have this built.

On the GT there are two sets of roller bearings allowing the point where the motor connects to move up/down and front/back. This movement is then restricted by the rubber donut on the left side.

With the LX I won't have any of the front/back movement and that may add some vibration but I think it will be ok.

I'm lovin' this!

Progress! Thought this one was dead.

On your mount, would simply notching the LX one for pipe clearance have worked?

Notching the mount was my first plan but after mapping it out the notch would have gone through the bolt. Figured I could shift the engine back a bit or come up with a mount that bolted in from either side. Shifting it back seemed the easier path.

Did a test fit of the mount yesterday, everything fit perfect.

Oo! Oo! Now I'm getting excited!

Can't wait to see how you do the cooling sytsem install.

First round will be to hang if off the back.

Then I'll ditch the tail light and place it flush on the back of the frame. If needed I'll place ducts in the cowls to bring the air in.