Modern Vespa

Hey MV Gang! I'm running into a problem that isn't often addressed for modern Vespas....

The backstory: I have a big bore Vespa GTS 300 engine stuffed into a Genuine Buddy frame. As if this weren't enough, its now turbocharged.

Its capable of 20+PSI of boost which pushes the engine to somewhere in the neighborhood of 60 crank HP. This is all well and good, but the stock clutch just doesn't like that. It slips badly with any major throttle movement, so I'm in the market for a clutch that can handle how I'm abusing it.

I've heard good things about the Dr Pulley HIT clutches and I've run them in some big build GY6's so I know they're decent there. I've also been looking at the Reveno STC 2.0 dry plate clutch as it seems like with it's larger clutch surface it might hold decently and it might be possible to add clutch discs to increase the grab.

I know this is a wild shot, but at $4-500 a pop for a performance clutch I don't really just want to guess on which one is right so I was hoping some of you might have some opinions on which clutch might survive my madness (At least for a while!)

Do I read this correctly? You pushed a GTS 300 engine to 60 HP? 200 HP/litre.
That is insane. I do not know how long that engine is going to cope with that.

But if you need a proper clutch you have to look at variator clutches that are used in that power range.
I am afraid you will not find them.

At that power range the final transmission is usually by chain with the clutch before the final transmission.
Examples are the Yamaha T-max and the BMW 650.

Yep, you've read that right. And even with the clutch slipping it *IS* insane... Sorta how I roll. And yes, I realize I've shortened the life of the engine, but I'm ok with that too... It was an engine from a wrecked bike giving a project Buddy 125 thats been dead in the back of my garage for the last 10 years a new life. And it was one of those "Can I" not "Should I" sorta projects!

The Reveno clutch is a variator clutch which is another reason I'm sorta leaning that way. And yeah, I know there's not really anything purpose built for this level of insanity. But I was hoping people with more standard performance builds might chime in on the grip ability of clutch swaps they've done.

a quick search of this forum doesn't give positive posts about Reveno. have search ...

I wore out the stock oem clutch in my gts hpe at about 25,000km which is considered way way quicker than normal - I ride with a lot of passion . I stuck a malossi in it and have have done 12,000km and going well without any real wear. malossi do have different springs that can be installed in their clutch that might help with the slipping at high power ... really don't know as I think these springs are designed for changing the number of rpm at which the clutch engages

also we need pics and videos of your scoot in action

why did you stick it in a buddy instead of keeping it in a gts?

The MP3 500 clutch - if you can get it to fit - might be an answer.

Ahh, interesting! Thanks for the heads up I'll search that... I've been finding lots of hype on them but not a lot of info on the Vespa version. The GY6 guys seem to like them, but it sounds like at least the 1.0 version is not well liked on the Vespas. Reveno CLAIMS they've fixed the wear issues on the 2.0 version, but I can't seem to find anyone who's actually tried one.

The easy answer as to why is I had a Buddy with a blown motor and I picked up the GTS engine at a local motorcycle junkyard sans GTS. The bike it came from was totalled and was being parted out. I was looking for a 250cc+ engine to see if I could make it fit and the GTS engine lined up with the frame dimensions really well. So I bought it, carted it home, and started building. Then I discovered the joys of the Vespa ECU's immobilizer that couldn't get a key for, lost interest and stuck it in the back of the garage for 10 years. Then one day I realized I had done Megasquirt ECU installs on lots of things and there was no reason the GTS engine wouldn't run with Megasquirt. Found out the engine had super low compression, put a big bore kit on it to fix that, got it running on Megasquirt, installed a turbo and now you're caught up!

Here's a quick shot of it as it sits today. The custom logos my friend made me call it a 250, but its actually 282cc right now. I'm working now on trying to fit the missing bit of bodywork around the turbo, and I'm not sure I like that pipe yet. But its a work in progress!

I was looking at that, and it MAY be an option. The stock clutch is 130mm and the MP3's is 160mm which I THINK would still fit in the transmission casings ok, the center hole on the clutch is slightly bigger but not enough to be an issue. The trick will be if the transmission splines on the bell are the same between the 300 and the 400/500. I've not yet found an answer for that.

That's ridiculous. And I mean that as a compliment.

Love your Westy - we have an '84.

Thanks! Its my favorite compliment when it comes to this death mach.... Errr.... Totally sane scooter project.

Thanks! Mine's an '80. Sporting a 2.2L aircooled stroker motor from a Porsche 914 and ALSO running megasquirt EFI. Its airbagged for suspension shenanigans as well. If you can't tell I have a ridiculous vehicle problem

That's becoming apparent, yes.

Stick around and show off your work, if you are inclined. We like ridiculous.

Thanks, I will!

I'll also drop this little clip here for you all to enjoy. I tried to run a quick 1/8th mile to see what it'd do but at 20PSI when its this cold(it was 38 degrees when I ran this) I'm having some spark blow out issues so it wasn't real conclusive. But you can see how it sounds and rides. You can also hear when my clutch finally fully grabs around 60MPH and the RPMs drop slightly.

https://youtu.be/shxkTzYMlHI

Very cool!

Kaos is well known to the old timers on Modern Buddy. He got a !25cc Buddy up to, what was it, 88mph?

Yep, 88 was my record. It wasn't actually 125cc at that point though, it was up to 180cc by then. I'm pretty certain I'm capable of well over that now, I wrapped the speedo clean to the end and bounced it a few days back I'm working more on acceleration than top speed right now though. I don't often get a lot of opportunity to use 80+ on my scoot. But shooting off the line is fun everywhere!

Ye gods...is that the original voodoo buddy or a later version? Either way... I don't have any knowledge to impart, just more of the same excitement about your experiments.
I still have a Voodoo Buddy patch.

A clutch from a 500cc MP3 was mentioned...I don't know if it's compatible, but there's also the Scarabeo 500?

Awesome! I didn't expect any of those patches were still around. Makes me happy to hear.

Yes, this is the original Voodoo Buddy, it took a 10 year sleep after I blew up the motor around 30k miles but its back on the road with 110% more voodoo!

The Scarabeo 500 is the same engine, as is the Beverly 500 and any other Piaggio 500. So if one clutch works they all do... After some googling I found that the clutch shaft nut is bigger on the 500 vs the 250/300. Its M12 on the 300 and M14 on the 500's. That leads me to believe that the splines on the shaft are more than likely too big for the 500 clutch to fit the 300 engine sadly. Though I haven't yet found the actual spline measurements.

Very interesting project.

As far as heavy duty clutches, you might want to look at companies that make these parts for competition. Malossi's Delta clutch for 50cc scooters holds up on the track to 30 horsepower. The Delta clutch is designed and built by a company that has ongoing racing programs. Very few companies have the real world experience they do putting horsepower into large four stroke scooters. I do know that people have used the Malossi delta clutch and bell to drag race a GTS 300 with nitrous, and this wasn't a part that broke.

That said, 60 hp is quite an output for a 300 cc scooter.

I looked at a couple of Malossi's different clutches, and the one for the Honda 300 is designed to work with a clutch bell with an inside diameter of 135mm, slightly larger than the 134mm of the Piaggio clutch. In addition, the shoes themselves are significantly thicker where the pins go in, and hold them in place. This is where most clutches break under load. There would be a bit of modification necessary to make the Honda clutch fit, but that's probably not an issue, given what got you to where this is an issue. As you can see, the backing plate on both clutches is the same part number, which means the pins that hold the shoes in are the same distance apart. It may be as simple as switching the outer plate and pins on the Honda clutch for one from a Piaggio clutch. I'm not sure.
Here are some photos, the Honda clutch is on the left, Piaggio clutch on the right.

This looks like something that would be fun to watch come to fruition. I have a few complete Piaggio Delta Clutch and Bell units that were built for various competitions and are just taking up space. The wing clutch bells were reinforced to contain the pieces if your clutch explodes. Let me know if you want one.

Ahh, thats fantastic info. I'd imagine I could figure out how to deal with a 1mm difference, like you said: Using the same backing plate would be the harder part.

I've already blown up one stock style clutch, like you said, the pins failed and one of the clutch arms grenaded. The only reason I've got another stock one on it right now is I had one on the parts shelf to hold me over tuning other things while I sort out this clutch issue.

Those Delta clutches sound promising, if they'll hold up to a nitrous bike they're likely in the ballpark of what I need to get my hands on.

If you're not using those Deltas for anything, I'd absolutely love to get my hands on one. Let me know what you want for one and we can work it out.
Looking at specs on them online they seem to have a LOT more meat to them and are all around beefier. Exactly what I'm looking for since I'll be asking a lot of its poor parts!