Modern Vespa

Following Ginch's thread on the new Malossi 177 kit, I've been thinking about an engine that I'd like to build over the cold winter months. I have a fairly ratty but serviceable 200 engine casing (PX EFL) which has already been molested for reed induction by the previous owner, so a rotary build is totally out of scope. I'm now considering the components that I would need to build a 25+hp motor. My build objective would be dependable street racer, as I already have a great touring setup.

The cost of crankcase reed induction is considerable when you add the cost of the reeds (RD350) + block (MRP/MMW/MBD) to the cost of the cylinder kit. The more expensive Pinasco 960 VTR Slave (cylinder induction) kit looks better value because it includes the reed setup.

Questions:
- Can anyone vouch for the Pinasco VTR kits with direct/cylinder reed induction?
- Is cylinder induction a better (and sensible) option, given the objectives?
- Is Malossi still king for 200 based power builds, and would the Sport or MHR be the better choice? I'm assuming MHR, but never used Malossi before.
- If I went cylinder induction, would I just blank off & seal the crankcase inlet, or is it better to fill it in completely? Does it matter?

Like where you are going with this. Not going to be cheap though.

I can't get over excited about the VTR slave. I think it would make decent power but the whole thing would be a compromise and not as powerful as an MHR project.

Fastest street racer at the moment would be something like a 221 MHR, 60mm bell crank, 39mm carb, V4 Reeds, 22/68 primary and some big fat expansion pipe. Quite an expensive shopping list, I assume you have no interest in adding water cooling to that?

Have you got the casings split? Any issues that need fixing first, helicoils etc. ?

Whatever you decide, please make a build thread on it, this sounds very interesting....

The Pinascos for whatever reason always seem to have very low port timing. Without seeing power figures you would have to think Malossi is the better bet. Although I do like the reed on cylinder.

There is another option that looks great. As long as your pockets are pretty deep of course. The Quattrini M232/244 are cast with this in mind obviously. This work was done by Patrick at P-Town scooters according to this -
https://www.facebook.com/groups/VintageScooterBuildersShowcase/permalink/1746613352030145/

Ha ha, pockets not really deep enough for Malossi or Pinasco, let alone Quattrini M244 or H2O cooling, but over spending on Vespa bits and bobs is the only way for me to get through the long winter months!!

Once the cases are clean and fully inspected for cracks etc., i'll know how to proceed. I may need one helicoil where the old reed block was mounted, hence the option to go with cylinder induction (Pinasco VTR). Will do some research on port timings vs the MHR.

Just something to think about with the Pinasco. I wonder how much more street racer the port timing is with a 60mm crank in the 57mm cylinder?

If anyone has the measurements of both cylinders down from deck, It might be the way to go to get the Pinasco more interesting.

Some info from the GSF - No 'sequel' as yet, however the same guy did one of the traditional (case intake) cylinders and said this - Not the same cylinder but perhaps an indication of where the VTR might get to? An interesting comment about the height of the piston was that it would make it easy to run a 62mm stroke. Here it is shown alongside a Malossi piston.

They are some quite strong figures from the Germans. That's got to do near 10,000 rpm in gear. Any follow up on how it went?

I found some more posts on the GSF and they seem to think the previous Pinasco cylinder 60mm version gives the following.

Auslass :177 Grad

Überströmer: 126 Grad

Vorauslass: um 25

If the new Slave is similar to this, then a slight brush with the Dremel here and there and it would be quite a street racer. Chances are the new Slave one is further improved already but they always leave something that can be tweaked.

I have always cut several mm off the bottom of the old Malossi pistons. They were just too long. New MHR ones are shorter.

Now, a 62mm crank in a Slave cylinder. There's an idea....

Cheers chaps. Port timings to one side for a moment. If rotary is not possible (definitely the case for me), what technical and power advantages/disadvantages are there between crankcase and cylinder reed induction? Is there a clear winner, or does it depend on the build objectives?

I found this on a dirt bike forum. Not something I had given much thought to but makes sense. I guess though that they are not dealing with a Vespa case where the crank blocks the path for a fair percentage of the time.

Kingwelle are doing a 64mm crank for quattrini. I have no experience above 60mm but I'm assuming your going to get a few HP more with that monster. For example Quatrinnii 244cc goes up in displacement to 255cc.

I assume they to a malossi 64mm also. When I next feel like spanking a couple of thousand dollars I will do a 64mm malossi.

They probably do. The only difference that Q. crank has from other ones is the 125mm (or maybe 126?) rod.

Over a year late, but I've just committed this one to the build by ordering a 60mm bell crank, and I have now assembled the gearbox components. I'll be using a PX125 setup with a 21T clutch and a 3.00 x 11 wide SIP rim at the rear, most likely with a 130/70 x 11 tyre.

I'm on the lookout for a Malossi MHR kit at a good price, so the displacement will end up at 221, but first of all the case halves need to be vapour blasted, checked over and somehow strengthened around the primary shaft and the flywheel side bearing. Perhaps the CMD CNC back plate is a good way to address the input shaft. I'll then use a Malossi base packer as a template to get the case ports looking good, prior to buying the top end kit.

Does anyone have a recommendation for base packer thickness? This will be a street racer motor and will be used in a freshly painted 1987 PX200E (Piaggio red). The idea is for the scoot to look absolutely factory, but with a very peaky motor under the hood. The only giveaways will be a front disc and the fat rear tyre. I'm even thinking a modified box exhaust to keep it looking close to original.

Have a look at this, second page. Nice solution!
P221 from Rotary to Reed

Packer thickness depends of course on where you want your squish. I've had a few 60mm cranks and they all seem to end up with about a 1 - 1.1mm packer, never got as far as 1.5 which you would think would be correct.

So, 11 inch wheels? I didn't know they existed!

I'll definitely check out that thread Ginch. The rims are quoted as 11" by SIP, but the main attraction is the width. They need the mods to the swing arm and they need a packer on the hub.

https://www.sip-scootershop.com/en/products/rim+tubeless+wide+tyre+sip+_83045000

I've not thought about the head and squish at this point. Just looking to get the cylinder raised sufficiently so that the ports are in the best position. I gather the MHR will have no problems with 9000 RPM, assuming other stuff is done properly.

On the description it says that no spacer is needed...

3.00-11: The premier league of wider section tyre conversions ! Our 3.00/11“ size wider section tyre wheel is delivered including two aluminum sleeves for the engine pivot. No further spacer is necessary. To compensate for the wheel being off the centreline of the scooter the pivot on the swing arm of the motor needs to be shortened by 1cm on the right hand side. The motor is so moved to the right. 110/70-11, 120/70-11“ or 130/70-11“ tyres can be used with this conversion kit. Because of its wider rim width we recommend the use of a 2.50-10“ SIP tubeless rim at the front.

Even better that no spacer is required between hub and rim. Cheers, I missed that bit.

SaFiS, how is your motor since the rebuild? Will you be using the CMD backplate on this motor, or do you think the welded plate in the gearbox is enough to strengthen the input shaft area of the case?

To tell you the truth, life and work (new employer) got in the way and I have put it aside for a while. It's running great but I still need to fine-tune the carb. It's a bit rich at low rpm and behaves like it's flooding, especially when I'm in traffic. I have the two-stage Boyesen reed petals and all the plumbing for a fuel pump at hand, but not the time. I'm also planning a respray, the PLC Corse wheel hub and some other stuff (install SIP speedo, change to AC/DC and install a battery, an Arduino EGT I had built way back, etc.). I just hope I'll find the time. About the CMD backplate, yes it's going on this motor. Better safe than sorry and I also love new shinny things...

Just been reading that the 221 MHR cylinder is longer, with port positions to suit. I hadn't realised that, so no need for packers with a 60mm crank. Hopefully the supplied base gasket is all I will need.

Personally, I would go for the "normal" MHR and play with packers. The longstroke version limits you to a longstroke crank and you can't play with port timings...

Agree. The 60mm cylinder is too restrictive. You won't like it.

I assume that with an MHR you would not consider putting any packers on the head? In which case there is nothing to be lost with the 57 version, and potentially a bit to be gained?

Cheers chaps.

Does anyone have a table that shows the TD for a 57mm MHR cylinder, with a 60mm crank, with different base packers?

I understand about TD trade offs, but I want to avoid it being painful in the lower rev range and climbing hills. I'm not into wheelies and doughnuts, but strong acceleration is appealing. I have a torquey PX225 for touring and pillion work.

I was thinking that a 0.8mm base packer would be a good start, but where would that put the TD? I would most likely use the supplied head, unless good squish is not achievable. As stated earlier, I'm going to use a 68T primary, probably with 21T clutch to compensate for the 130/70 - 11 rear tyre. Otherwise it's a PX125 box. Assuming it can achieve 8000 RPM in 4th, 78MPH is good enough for me.

The exhaust I have in mind is a big box style, maybe the Pipe Design S-Box, to keep the [almost] standard look to the scoot. PD quotes 'up to 128TD/188ED' with an MHR for this pipe. Otherwise you're into proper expansions.

Given the above, is the MHR the right choice?

I don't think there is any quicker than the MHR. The Germans say the big box is no slower than an expansion. I can't quite believe it but even if its close it will do.

The MHR 57 primary transfers are an average of 45.3mm down from deck. And secondaries average 45.6mm. A 0.8mm base on my cylinder would be 186/129/28.5.

You'll need variable timing but not going to have any issues going up hills. With so much power this is all a thing of the past.

Did you decide rotary or reed? And what size carb you have in mind? If just a 30mm, then rotary is quicker and cheaper.

The rotary pad is long gone on this set of cases. The previous owner saw to that. I've not thought too much about the carb, but I'd like to buy the manifold base, really just for the template at this stage. Current thinking is a 34mm VHSB or TMX 35, but not as big as 38/39. To stick with the 'sleeper' theme, it needs to fit under the side panel without modification.

186/129/28.5 sounds fun, without being OTT. I'll probably buy the kit without a head. With only 0.8mm packing at the base, I'm going to need some extra clearance up top, and the MRP 'touring' head, with ~0.7mm shaved off it will get me to ~1.2mm SBC in theory.

Out of interest, where would the port timings be with just the supplied base gasket and the full 1.5mm in/under the head? Sufficiently different to make the Sport a better option than the MHR?

If going for speed the sport is not the best kit for the job. Before getting the MHR I was wondering if it would be too peaky and unstable but seems to cruise fine, surprisingly good economy and if you need to go anywhere, just buzzes along in the pack. I think the new scavenge pattern really works.

Just a single 0.1mm base gasket on my cylinder would be near to 183/125/29. Compared to what I'm used to this would be......um......slow.

As reed is no choice, then the 35mm carb is a must.

Jack, so you're in favour of the 0.8mm base packer with 57mm MHR cylinder and 60mm crank? I guess I'm really after a 1.0mm packer and use it without the supplied base gasket underneath, or is it better to go 0.8mm packer + base gasket, to get the 'crush' effect of the gasket and therefore a better seal?

Would a 1.5mm base packer make it a bit too peaky in your opinion?

0.8mm is a good place to start. The fewest is preferred to avoid shrinkage but it all works. These kits like any other kits are more like hand made than mass produced. Pretty much the same but not exactly. Depending on what you are after there is actually a lot of scope to move in the 1.5mm but there is too much. As they are close to the limit they lack overrun but not really an issue.
I am just about to change my packer for the third time and hopefully the last but with a new crank and flywheel there are a few unknowns to deal with.
You'll need to run yours and see how it performs. Its easier to adjust the barrel to the gearing than messing about with cogs.

My reed block base arrived, so it's time to use it as a template and get the inlet opened up. The previous owner of the cases had already taken out the rotary pad, but the shape and size of the inlet is a long way from the Scooter & Service block that I bought. It extends a little further to the back of the case, but it looks like I need to remove a lot of material at the front (cylinder end) to match the S&S cutout. This will take out the threaded hole used for the carb box, but I guess I'll never need that again!!

Before I get the Dremel out, are there are gotchas? Can the inlet ever be too big? The S&S outer edge gets really close to the case mating surface, so I may retain an extra couple of mm to be on the safe side.


Blue marks the S&S cutout. Getting a bit close to the case mating surface!

I do like that the S&S block is angled slightly so that the reed opening points more towards the gap between the crank webs (that's what I imagine it's like that for anyway).

Like the reed block too. There is no too big for this hole. The bigger it is the more high rpm power there will be. With this in mind, where the previous owner has opened up further than the reed block on the clutch side. Brace yourself and cut the shiny new reed block out to this point to blend it all in together. While your at it, I would radius the entry edge in the reed block to remove that sharp edge.

I just placed an order for the Malossi 210 MHR 2016 kit (57mm version), and have opted for the one that includes the head (the price was right). Will the head have enough SBC for a 60mm crank with 0.8-1.0mm packing under the cylinder? If not, is it worth using a ~0.5mm head gasket or getting the head machined for a little extra SBC? I've not used a head with the O ring before.

No issue adding a head gasket, as needed. Makes no difference with an O ring or not, except O ring wont leak.

You finish the inlet? Any pictures?

I'm most of the way through the cutting, but my Dremel's battery is flat and I've misplaced the charger! Hopefully get it finished this weekend.

Rough calcs suggest that I'll need a 0.5mm (ish) head packer, but I'll not know for sure until I dry fit the cylinder. If I'm very lucky, I won't need one, but that might leave me with a sub 1.0mm SBC, where 1.2mm appears to be the accepted norm for a longstroke MHR setup.

MHR kit arrived yesterday. Preliminary measurements are:

Top of exhaust port to top of bore = 32.5mm
Top of transfer port to top of bore = 46.5mm
Squish clearance in head = 1.0mm

I've no idea where the piston crown is going to be in relation to the top of bore until I dry fit the crank and top end, but assuming I can achieve zero deck height with the right packer, my estimated port timings would be:

ED = 186.33
TD = 128.03
BD = 29.15

This would mean an SBC of 1.0mm, as I would only have the clearance in the head. A thin Polini 210 Alu style head gasket give me ~1.2mm squish if 1.0mm is considered too little.

[EDIT] when a Malossi head is torqued down, does the compressed O ring create any amount of clearance between head and cylinder? Could this give me my extra 0.2mm??

Your measurements prove the kits are all unique. For yours you need more exhaust and less blowdown.
Set the piston 0.2mm below the cylinder and this gets better. This will also give you a 1.2mm squish. The o ring crushes flat.
More important than the SBC is that the compression doesn't get too high. Compression limits rpm and makes heat. For this set up on this basic head not far from 11:1 should be the target.

Cheers Jack. I have the gasket that came with the kit and 1.0mm and 0.8mm packers. I'm secretly hoping to use the 1.0mm because it's cut perfectly for my MHR cylinder. The 0.8mm packer would need some work.

According to the calculator, 0.2mm between crown and top of bore at TDC will give me:

ED = 187
TD = 129
BD = 29

This is still just within the upper boundaries for a box exhaust. Let's see what the actuals are when I dry fit the cylinder. I have to finish off the inlet first. It's looking massive!

It's beginning to look a lot like......a very large inlet port. Still plenty to do with a few hand files, but the Dremel work is done. I've had to compromise a little on account of the grinding that had already been done by the previous owner.

I'm still nervous about getting any closer to the edge of the case, for fear of losing too much gasket face.

Looks great!

I need to work on that indent on the clutch side of the inlet. The wider part in the top part of the photo is the previous owner's handiwork. As Jack said, I'll need to take more off the case and then some material off the reed block housing to make a straight line. It will then be a case of blending it all together.