Modern Vespa

...but I thought I would share this anyway. If you want to try it, it's definitely gonna have to be at your own risk. Let's just call this 'Crude Port Matching for Dummies' and if you want to do it the proper way I suggest you look here where the topic is discussed in depth: Porting 101

My problem was the tiny intake ports in the stock 50 & 90 cc cases compared to the 125cc Primavera top end I am installing. The motor has been running perfectly, clutch & tranny working great and no oil leaks. I'm a lazy old fart and the idea of splitting the cases just to open up the intakes a little bit really didn't appeal to me so I came up with a Rube Goldberg method to do it w/ the cases intact.


Giant 125 top end wants bigger ports to suck fuel/air thru.

So far so good, the motor runs great on the stand after finishing but I know the proof will be if it still runs OK after I get some serious mileage on it. Fingers crossed!

Dangit Voodoo, do you make your own candles too?

Whatever works, I think it's a great idea for a quickie job.

However, and for the record... I would also NOT recommend

Really.

You could also smoke crack out of there.

Used to use evostik glue as it thixotropic and smells nice as a way of catching alloy swarf.

Grumpy

pretty sure the standard ports on the 125 are the same as the 50. Melting a brick of parafin in a small pot and pouring it in a well taped off bottom end would make for a tidier version f what you've done- not that I'd recommend that.

Nice one. I did something similar using some dense closed cell foam as a plug. It worked fine. But you must pay attention to detail and get it super clean before you pull the plug out.

Yup been there done that same as warhorse closed cell foam and lots of grease to seal it.

I kind've like this approach, but anyone who does something like this needs to understand that it's risky and be prepared to either have things go horribly awry (which could happen anyway once you start opening up ports) or wind up having to split the cases anyway, in which case all the extra pain and effort was for naught.

I'm curious how you measured everything up and how you feel that turned out. You just marked out the new port sizes from the head gasket and went for it, right?

Repeatedly dry-fitting the head into each case half was an important piece of how I made sure my porting was juuuuuuust right, but I did a lot more work than you did, too.

I haven't worked on a small frame motor (yet!), but is it really that much extra work to split and re-assemble if you're not going to be replacing the bearings?

Personally, I think I would use this approach before I split my VBB cases again if I didn't need to open them up anyway, but not the Stella.

A huge "A" for effort.

In the future if you have to port with the lump assembled, "Play-Doh" is more effective and easier to use/apply than foil/wax.

Perhaps it's the photo angle but the last photo showing the finished work appears to have mismatched transfers. The fly side looks far smaller than the drive and not very ideal. Measure 3 times cut once and then measure again.

The goal is symmetry so measuring devices are your best friends.

Well that's interesting, some are shocked or sobbing, but seems I'm not the first by a long shot and many have found better techniques and materials than my crude efforts. I don't have all the fancy stuff or even Play Doh available here, so I gotta use what I can find. I did think about using paraffin, like my Mom used to use to seal jam when she was canning, but can't even find that here.

@SoCal, the traditional beeswax candle was left over from Easter services - I do like to recycle.

@ Chandler, yep, used the gasket to size the port inlets - you can see the scribe marks in some of the pics.

@SFD, The picture isn't so good but the port mouths are the same size(roughly ). I just got done doing the same job the usual way on another smallie motor where I could check & match against the cylinder ports, look here https://modernvespa.com/forum/post1904591#1904591. I pretty much tried to copy what I did there as far as the port shape below the surface, but this is an admittedly fairly rough job - I don't even have my good cutting burrs with me

Using what you got effectively is the key so good on you. FYI I make my play doh from everyday pantry items. 8)

but I'm kinda on the fence on this, so I might recommend it if it's still working OK in a year or so.

Friend of a friend's dad rides a P200 and he busted the kick starter shaft off. He was told I could fix it so he brought the scoot and the busted off kick start lever to me a fair distance with a trailer. I glanced at the scooter and examined the lever a bit and agreed to apply my best efforts in trade for a good air compressor setup. I won't work for cash, especially here in Greece.

Next time I'll glance at the lever and examine the damn scooter a bit. I'm sure those with more experience would have considered all the possibilities, but this was the first busted kick start I've had to deal with other than stripped teeth in the lever.

Play dough... I think the recipe should be ok even in Greece!
http://www.bestrecipes.com.au/recipe/play-dough-L926.html

I wonder if instead of what you're showing you could instead mill it level, then glue an oil seal there, open side out. The lip of the seal should have enough give in it to allow some lateral movement of the shaft. There's no pressure on the oil so should work fine.
Or does the guy worry about what it would look like?

Well Ginch, that might work, and I am one who will sometimes do a reasonable bodge repair, but only for myself. Also this wasn't really all that much more work than what you are suggesting.

It's looking good so far, had all the machine work done at a little local one man shop for 30 euro and the welding done at another one man shop for 15 euro. Both guys were wizards, especially the guy who did the argon welding. He was welding some damage on a smallie motor when I picked up my parts and told me he'd done lots of Vespa motor repairs, even building up trashed rotary pads for remachining.


formal subcontractor drawing submitted

So, not too bad, my 'customer' pays all my out-of-pocket and I now have two good new resources at the cost of a little running around on my scooter. The motor is now assembled & fires right up in the stand with the kick starter working perfectly several times so far. Tomorrow I put it back in the scoot so I can collect my new air compressor.


case milled off flush to o-ring surface and custom snout with o-ring channel


in place with spare kick shaft in place to provide perfect alignment for welding snout 360 degrees at base


fully assembled to check fits prior to welding, the big washers are to protect the bearings




360 degrees of excellent non-ugly welding

That looks great... and very cheap too. Well done Mr V, I tips me 'at to yer.

Looks great Terry!

I want to live near you, Terry.

I love this place! Great save, Terry!

Thanks a million for the kind words, they really are what keeps me going sometimes. Also the brand new compressor and bonus set of accessories being delivered tomorrow. No more running down 2 blocks to the tire shop to blow the small crud out of random motor and carb parts for me!

My 'customer' was pretty happy and fortunately the scoot started right up when he arrived today to pick it up. The motor had recently had major work, at least a new piston and a rebored cylinder that I could see . What is hard to understand though, is HOW COULD ANYBODY REBUILD A MOTOR AND NOT CLEAN IT? Yuck......

Oh well, he's happy and driving it back home(no trailer this time) I'm happy and as long as I don't get an emergency phone call in the next hour, I'll stay happy

Terry- My first reaction was the easily recognized (at least by some of us) beeswax candles. Definitely a pudent choice, considering that they are hand made by monks and nuns, and thus well blessed to protect the engine.

Since you are in the neighborhood, why not pop over to Paros for a coffee?

Or, we will be overnighting in Athens, near the airport, Saturday, enroute home from our travels. PM me if you can come out for a coffee.