Modern Vespa

Over in my VBB resurrection thread, a fellow from the other side of the planet suggested I soak my rusty crank in some 'soft drinks =Coke! and let it do its work.

I am wondering "crank and pad" interaction in early engines... (what goes on there - how tight is tolerance, what if there is some pitting on crank surface that interacts with "pad". Pad is in fine shape)

Obviously if chunks of metal come crusting off the crank it's to the scrap heap.
My restoration is mostly for fun. If I clean up the crank in the suggested manner, what is the tolerance and interaction of the crank and "pad" area?
How tight (do they "touch" in oem spec?)
I've been a 4cycle and rotary (wankel) tinkerer up to now.

My son is off to college in the fall so while I am not eating ramen noodles daily., the need to economize on my "fun" is obvious. Willing to half ass this as I will likely ride the scooter for tens of dozens of miles in coming years.

Thank you...

I found the thread on leak down testing, and especially the test on the pad crank interface. So I guess now I understand. I guess converting my engine to a reed engine or 3 port wouldn't be an economizing step either.

Looking at those sub $100 cranks from India... any experience from folks in my situation?

Can't believe I haven't had someone with a parts hoard offer me a used crank for $45.

Have a great day.

Photo or rust that fellow Vesper says soft drinks may resurrect to somewhat useable condition. I am in little to no delusion that the rod or piston would be salvaged (will be tossed). Perhaps the cylinder could be done one or two over if the piston came out.

^^That is f'd. That is a small boat anchor.

Go to scoot.net, part wanted, and post that you are looking for a VBB crank and probably a top end too.

That would still be an interesting subject for the Coke cleaning method just to see how it turns out. If you do please post the "after" pics too. Don't count on it being useful in a running engine though. Scoot.net can be your friend as well as the vintage shops.

Gick told me the same.

Like I said, I am nut exactly sure as to what the interaction is between the crank and pad. After reading I see it is sort of a valve system. I thought the piston and ports were the only parts that functioned that way... 2 cycle induction and exhaust are new to me.

I guess it has components that act like the Wankle engines Mazda produced.

It is a valve. rotary valve/disc valve. 2 strokes are traditionally - rotary, piston port or Reed valve.
- Rotary has a section of the fly side crank web cut out to be open on intake stroke and carburetor feeds crankcase and transfers to combustion chamber.
- Piston ported has a section on cylinder where intake/carb mounted and feeds combustion chamber.
- Reed valve can be mounted on crankcase or cylinder. Uses a flexible Reed between manifold and case or cylinder that uses the intake/exhaust charge pulse to open and close.

Vespas are mainly rotary valve with exception of Gs160/SS180 and some other early models which are piston ported. Lambrettas are piston ported. Reeds are usually found in high performance motors

I might have a 2-port cylinder and head I could hook you up with. I'll have to dig around and see where it is and what state it's in.

aw man, I hate when the pistons seized in the barrel. Makes a good rally trophy tho.

Been busy raising kids. I rebuilt a 1964 MGB in a couple months when I was 19, I thought it would get me laid. I have a lady now, and kids, getting laid no longer a issue. Anyway since I last posted, I got some parts from I the ScootsOriginali... I can't remember right now. Anyway I've had all the parts out in the garage for awhile, gaskets bearings, and an original Italian crank, piston, and jug. I am back here reviewing how to put the engine back together. Guckspped took the engine apart and fixed the missing exhaust hanger stud, I probable shoul go back to Gick, but I'm part hard headed Italian, and Irish... And part French. That is the news from Indiana today, where it has; snowed, rained, hailed, sunburned, snowed, and rained today.

Shit you rebuilt a MGB in a couple months, my dad had a MG Midget back in the day, a Vespa should be no problem. They were made so a drunk Italian farmer could fix it in a night so the next day he could go into town to buy a new shovel. I mean that in the best way possible. The Honda Super Cub was built so a drunk Japanese factory worker could rebuild it in a night so he could get to work the next day.

Ah, alcohol, the fuel of civilization. Some anthropologists say that humans invited agriculture so they could make beer. Imagine that, two cave men around the fire one night after a shitty mammoth hunt:
Grug "Ug, this drink you made from half sprouted barley and left in a mammoth's bladder for a month is making me feel good, I can almost forgot about not getting that mammoth today and nearly being killed by a saber tooth cat."
Ug "I know Grug. Maybe we should settle down and grow barley so we can always make this tasty beverage that makes me all warm inside."
Thus the art of beer, and civilization, was born.

@Neorotic guy living in Japan. Thanks for the encouragement, or history lesson.

Beer was made from the run off material from making bread. The Egyptians were the first to do this. And I'm glad they did.
Lesson over - Jon Gick is one in a Million - you could not be working with a better guy. Toss the crank, it is not worth your time or the coke that may free it up.