crazy rotary valve vespa idea.

Wow the forums are weak lately, thats probably because everyone is out riding now that its nice, but its shitty and rainy today, so i'm bored. There are like, ten threads about fucking expresses and scooters and shit on general. If you dont have anything not stupid to say, seriously, just stay off the internet.

So, in the interest of debate, i'm gonna throw an idea i've been kicking around lately out there. I invite you to steal it as long as you post pictures of how you did it, and do it well.

Side-rotary valve vespa engine. The crankcase on the starboard side of the engine could have a port cut into it and an intake manifold welded on, and the crank web could be cut, or have a plate welded into the gap, to make the timing work, you could theoretically have a huge fucking port in the side, like most conventional rotary valve motorcycles. The kriedler land speed bike was set up something like this. Anybody see it done, anybody think it could work... anything else you guys want to talk about besides fucking scooters?

Re: crazy rotary valve vespa idea.

Re: crazy rotary valve vespa idea.

Naw, he means an actual rotary valve, that's a reed valve setup. The vespa engines are pretty close to having that now with the crank controlled intake, although you can't make it too much larger. Rotary valve engines used to be the big thing but had since fallen from the spotlight when reed material got to the point where it wouldn't break off all the time and could sustain high rpms. I'd like to see it done. Be tricky though.

Re: crazy rotary valve vespa idea.

ah! signs of intellegent life on the interweb!

yeah i'm thinking if i shimmed it differently so the web on the enclosed side made a really tight ground seal... the crank is already machined smooth, so is the case, i could modify the shape to make the web be the actual valve, but it would be on the side, so it could easily be a couple hundred square mm. this business of the tiny litttle crank web port is just silly... anyone have an extra vespa engine laying around? I really want a stock cylinder 40 mph nonvariated, rigid, ciao.

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im pretty sure kinetic engines are rotary valve

Re: crazy rotary valve vespa idea.

they are rotary valve, but the rotary valve is on the crank web perpendicular to the axis of the crankshaft, the port is like, 60-70 mm^2 tops.

Re: crazy rotary valve vespa idea.

If all you want is 40mph then I'm sure you can do that with nothing more than porting, pipe, carb, and maybe head work. No crazy intake work arounds, just the usual tools.

Re: crazy rotary valve vespa idea.

probably right.. ok lets try for 50/50 then shall we?

i wonder if i could make up that difference in spacing by machining the bearing race 'in' a bit on the dead side, and shimming it on the other? or would it be easier to build up a 'sealing face with the tig welder, then machine that down so it sticks out a lil' past the normal case face.

Re: crazy rotary valve vespa idea.

I have a spare motor planned to become a super vespa but alas I can't weld, this idea seems alot sicker than just adding a reed block to the side. But what would be the advantage over a large reed block instead, higher peak rpms?

Re: crazy rotary valve vespa idea.

more torque, more tuneablility.. rotary valves are really rad.

plus you could still say 'stock modified engine'

Re: crazy rotary valve vespa idea.

If you are going to put a port in the crank cheek it would make the crank out of balance if I understood correctly

Re: crazy rotary valve vespa idea.

well, the crank already has a good sized window in it, and its already quite a bit out of balance. i could cut the other web at will to bring it back into balance again.

Re: crazy rotary valve vespa idea.

Aaron McTaggart /

found this thread over on puchforum, and then remembered this one...not a vespa, but interesting nonetheless. also, have you checked out the sprocatti motor for the ciao? will run to the tune of a couple grand, but is case inducted flatside cdi watercooled amazing. just search "sprocatti motori."

http://www.puchforum.net/viewtopic.php?f=18&t=9170

Re: crazy rotary valve vespa idea.

Aaron McTaggart /

oops...don't know why i said "case inducted." ...i should hope so. and it is in fact a rotary intake.

Re: crazy rotary valve vespa idea.

i would be willing to steal jasons ciao to do this.

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