vespa tuning

i posted this in moped repair, but it think i'll post it here too, as it's and already running moped, and more people probably check performance...or at least i do.

ok so, I

Re: vespa tuning

which side did you cut 10 and which 5? sure you don't have air leaks? 25 seems slow. and yes if you improve flow you should up jet i would GUESS high sixties low seventies.

Re: vespa tuning

also when you bored the intake did you leave the sides of the "cheek" on the inside intact? you can't go bigger than that rectangle guy on the inside, or it will never close.

Re: vespa tuning

if you're looking at the crank with the cut at the top, and the two rounded out sides on the left and right, I cut the left side 5, and the right side 10, the right side doesn't have much of a curve anymore, basically flat. this pic is of it before, and lines drawn in to show where it's at now, to give you an idea. i'm pretty sure i don't have any air leaks as i was really careful. my friend jasonw suggested that i could have a crank seal air leak, i'll have to spray some carb cleaner when it's idleing and do some tests.

Re: vespa tuning

yeah, that little window, the area where the cheek is, i didn't even touch...and i'm regretting that now. i need to open that up, i've been looking at pics of people's on vespa-ciao.nl, and they do some crazy opening up of that area, but yeah, they leave a few mm on all sides so that the valve can close.

Re: vespa tuning

how are you gonna spray the crank seal, its behind the flywheel? I would check the gasket between the case halves though.

Re: vespa tuning

that's a good point about the crank seal. not too sure. i think i'll try different parts of the case and near the cylinder and head, i'm hoping that it's just a jetting issue. as it idles fine and is easy enough to start.

Re: vespa tuning

check the whole thing it's all connected.

Re: vespa tuning

Success! I went over to my friend Peter's garage and upjeted to a 72 for now, and we checked the timing, and whatever he did fixed that and now it runs great. i'm gonna have to check the plug tomorrow once it's warmer outside, just to make sure i'm not too lean still. also, i realized that i have an exhaust leak, so i need to fix that too. lastly, i have my leo vince on there, but i also have a calibrata, and i was toying with the idea of trying that out on their but didn't think i had high enough RPMs for that pipe. however, my headlight blew out pretty fast, so maybe i'll give it a try, who knows!

Re: vespa tuning

I'd try it, but you might have to jet even higher. buy a range and start high and work your way down to where you think it should be.

Have you seen the Tuning Spreadsheet? It is your friend.

Re: vespa tuning

I've seen the spreadsheet. there really wasn't anyone up there (as far as i could tell) without a kit who had the crank cut. i think i'm still a bit lean. i forgot that you can't put the calibrata on without removing the stand...so i haven't done that yet, maybe when i get down to louisville for whiskey business II. thanks for your help

Re: vespa tuning

I doubt a 72 is lean on a stock jug. I run a 76 on my Grande with a Leo, 64cc Malossi, cut crank and intake and 13mm carb and so on. Maybe so, but I would think not.

Re: vespa tuning

how big of a difference has the cut crank made for you guys? do you guys balance it out with holes in the other side? what tool you guys use to cut it off too?

Re: vespa tuning

no holes on the other side, Ive run mine for 6000 miles or so now. I use a dremel and chainsaw sharpening bits.

Huge difference, it is a must to really get power out of these things, since the carb is limited to 13mm, you gotta increase that intake duration as much as possible.

Re: vespa tuning

how do you set the timeing on these things?

Re: vespa tuning

Timing on a vespa, such as it is, is controlled by the point gap.

Re: vespa tuning

timing is "self timed". its all in the point gap.

« Go to Topics — end of thread

Want to post in this forum? We'd love to have you join the discussion, but first:

Login or Create Account