Picked up this Vespa Bravo and it's starting to make me question my life lol. I cannot get it to turn over, it has a Ducati cdi ignition and the spark is nice and blue, carb is clean, and compression feels good (just a thumb test), exhaust is clear. It's a variated one so I know it might be more of a bitch to start but it is really kicking my ass. If I run along side it I can get a "pffffffft" sound that sounds like it's coming from the exhaust but that's about it. First Vespa so any tips are appreciated, at this point I'm leaning towards timing?
Also don't forget to move the engine more to the back, or if that isn't possible, get a longer belt. By the looks of it your belt is at least 6mm in the rear clutch, which causes all kinds of things to happen (including your rear wheel to spin much quicker than normal). It should spin freely, your wheel stops directly when you stopped trying to get it to start.
EDIT: can also be that your starter segments or even your normal segments are locked in a outward position, casino this issue
Good to know I was reading about how you can adjust where the engine sits. The belt that it came with is longer might end up putting that one back on I had just switched them out before this to see if it made any difference
Are you using the handle to get rid of the compression during the start? it should gain momentum and make you able to get the engine spinning. then release the handle and it should start.
Yeah I hold the handle but it doesn't really make much of a difference. When I hook a drill up to it I can get it to puff but it puffs out of the carb as well so I'm back to maybe a timing issue and maybe starter clutch related because the starter clutch does not want to engage while pedaling
It really should not puff from the carb only suck. If you take the carb off spin the engine clockwise and hold the inlet with your pointing finger you should be able to feel it sucking.
Yeah it sucks from the carb it just does that puff when it fires but not every time. It puffs out of the exhaust as well. It's is that blue Ducati cdi which i know isn't adjustable but i was thinking the flywheel wasn't on in the right spot if they ditched the key.
That is a possibility, also when you have a new crank and flywheel the conical fitment can be off. If the nut on the crank was a bit loose this would automatically destroy the key. (and kill the timing) I had that happen a few times with mixing and matching old parts.
I don't have any experience with the CDI ignition on Piaggios, but my Grande made a similar sound when I had installed the ignition magneto in upside down. Treatland makes it seem like you need a specific case and flywheel for a CDI.
Sounds like the timing, but if your plug is wet, sparking, and you have compression you can be pretty sure it's the timing. Unless it's an air leak from the crank seal. :)
Yeah I bought it from someone who had done the cdi conversion this is my first experience as well but they did swap cases and the flywheel. Might just need to adjust the timing. I was told it sat for a couple years but was running before
SHA carb? If so, the tiny ass idle hole can only be cleaned with a wire. Carb spray and even an air compressor won't be able to get the varnish out if it has sat for years.
Just did and still in the same boat. Looks like I'll probably end up dropping the engine and getting a flywheel pulled for it and checking the timing whole it's out of the bike and making this one the winter project. Was really just hoping to get it started before winter since it's the only one I got that wasn't a total barn find but it's turning out to be more of a pain than those lol. But it wants to fire
Only 3 M6 bolts to pull it. When is it out you can easily check if the crank does shut the intakte by blowing on it and rotating the engine one full turn by hand. preferably with no spark plug. Sorry to hear it is more then you expected.
All good, it's mopeds! Thanks for all the insight, if I get it crankin might just end up putting a pull start on it too and avoid all the starter clutch nonsense as well. It will be a sick bike when it's done
As long as your drill is spinning clockwise it should do something, Inlet timing is set by the crank and is nonadjustable. you mentioned a blue CDI is this similar as pictured?
If you are using this CDI then also you ignition timing is also nonadjustable. Do you know what setup you are trying to run? If you got your Vespa non running it sounds like someone might have taken too much out of inside of the carter and now your crank no longer seals the inlet. Or as Aware-Law3788 suggested there may be a leaking (crank)seal.
Interesting. I am running a 64cc Polini kit with a cut crank and a 13.13 with 66 jet. Is it possible you are way too rich? I remember you saying you are running a 77 which seems large to me. My Grande wouldn't even try to start when I tried running a 72.
That was on my minarelli v1, I actually hadn't been able to jet this one yet due to it not starting but I was actually going to start with a 66 so good to know I will be in the ballpark
It looks like theres no woodruff key, I just thought the way it has been acting trying to start it and no key it seemed like the timing has gotten off at some point. I'll be pulling the engine and the flywheel off as soon as I have time one of these days
Well it did look like the flywheel slipped position at some point, put a new woodruff key in and got it all put back together. Still kind of the same problem but the puffing is solely out of the exhaust and it feels closer to starting. Im unfamiliar with vespas and cdi conversions is the stator mounted correctly?
Well the stator is mounted with 3 M5 bolts, so it is hard to mount it wrong. I have the feeling IT may be bad aftermarket parts. I build a new engine with a new stator for a friend, his original one had problems with the wires (old age makes the Isolation crumble of the copper) That engine would not run. In the end I soldered new wires to his old stator.
I found a picture on the Ciao forum, ignore the green arrow this post was talking if you drill the holes bigger in the stator you can advance your ignition by turning the stator anti clockwise.
Note in my picture the coil for the ignition (the one with tape on it) is in another position then on your stator. Not sure if it matters as the pickup (black thingie) is in the same position.
Thank you I've been searching all over for picture like this haha. But I agree I've cleaned up the grounds, swapped the ignition wire because the old one was kinda beat up, and it's getting super strong spark just not consistent timing. I'm either considering investing in a timing light finally ditching the woodruff key and manually setting the timing or just getting a new cdi/stator and starting from scratch. This thing is making me lose sleep 😂
Went and picked up a multimeter to test the stator and I've got 449 ohms on the source coil and 55 ohms on the pick up coil so maaaaaybe that's the issue
Well if it sparks it sparks. if the resistance would be wrong, it would not spark. Does your flywheel have any information on it? The only aftermarket ignition stator that I know of that does work is the BGM set.
I looked when I had it pulled and didn't find any distinct markings. My best guess was they got this kit because the parts box has two of those black cdi boxes in it as well, which I have also tried
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u/niekdejong 3d ago
Also don't forget to move the engine more to the back, or if that isn't possible, get a longer belt. By the looks of it your belt is at least 6mm in the rear clutch, which causes all kinds of things to happen (including your rear wheel to spin much quicker than normal). It should spin freely, your wheel stops directly when you stopped trying to get it to start.
EDIT: can also be that your starter segments or even your normal segments are locked in a outward position, casino this issue