77 Vespa Bravo Hard to Start wont stay running.

So I picked up this really cool Bravo hoping to get it running for the wife. Have done all the normal needs from a moped setting for years. Derusted the tank, new petcock, new plug (nice strong blue spark, cleaned the carb following the wiki and other posts. I have good gas flow to the carb and it will start up initially then acts like it is flooding out. Have fuel spitting out the exhaust . It is the original carb, air box and filter. Like i said it acts like its flooding, but original jet in carb. Does the float height need to be set? After it dies and I remove the plug its always wet. Any ideas let me know.

Thanks for any help.

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Re: 77 Vespa Bravo Hard to Start wont stay running.

Sounds like it's too rich .

Try removing the air filter . Check that the choke is functioning as it should .

You know for a fact that no one has drilled that main jet ?

Re: 77 Vespa Bravo Hard to Start wont stay running.

Bad Cadillac™ /

The carb is probably still dirty. Did you clean out the idle hole in the carb?

See this thread here for what I'm talking about.

https://mopedarmy.com/forums/read.php?6,4023519,4023557#msg-4023557

Re: 77 Vespa Bravo Hard to Start wont stay running.

I did try removing the air filter completely and had the same result. What more does the choke do other than blocking the opening then allow full flow when off? I have tried with choke on, its starts, will idle short time die. When I try to restart with choke off it will start then die. After this most of the time then I have to pedal fast with throttle wide open to get it to run will run short time then die. With fuel coming out the exhaust. I purchased this from original owner 84 year old lady that stopped riding it years ago and has set. I't doesn't look like the main jet has been drilled but I may purchase several different sizes to play with.

Thanks for the help.

Re: 77 Vespa Bravo Hard to Start wont stay running.

yes BC I did on the 3rd cleaning and finding that link clean the idle hole. It was plugged but didn't make any difference, still runs then dies.

Am I missing something on the float height? It doesn't appear to have any adjustment at all but for some reason it seems when I allow the fuel to almost empty the bowl it will run longer. If I allow the fuel to flow freely it seems to flood worse. Does that make any sense at all??

Thanks for the help!!

Re: 77 Vespa Bravo Hard to Start wont stay running.

Does it leak gas out the carb? You may have a float need issue

Re: 77 Vespa Bravo Hard to Start wont stay running.

No gas coming out of the carb, I followed the wiki cleaned and polished the needle port, and needle has nicely shaped rubber tip in place.

Re: 77 Vespa Bravo Hard to Start wont stay running.

Bad Cadillac™ /

> Kenny Shinneman Wrote:

> -------------------------------------------------------

> No gas coming out of the carb, I followed the wiki cleaned and polished

> the needle port, and needle has nicely shaped rubber tip in place.

You have to replace that needle. While the tip "looks", it's not soft like it was 42 years ago.

These parts do not last forever and get dry from age and gasoline.

See Treats for a rebuild kit, until its rebuilt you'll never get it to run right.

You should replace the plastic intake piece too so you know you don't have any air leaks. This part also gets dry and develops cracks due to age.

Re: 77 Vespa Bravo Hard to Start wont stay running.

Bad Cadillac™ /

Also, you don't adjust float height on vespa.

Re: 77 Vespa Bravo Hard to Start wont stay running.

with the bike tilted back, petcock on with filter off u should be able to see if gas drips outta carb. r u running a fuel filter? is the stock banjo filter there? the stock main is pretty small, 42 - 52. maybe get another known good carb off buy sell.

Re: 77 Vespa Bravo Hard to Start wont stay running.

I'd want to know how you checked your spark. Unless you use an adjustable gap spark tester, you're just guessing whether you have enough spark.

I had a brand new HT coil that showed spark but wasn't giving enough to run the bike, that's why I know.

Re: 77 Vespa Bravo Hard to Start wont stay running.

OK, I'm back working on this Bravo. So I purchase the rebuild kit, replaced the float needle and all seals that came with the kit. I purchased an adjustable spark gap tester. I have bright blue spark with the tested set to 5mm. Removed the carb and completely cleaned again and installed the new gaskets and float needle. Reassembled and installed and still have the same symptom. Hard to start, dies and has fuel running out the exhaust. No fuel is leaking anywhere around the carb at all. I do still have the banjo filter installed but it was removed and cleaned and new gaskets. The jet is tough to read but I believe it is a 45 or 48. Jet doesn't appear to have been drilled (not bright and shiney inside) Does anyone know what numbered drill size a 45 or 48 jet is? I could possible confirm the size before randomly trying smaller sizes. It still acts like it is flooding. The plug is always wet after it dies and is removed. I'm trying not to pull the carb off my grande just to test but may have to. Any help is appreciated.

Re: 77 Vespa Bravo Hard to Start wont stay running.

5mm is not a lot of gap. You want to be closer to a full cm. I'm still thinking that a new HT coil is in order.

Assuming your spark is fine, the only other reason for a wet plug with no firing is flooding, like you said. However, the carb is designed to overflow out of the top of the carb, and it would be hard to flood the cylinder even if you had a bad float needle. So too large a jet would explain that, but it seems to me to be an unlikely scenario.

The fact that the bike runs and dies also points to a bad HT coil. When the coil warms up it performs worse, classic HT coil issue.

New one on Amazon is 15 bucks. Emgo universal coil is a perfect fit.

You might consider making some videos of your symptoms. Show us the spark. Show us how it runs and then dies. Pics of your parts also. That would make it easier to help you.

Re: 77 Vespa Bravo Hard to Start wont stay running.

if its obviously flooding and you've mess w carb for a while, id start looking elesewhere. start w changing to a clean plug, turn petcock on then off complety filling fuel in float bowl. will it start n run, wot? tons of smoke? if yes, good, if no check, for air leaks including decomp and that one seal. no compression wont let it run as well.

Re: 77 Vespa Bravo Hard to Start wont stay running.

Richard Eberline /

Remove the pipe. no start? Air leak? Runs and won't idle. Worn rings.

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