Vespa Bravo dies

Althea Erickson /

I've also been working on a Vespa Bravo in recent weeks. As a brief history: It wasn't starting. We checked for fuel, spark, both which it had. Figured it was compression. When pedaling, if someone puts their hand in front of the head you can feel a strong breeze. If you stick your finger in the spark plug hole and pedal, the air does no force your finger out. Also, the last plate on the head is broken. BUT: We took off the head, cleaned the inside, retightened everything, and also reset the clutch cable, which know moves much easier than it did before. Once it all went back together it started right up.

Now:

When cold, it starts right up. After a five/ten minute ride, it doesn't want to start again. Sometimes after being riden it'll start, run for a couple minutes and then die. Then it won't start at all, but if i let it cool down, it's more likely to start. Also, last night i got frustrated, kept pedaling and then this huge pop sound exploded from the back. i'm a little nervous about that.

Anyway, any ideas about this? My first inclination is to clean the carb, which i haven't done beacause I'm uncertain about how to get it out. So my other question is to those with a bravo: how do I get the carb out? And then there's the main question, which is: what's going on with this bike. any ideas?

Althea

Re: Vespa Bravo dies

Is your `compression release' stick open? don-ohio

Re: Vespa Bravo dies

what is this compression release stick and how does it work?

Re: Vespa Bravo dies

Could also be a bad condenser.

BK

Re: Vespa Bravo dies

Bruce Wilkinson /

Clean the carb and check that the choke is not staying on. Check that the airbox is on tight and doesn't have any cracks in it. If that does not fix the problem then you can check the points gap. There is a rubber plug under the variator on the flywheel that you remove to get at the points. The gap should be .015 ". The condenser is with the points and could be bad like BK said. The motor and flywheel have to come off to replace the points and condenser.If you need more info on this ,let me know, but clean the carb first. bruce

Re: Vespa Bravo dies

Bruce Wilkinson /

I do not own a Bravo, I have a Si and a Ciao which are much the same. I don't know how tight the carb is tucked into the frame on the BVravo. Ciberian , or Zippy are the ones to ask about that. bruce

Re: Vespa Bravo dies

Althea Erickson /

Thanks for all the input. i'll try to figure out how to get the carb out tomorrow morning. it looks hard to get to. not like my sachs at all. But as for the other things. the airbox has three holes in it, one of which matt from seattle covered with tape when they came and the bike ran fine for an extended period of time with lots of stops and starts. as far as adjusting the points gap, would you still be able to ride it around a lot if they were incorrectly gapped? cause it runs fine after the first time you start it, it's just after riding it for ten minutes or so that ihave trouble starting it again. Also, is there a way to check if the condensor is bad, or just replace it? Thanks again, Althea

Re: Vespa Bravo dies

althea -

Make note of this procedure, posted by our very own 'zippy'!

http://pg.photos.yahoo.com/ph/bwebb08/my_photos

Removing the carb is really quite easy, but I am really not good at explaining things in the abstract.

Remove both side covers (long, grey, plastic covers - one on each side of the engine.) 2 very large plastic screws on each side that will turn about 90 degrees Counterclockwise to release the panels.

Remove the 'step-plate?', the horizontal piece just above the the engine - 4 screws total.

Remove the air filter (white plastic piece under where the step-plate was. One screw in a collar secures it to the carb. You may have to jockey it a bit, but not much.

The carb is also held on to the intake manifold with a screw into a retaining ring.

You'll have to remove the small plate on top of the carb where the throttle cable connects (2 screws) - BE CAREFUL putting this plate back on, and refer to Bill's (a.k.a. - zippy)

photos.

The carb can now be tilted up slightly at the rear, and extracted between the frame rails.

Seriously, this is not nearly as difficult as it sounds.

Please feel free to e-mail me if I left something out or if you just don't understand my ramblings.

Best of luck,

Dave

Re: Vespa Bravo dies

Hi Althea,

My Snark used to do something really similar. I don't know how similar it is to this Vespa, but for what it's worth, I'll tell you what we did.

It would start up on the 2nd pedal when cold. Then, if I killed it after it had been running, it wouldn't start for anything. Brett was the only one who could get it started. One day I turned it off while riding with a friend and it took us 45 minutes of constant pedaling to get it to start again.

It got to the point where if we were riding and someone had a breakdown, I'd leave my bike running for up to 45 minutes to avoid turning it off and having it not start.

We finally figured out that it was the clutch. We tightened the clutch cable (well, ok, Brett did) and it works like a charm now. I'm sure if you email him he'll tell you exactly what he did.

Sorry, that's long-winded but I hope it helps. :)

Re: Vespa Bravo dies

Sorry,Althea........I didn't read closely enough. It is not the compression release sticking open.

Zippy and JimC. are VEspa experts and may have an idea.

Does sound a lot like condensor to me,too. don-ohio

Re: Vespa Bravo dies

Bruce Wilkinson /

You said there was a huge pop sound. Sounds like you're describing a backfire which might be caused by timing. That's why I suggested the points gap after you clean the carb. bruce

Re: Vespa Bravo dies

Althea Erickson /

Thanks for all of your help. I managed to get the carb out to clean it, and in the end it wasn't nearly as difficult to remove (like you said) as it looked. Cleaning the carb seemed to solve the problem, cause i kept it running for awhile, killing it and starting it again no problem. Unfortunately, I can't tell you for sure cause I took it for a ride, brought it home, turned it off, went to restart it one last time, just to be sure, and immediately snapped my clutch cable. Alas. But I think it was just a dirty carb. Once i replace the cable I'll report back.

Re: Vespa Bravo dies

get a new spark plug

Re: Vespa Bravo dies

Althea posted ove 24 hours ago that cleaning the carb took care of the problem.

I'm also not sure how a bad plug would cause a bike to start OK when the bike is cold, but not when it's warmed up.

Re: Vespa Bravo dies

i am having very similar problems with a morini 1 speed right now, in fact many people have told me its the condensor, if you hold the plug against the cyclinder it sparks for about 5 seconds then dies out

if this is the condensor how does one go about replacing it

Re: Vespa Bravo dies

You have to take the magneto off and the little silver cylinder on the stator plate is the condenser. You need to solder a new one in it's place. The easiest way is to use you soldering iron to remove the wires and then palce a new one its place. I just changed one on Sunday. It only took about 15 minutes (and that was waiting for the iron to heat up).

BK

Re: Vespa Bravo dies

okay, well what holds the condensor in place, the puch stator I am looking at seems to just have a condensor sitting in a little hole with a black and white wire soldered to the top, do i just haver to pop it out from the back, and where would i find a replacement condensor for a morini, or could i use a puch condensor

Re: Vespa Bravo dies

You just have to pop them out. I found when you put them in put a small (very) layer of grease around the bottom 1/4 of it. I think any condenser will work, but I may not be right.

BK

Re: Vespa Bravo dies

cool thanks for the tips, i ll see if a condensor off a puch works, since i have an abundance of them

Re: Vespa Bravo dies

HELLO DAVE OR SOMEONE WHO MIGHT HELP ME. i HAVE A 78 VESPA BRAVO THAT DOESN'T KEEP RUNNING ALSO. i'M GOING TO PULL THE CARB OFF PER YOUR INSTRUCTIONS HOWEVER WHAT ADJUSTMENT DO i USE ON THE SLIDE SETTING SCREW ON THE CARB?

eCK

Re: Vespa Bravo dies

ECK: definitely sounds like a bad condensor if it was doing what althea's was doing. i'm a little confused though when althea says that their clutch cable broke. as vespa mopeds don't have clutch cables. probably meant the decomp cable...

Re: Vespa Bravo dies

There is no clutch cable on vespas. Holding that lever lets the compression out of the cylinder. Possibly your problem?

Re: Vespa Bravo dies

this thread is five years old.

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