1977 Vespa bravo starting issues

Hey guys just bought a new to me 1977 vespa bravo that looks to be in pretty good shape, only issue is I'm having issues getting it started

I've looked in the wiki and the Haynes manual through this site

I've put the bike in "motor" mode by pulling the button out on the rear, the clutch bell housing spins freely with pedaling but the belt and variator off the crank shaft do not spin. I have depressed the decompression lever too as I know that's important for compression. Eventually the starting clutch shoes do engage turning the belt for a second as well as the variator but that's it. If I keep pedaling it will continue to try and catch with the belt moving slightly.

I have had the plug out and a compression tester connected to test for compression the only way to get anything is to manually rotate the variator, which does turn the belt and the clutch bell housing but it's pretty much maxing out at 30psi if I rotate by hand.

The belt tension may be slightly loose but I read the engine location isn't movable in the variated models, also when I rotate the variator portion by hand the belt and bell housing rotates as it should.

I've taken apart the clutch bell housing. The starter shoes look to be in shape although they are on backwards from how they should be. Although I've read that that is ok through this forum. I'd be happy to attach a photo

When I bought the bravo the spark plug was slightly fouled with oil (running rich?) But I haven't yet managed to get any spark.

Does anyone have any ideas of how it should go? I'm hoping it's something silly and I'm missing something small, thanks!

Re: 1977 Vespa bravo starting issues

Skip the pedaling. Buy yourself a 24mm socket and a drill adapter and drill start.

The engine is actually movable. The rear engine mount, the lonely bolt at the back, has a plate riveted on. If you dremel away the soft, aluminum rivets the plate will come off and you can adjust the engine. (remember to loosen all the engine bolts as well as the exhaust bolt in the subframe on the other side.)

When starter shoes slip, it is often because of some dirt or grease in the bell or clutch. Clean the assemblies where they make contact using some brake cleaner spray.

I would tend to disagree about shoe orientation. I think it matters.

Finally, if you're still using the old belt, you should consider replacing it. An inexpensive 10 dollar belt will be good enough to get you going and is a vast improvement over the 40 year old belt it came with originally. Ax39 is what I use.

Again, save yourself the exhaustion of pedal starting. Use the drill start method. Once you get all the problems fixed on your bike, it should pedal or push start easily. Until then, use the drill to help you out.

Re: 1977 Vespa bravo starting issues

Don't drill start, when the engine starts the nut will loosen then the variator will fly off. Then its likely the magneto will loosen enough to shear the key.

The belt is probably fine for now. I'd agree with cleaning the assembly and try flipping the shoes. Can't hurt to try them in the other direction to see if it will catch easier.

If it's all stock components there's no real reason to readjust the belt tension. As you said yourself it is catching and rotating. I wouldn't start with replacing it unless it seems to be slipping too much or is falling apart

Re: 1977 Vespa bravo starting issues

I don't have a Bravo , but , it seems to me that the nuts should be tight enough to handle drill starting without the whole thing flying apart .

Re: 1977 Vespa bravo starting issues

> P D Wrote:

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

> I don't have a Bravo , but , it seems to me that the nuts should be

> tight enough to handle drill starting without the whole thing flying

> apart .

I think It's a 10 mm nut.its Not very big to get tight, and they are notorious for stripping crank threads if you over tighten. So when the engine starts, spinning more rpm's than the drill, off comes the nut. Supposedly. I can't verify from experience, ;)

Re: 1977 Vespa bravo starting issues

10mm on a crankshaft is rather small and then adding an insult , they use crap steel?

Sounds like a pretty sorry affair .

Re: 1977 Vespa bravo starting issues

It may be 12 mm, but I don't think so. A lot of Vespa cranks with screwed up threads out there. And to make matters worse, if you buy an aftermarket Polini variator, it's 2mm thicker than oem, so you can't even get full threads. I had to remove material from the variator hub with a large flat file to get a full nut of threads.

Re: 1977 Vespa bravo starting issues

There's always more than one way around a bush . ;)

Re: 1977 Vespa bravo starting issues

I drill start. I don't strip the crank either.

The nut can come loose, sure, but if you're drill starting, you probably shouldn't be riding it. If you pull the drill when the engine catches, you usually don't loosen the nut. Make sure you tighten the nut before you ride it.

I find that using a drill to spin the engine is helpful when doing things like checking for spark. It is easier than trying to pedal it.

Anyway, like I said, a bike in good repair should easily pedal start or push start. But, sometimes the drill shortcut helps you figure out what's wrong.

Re: 1977 Vespa bravo starting issues

thank you for all the replies

I cleaned up the starter clutch shoes a bit and got it to engage the engine like it should, I've tested for spark and there seems to be good spark now after letting go of the decompression lever... I did notice that the spark plug is close but not the one recommended in the haynes manual

Put a bit of 2 stroke oil down spark plug hole as the engine hasnt been turned over in quite some time according to previous owner

Hooked up a compression tester and after a lot of pedaling got it up to 110, noticing that there are signs of oil on the spark plug... i figured i could get it started via. pedaling if compression is over 100 with throttle wide open (and choke automatically on)

Put some 40:1 premix in spark plug hole, pedaling until clutch engages, engine turns, letting go of decompression lever, and it still wont start

Any recommendation of what to do from here? I can try and start it with a drill but there seems to be some discussion if that will be ok, i figured 110 would be enough to get it fired up.

Should i take a look at the points? Carb? Thanks for your advice everyone

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Re: 1977 Vespa bravo starting issues

How did you test your spark? I know a lot of people touch the plug to the outside of the cylinder and spin and look for spark. While that will tell you if spark exists, it is an unreliable way to test strength.

I use an adjustable gap spark tester. That is the best tool for determining if your spark is strong enough. It should jump a gap of 10mm minimum.

If you put gas in the cylinder, and it didn't at least pop, it probably is a spark issue.

If that is the case, it could be dirty points, but more often for me it is a bad HT coil (the one the spark plug wire comes out of.)

Clean the points, check the gap. There's a chance it could be a bad condenser, but that's less likely.

If it is not electrical, then make sure your carb is clean and fuel flows nicely.

After that, the next most likely cause, I think, is a crank seal. That inexpensive part is a pain to get to as it requires engine removal, but it is often the cause.

I go with a double-lipped seal from AVX seals. Cheap but good quality. I buy them a handful at a time.

Those should be the most common causes.

By the way, what year is your bike? It's neat! The rear rack is very different from mine.

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Re: 1977 Vespa bravo starting issues

Thanks for your feedback!

I've read in that Haynes manual that the hc coil rarely goes bad and you need special equipment to test it, is that true?

I'll get an adjustable gap spark tester, I've used multiple plugs from different bikes that I have with the same result so I'm starting to think it's not getting enough spark?

I feel like 110 psi should be enough to get it started so it's strange. I'll take a look at the points, again any way to check that hc coil? I'll recheck connections too

It's a 77 bravo (Well manufactured 2/77 So is that a 78?) Yours are in much better shape lol, next I need to find a gas tank which I know I can find in the buy and sell section of this site

Thanks !

Re: 1977 Vespa bravo starting issues

A 1978 Bravo was my first moped, six months ago. Seems Vespas are many peoples firsts. It was an experience, getting it going. So much to figure out on these strange Italian contraptions. Aggravating, to say the least. There is tons and tons of threads on here about them, and you can read for days learning about their nuances. I suggest you do just that. Do searches here for your issues, and familiarize yourself with this website. Read my early threads, and learn from my(and others) mistakes and successes. Learn that little Dellorto carburetor like the back of your hand. Clean it super well. For real, clean it well, everywhere. Take it apart and remove the jet. Don't miss the tiny idle passage. Clean your points with fine wet dry sandpaper, and gap to .014", or spark plug box thickness. Make sure you have the air filter installed. Install a new NGK B6hs plug. Make sure you have a good tail light bulb, or it will never start. The ignition grounds through the tail light circuit.

Be patient, and have a thick skin. You'll learn why soon enough, but there are some, uh, abrasive personalities on here. Present company included at times. Sorry in advance. There's a lot of us arthritic, grumpy old dudes with artificial parts on here. But you'll get it going, and you'll be hooked. Six months later, and I now have nine mopeds. Just picked two up today.

Re: 1977 Vespa bravo starting issues

So while Alex is the expert by a long margin, I don't recall drill starting the variator nut off. Especially if the correct lock washer is behind it. What my drill starting does is destroy the variator nut angles. I've tried six and 12 point sockets btw. So make sure u buy a couple of extra variator nuts if u need to pursue drill starting to get this thing running. And Ike otherwise is got a good set of recommendations. B5hs or b6hs is the usually suggested plug.

The rationale behind drill start is that maybe your idle bypass port on a car b blocked , or some other imperfection if you spin the engine fast enough spin the engine fast enough Glover, all the deficiencies in the setup to get the motor running and get it at 8 beyond and idle or holding idle and get it all the way up to see if you can grab the engine in a reasonable manner pedal starting is fine once you get everything said and clean and you definitely should probably think about taking that played off the rear screw that holds the engine on. For as far as you know you have the wrong it felt little loose . you take the plate off just put a little bit more attention by moving the motor a little bit more followers type it up see if they pedal starts the first thing to do is drill starting is put it into the pedal mode not the training or just get the motor to run with the drivetrain disconnected by the rear button and and get the engine running it sure if you're in a semi warm place which of a fan running do you have the door open where you playing ,don't get carbon monoxide. Sounds like you're just about there

Re: 1977 Vespa bravo starting issues

@Seth

The tail light will kill the engine when the brakes are pulled, but otherwise a dead bulb shouldn't prevent starting. The ignition only goes through the brake filament, and only when the brake lever is pulled.

@John

The adjustable gap tester will test your entire ignition system. To test your HT coil alone you just need a multimeter. Harbor Freight has them cheap and occasionally free.

If you need to replace the HT coil, I recommend the Emgo universal. It is inexpensive and works great. Also the mount holes are the same as Vespa.

Re: 1977 Vespa bravo starting issues

Hey Ike, thanks for that. But if the bulb is missing, it won't fire, right?

Re: 1977 Vespa bravo starting issues

Seth, it should fire bulb or not. The only time the ignition runs through the bulb is when the brake lever is pulled. That's the "safety" feature.

It is possible to wire the tail light out of ignition circuit. If you run the wire from the points directly to the HT coil it cuts out the tail light and kill switch. With a little bit of work, you could set it up to eliminate the brake light but still use a kill switch. I imagine also being able to put that brake light on the other coil instead. It would dim the headlight when the brakes were applied, but otherwise shouldn't affect performance. I haven't tried it, but I can imagine the possibility.

Re: 1977 Vespa bravo starting issues

A few months ago, my Bravo lost spark. After an exasperating search, I found a broken wire, going to the brake light. It broke right inside the rear fender, where the sheet metal was rolled into a tube for the wire to pass thru. With that wire broken, I had zero spark, but as soon as I spliced it back together, good as new. That's why I wondered if the bulb was missing, if there would be spark. So maybe check continuity in the brake light circuit, because that wire can break where you can't see it.

Re: 1977 Vespa bravo starting issues

Also, with these, the brake light switch sometimes sticks, leaving the brake light on when you're not squeezing the handle. Most bikes I pick up, the switches are either sticking, or the wires are busted off the tiny spade terminals, so on these normally closed switches, that causes the light to come on. So, if the bulb is bad, and a switch is sticking or disconnected, no sparky.

Re: 1977 Vespa bravo starting issues

PayPal ready.

Re: 1977 Vespa bravo starting issues

ground blue wire n drill start, get use to pulling the drill away from nut b4 letting go of trigger. spark?

Re: 1977 Vespa bravo starting issues

You guys were right! Really frayed blue wire coming out , snipped it back and grounded it to the engine block- can't believe I didn't see this in previous posts (my mistake) but you've been a great help.

The bike fired then died when I put gas/oil pre mix into spark plug hole, I've now taken the carb out (it was leaking out of float bowl) to clean and will update on progress, by the sounds of it they can be finicky carbs

I'll chase the electrical too to see if the wiring is frayed back to the tail light.

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Re: 1977 Vespa bravo starting issues

If you dont care about brake lights, just ground the blue wire and save yourself some hassle.

While i have never spun a variator nut off drill starting before, i did do it on a single speed some years ago. When the nut came off the clutch exploded and my life flashed before my eyes and shoes springs and shrapnel flew in every direction. One the clutch retaining disc flew like a sharp frisbee and was embedded in a 2x4. I could see variator weights causing a lot of harm too in the same scenario.

Fuckin lucky i came out unscathed. So yeah, i dont drill start bikes anymore. Totally to chase a spark demon with the plug out though(edited)

Re: 1977 Vespa bravo starting issues

Bad Cadillac™ /

Other then the broken wire you found the bike sounds completely normal on how it's attempting to start. It's just a matter on learning how it starts and what to expect.

Your white Bravo is cool, never seen a white one before myself!

Re: 1977 Vespa bravo starting issues

Right on! You're on the right track now. These Dellorto carbs are super simple and easy to work with, just need to be super clean. These little engines really hate air leaks, and they notoriously leak where the carb meets intake. Use an o ring. Clean the needle seat with a q tip and toothpaste til it's shiny. Make sure the rubber tip of your needle isn't deformed, and it won't leak. Run an inline paper fuel filter. Have fun.

Re: 1977 Vespa bravo starting issues

> Bad Cadillac™ Wrote:

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

>

> Your white Bravo is cool, never seen a white one before myself!

Yeah that was the first thing i noticed. Didnt know they existed!

Re: 1977 Vespa bravo starting issues

Yeah, white Bravo is cool. I hope you find a tank for it!

It's weird, I happen to have a white Bravo front fender. I thought somebody painted it because I haven't seen a white one.

So the wires to the back light (at least in all my 78s) run through the rolled edge of the fender. I've replaced the wires in a couple of them. It's a bit of a pain, but it can be done. I unbend the roll using a roofing nail. It's all I had that would fit in the gap and allow me to bend it. Once you get the rolled edge opened up, you can run new wires. It's not complicated, but it's a bit tedious. I though it was worth it in the end.

Of course, you could just run new wires in a protective sheath. Just have to figure out how to attach to the fender.

@Alex

I appreciate the lesson about drill starting. If I had that happen I'd probably feel the same way.

Re: 1977 Vespa bravo starting issues

Thanks for your feedback! I've been working on the carb today these things seem pretty finicky I'm sure there are lots of posts on it. Put it through the ultrasonic cleaner put it back together carefully (I thought) and still doesn't fire on its own

Thought I might have lost spark but when I put pre mix into spark plug hole it fires up then dies so it must be a fuel issue

One thing I noticed was that when blowing out with air compressor I couldn't see through the gas inlet (without needle seat obviously) but when I pulled the carb yesterday it was leaking out the bottom so I figured something had gotten in there. I will do some more research. Thanks!

Re: 1977 Vespa bravo starting issues

Thank you for your tips!

I pulled it all apart and put it through the ultrasonic cleaner (minus the needle seat and any rubber) and thought it was clean but apparently not! Still having issues starting should have followed your advice specifically, I'll take it apart again and follow what you said. I did blow everything out with compressed air afterwards, and the needle seat looked good and didn't leak through gas inlet when I tested it, but when I tried to fire it up it wouldn't go. I did notice I couldn't see any light through the gas inlet

Re: 1977 Vespa bravo starting issues

Sometimes stock jets corrode shut and you need to run wire through them

If your float needle is leaking, just order a new one. They are like 3 bucks and you cant repair an old one that doesnt seat anymore

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