Modern Vespa

Okay, so I have a Beverly 200, and replaced the carb on it. Now, when I ride, the bike gets bogged down after a trip of about 10 miles or so. By bogged down, I mean that I can be doing 60 mph on the freeway and will dropped down to about 40 and cannot give it any gas at all or it will stop running all together. If I stop on the side of the road, the bike will stay running, and will eventually be able to speed back up and proceed, but this could get very dangerous for me or other drivers on the road. Any ideas on what could cause this and what the heck I could do to fix it? New to scooting, loving my bike, but hating this dangerous happening. I am trying to fix this myself without going to a shop because I don't really have money to put into the scoot, but have to be safe.[[/b]

Did you replace it with another Keihin carburetor from Piaggio?

Yes, replaced it with the same exact carb, actually just used the diaphram from the old one to replace a torn diaphram in the original.

how's the spark plug?

Did you seat the diaphragm correctly and is it hole free? Also like Lemur said did you check the spark plug?

Spark plus is brand new and seats great in the boot, read somewhere this could be a problem, and the diaphragm seems to be seated perfectly with tabs in the right place and tested with water to check for leaks with nothing coming through via dye check.

what about the fuel valve could fuel be passing the diaphragm to the vac side.

is it a rich or lean bog?

Air box compromised hole or crack or the connecting hose. What does the plug show?

John





Last edited by tvnacman on Tue, 07 Feb 2017 20:46:18 +0000; edited 1 time

Beginning to think I might ha e a fuel line that is torn inside and when it gets a good run on it, it has a flap that cuts of the fuel for a few seconds or something? Is this something that could be possible?

The fuel line is pretty easy to check and pretty easy to replace.

It might be a good idea to replace it anyway for the piece of mind.

I will post pics of the old plug when I get home, actually at work right now. Should be home around 9 EST and will post pic then.

And honestly, I have no clue if it seems like a rich or lean bog, it just kind of groans when I try to add throttle and slows instead of picking up speed. I pull over for a second, let it idle, and then go on about my way. I also noticed that I have about 1\4 throttle left when at max speed of 70 mph (80 downhill) and when I try to throttle into that 1/4 area my scoot does a bog shimmy, where it seems to want to slow and speed up, slow and speed up, almost like it us choking itself with my wrist turn.

i'd recommend replacing the fuel tap, fuel pump, filter and all of the associated lines to eliminate that possibility. for good measure you should do the vacuum lines as well.

it's unlikely to be carb related in that it runs good else where and you can achieve top speed.

my best guess is fuel system. start there and then ride & report.

good luck!

-g

This is what the old plug looks like. Sorry about taking so long to get this up here, I ended up having to work a little later than expected.

that is way too rich, too much fuel. needle and seat problem ?

was that plug used with the old carb too? You could be reading from the old carb too. Have you checked your air filter? Open the air box clean the air filter. Put a new spark plug in it go for a hard ride, then post a pic of that plug.

Do you notice any smoking, if so what color?

John

I'd change out all the fuel lines and vacuum lines. Haven't seen a BV in the flesh but my fuel line lasts 4yrs. Vacuum goes a bit longer. How old is the bike?

There is no smoke that I notice whatsoever. I just replaced the air filter when I replaced the plugs, and how would I change the fuel air mix on the keihn (probably misspelled that all together) carb?

what air filter did you put in, do you still have the old one?

I'm thinking the diaphragm in the fuel valve could be comprised bleeding fuel into the vac side. It could be just to restricted air filter.
John

The air filter that I put in it was a replacement. It is found here:

https://www.af1racing.com/store/Scripts/prodView.asp?idProduct=5142

And now, it is backfiring while I am riding at constant speed of 60 mph. This is getting frustrating to say the least.

the BV has got to be one of the most unpleasant scooters to work on ever made. Everything has to come off, and then you have to put it all back together in order to go for a ride and see if you've fixed it.
It does sound like a fuel side problem. There is a small filter on the side of the carburetor, in a clear plastic cover. Often, as in I've seen it in just about every 200 or 250 with a carb, that filter gets sucked into the carburetor and sits under the diaphragm, and causes a whole variety of different symptoms like you are having. It's something that gets overlooked all the time. Also, if you sort of disconnected the evap system, but didn't put a pinhole in the fuel cap, you can have venting issues. The vacuum in the evap system is designed to open up the vent for the gas tank.

Yes MotoVista, I have become quite the expert in removing and replacing all the fairings and plastic that the 200 has on it unfortunately, but I have gone through this thing from front to back and cannot figure this one out. I have checked the filter that is in the plastic cap on the side of the carb, and it is still there and not under the diaphram, and have actually removed everything from the carb in order to clean it, and have put it all back together. I don't believe that I have messed with the evap system at all, but will try putting a pin hole in the cap to see if that fixes it. If nothing else, it only costs me about $7 to get a new cap, but if it fixes my scoot, I will be more than happy with that result.

where is it backfiring from the muffler or the carb?

John

I suspect its your fuel pump, here is why. You have had the same problem with the old and new carbs. You have not mentioned that you overfilled you fuel tank.

The other way to get more fuel is via the vacuum side. The cross is the vacuum operated fuel pump. If there is a breach in the seal or diaphragm it will bleed fuel into the vacuum side.

Don't drill your cap the tank has a vent. I would rather see you stuff a ran in the tank opening and go for a ride.

By the way I have a 2003 bv200 also any tips for removing the plastics?

John

Well, that was going to be the next replacement honestly, as I have replaced the rest of the line all the way through, including the vacuum lines. So, off to the parts shop on the internet I go...LOL

I will try a ride with the rag in it, see if that changes anything, but always good to replace the pump anyways, and they are only about 20 bucks.


As for the plastics and how to remove them easily? Start with the center plate for the gas tank. The four screws there are an easy remove, lift the front a little, then slide the back up and over the back two fairing parts. The front lift gives you just enough room to slide the back past the fairings without scratching.
From there, it is a fast remove of the screws along the line of the body, but don't miss the two screws that are behind the foot rests for the rear passenger, there is one on each side and those fairings won't come off without removing the allen screws holding the foot rests on. Also, there are two screws per side under the rubber on those fairings as well. Easily removed with a screwdriver though, just lift the back half and they are exposed.
you have to remove the tail light and helmet rack (if you have one) to remove the back half of the fairings. There are two screws that are hidden by the taillight that you can easily miss. And you have to remove the seat to remove the underside vent cover, and get to the two screws that hold the fairing together under there as well. All in all, there are about 30 screws in total that have to be removed and the rear plastics are all off.

If you are talking about the front plastics though, pm me and I will give you what advice I can about that load of baloney. My advice about the front? Don't pull it unless you absolutely have to, trying to get the glove box release to line up after a removal is a pain in the tuckus.

I had the front faring off, I removed the headlight assembly. The auction people got white paint on the lens. There was a headlight mod made to alternate flash that was partially removed leaving the headlight dim. I fixed that up cleaned up, needed to have the front faring off the figure it out.

John

So, removal of the front fairing and headlight, and the back of the front fairing with the glovebox and water coolant reservoir? You need to know how it all goes back together?

If so, let me know and I can actually shoot a video of it. I have to redo mine once again because my glove box release sometimes hangs up now and I hate to not have it perfect to be honest. When I am done with my scooter, it will be perfect, but I have to put the time into it to get it there.

Just let me know what information you need and I will provide what I can. I have had the entire front end off of mine, checking lines and making sure that when I went on the road with it that I wasn't going to end up butt over tea kettle....So, just let me know and I will be more than willing to help with the 200 information.

AND...word of advice about paint on a headlight? Remove it with a Mr. Scrub eraser pad. Won't scratch the headlamp and will pull that paint off rather easily. Same for scuffs on a helmet, works a charm for only a couple pence.

So, I changed the spark plug, adjusted the air mix a little, and this is what I have after going through a tank of gas, about a 100 or so miles. Any thoughts on what is going on?

Looks good to me but i'm no mechanic. Have you cleaned the air filter?

I didn't clean the air filter, I actually replaced it with a new one and saturated it with filter oil per specs. Replaced both air filters, the one in the case and the one under the front intake. On the Beverly 200, the case actually has two filters to it. But I have replaced them both now, adjusted the carb needles, and made sure everything was clean.

Still having the stuttering at high speed though, so waiting on a replacement fuel pump, pickup valve, and o-rings. Going to replace those parts, check it out at that point, and if that doesn't fix it, I am taking it in to the shop to let them deal with it.

Spark plug seated properly?

Yeah, I thought about that too, so pulled it again, wiped threads with a little oil and reseated it. Still seem to be having the issue. I am basically chasing my tail here I think. I want it to be perfect, but am beginning to wonder if it ever will be. I am going to keep plucking away at it though. At this point, I may end up with enough parts to build a second scoot though...ROFL.