Modern Vespa

OK. I know this is ANOTHER P200 question. I did a search, but I didn't see any good answers.

The scoot starts and runs rather well, except a few things that bug me.

1) If I try to start the scoot from cold without the choke, it doesn't seem to want to start. I end up needing to pull out the choke for like only 1 or 2 seconds after the scoot starts. If I leave the choke out for more than a couple of seconds, the scoot dies. After those couple of seconds, the scoot will start with no issues (except the one I list below) with or without the choke being out.

2) The spark plug gets gummed up like every 200-400 miles. Its one of those things where I am riding around just fine, but when it gets gummed up and I need to turn off the engine, I end up needing to change out the plug with a brand new one in order to get it started again. I am using a B7ES right now, and I might drop it down to a B6ES at a bunch of friends suggestions.

I just can't help thinking the two issues might be related. Like I don't have the baby dialed in right. Its Stock Stock Stock. Spaco/Dellorto 24/24 carb. Whatever jets came with the carb. Stock exhaust. etc etc

What does a plug chop tell you? Is it running noticeably rich when you do the test?

Hi mate, our wee scooters are cold blooded they need choke and like it too.

Pull out the main and make sure you are running a 118 main. 116 is just too small IMO.

If you need help "Fine tuning" then give me a call and we can sort out any issues

Cheers

I always need to have choke when I cold star .But after that its pretty good to go unless its real cold out. Clean your plug or buy a new one (I run B7 in mine)Clean your jets (just lightly tighten them back in !) Turn your mix screw (on the side) in all the way. Then turn it out 1.5 turns out. Start your bike with the choke if needed. Push choke back in when your bike starts to die. Go for a 15 min. ride come back home and check your idle (the big screw on top sticking out). Screwing in is more rev screw out less idle. After that check the plug. Tell us what happens. Best...Brian

have you checked your choke jet? it's possible that it's too big. Your idle jet may be too big, too ..so make sure that those two are still the stock things.

I've seen people fouling up plugs because their choke never stopped fully disengaging. Like, it would pull out more for the start, but when they pushed in the knob it would only go half-in ...so it was ALWAYS richening their mix and causing them to foul regularly.

Well, the carb is all stock. I basically put it in right out of the box from scooterwest.com. The mix was tuned in at 2 turns, because thats about where it sounded like the idle would change speeds. BUT I might as well check just to make sure, because Jimh made statement about checking the the main jet.

Also, school me again on verbage. When I hear "richening", I think of more oil in the mix. But the other day, when I was going through posts, I read that adding more oil to the mix actually mean thinning since there is less petrol. Am I the only one that gets confused on this point?

Also, also, I was talking to another friend that fixes 2-stroke motorcycles. He says that I should check the reeds, and he said if the reeds are partially stuck open I will get gummed plugs. I told him that I didn't think Vespa's had reeds, and I only heard of reed valves on custom modified cases.

Modern carburetted Vespas have reed valves, but a stock P does not have a reed valve

Am I also assuming that bumping up the sprk plug to a B6ES is not a good answer?

Alright, well, that's potentially one problem. Just out of the box assumes it's new. The fact it's new assumes it's a spaco. If it's a spaco, 1.5-2 turns out is NOT the stock setting. The pitch of the threads is different, so if it's a spaco carb there's a different default setting for the idle mix screw versus the stock dellorto. Richening just means you're increasing the oil/fuel mix relative to air. This may be a no-brainer or it may blow your mind : air is what's exploding in your engine, not gas / oil. The gas/oil mix is actually what's cooling down your top end. More air = bigger explosion = hotter More gas / oil = cooler = richer = potentially fouls your plugs if it's richened to the extent where it's not burning completely. Not a concern ... unless you have a Stella you don't have reeds. I don't know of a single carburated vespa that came stock with a reed valve. Some people will put them on when they kit up their bikes, because it gets you a snappier throttle response ( but with the downside as it's one more link in the chain that could break or fail ). It's not an issue with you.

You are correct, sir. It is a Spaco/Dellorto. You made the statement regarding the thread size being different when I first got my carb back in February, and I took it to heart. I instead used the method I read about in the Haynes Vespa Maintenance Manual for the P200e. I might not have been doing it right. Anyway, after I tuned it with what I THOUGHT Haynes was describing, I then checked to see how it was set by counting the tunrs in until it stopped turning, and I came up with 2 turns.

BUT, I am still learning my ninja skillz and my tuning could be off. I guess it might be more on the rich side as I'd rather deal with fouled plugs than a stuck piston. But fouled plugs are a pain and sorta embarrassing. PERFECTO. Thats what I wanted to know. WOOHOOOOOOOO! Then I answered my friend right! Now, I'm on my way to my 3rd stripe on my ninja white belt. Man, I just know its gonna take me 10 years to get my black belt in Vespa Fightin' Skillz.

So, when do I get my yellow belt? Or do I just jump straight to pink?

I would think that would make things worse... 6 is a colder plug and therefore more likely to foul IIRC.

Do I have that right? edit: Nope, I'm backwards.

A couple more things.

I wouldn't necessarily assume that because you just used what was in your carb when you bolted it on that it has the correct jets in it. You should confirm that stuff.

Also, what you described as a bogginess when you rev ... a latency to accelerate that goes away if you hold the throttle a minute... a hesitation... that's not out of line with it that screw on the back of your carb being too far in, i believe.

I think you have that backwards. A B6ES should run HOTTER, and from my understanding, thats why you want to run it during the winter.

I was under the impression a B8ES was the cooler plug, and it should be run on hotter days and on long rides

you're correct, oldstl...

b6 = hotter
b7 = normal
b8 = cooler
b9 = damn cold. your engine better be kitted and run with very high compression to necessitate this cold a plug.

Yeah, thats bogginess I described back in February. But that seemed to resolve itself TOTALLY after I got the new carb. The new carb seems to run like a champ, other than when leave the choke out immediately after I kick it over and when the plugs get fouled.




BTW, Thank all of you, especially R Eric on your patience. I always get great answers (helpful, and frequently, funny ones) on this board

no problem. Just trying to keep you on the road.

Correct, my bad. Will edit my post above.

A hotter plug might help burn off the gunk, but the root of your issue is still poor fuel/air mix. As the earlier poster said - don't trust that the base (new) carb jetting is correct for every application. Each jet affects different parts of the powerband, dependent on your setup and local altitude/temperatures.

I haven't had a chance to look at the jets, because my lcutch cable broke on me the other day. I've been playing with that. I'll try to get the jets sometime tonight.