Modern Vespa

So every once in a while when I ride my scoot, randomly at one point or another during my ride, the idle goes to redline when I hold the clutch in and in neutral. If i let it sit for a while then start it back up, all if fine.

Can anybody shed any light?

Also (unrelated), My muffler has fallen off 3 times now. I've been ussing the factory U-bolt. What should I do?

sticky throttle cable, sticky throttle tube needs clean and lube, slide is warped and once heats up sticks, air leak somewhere. Could be any of those or more.

U-bolt? That doesn't sound 'factory' can you post a picture?

Oh, almogavar covered it on the revving.

leaning out due to low fuel... breather in fuel tank is blocked

The fuel tank was topped off that morning, and the throttle cable isn't sticky really. It has no hesitation or slack.

Does the Haynes Manual cover changing seals for the air leak? If not, can you give some direction?

Thanks all

That's not stock. What kind of exhaust do you have on there?

I thought it was stock . Sorry I'm still new to this. I'll attach more pictures.

This time when it came off the piece connected to where cylinder fires completely came off. If anyone knows the name of that part it would be helpful!

Cylinder exhaust flange.

oh did you buy that ridiculously ugly P off ScootNet? I think i saw it on CL too, PK horncast? http://scoot.net/classifieds/forsale.html?id=53747 if so I'd paint the purple parts off the bike.

Yeah, sort out your exhaust problem. Exhaust flange in proper, with some threadlock. Clean out the carb jets, check the float needle and the carb filter.

Don't jump to conclusions about an airleak just yet. The manual does cover how to replace seals worst case. You'll want to get the carb dialed and jetted right before you think about splitting the engine cases.

I'm out in West Philly, close enough to Ardmore. Hit me up if you have gen questions/need tools.

Yes bigben! She's all mine (I gave a low ball offer and he took it, plus I'm only 17)

Okay, I'll try everything you said. I you ever feel like taking a ride to Blue Bell, I would love and sincerely appreciate the help!

Hello

The bit on the cylinder the exhaust attaches to is the port.

Grumpy

hahaha he said flange

Update:
I just checked my carb and there was a loose screw near the outside of where the float was. Is that enough to cause such high rpms?

Also: I checked my jetting, and it was stock (according to scooterhelp) and the exhaust that I have is nothing close to stock. I'm getting nervous as to what problems can arise from that being the combination for so long...

Pictures would help here again, since you're still learning terminology. That could do it if it was one of the sleeve nuts, though (the nuts that hold the carb onto the motor). Can we get a better picture of the exhaust?

And I agree that you should be nervous riding it hard until you've had a chance to upjet. You may need to up both your main & idle jets, possibly your atomizer, too.

Definitely take advantage of any local experts you can meet up with--these carbs simple, but can be incredibly frustrating.

Welcome to MV!

Here are some pictures. I am googling the engraving on the exhaust.

the carb flap that you're pointing to doesn't mean squat. it comes with a carb when you buy it. there are numbers on the carb proper that you'll point to to show what carb you have, its either a 20/20 or a 24/24. Likely though, that carb's relatively fresh as the tag goes in the trash pretty quickly.

You have a Mikeck LeftHand(LH) pipe, not sure which edition/marque but I'm gleaning from July of 1988. They make them for Largeframes (saw a couple posts about a Mikeck on a T5, couple Rally models) and Smallframes. It is not a wellknown brand, from everything I found searching just now, they were popular both in the 80s and amongst brits.

I'd junk it if I was you, or shelf it if you don't want to chuck it. Go with something more standard, reliable: Get a Sito+ exhaust, theres a guy selling one on Scoot.net right now thats "pretty good": http://scoot.net/classifieds/forsale.html?id=54243
I'd try to get it off him for $75 shipped, but otherwise you can get them from scooter parts companies like Scooter Mercato in GA for about $130 shipped. They're a standard 'super stock' upgrade for a p200 engine. You can get crazy with pipes in time, but otherwise, a sito'll get you on the road: they're easy to jet.

If you've been scootin since the 80s you know what a mikeck was. It's actually pretty good by 80s performance standards. You can hey easily. Sito plus is Ok. SIP or BGM better

The carb is a 24/24. I am still looking for the source of the high revs. The carb honestly looks super clean so I don't think there is a problem there.

Where else should I look for the high rev problem?

Exhaust-wise: I was thinking about a SIP 2.0, but I know I would have to bump the jet size. Does the SITO+ not need a bump in jet? (I've found mixed answers)

you go up a size or two on a your main jet when you upgrade your pipe, yes. some exhausts are harder to jet than others.

i have a sito plus on both a p200 and a 177 kitted stella with a 120 on the p2 and a 118 on the Stella.

cross the bridge when you come to it with jetting, there are plenty of threads on here with people asking about the comparison between sip road and sito (depends on how you're intending on riding) as well as jetting charts and additional threads about jetting X pipe with X setup.

Would you say 118 or 120?

Do you think that incorrect jetting could cause the over-heating and extreme revs?

It sure could be if thats bolt is the top f the float chamber. But that also can kinda cause the opposite, where it will run but won't rev out.

Keep going. this is how you learn to rise and work on these things. AFter a while you know it inside and out.

I'm not sure I'd bin the Mikek just yet, but you definitely should be up jetted for it over stock. Sort out the revving/lean situation and the n see if t works for you.

Looking clean doesn't mean anything when a tiny piece of crud is trapped inside a jet... or the carb body has been improperly torqued causing the throttle slide to stick... etc,.
All possible with a brand new shiny carburetor.

Now is probably a good time to mention the importance of buying a decent torque wrench if you're serious about going down this road...

Everything inside the carb is fine. I did tighten that one loose screw though.
The throttle slides freely, I know it's not that.

I want to know how to check for where the air leak is. I'm going to try the spray trick

one thing with these stock carbs is you do not want to over tighten. The bodies are soft and can warp. I learned early on. Not on my part. But a friend. He would tighten everything down super tight on a scoot. Never use a torque wrench. He warped the body and went on a substantial ride up in the mountains. i get a call later that evening to come and collect him because when he kicked the bike over it would spin freely no compression. When I got there I pulled the head offf. Yep - nice big hole !!!! I could barely break the nuts off thread on carb. Once I did I set carb on bench on piece of glass and it was warped. So- even though the carb is new give it a check to see if you are too tight. Pull carb off and check if level on a flat surface.

the jurys out on the spray trick. some say, and correct me if im wrong, that if you spray carb cleaner near the base of the carb it's going to go somewhere reguardless of if there's a leak or not.

yeah the spray trick is ok if you dont want to fuck around and you can get the engine going

you can use a spray bottle and some liquid soap. when you kick it over you get a nice blob of dirty bubbles where the leak is. dont do it with the engine running.

on upjetting for a sip road, get a jet kit, theyre like 15 bucks. start with a 122 or 126 even and work your way down. theres a billion posts on this, do a search and find out what you need first then get your questions together.

Can you give a little more detailed instructions? You seem to understand the process pretty well

http://www.madsens1.com/saw_airleak.htm

its not rocket science. or is it? what's a rocket?

start the engine, get it idling, and take an old febreez bottle with dish soap + water mixture in it, and spray it all around the engine. base of the carb (keep the carb top on for starts), exhaust stub, and if you see any extra bubbles popping around from anywhere specific, it'll likely indicate a little leak. let us know, we'll advise from there.

i'm not sure if the haynes manual covers this type of troubleshooting. my mindset is that book was created for someone owning a relatively new vespa as opposed a 30+ year old bike, restoring it and the such. i'm not sure if the word 'rust' is in there as frequently as it should be.

Cool, as soon as I get the exhaust on I will do it.

Just IDed another issue:
I guess I wouldn't have noticed with an exhaust on, but there is gas leaking out of the flange. There is a 4x4 inch puddle I come home to every day. Is this normal? I guess I never noticed because the gas would just go into the exhaust chamber. I just ended up masking it with a couple shopping bags to kill the smell that is lurking into my house (Dad yelled at me).

I know scoots leak a tiny bit, but even with the fuel cock off, should it be leaking like this?

No, leaks aren't normal. It's probably the float needle in the carb. They wear out and are easy to replace.

SoCal's right in that the needle is a likely suspect. Your fuel tap may also be leaking but if the needle is right it shouldn't matter if the fuel tap is leaking. So you likely have one or both of these problems.

i'd order a fresh needle just in case. they're always good to have around. if you're concerned about a gas leak, when you're done running the bike, run the gas out of the line (turn the fuel petcock off and run it until it dies). you can then remove the fuel line from the carb banjo and let it sit for about a half.

if theres no new gas coming from the fuel tap, then your tap/petcock is in good condition. even after you ran the fuel out of the line (again, run the scooter with the exhaust on the bike), if you leave it in the off position and gas flows through youll likely have a bad tap and would need to replace it.

a tap isn't expensive per se but its sort of a bitch to do because you have to remove the entire tank, get a special fuel tap removal tool (i borrow mine from a vespa shop every 5 years i'll need to replace the tap on a project because i'm cheap like that).

disreguard most of that. sort one problem at a time and don't get too ahead of yourself. if you keep that pipe, consider putting some copper RTV silicon gasket sealer. they use it on lambretta pipes where the ubend meets the muffler.

i can meet up Fri and can loan out a couple jets for your tuning in the interim. i've got 120, 122, 124, 125, and 126. The 120 may be being used, i'll have to crosscheck. shoot me a message.

bigben

Thanks so much for all the help and advice! I am out of state until next week. I actually ended up ordering a jet kit and a new exhaust. (The guy on scoot net took my $70 dollar offer, but my paypal wasn't set up right so another guy snatched it). I ended up just getting a sip road because I figured if I had the money now.

I will message you when I get back to PA