Modern Vespa

Thanks so much!

Yes, way better once warm and I have been riding like an old granny. I think I can ride it a little harder as I'm nowhere close to thrashing it. Turning in the mixture half a turn helped too.

Thanks again.

Saturday I took the missus for a ride. It felt like I was auditioning another one of my weird hobbies. She really enjoyed it. A little buy in from your SO always helps.

It seems to be running better, especially when I give it a little throttle. Still a little gun shy after the hard seize earlier in the summer. In 3rd gear at 50mph it's not feeling wound out. 4th feels a little like the 200 4th, but wakes up with a little more throttle. I think I have not been going much past half.

First attempt at a plug chop. 2nd gear at WOT after a long ride. 160/BE3/112, 42/140 idle. How does it look?

Thanks!

Another thing I tried was pulling the choke at speed to see if it accelerated or spluttered. It started 4 stroking like it does at low throttle, so I think I'm getting close. It rides nicely and at 55 feels like it has a lot more to go. The highest CHT's I have seen are 260F, but only briefly. I am going to take it easy until I put about 500 miles on it to make sure the new rings are broken in. I probably won't put on that much before riding season ends.

I keep getting the same issue with fuel starvation. It happened when using the 200 engine too. I have replaced the fuel tap and cleaned the gas tank. The carb had been rebuilt. First time it happened with the new engine was just after a fill up. Took out the jets, blew through them and it went away. Came back a few days later, pulled the carb and found crap in the float bowl. Pulled apart the carb, soaked it in gas, blew it all out with compressed air. Came back next day…blew out jets and cleaned out float bowl and it was fine. I'm looking for a more permanent solution. The tank looks to be in perfect condition. I'm still on the same tank. Maybe bad gas, but that's usually moisture. Maybe buying premium is a bad idea. Nobody buys premium anymore. The premium tank at the gas station is probably halfway back to dead dinosaurs. I've heard of getting moisture in pump gas, but not debris. I've ruled out the tank vent. It starts every time after it happens. One thing I noticed was when it was happening my runleader gauge shows high rpm's at idle even though it's at idle speed. I can either pull apart the carb in the side of the road or jug home in first gear on the idle jet. It's getting old.

This is how it sounds: This was awhile back with the 200 engine, but it's exactly the same with the LML engine, cleaned tank, new fuel tap, different rebuilt carb:

Try replacing the fuel line, or at least pull it, flush it out, and make sure there are no bends that could form an air pocket.

Will do. It's the clear type with the metal coil inside and was replaced over the summer. I might just drain the tank, rinse it, blow it out with compressed air, shop vac etc. Could have just picked up some sediment my last fill up. Next is an in-line fuel filter.

You're already running the best fuel line, and you should be able to see if there's crud in it. I run fuel filters myself, but others around here consider them heresy. My philosophy is that every other fuel line in the world has a filter on it, so why not these.

That's not fuel starvation.
Sounds electrical from here.

Remove the carb cover and filter and you'll likely see fuel flying all over the place.

Having had a chance to watch/listen to the video, I'm with Ray on this one. It's misfiring due to the ignition.

Do you have a tach? If so, I suspect you'll see it's producing weird spikes and drops in RPM's.

That was my other thought.

Tach shows crazy high rpm when it is sitting there at idle…just in the chugging condition.

And, wow, duh…A shit ton of fuel blowing out the carb when revving it in that condition. I have stared at it a million times and it did not occur to me.

Add to that, the on again, off again cock tease that only electrical problems can cause.

One minute, it's all heavy metal thunder. Just as your about to shoot off all your guns at once…chug, chug, chug and yer pushin.

CDI is new. Can only be the stator. I have a new PX stator and will revisit getting it to work with the Stella wiring…after replacing the plug wire and elbow.

Thanks.

I'm thinking the electrical issues might also be contributing to the 4 stroking at low throttle. Before it started chugging the last time, I was getting some 4 stroking/misfiring at higher speeds too. I never replaced the plug wire or connector. Funny to skip the cheapest and easiest things to rule out.

Question about the Stator. Would this one fit a Stella?

https://www.scootermercato.com/Scooter-Parts/Complete-Stators/217866

Yesterday, I pulled the flywheel and checked the woodruff key, all good. Checked the Stator with the multimeter. 493 Ohms for the pickup and 95 for the ignition coil on the Stator. These seem to be within spec. I swapped out the plug wire with a good spare from my bus and made sure I had good connections at the cap and CDI. I also shrink wrapped the base of my CHT censor. It had been scraped down to the copper by the plug wrench.

Took a ride to get it warm and all seemed well. Will see how it goes on a longer ride today.

Also noticed the seat for the mixture screw had some slight damage. Not sure how much this effect things, but I will swap another rebuilt carb just to check.

Better just to go through things one by one than play new parts roulette.

I have been out for some nice fall foliage rides. It seems like the electrical issue is resolved.

As for jetting; I have given up on trying to get rid of the 4 stroking at 1/4 throttle. The PO worked at it for a long time and even ran a really lean idle jet. It is not much different with a richer jet and my plan is to run the richest idle jet I can without making the 4 stroking worse. I am at a 42/140 now. It really doesn't affect how the bike performs.

Just for fun, I switched the main stack from: 160 AC, BE3, 112 MJ to 140AC. BE5, 115 MJ. It made the 4 stroking worse and extended it past 1/4 throttle. It didn't splutter at WOT though. The previous stack seemed to run well with reasonable CHT's, topping at 260F. Not high speeds, but lots of hill climbing winding out 3rd…hills so steep that descending them with the clutch in would put me way over the speed limit without braking. Plug color was nice, though it was a used plug.

I am not sure what direction to go in at this point. Any thoughts?

You need to get a slide with a longer cutout. That's going to lean out 1/4 throttle a little and should get rid of the four-stroking.

Thank you. Such a slide might already be installed. I will have a look. I have a number of them.

I have tried a few different jet combinations and ended up with AC160, BE3, 115 main. I tried a richer 55/160 idle jet. I think I am pretty close to just about bogging on the main and the richer idle didn't make the 4 stroking worse. I need to order a more complete selection of jets and slides and some new plugs. I don't have any mains between 115 and 125. As riding days are numbered, I'm just going to enjoy them and resume setting up the engine in the spring. I had the chugging situation again, which was resolved with cleaning the plug. I also have trouble at times shifting into first in spite of changing the cruciform. I think I need the selector box needs some fine tuning.

I have started working on the 200 again, now that I have 220 hooked up in the garage and it's still warm enough to sandblast outside. I have been tempted to respray the whole bike, but the time involved isn't worth it. It has been resprayed in the past and some of it has chipped where the paint didn't adhere as well. I think careful touching up is the way to go, as it will be a rider and not a museum piece. The rust is gone, inside and out.

The 200 engine has a under 1500 miles on it and the crank and seals replaced by the PO after it lost the clutch side seal. It needs a new piston after I seized it over the summer at low speed. I'm pretty sure it was because of a badly connected oil line. It was leak free as I had pressure tested just before. I will probably end up rebuilding it over the winter or at least opening up the cases and having a look. I'm not sure whether it's worth replacing the bearings and seals, though for peace of mind, I prefer to go through everything while I have the cases apart. This will be my close-to-stock, first kick, go anywhere bike.

At some point, I hope to build a mildly tuned engine using the Malossi cases. It would probably end up going on Stella, which I consider the most capable chassis. They are great platforms for a scooter build. The chassis seems to be made from a heavier gauge steel and the disc brake is simple and reliable. The wiring and rubber aren't great, but those are cheap and easy things to replace.

The Polini engine will probably end up in the VBB. I am looking forward to finishing the metal work on it, which is my favorite part of restoration.

Thanks for reading along and all the helpful advice.

Pulled the carb to look at the throttle slide. It does have a cutout on the bottom.

Going to try a different 20/20 carb. Started by opening up the passage from the float bowl to main jet, though I doubt it as I will probably not be using a main jet needs it.

A couple of other things:

I have been running a short reach plug and I think the Polini requires a long reach. Also the filter I'm using has the heart holes above the jets. I would guess that this lets in more air.

yeah, i did the heart drill out and bought the cutout slide as it had the flat slide. all to try and get rid of the 4-stroking at low RPM and part throttle. It helped but never really went away.

It really doesn't seem to affect performance, so I'm not going to make a career out of trying to get rid of it. It's running quite well at this point.

Btw, did you run a short or long reach plug with the Polini kit? The instructions suggest a long reach, but I can't remember what you had in there.

Thanks.

Yeah, verify proper plug before you chase anything else. You should be able to check which plug it takes by checking the head with a flashlight if you can get a good angle. Here's pics of both taken with enough light that it seems obvious.

Thanks! That's way easier than reading the Polini instructions. They are awful.

No first-hand experience, but the references I've seen say the Polini 177 takes a short reach plug.

Thanks!

And I may have thrown a non autolube carb on there. Started it up and it sounded great. Glad I didn't go for a ride. I found out how to check.

I hate when a way from home, realize I goofed on a project, but can't check for sure.

Looks like I may have put a non autolube carb on. It had a non-autolube throttle wire which I swapped out. I'm pretty sure that it had the extra hole in the carb base, but I will have to check for the plugged drilling near the mixture screw as pointed out in an FMP video.

It's confusing because both carbs are marked 20/20D. Haynes manual lists 20/20D for the Stella. You would think that such an important distinction would warrant stamping an extra letter on it to point that out.

I started the bike and gave it maybe 3 or 4 sharp revs before turning it off after a couple minutes. Nothing seemed amiss. I'm hoping there was enough oil sitting in the engine to avoid damage.

I might end up going premix on both bikes. The 200 engine seized because of a loose oil line clamp. The hose was still on, but had filled with air. One less thing to go wrong.

you should be fine, just make sure it's an autolube carb before doing more

Thanks! Good thing I quit while I was behind.

Definitely non-autolube. Looks like I dodged a bullet.

Engine seems fine, so I was lucky there.

After going for a ride, the bike started chugging again a few miles out. Every time this happens, I try something logical and it fixes it….but only once.

Clean out jets and ride away…but next time that doesn't help.

Clean the plug and make sure plug wire is tight and ride away.

Yesterday, cleaning the plug didn't help. Tried a brand new plug. Nope.

After getting home, I opened the gas tank and cleared the vent and it ran great…But. That was something I tried the first time this happened and no luck.

New fuel line with coiled metal, fast flow tap, new CDI.

Timing has been checked with a strobe and I have checked the Stator with a multimeter.

I am completely perplexed. It's maddening and I'm starting to wonder what I'm doing that makes it run again. Is it only when I wear my special scooter underwear? Walking at least three times around the bike? Is it only when I say mutherfucker more than 3 times? I just don't know.

Went for a long ride last week with no issues.

Yesterday the bike starting chugging exactly the same way a mile down the road. 10 minutes later it was running fine again without doing anything.

It has to be the Stator. Bad timing would be awful all the time. The only consistent part between 3 engines that have shown the exact same problem has been that Stator. Also pulled the green off wire to the CDI to check that.

The new Stator I bought is for a Euro PX and has too many wires for a straight hookup.

I'm going to charge the battery which will allow me to run lights long enough to test it with just the CDI hooked up.

Pretty sure the Stator could be adapted to run whatever configuration. The Trailtech regulator I have allows me to run DC only or a combination of AC/DC. Reading up I think modifying the Stator requires wiring the lighting coils together in series rather than in pairs so that they can use a common floated ground. I didn't quite get it before.

I installed the new Stator and checked the timing, but didn't get a chance to go for a ride.

I cut the grounded coil and soldered the leg to the adjoining coil. I ran the yellow wire to the Trailtech regulator and taped off the unused wires. I'm not sure the battery is charging and what I should expect for output voltage when I check it to the multimeter.

Thanks!

So I think what I need to do is run both the blue wire and the yellow wire at the ends of the coils to the Trailtech regulator/rectifier. It has 2 input leads. The red wire will no longer be used as those coils have been bridged.

I hope I am understanding this correctly.

Hopefully somewhere between 13.3 and 14ish volts?

I'm not trying to rain on your parade here but if you are trying to debug and think the stator is the problem, is rewiring a non-matching stator to a nonstandard condition really the way to feel confident that you know what is going on?

That's a good point. Since the charging system was already converted to DC only when I got the bike and I wasn't sure if it was working to begin with, debugging has been unavoidable. I might be slightly further ahead if I had a stock LML stator in my hands…but probably not much.

Since the bike should run properly with only the CDI hooked up, I thought it would be worth a try. Running CDI only with the old stator gave me the same issue, so I'm not sure what else I should consider.

I will try it out tonight before I get too heavily into rewiring.

Thanks.

for sure you should be able to sort out running issues even if you can't sort the lighting stuff.

It sounds like you inherited a conundrum with the P.O.'s changeover.

I did end up going for a short ride and didn't have any issues, but it's pretty much random so I will have to wait and see.

I also hooked up the charging system. The lights brighten a little when I rev the engine which didn't happen before. I will check it out with the multimeter tomorrow.

The PO's set up was decent work, just unfamiliar to me with a couple mystery wires. I'm not great with electrical either…I can just follow a wiring diagram.

I'm reading 13.7 volts at the battery with the engine running, but the lights switched off. It drops to around 10 v with the ignition/lights on. I currently have the stock bulb in, but it had an led headlight in before. I only put it in for the state inspection. It also had a larger sealed battery in it and I am running the type that would go into the P200 as the Stella no longer has the electric start.

Is it charging enough?

Does your bike still have a kill switch? Check it's resistance. My stella had random weird running issues and it was a half failed kill switch