Modern Vespa

Have you bled the pump?? If air is present in the main line it won't prime itself…

As for the choke brackets. I always used the 90 degree one, along with the clamp, to mount the choke on one of the CVT's cover bolts so it's easily reachable…


Bleed screw…

Safis-

Aha! Totally forgot about that. I'll bleed and report back.

I thought about putting the choke on the belt cover but there was no weatherproofing/ rubber to protect it. I figured it would get dirty and cause problems so I went with it inside. So far it's been a one push start with immediate idle. I doubt I'll even have to use it as I'm in such a warm climate area.

Ok bleed screw did the trick. Much better now. Took her for a one block run. 84 main jet too big. Will drop to an 80.

I was wondering about with a 5k RPM clutch engagement.

We'll the plot thickens. Riding it around I have to baby the throttle to get it to rev out. Doesn't matter which jet. 70, 80, 84, 90. Big wide open shot will kill the motor. If I flip the choke on (or what I think is on) the motor revs out cleanly and I can get wide open.

So, is it a jetting problem, or do you think I've been riding with the choke off (But really on).

On mine, when lever is at a 90° angle it's not on or adding extra fuel for enrichment. When you pull it straight out, in line with cable it pulls cable up a little and opens extra jet for enrichment. If it's like mine disconnect cable, spring above plunger on carburetor will hold plunger that caps off jet in place and see what you get. That should be enrichment circuit off with cable disconnected from lever.

Last edited by Christopher_55934 on Thu Jun 23, 2022 12:46 am; edited 1 time in total

Ok so disconnected choke, 90 MJ, stock needle W16 at highest clip setting. Still have to baby to get it to rev to 70% ish, won't go past it.

Lowered the clip to the lowest spot. Still same.

Put the choke back on and I can rev out cleanly to 90% and then it's bogging. Ease off the throttle and it'll keep revving clean.

Everything I've researched and seen online has folks with expansion chambers with 19 mil carbs jetting in the high 80s. Weird I'd need something higher than a tuned scoot.

One idea I'm thinking of involves the air filter. I haven't had good luck jetting PHBH or PHBLs with the air filters installed. Since this is the younger brother to those, could there be some correlation? I've got the stock airbox with the 3 holes per the carb instructions with the red mesh Malossi filter element (oiled).

Worth a try unless anyone has ideas?

Ok scratch that. Definitely needs the air filter to run right. Couldn't get 10 feet either way

Google search says to swap to a W7 or W9 needle from the get go. Figure I'll buy that and a 95& 100 main jet tomorrow unless anyone else has ideas?

Got the 90 MJ and swapped to a W9 needle, second clip from the top. Too fat right now and lost some top end. Going back down to an 85 MJ.

Getting max revs but still can't break the 40 mph barrier. Any variator tuning ideas?

I'm having flashbacks :-p

I would try lightening the variator weights because the stock ones might be "shifting up" too early essentially for the powerband of your setup. I used Dr Pulley sliders and liked them a lot because they had a smooth feel.

That being said, i feel like something else is going on. I think you'd brute force past a low shifting vario tune and still eventually break at least 45

Something seems fishy with the carb/mix stuff you were describing above

Your not asking about getting there quickly or staying on pipe. Are reaching your max RPM trying to get to max speed? To go faster without changing pulleys only options are to move further out on front pulley and further in on rear. Basically change gear ratio.

Start with a marker and color in lines on all pulley halves, run it to WOT, max speed for a few miles. Post pictures of what you have for marks after that. If it is capable of faster with what you have you're not out to edge on one of them. Last variator I tuned, challenge was getting belt to outer edge of front pulley.

Make sure front pulley halves can touch in center under normal operating conditions. Just because you took out speed restricting spacer doesn't mean they can touch. I had to spend time understanding how my particular variator worked to get to edges.

Repeat for rear., except you need to get all the way in.

After that your getting into finding an exact length belt to get to edges if your not there.

Overdrive pulley setup is easiest but can be expensive unless someone knows of factory pulleys you can bolt on from a bigger bike.

I was just screwing around to see what I could get, in the end an overdrive pulley kit set got me to 53 or 54 mph with a 70cc kit. She was WOT at max RPM.

Example

Vespa ET2 Polini Hi Speed Control Variator Review

Last edited by Christopher_55934 on Sun Jun 26, 2022 5:19 am; edited 2 times in total

That's a great idea.

Thanks for the replies fellas. I'll get a marker out and see where the belt is rubbing to.

On the lines of gears, the only thing that wasn't in the multivar kit that I installed was a torsion controller. I'm wondering if it's not allowing the clutch pulleys to come together as much as they need to?

Engine rpm wise, it revs up pretty linearly. Clutch engages around 3-4K mark and you feel the back tire go. Then nice wind up. Pretty standard CVT feel/sound.

Definitely not screaming engine revs and then back tire catches up. No bogging.

My 50cc Challenge - ET2

Good read here, should help.

It's a good one. Read that when I first started this project. Sadly doesn't have specifics ie the red clutch springs. Ok, who made those red clutch springs??? You can bet that when this is done, I'll post a detailed list of everything on it.

Today I have other plans but tomorrow is to rebuild the clutch and try out my torsion controller theory

I would try dropping to about 5.5 grams on the rollers and an 80-82 main jet. The rollers are not allowing the bike to spin up properly, and it sounds like it's running really rich.

Just disassembling for the rebuild tomorrow. Pics of the belt wear on the brand new pulley.

Looks like belt isn't making it to outer edge, that's one thing to figure out.

So spent the last few days messing with things. First issue was the torsion controller. Guys at Scooterwest eyeballed it's and said it wasn't letting the clutch open up all the way. I guess it's meant for other springs? Maybe stock? Wasn't part of the multivar kit so don't install it!

Changed the small clurch springs from Malossi yellow to the Malossi white ones. It's a little jerky but much easier to use for everyday riding. I checked the black ones and managed to lose one 80 MJ installed and babying the throttle got me to 46 mph. Had a bogging issue mid throttle.

I was having problems getting to WOT and was thinking my main jet was too large. Goose it at any speed and it would bog. I just had an epiphany and thought about the special washer that goes under the main jet. I think I read that's for diffusing bubbles? I was running out of things to try and did a 180* with it. That cured my throttle issues and acceleration/WOT is instantly smoother.

Top speed with the 90 MJ is 42mph now. I can hold it wide open and it doesn't bog but sounds better if you let off the throttle some. Gonna buy an 88 MJ and see if that helps increase top speed without sacrificing cooling.

If I'm happy with that, I'll swap to 5.5g weights and update.


Washer/ weird thing under the main jet in the CORRECT orientation.