Modern Vespa

Apologies if I do any of this incorrectly, first time posting. I've looked for answers to this question in other posts and I can't find anything but I may just be missing them.

Anyway, I have a 1967 Bajaj Chetak that, according to what I've been told by the guys at Scooterwest, it's very similar to the VBB and VBC models. Mostly the same guts as a Vespa but sold under the Chetak name.

I was having trouble with it stalling out. It usually kicked ok (important point) and would idle fine, and sometimes I could even ride it for a bit, but eventually I'd get to a point where it would stall, especially at stops/stoplights.

I rebuilt the carburetor with a Scooterwest kit. Same problem. I read that sometimes if there is a problem with the clutch that could cause a stalling. So I rebuilt the clutch. But when I put the clutch back in I could no longer get the kickstart to engage. I could push it down, and things would spin, but nothing that will start the engine. I can't seem to figure out what I could have done that would have caused that to happen. I pulled the clutch out again to check, and everything seemed fine.

I'm really hoping I don't have to open the engine case, but I did buy this thing to learn more about working on scooters, so maybe that's my destiny. So two questions I guess:
1. any idea what might have happened in my clutch rebuild process that could have made it so that I can no longer start the scooter?

2. Original issue was the stalling? Assuming I fix the kick, any recs of what to do next to solve that now that the carb and clutch are theoretically done?

Thanks so much. And apologies in advance for asking tons of obvious follow-up questions.

sounds like your clutch cable is too tight.

Can you describe the stalling symptoms and why after rebuilding the carb led you to the clutch? Both operating different aspects of the engines functions.

The chassis appears to be old school but is the engine? Looks newer maybe even LML? Does it have a rotary valve or reed?

Could be I can't see the adjuster barrel

Did you disassemble the clutch actuator? Maybe it isn't correct and when you tighten the clutch cover down it presses on the clutch.

Try backing off the clutch cover a little bit and see that fixes it.

Do you have a picture of the inside of your clutch cover?

Do you feel a bit of free travel before the clutch lever hits some resistance? There should be a couple of millimeters before you feel it engage.The adjustment is a small threaded barrel where the outer part of the cable goes through a fixed "boss" under the motor. Back off the lock nut and screw it in for more free travel before the clutch arm engages. If there is no more adjustment there, the little barrel clamped onto the cable at the clutch lever has to be moved.

How did it run when it ran? Just putting new kit parts (float, needle, and gaskets) only addresses the flow of fuel into the carb and won't do much if the internals are dirty. You have to remove the jets and clean them and the passages in the body. A sonic bath and a good blast if air works best. I'd also replace old points and condenser and set the timing properly.

Also,it looks like two of the wheel studs have been replaced and are short and not engaging enough threads in the nuts.

Clutch cable has no adjuster. Also, check that the baseplate (center of clutch) protrudes the brass bushing and gear cog…

Yes, I can see than now in the picture.

I loosened the clutch cover a little and tried kicking it, still nothing. Took the cover off and here is the pic along with the clutch inside. Hoping to avoid pulling the clutch back out again to check the brass bushing protrusion if possible.

Couldn't tell if I should try adjusting the clutch cable. Sounded like maybe that wasn't possible or at least wasn't likely??

As far as running before this, it would usually get going ok (I don't really have any reference points with other similar scooters, I assume that older vehicles will not start up right away and may take some coaxing). It definitely wasn't one kick and we're good. But when I got it running and stable, it would idle fine. It was always a little iffy as to whether it would stall once I put it into gear, but I could usually just get give enough juice to get going. On the road it would be fine for maybe 15-20 minutes and then it would increasingly want to stall at stops.

I'm pretty sure I cleaned all of the jets when I redid the carb although I know I didn't give it a sonic bath.

After the carb I read somewhere (and it was awhile ago so now my recounting is likely going to sound even more suspect) that sometimes, if the clutch isn't working well, that the delay can cause stalling.

The guy who teaches auto at the high school I work at suggested (based purely on my probably unhelpful description, he didn't look at it) I try putting foil around the fuel line to prevent it from heating up.

Presumably there are 4 springs in there but 3 appear to be missing what is up with that?

I replaced all of the springs that were in there with new ones. And the kit that came from Scooterwest only had that many springs so I think there is some variability.

Clutch needs to be rebuilt correctly (all 7 springs and caps)…

Interesting. When I pulled it out I remember being surprised those were missing, but since it had run ok and because the replacement kit didn't include enough springs (nor had any replacement cups) I figured it was one of those things where parts were used for different scooters and didn't need everything for every scooter. I'll see if I can get those extra parts and if it makes any difference.

Maybe place an order with scooter Mercato and start fresh on the clutch rebuild maybe even 'spring' for a complete new clutch or even upgrade. Could be the root cause and continuing issue. Also we can't see an adjuster barrel on the clutch cable there should be one on the casing where the housing terminates.

Sounds like the clutch is slipping due to insufficient spring pressure.

Is this the barrel you're asking about?

I'll start with putting in the remaining springs before doing the whole new clutch. I'm still not totally convinced it's even connected to my initial issue.

It should have one of these
https://www.scootermercato.com/Scooter-Parts/Cable-Bits/90527

Like this.

If you zoom in on the second picture, you'll see it's missing.

Definitely put all springs and cups in.

If you pull the clutch out and compress it with a large nut & bolt and washers, you should be able to spin the geared plate. As you undo the nut slowly you should get to a point where the geared plate friction becomes greater until you can't turn it at all. That at least proves the clutch in isolation is "working".

Ok. Parts are ordered. Will install and update. Thanks for all of the help.

New springs and cups have been installed. Same result. Nothing catching when I use the kick.
[url]https://youtu.be/hFfsBkiBic8[/img][/url]

Did you add the adjuster for the cable?

How are you tightening and setting the arm with the cable & pinch bolt?

if the cable is set too tight, it will compress the clutch, which disengages the primary gear stack & kickstart gear from the crankshaft.

Unhook the clutch cable completely, then kick it over and report back

Sorry for the delay, it's been rainy all week. I unclamped the clutch cable and tried again but nothing has changed.

Sometimes the cover will compress the clutch if the clutch isn't seated properly.

Does it kick over with the clutch cover off?

Have you checked the height of the baseplate?? If the cog sits taller than the baseplate, the engine won't turn over…

Take a picture of the clutch with enough of an angle that we can see the plate stack.

I don't see the top tabbed cork plate, so you're probably missing at least one plate, which would be enough to keep the clutch from properly grabbing.

Responses in order:
> does not kick over with clutch cover off
> cogs are not above base plate
> This is the rebuild set I purchased (2 steel plates and 3 cork plates)
https://scooterwest.com/products/deluxe-clutch-overhaul-kit-w-specialty-tools-for-125-150cc-6-spring-type

Thinking on this some more, I'm 95% certain that your bike was one of the container bikes that Scooterworks imported from Pakistan back in the early 2000's and then sold into the Chicago market. I lived and rode in Chicago for 25 years (and still have the Stella that I bought new from ScooterWorks).

Anyways...yours is one of the colors those bikes were painted, you're in Chicago, and it has an LML motor in it (LML fuel line guide on the cylinder shroud, LML CDI mounted to the frame). Weirdly also a Piaggio clutch cover, but whatev's.

That's a Good Thing overall, but it means that some of the parts are not what you're expecting, starting with the fact that you have a 7-spring rather than six spring clutch.

So I'm pretty much certain (as certain as I can be from 600 miles away with some photos that don't quite show what I need to see ) that the cork plates in the rebuild kit you bought are too small and the tabs in the plates don't reach to tabs in the bell, so the force never gets transferred between the gearbox/kickstart and the crankshaft.

The tabs should be interlocking with the clutch bell and alternate with the steels, which engage the center cog.

It looks like Robot at ScooterWest did a video comparing six & seven spring along with Cosa clutches. I didn't watch it yet, but I assume he does a good job of explaining it all because his videos are generally top notch.

For comparison, even though their center cogs are the same size (and thus interchangeable-ish), here's a six spring clutch sitting inside a seven spring basket so you can see the size difference.

I hope that helps, and then we can dive into your stalling out issue, which is most likely something gummed up in your carb.

Don't forget the spacer.

In my experience, a missing spacer causes the clutch to bind up as the rivets on the center cog bottom out, so it fails the other way (locks up).

I totally thought about that though the first time I read through the thread, though, and it's an evergreen thing to remember

I think you might have nailed the issue. I'm so impressed with that pull! The replacement clutch plates I got were way smaller than the ones they were replacing. And as I was trying to put the old ones back I couldn't even get the last cork plate to fit. I have no idea how the last guy got it in there. You can see in the pic that the bottom tabs are in and how that causes a lot of space on the opposite side. So the basket appears to be slightly too big and the slots aren't perfectly aligned. Probably a lot of Frankensteining going on.
[/img]

Should I just buy a whole new basket? Can I keep the drive gear part (not sure of the right term)? Can I buy a smaller basket that will fit the plates I already purchased?

Should I get this? https://scooterwest.com/products/complete-clutch-21-tooth-vna2-vnb-1-3-vbb-vbc-vlb-early-1960-s-125-150?_pos=9&_sid=219118265&_ss=r

Bigger picture, could the fact that this top cork plate was somehow forced into the basket be the reason why the scooter was stalling?

Thanks again!

I'd love to get your feedback on my last post if you are able.

Oh, yeah. Sorry. I've been focused on my own project among other things.

Your best bet is going to be just buying the 7 spring plates and stick those in it. It'll be a better clutch and the hard part (breaking off the oil guide, which isn't actually hard at all) is already done.

So rather than spending $200 on an inferior clutch, you can spend $40 (including shipping) for some new 7 spring corks, assuming you have 7 spring steels. If you don't, the only place I could find corks+steels was going all the way to Germany. (fuckin' tariffs are killing domestic inventories/suppliers).

Oh, and while you're at it, you should ditch the castle nut and get a modern flanged nut.

I appreciate the reply and apologize for seeking further clarification as I'm trying to learn the terminology and make sure I get the right things. You say 7 spring corks and 7 spring steels. The old plates? of steel and cork are the 108mm diameter ones and there only 5 of them, 3 cork and 2 steel. I see that there are kits with 7 plates of 4 cork and 3 steel, is that where the 7 is coming from? My current set was only 5 and the set recommended to me by scooterwest (bc they thought I had a different clutch) was only 5, so I'm nervous about getting a different number of plates.

Currently I can't get the last plate to fit inside the basket so I worry that the basket may be warped and wonder if getting new plates would actually solve the issue. The basket accepts 7 springs if those are the spring steels you are talking about. I found this set that appears to match the one you found at SIP. But again, both are only 5 plates, not 7.

Review:
Will the plate set I sent work?
Should I get a new basket?

Thanks for the tip on the flange nut, didn't even know that was an option, but much preferred. Does that mean I can stop using that stupid lock tab washer? That's for sure the most annoying part about getting the clutch on and off.

Again, tremendous amounts of gratitude!