Stellauto starter Bendix issue

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mr72
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Posts: 7
Joined: Tue Oct 12, 2021 2:13 pm

Stellauto starter Bendix issue

Post by mr72 »

Hey all, new guy here. I just got a basket case Stella automatic back on the road, and it's having an issue with the starter Bendix. When I first began diagnosing all that was wrong I found the Bendix was only intermittently engaging, and I found the bushings were extremely worn and the Bendix had some chipped teeth. So I replaced the bushings and put in a new Bendix, and for the last week it's been starting and running fine, until yesterday.

It's back to one of the original symptoms. Starter spins freely and doesn't engage the pulley. I suspected the battery may not have been absolutely full (it's a new battery) so I put it on the tender overnight, I bet it will start now, but it should work even if the battery isn't absolutely 100%. I'm going to go clean the connectors in the starter signal path in case that is related.

How do I fix this?

EDIT: a little background. This scooter has about 10,800 miles on it, and most of the starting electrical system was apart when I got it. Guessing it had a starting problem years ago when PO abandoned repair. It was last registered in 2018, looks like it sat outdoors most of its life. Lots of boat owners seem to have a similar problem and it seems to be if a new bendix doesn't fix it, the starter may be on the way out.
mr72
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Posts: 7
Joined: Tue Oct 12, 2021 2:13 pm

Re: Stellauto starter Bendix issue

Post by mr72 »

Well, never mind. I figured out the problem this morning.

Charging the battery didn't fix it. I took the variator cover off and discovered the bendix was still engaged into the drive pulley teeth. So it wasn't the bendix at all. I took it out, cleaned and lubed it anyway. And that's when I noticed two things, #1 metal filings inside the variator cover and #2 no splines on the outer pulley. Looks like the drive pulley has sheared its splines.

So the starter is doing its job but the pulley just spins on the crankshaft.

Q: Will a generic GY6 variator fit? Or do I have to get a LML part from India?
mr72
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Joined: Tue Oct 12, 2021 2:13 pm

Re: Stellauto starter Bendix issue

Post by mr72 »

In case anyone is following this...

I ordered a variator from an ebay seller in India, and it doesn't fit. The stock variator outer drive face is about 123mm diameter with 69 teeth, 14mm or so shaft diameter with 19 splines. The pulley they sent me had 76 teeth and was about 132mm diameter, would not even fit under the variator cover even if a bendix could be found to mate up.

SIP says they have the correct drive face "inbound" which I guess means on order, now over a month over due. They have whole variators in stock for astronomical prices. Actually both of these parts are very high priced, but when there is virtually zero supply, I guess they can ask whatever price the market will bear.

I am investigating whether an alternate part might work. A 50cc GY6 variator has only 62 teeth on the edge and is maybe 10mm smaller. Unlikely a bendix could be found that would "just fit". Machining would likely be required. There is a Piaggio / Vespa PX4 125 pulley that is the correct outside diameter and tooth count, but looks like it has an 18 spline drive and unlikely the correct shaft diameter anyway. They are expensive as well, but at least they are available in abundance. $60 for a drive face pulley is fine, if it works. $200 for a whole variator just to get the drive face pulley from it is a bit steep, but might be my only choice.

A 125cc GY6 type variator won't work because there are no teeth on the outer pulley to engage the starter. However, man they are cheap. If I could get along with kick-start only, this might be a worthwhile thing to try just to get the scooter on the road.
tev
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Location: oakland, ca

Re: Stellauto starter Bendix issue

Post by tev »

:shock: ha! i am TOTALLY following this. thanks for all the updates. it’s a good story to follow and i appreciate that you keep the thread going.
stella 4t & a p200e
mr72
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Posts: 7
Joined: Tue Oct 12, 2021 2:13 pm

Re: Stellauto starter Bendix issue

Post by mr72 »

Since this is mostly a one-sided conversation, I'm not saying much on this forum.

But quick update: yes, there are no parts available on earth. The JCOSTA "complete variator" which is avialable at SIP, Tasso and others, does not include the outer drive face. Nobody has a '13-14 LML Star variator in stock, and the outer drive face is "inbound" at Tasso and SIP but is over two months overdue. I am not holding out hope.

I did attempt to drill holes in the kickstart drive pulley to try and pin it using roll pins to the drive face. The kickstart drive pulley seems to be hardened steel. My cobalt drills won't touch it. So I could keep this effort going if I want to buy some carbide drills.

My current thinking is maybe I could use some industrial bonding adhesive like a specialty epoxy or even red Loctite to fix the kickstart washer to the drive face, along with the bolt clamping force, maybe it will work as a stop-gap. Some epoxies have a shear rating of 3K-5K psi, which should be more than enough, as long as some kind of transient impact/force doesn't knock it free.

In the long run, I need a new outer drive face, and a way to replace it. I figure once I get the rest of the scooter sorted and determine if I am going to be using it regularly, I'll come up with something. That something may be to have a spline/shaft adapter made so I can use a Aprilia pulley on it.
mr72
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Posts: 7
Joined: Tue Oct 12, 2021 2:13 pm

Re: Stellauto starter Bendix issue

Post by mr72 »

Well, I did succeed in pinning together the kickstart drive plate and the old stripped pulley. I first glued them with Loctite Metal & Concrete epoxy, then drilled with a carbide bit and pinned them with 3/32" roll pins. The good news? This actually works, and works well. I also discovered that there was a part missing all along, a spacer that fits under the pulley, which is likely why the thing self destructed anyway. It made it impossible to get the pulley tight because the lock nut bottoms out before the pulley is tight. I added a 1.2mm thick washer in there and also added an extra 1.2mm washer between the bendix and the crankcase in hopes this will make the bendix align correctly.

Bad news though, it doesn't reliably start. It seems to be a confluence of issues, chief among them is wear on the pulley ring gear so the bendix won't consistently engage. It often bounces off the back of the pulley before engaging the teeth. It will only engage when the battery is absolutely 100% topped off, like coming fresh off the trickle charger. It seems like if the battery is not 100%, like if you start it, ride it, then stop and try to restart, then the bendix doesn't have enough force to get all the way into the gear. And if it does when the battery is not 100%, then the starter doesn't actually have enough oomph to turn the engine over a lot of the time.

So I am going to do a couple of things to try to sort this. #1 is, find the least worn part of the pulley's starter teeth and align that spot with the bendix. #2, remove the spacer and put another spacer on the outside of the pulley so it pushes the pulley closer to the bendix. And #3, take apart all of the electrical connections and clean and rebuild them so hopefully the starter will work better and maybe even the battery will charge better. Truth is, it seems like this battery is just barely big enough for this scooter.

In the long run, I have to source a new pulley. I have ideas on how to get a pre-leader ET4 Piaggio pulley to work. I will probably order one from Aliexpress and see if I can get it to work once it's here.

While I'm at it, any of you have experience with changing the weights for sliders in the Stellauto variator? It has 9g weights in it stock, and mine seems to be very quick off the line but wants to max out at just a hair over 40 mph. I think it's got more than enough power to run with heavier weights and maybe get up over 50mph... My wife's Vino 125 with 12g sliders easily runs indicated 55mph and feels like it has less power. I am thinking of switching to 10g sliders. Any reason not to? Or what's the ideal? I need it to have enough low-end acceleration to drive two adults, which the Vino really doesn't, and enough top end to get over 50mph in routine use.
mr72
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Posts: 7
Joined: Tue Oct 12, 2021 2:13 pm

Re: Stellauto starter Bendix issue

Post by mr72 »

So. Nobody cares about this topic, but I'm going to post a final result here.

The dodgy scooter is finished as a project for me. Basically, it's in a state now where it will start every time if you are willing to use a combination of kickstarting and electric start to ensure the starter ring gear is lined up so it'll catch. It's super difficult to kickstart if it's cold, so e-start is required at least to get fuel into the carbs. When it's hot, you can kickstart it easily. Sucks that this is where it'll end up, because the whole scooter has some cool factor going on, it's in basically good shape and runs like a top. It would be good fun transport for somebody, if it could just get that one part changed. But it can't, and I don't care to reengineer it since nobody, including "Genuine" Scooter co, cares.

I am going to pick up a new-old-stock 2014 Stella Auto this weekend, it's only got 8 original miles on it; it's been parked for 7+ years. I'll get the new one running and then eventually let the old one become someone else's problem. I'm going to rebadge the new one, mostly because I really don't think Genuine deserves any credit for a good running Stella automatic. 99.99% of people will see "Vespa" and never know the difference, won't even ask. That 0.01% who do know the difference will understand. It's a bit like a magic time capsule. It's a Vespa PX with updated engine, modern transmission, better brakes, but still 99% of the charm and feel of an old one. But it's brand new. It's like a factory built restomod.

Really a crappy move for Genuine to abandon the Stella auto owners like this. I get that they were in the business of importing a rebranded LML scooter, and that necessarily tied their fate to that of LML. But leaving the owners out to dry with no ability to maintain or repair their scooters was plain old bad business.
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