Modern Vespa

Went to take Little Red (1974 Primavera) for a jaunt and the kickstart's not spinning the engine. Goes up and down fine, just feels like the clutch is disengaged. Don't think it's the clutch though, because when it's in gear, squeezing the clutch lever disengages the clutch and lets the wheel spin freely.

Any guesses/suggestions before I pull the engine?

Thx.

Sounds like slipping clutch…

Worn plates or soft spring (spring has lost its tension)…

Possibly a Gummed up starter gear. It rests in the disengaged position. Coil spring for starter gear is not strong enough to push it to engage the xmas tree.

Try bump start it in second gear and ride it around and get it to operating temperature. That will free it up most times. Then change the oil.

If you can bump start it, the clutch is fine.

Worst case scenario, starter gear spring (not quadrant) broke and you will have to split cases to remedy that.

I'm going for a Hail Mary here and saying broken clutch woodruff key on the Christmas tree.

I like Poi's suggestion.

Assuming it can be bump-started, that confirms the drivetrain is okay. That means no sheared woodruff keys or any of those nightmares.

I'm going to assume that it was running last time you put it away, so something is just stuck. Getting it running so the gummed up bits can work themselves loose is probably the best next step here.

After that? I'd take a look at the clutch for stickiness. Splitting the cases would be my last step.

We have a winner.

I liked poi dog's suggestion too. Tried to bump start it, got halfway down the block and had no clutch at all.

Pulled the clutch and found the key sheared. Clutch was hanging on by the taper and a not-so-tight nut.

Little Red puts out a little extra HP since the o tune, so good time to upgrade the clutch.

Thx all.

Glad you have it diagnosed 😀.

Son of bitch, shit! Love it when a plan comes together! Love that scoot. I'm dreaming of a Primavera 125 or a Ray8 100 smallie some day. You'll be back on the road lickidy split.

Glad you got it figured out without having to split the cases! Whew!

FYI. Smallie stock or stock-type clutch is held in place by the taper of the Xmas tree, more so than the woodruff key. Some of the higher end clutches do not even have a woodruff key. Make sure that clutch nut is torqued on good and tight, and use some loctite if not using the bend washer. Lapping compound will get you an awesome fit much like people do on the flywheel taper.

+1, it's the taper that does the heavy lifting, there's no need for a key to 'clock' the clutch like with your flywheel. I leave the key out on the clutch, I think they can do more harm than good, and I wish I could get plastic or brass flywheel keys.

What Poidog said.

I was going to say that last night, but I was on my phone and that's waaay too much phone typing for me.

Thx Mark! Yep taper's what holds it.

Which makes me wonder why smallies even have a key for the clutch.

I have a short 4th DRT tree in there, with a wavy washer & nut. It held fine in the past. Probably just didn't torque it enough after the rebuild.

The clutch half moon key is there to prevent slipping whilst torquing the nut until the tapered surfaces lock. Tapered joints need to be clean, dry, and burr free. Lapping is actually detrimental to a proper fitting taper, it prevents the proper wedge fit. Lapping and luck go hand in hand.

I understand "doing what you gotta do".

On the motor I'm having built (Malossi 136) using this clutch.
https://www.sip-scootershop.com/en/product/clutch-egig-performance-sport-one-finger-clutch_93499910
The fellow that is assembling has them in both of his smallies.

The egig one-finger is great up to the mid-20's HP. Past that, you just gotta suffer.

but if you don't already have one, the Crimaz PK XL-2 cover makes a HUGE difference.

Using these I saw on SLUK YouTube channel

?si=mvOPAIbow2JO-16M

Got them thru Adie Horrocks from the UK.

Can't keep myself from buying trick looking things.
A holdover from my 60's SoCal hot rodder background.

That FRT looks identical to the Crimaz. I'd buy whichever was cheaper.

Extremely random question …

Does anyone know the thread pitch on the DRT tree? It came with its own 11MM nut and wavy washer. It's beefier than the stock tree.

11MM x 1.00? 11MM x 1.25?

I *may have* bonked the threads and would prefer not to ship one nut from Germany.

Thx.

I don't have a DRT tree, but do you have a thread gauge? Might be able to suss it out from there.

Looking at the pics on SIP, I want to say that's a 1.0 pitch.

The description for the nut itself says Fine Pitch, so I'd guess M11x1.0

I have a broken DRT tree. You can have the nut if you like.

That's very kind of you. Pm sent!

Split time.

gmontag was kind enough to send a new/used clutch nut. No go.

And just to be sure, I bought a new one.
Nope.

Threads on the "super extra heavy duty" DRT tree are bonked.

~ sigh ~

how borked? think you can cheat it with a thread file or a chase (split) die?

fingers crossed for you amigo

Have you tried to chase it with an M11x1.0 thread die?

Don't have that die, it's a bit of an oddball. I may be able to clean it up with a thread file, but there's no room while it's in the engine.

Dunno about delivery times out by you, but I could get one from Uncle Jeff by Thursday.

I was thinking this one, for use in situ

That should also work.

f'in you're looking to do it in situ and you have the room, gets ya a split die. that way you're not technically cutting new threads but chasing back the bad threads.

I just looked at my chase 'em back kit and it only has 11X1.5 otherwise it woulda been in the mail to you!

Thx g, you're right, split die's the call.

The more I look at it, the more I think it's gonna have to come apart. If I didn't have so much pesky real work to do it'd be done by now.

I may be talking to myself at this point, but in case anyone's following along, re-threading the tree actually worked! Got a new nut on and clutch is torqued down extra tight. Engine's kicking over nicely.

Cheers fellas & thx.

Awesome to hear!

Did you end up using a split die from the bottom or just cutting down with a regular die?

I ordered this before greasy recommended the split die. It got the job done.

I assumed from the very first post, that this was Chandler's fault.
Decided to bite my tongue

The one time I'm totally innocent, I still get blamed. Lucky for me I'm used to it.

Saint Chandler, Patron Saint of Chingered and otherwise Kersploded Engine Gubbins.

The miracle for which I obtained sainthood is that one time, all of my bikes were running at once.

Great to hear this. I was expecting a tale of woe and heart ache.

Haha, I'm kind of surprised myself. Hardest part was was finding a way to keep the tree from spinning. Ended up clamping a vice grip on the axle and wedging it between the brake plate studs. Should've taken a picture.