ET4 starter goes Clunk (not click, not whine, not crank)
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Member
ET4 150cc 2002
Joined: 13 Sep 2020
Posts: 5
Location: US
Sun Sep 13, 2020 12:27 pm quote
2002 ET4 150cc 3000 easy miles. Had been running fine. Went to start it the other day and it makes a single "clunk" when I press starter but will not turn over or crank the engine in the least bit. What I have done so far:
1. charged the 1 year old battery - no change
2. borrowed another battery from different bike - no change
3. jumped with car - no change
4. pulled relay - no luck finding another locally - 12v applied to primary and it definitely clicks like a good little relay should and it closes the secondary terminals - no change
5. removed starter, lightly buffed brushes and commutator with 600 weight sandpaper, cleaned and reassembled. BTW brushes looked good. - no change.
6. wiring looks good. no loose connections found.
7. started to get mad

I feel the starter is getting good juice because it makes a pretty good "clunk" every time I hit the button. It is almost as if the engine is seized and the starter just can't turn it but I know that is super low probability (ran fine, oil good, no previous signs of overheating). Unfortunately, I can't test this with the kick start because the return spring broke a couple years ago. I tried to connect a jumper between the positive battery terminal and the positive stud on the starter to rule out relay or upstream wiring issues but the sparks got in the way javascript:emoticon('')

Is it possible the relay closes but can't carry enough current, or maybe the starter runs but is for some reason suddenly too weak..... any suggestions appreciated!

Thanks, Dorydan
Moderaptor
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
Joined: 26 Aug 2007
Posts: 38979
Location: Pleasant Hill, CA
Sun Sep 13, 2020 1:18 pm quote
Open up the transmission case and ensure the engine can be turned by hand. If so, then double check the Bendix gear isn't jamming somehow on the flywheel.
Member
ET4 150cc 2002
Joined: 13 Sep 2020
Posts: 5
Location: US
Thu Sep 17, 2020 2:41 pm quote
Thanks for the advice Jim. I think this might be a case where hoofbeats actually do herald zebras!

i pulled the transmission case and pulled the variopah mechazini thing. Nothing jammed behind it. Very clever design. "Flywheel" teeth all fine. Pulled Bendix and it is also fine. Big Problem: put nut and large wrench back on end of crank and, only with great force, was able to turn it a few degrees while generating a nice metallic scraping sound.

Sooo, i am thinking next step is to take of the head and look for broken valve, piston ring, etc... Hard to believe that could be the problem as the bike has only ~3k well maintained miles was running fine and without any abnormal noise when i took it to work. Came out after work, pressed start button and CLUNK!

Any other recommendations welcome as i am not all that enthusiastic about digging into the cylinder. Also, Haynes vs genuine Vespa repair manual- is one clearly better?

Thanks!
Moderaptor
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
Joined: 26 Aug 2007
Posts: 38979
Location: Pleasant Hill, CA
Thu Sep 17, 2020 3:09 pm quote
Ouchy.

It's engine out time. It's less of a huge deal than you might think if you've not done it before. The engine will sit on the bench quite happily on the centre-stand and a small block of wood to persuade it not to topple over.

Manuals - all you really need to know are the torque wrench settings for the head bolts etc. There are several videos around showing how to dismantle if you're not willing to just dive in.

With your symptoms don't spend any money on parts until you've some idea if it's worth fixing. A broken crankshaft might indicate a replacement engine from a write-off might be the better bet.

There are a couple of pro-tips: hang a weight on the timing chain (zip-tie a wrench to it) so it doesn't fall inside and kink. Also, ensure the chain tensioner is fully set at 'slack' before re-fitting, otherwise you'll be waiting for a new one to arrive...

Good luck, it sounds as if you're capable of tackling this.


Do NOT start the engine without the variator installed.
Sergeant at Arms
Weird 80's Vespas & Cool Vintage Lambrettas
Joined: 21 Oct 2005
Posts: 8019
Location: The state of insanity, SoCal
Thu Sep 17, 2020 3:26 pm quote
Before pulling the engine and tearing down, check the flywheel side for debris. Occasionally something will get sucked in or dropped and gum up the works.

Worth a shot before a complete test down.

Btw, hows the oil look? Is the prefilter full of trash?

Good luck!

-g
Moderaptor
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
Joined: 26 Aug 2007
Posts: 38979
Location: Pleasant Hill, CA
Thu Sep 17, 2020 3:28 pm quote
^^^^ Very good points! It could just be a stator magnet has exploded, or something else that side.

So keep digging.
Sergeant at Arms
Weird 80's Vespas & Cool Vintage Lambrettas
Joined: 21 Oct 2005
Posts: 8019
Location: The state of insanity, SoCal
Thu Sep 17, 2020 3:35 pm quote
jimc wrote:
^^^^ Very good points! It could just be a stator magnet has exploded, or something else that side.

So keep digging.
Itís a remote possibility, but as long as weíre throwing out WAG I figured might as well toss one that Iíve seen

Iíd also pull the valve cover and just have a quick look see. Thatíll tell you loads what youíre up against because you can see and inspect the valves, cam, chain.

Yank the plug and see if itís covered in metal or melted. Then go from
There.

-g
Member
ET4 150cc 2002
Joined: 13 Sep 2020
Posts: 5
Location: US
Fri Sep 18, 2020 2:47 am quote
Thanks for the encouragement and advice guys. sounds like you are as curious as i so i'll keep you posted. pretty busy so it will probably be a couple weeks...
Member
ET4 150cc 2002
Joined: 13 Sep 2020
Posts: 5
Location: US
Sat Oct 17, 2020 1:32 pm quote
My Sea Turtle swims again!

Guys, you nailed it. I got the tool to pull the "flywheel" (I call these things rotors but whatever) and take a look at what I found. I can't believe I didn't hear anything! Put the new rotor and stator in and, since the other side open, I put in some new rollers and a new belt. Purrs like a kitten.

I was going to use the variator tool to hold everything quiet while a torqued the flywheel nut but then I wondered if the crank would like that. Instead, I fashioned this tool from 1/8 scrap aluminum and it worked really well. It butts up against the muffler bracket when the nut is tightened so I could concentrate on the torque wrench.

stator.JPG

rotor.JPG

flywheel tool 2.JPG

flywheel tool.JPG

Member
ET4 150cc 2002
Joined: 13 Sep 2020
Posts: 5
Location: US
Sat Oct 17, 2020 1:38 pm quote
Had one part left over after the repair- anybody know what it is? its black plastic and oily.

mystery part.JPG

Hooked
2005 ET4 150
Joined: 04 Jun 2013
Posts: 403
Location: Portland OR
Sat Oct 17, 2020 4:29 pm quote
Looks like a dust cover/plug
Addicted
GTS 250ie Super, Italjet Velocifero, Scarabeo 150, S50,ET4
Joined: 22 Nov 2016
Posts: 516
Location: Winston-Salem, NC
Sun Oct 18, 2020 6:20 am quote
That stator looks pretty bad. I had a scoot that did that, it was the crank that had gone bad and caused it to destroy the stator. If the crank is running true it shouldn't do that. I'd make sure the crank is alright before you destroy more.
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Granturismo 218
Joined: 04 Feb 2013
Posts: 6356
Location: NWAOK
Thu Oct 22, 2020 1:07 pm quote
The first time I pulled a Vespa top end was because the flywheel had come apart. If you've worked on anything else, you don't think about this, because it's something you've never seen or heard of. But just about every time a Leader engine locks up, this is what I check first.
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