I FOUND THE PROBLEM!!!

And... It is something very stupid 

Look here, this is the freewheel mechanism as it appears from the engine fiches:


The starter engine is meshed with the small gear where there is number 1 call-out. The screws number 7 are tightened on the flywheel, and block the starter-clutch to it.

Well, I never dealt with freewheel devices, since until now I've ever had to deal with normal starter engine, like the ones used in the cars, but looking at it something appeared wrong: the big gear was free to move respect to the crankshaft, but the clutch (the one with parts 4-5-6 inside) was free to move too... So how could it transfer the force to the crankshaft?

Since I don't have the proper tool to remove the flywheel, I had to use a rubber hammer and a piece of wood, and after 10/15 hits, the flywheel went away... And this is what I found below:




Plus this, that was fixed in place by the magnetic force (I felt it moving while I was cleaning the part):



Now I know what the owner heard: the tinkling of the 1st and after some time 2nd broken screw!
And when the engine got stuck, it was the 3rd screw that went to "Oh my godness" and the friction sound was provoked by the broken screws that were digging into the flywheel 

GOOD! This engine will run again soon 

Quote from: GenTLe on December 24, 2008, 09:29:22 AM
I FOUND THE PROBLEM!!!

WHAT THE **** ARE YOU TRYING TO KILL ME?!? TELL US!

Quote from: tussey on December 24, 2008, 09:40:19 AM
WHAT THE **** ARE YOU TRYING TO KILL ME?!? TELL US!

LOL 
It was a fake post, now I fixed it

Amazing pictures as usual. I'm glad you found the problem! Keep us posted on the reassembly process.

Very thorough - great stuff! 

How in the world did the starter clutch and magnet manage to SHEAR 3 BOLTS!

That must have made a god awefull noise.

This is great.  Thank you thank you thank you for the pictures!

Interesting failure.

What does the inside of the sprag clutch look like?

Quote from: GeeP on December 24, 2008, 10:20:50 PM
What does the inside of the sprag clutch look like?

It's perfect: only the big gear has some scratch 

How is the starter?

Something must have suddenly stopped moving for the bolts to shear.

Could have been a backfire on starting.

GenTLe,  under what circumstances did the engine fail?

Many a  motor has been unnessesarily cracked open when it needed a valve adjustment, a cam chain fix or just plain cam shaft side drift whioch needs to be ignored.
A ban lower end, should be ridden till it locks up. A bad upper end presenting itself as a lower end problem, will never lock up. That is a sure way to find out.
Cool.
Buddha.

Quote from: coll0412 on December 25, 2008, 01:15:29 PM
How is the starter?
Something must have suddenly stopped moving for the bolts to shear.

Quote from: GeeP on December 25, 2008, 02:22:04 PM
GenTLe,  under what circumstances did the engine fail?

The starter is OK. I tested it with the battery 
I don't know WHY this happened, but what I've seen examining the bolts is that:
- 1st one bolt being cut... The owner continued to use the bike starting to hear some strange little noise. The bolt head in fact is heavily worn.
- 2nd the 2nd bolt being cut... The owner continued to use the bike hearing some more little noise. That bolt head is worn but not like the 1st one.
- 3rd, the 3rd bolt being cut... The freewheel started to seize with flywheel and the engine died. Fortunately when the owner was stuck at traffic lights, so light damage happened.

Buddha, I didn't really understand what you wrote here... Did you mean that it's too easy to be happy when, thinking about a big damage, I found a light one? But that in the meantime I would not have had to open the engine for nothing?
Well, I'm not a professional mechanic, and for me this is an hobby, so I liked to do this job, also if it wasn't probably necessary. And most probably I learned something new too. And for me this is more than fine

Now, since I don't want to spend more than 200€ (280US$ !!!!!!) to change the flywheel (I didn't find it on used market), I worked with special epoxy glue to fix it.


I firstly removed all the unglued original resin, then, using a VERY STRONG neodymium magnet took from a broken hard disk, I removed ALL the metal sliver attached to the magnets,  afterwards I cleaned perfectly the surfaces with nitro thinner, then I applied the 2 component glue. I also applied a clamp to the detached magnet to firmly fix it to the rest of flywheel.
With freshly applied resin, I "cooked" the flywheel in my oven, 1 hour at 160°C (320°F), to better dry the resin and give it more strength, according to glue technical sheet.

I used some sand paper on it to better refinish the resin surface, applied some other resin and recooked it again. And that's the result  :








In the meantime I checked all the crankshaft and balance shaft bearing clearances, finding them in tolerance.
I used Plastigauge that I bought in UK (it seems it's impossible to find this stuff here in Italy...):



I also checked the shafts run-out, again it's perfect:

I bet all the bolts where loose and the starter sprag was moving back and forth when starting and the engine spinning up. This resulted in the starter clutch housing rotating back and forth smacking into the bolts over and over again.

Booya ... goats disguising itself as a stuck motor ... choke on that moron.
Diagnosis ... waaaaaaaaay more important than the actual repair.
Cool.
Buddha.

Quote from: The Buddha on December 27, 2008, 12:55:21 PM
Booya ... goats disguising itself as a stuck motor ... choke on that moron.
Diagnosis ... waaaaaaaaay more important than the actual repair.

Don't tell this to me, say this to those professional mechanicals that made the old owner to sell this bike for 400€ (he was going to throw it away to a scrapyard worker, I saved this bike), and that made me to open everything because their diagnosis were "broken/melted con-rod bearings" or "broken gears".
When I bought the bike, it was just blocked (from 5 months!) and I couldn't make any test before start to unmounting.

Dude you didn't have to split it. First you analyse it, then take make a theory and make a diagnosis and slowly follow your logical path.
I know easy for me to say, however I still say you dont split the cases if the bike is still running. Noise, yea prolly somehting else. Anyway you dont even have a bad case of goats. The magnet bits in the oil can get into the bearings. Yours ... nope ... cos you didn't have magnet shattering at all.
Cool.
Buddha.

Quote from: The Buddha on December 27, 2008, 04:39:46 PM
Dude you didn't have to split it. First you analyse it, then take make a theory and make a diagnosis and slowly follow your logical path.

But I couldn't!!! THE BIKE WAS BLOCKED when I got it!! No way to make the engine to move! I took it in that situation with 2 professional mechanic diagnosis!!
What I had to do? Try to turn it on? Impossible! The engine DIDN'T roll when I got it. Try to force it could bring the engine (in case of broken gears as said by Suzuki mechanics) to make it worse.
Unmount the rotor? Impossible without having the crankshaft in my hand! I don't have the Suzuki extractor!

Anyway, it was dirty, inside. Now I'm comfortably sure that it's perfect. And this is what I wanted.
This bike is for my girlfriend, I MUST feel safe to give her a perfect bike.

Take the left side off, which you did, then you remove the magnet which you did, and that point it didn't look boogered ? You didn't take the starter clutch housing off ? Now I would have ... if I even missed it there, by the tile I yanked the cylinders off and didn't see the rods burnt or really really wobbling in their journals I'd have started looking elsewhere, possibly starting with the magnet etc.
I'd never have split the bottom end which was rolling fine and not wobbling in the rod journals.
Cool.
Buddha.