Flywheel problem?

[Dmitry]

Hi! I have a question: I changed the starter on my M900 (1997 year) and when I removed spark plugs and checked it I noticed that flywheel on the crankshaft turns unevenly like a figure eight. What does it mean? May be it is normal or defect of Ducati? Motorcycle feels himself great rides perfectly nothing hurts. Сrooked crankshaft or flywheel and it is possible? How it can affect on engine?

[koko64]

Sorry, Im not sure I understand what you mean.

[Dmitry]

http://ipic.su/img/img7/fs/Snimok.1437806993.jpg
Flywheel on the photo turning in the form of figure eight i.e. unevenly.

[koko64]

It should spin straight and true. Maybe the sprag bearing set up. Did you remove the flywheel? I would check it for sure.

[koko64]

I've only changed starters on two Ducatis, both hi comp 944s. The sprag bearing was failing on one of them. A Triumph America 850 had the sprag bearing (similar style) completely collapse and throw metal through the primary case. It is worth checking thoroughly so this doesnt happen later on. Is the crank moving or just the flywheel wobbling? Hopefully only the flywheel is wobbling.
Check the gears there. Did you match the starter gear on the new starter motor by transfering the small gear/cog off the old starter?

[Dmitry]

I can not say the crank moving or just the flywheel wobbling because I had already assembled a motorcycle But sprag bearing I watched one month ago - sprag bearing is OK. Now I need a motorcycle. I want to repair it again after two month because it will be winter in my country also I change valve guides valve stem seals and other. I hope that after two month nothing happens. Thank you. I will follow your advice. I think that I will ask you again about this problem. Interestingly: why engine is working? Why rotor not touches generator if rotor turning in the form of figure eight I think there are only two versions: working or not.

[ducpainter]

<snip> Interestingly: why engine is working? Why rotor not touches generator if rotor turning in the form of figure eight I think there are only two versions: working or not.

Good questions.

You'll figure it out when you pull the cover.

[Dmitry]

I did not notice problems. I pulled the cover repeatedly.

[ducpainter]

I did not notice problems. I pulled the cover repeatedly.

Then either you're missing something...

or what you're seeing is an illusion and there's no problem.

[koko64]

Maybe the flywheel ignition pick ups cause an illusion because they protrude from the spinning flywheel. 
I hope that is all it is, and maybe some . 

[Dmitry]

I will look again on it in October and tell more about it. Maybe it is true that ignition pick ups cause an illusion Thanks for answers

[He Man]

if your flywheel was unbalanced to the point where you could see it, you would have pretty bad vibrations in the handle bar. the bike would feel like it wants to jump up and down and tear itself apart.

[Dmitry]

if your flywheel was unbalanced to the point where you could see it, you would have pretty bad vibrations in the handle bar. the bike would feel like it wants to jump up and down and tear itself apart.

At any or only high speed?

[He Man]

more pronounced at high speeds since its spinning faster.