Peculiar flywheel assembly alignment - Ducati.ms

MassimoVSR · May 24th, 2009, 11:20 pm

The shifter on my 2001 Monster 750 had stopped returning from down shifts. So after replacing both springs, I put the flywheel back on.

Now, according to the Haynes manual there should be only one way for the flywheel to fit back in, I found myself to be the exception to the rule. I had put on the flywheel, aligned the timing, set the air gap, done everything properly, but the bike would not start. I had checked and double checked everything, voltage, gas, spark: it had to be the timing. I felt like an idiot when I realized I wasn't sure I had properly aligned the flywheel with the main drive.

My alternator has the coils bolted to the cover, with the flywheel spinning around them. Pictures on both the Haynes manual and the Ducati service manual show the exact opposite. According to both manuals, the alternator should go on ONLY one way. Well, there's only one right way for it to go on if I want the engine to run. In my case there's about 20 wrong ways to put the flywheel back on, though.

I figured I needed to find the dot on the inside of the flywheel and aligned it with the groove on the drive shaft (the single one right before the threads, not the two ones on the tip), as shown in the attached thumbnail. Put everything back together, timing, spacing, covers on, oil in, starter, vroom. The engine came back to life, and I felt relieved.

Main lesson learned: pay much much much more attention to where parts go, and in which position, when I take things apart. And also set aside plenty of time for a job, I was rushing things to go to a barbecue with friends. The bike wasn't running until 10pm. Enough said.

"Ever tried? Ever failed? No matter. Try again. Fail again. Fail better."
( Samuel Beckett )

Stick · May 26th, 2009, 2:29 pm

Sounds like the Haynes sescription and photos were from the earlier, single-phase alternators. On the older ones, the rotating magnet (rotor) was solid, and the stator coils and laminated stator core were on the outside of this solid rotor.

Too bad they didn't update their photos. I assume your Haynes claimed it covered 2001?

sebastian750 · May 26th, 2009, 6:53 pm

what did you do about tightening that nut back on the dealer i spoke to said it required a special tool and it is torqued to 162 ft lbs?

thanks

MassimoVSR · May 26th, 2009, 10:19 pm

I specifically bought the *updated* version of the manual, I can't compare it to the '91 - '95 manual, but it seems a somewhat lazy job. I have a 748 and its Haynes manual seems better written and with more photos. I read it for reference when I was stuck and it helped!

As for the nut it requres a 30mm bolt deep enough to fit over the end of the shaft. I managed with a 32mm with part of the breaker bar sticking out. I wouldn't recommend it to anyone, since it slipped once and I have a nice gash on one of my nuckles.

For the torque I used the highly scientific method of putting as much strength as possible, since I don't have a wrench that measures that much. Next time I do an oil change, I plan to take the engine cover off and check that the nut is firmly on.

sebastian750 · May 27th, 2009, 3:14 pm

i cant find a wrench to go that much either so i went with a similar method using a 3/4 in drive wrench i put as much as i had onto it which i hope got me close.