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Sprag clutch failures

Posted: Sun May 30, 2004 1:31 am
by duck-a-tye

can anyone help with common reasons (things to look for) for the starter sprag clutch failing (free wheeling) in a MHR Mille cause i'm on my third!


Posted: Tue Sep 07, 2004 11:07 pm
by Peter Mille
Hey Duck,

Don't have an answer to your problem, but:
The Suzuki GS400, GS425, GS450 and GS500 twins all use the
same Nippon Denso starter like the Ducati Mille!
Makes it a little easier to find replacements, right?
Good luck! :-D

Posted: Sat Jun 02, 2007 11:07 pm
by Desmor
What oil are you using? maybe fully synthetic would help?

Posted: Sat Jun 02, 2007 11:40 pm
by Vince
There is an uprated one avalable from the central coast,Gosford,
Made by Howdi Ingeneering,there is one for a Laverda on ebay at the moment,very strongly made.

Posted: Sun Jun 03, 2007 12:19 am
by Peter Mille
This was asked in 2004.......!!

Posted: Sun Jun 03, 2007 12:57 am
by Vince
Bit on the slow side,probably got grandkids now.

Posted: Fri Oct 19, 2007 11:06 pm
by duck-a-tye
Hi Guys

yes I posted this question back in 2004, but that's fine, I'm happy to get any advice/suggestions even if they take a while......... :-)


Posted: Sat Oct 20, 2007 12:58 am
by Peter Mille
OK, so what's the situation right now with your starter (problems)?
Never had any with the one on my Mille, though....!
A realy good battery is very important on a Mille!!

Posted: Sat Oct 20, 2007 4:38 pm
by duck-a-tye
I hate to admit it, but it hasn't run since 2005! I stripped it down to repaint the frame and tidy up the motor, and just then the missus decided she wanted two more rooms on the house!!!!!

This years just about finished, but hopefully 2008 will see some work being done on it.

Lucky I've got the 750 sport for the times when I'm let of the leash


Posted: Sun Oct 21, 2007 11:34 am
by Peter Mille
After endless starting problems with my Mille, and having this discussed on a Dutch Bevel forum, I found a sollution.
Varta LF 518902026 battery
12V 18Ah and......260A cold crancking power!!!!
This battery is actualy a little smaller than original, so the hold down strap will not fit, you have to make a shorter one yourself.
The battery, USA made, is actualy made for certain Harley models....!
Now I have the power to start the engine time after time, even if it doesn't fire right up!

Posted: Mon Oct 22, 2007 12:31 am
by BevHevSteve
the SVR20 battery I sell has 300 CCAs - and it is a sealed AGM battery which means NO SPILLS and NO MAINTENANCE.

You typically screw up the starter sprag when your engine is not in tune - it backfires while you are turning the starter and your sprag bearing is toast.

The answer is to rebuild your carbiew at least every 2 years with new seal kits etc, and, pay close attention to carb sync

Posted: Mon Oct 22, 2007 2:22 am
by duck-a-tye
Thanks Peter and Steve

When the time comes I will get one of these batteries, I remember that the starter would literally groan when the piston came onto compression, and then she would thunder into life (usually) a truly glorious sound. (thanks to the 2-1 exhaust) I can't remember any back fires tho'.

This is still the best duke site, keep up the good work guys!!


Posted: Thu Dec 24, 2009 12:19 am
by scott
I know its acouple of years since last message so I presume you still have the same problem. Me too. Ive lost count how many starter clutches Ive been through.
The clutch is simply not up to the job of turning over the motor with a starter motor half the size of my old darmah to drive it. I have had my starter motor done up and considering getting a four brush one built. Expensive but may provide the solution.
I have also had my cam timing (advanced I seem to remember, several years ago now) not ignition timing! to take load off the starter clutch as much as possible.
Plus I had the howdy sprag fitted, Now after it was in I was told it is not the one he builds because they dont fit the mille, but apparently it is out of a pontiac gearbox??? dont ask.
Anyway after the engine came back I unpacked it to find grit in the exhaust manifold, so being over cautious and checking inside the the cylinder for the mysterious grit, i upset the bevel timing. So there it has sat for a couple of years but I'm getting keen to get up and running.
So basically thats my story any help on the topic would be greatly appreciated.
If the suzuki 450, 500 have the same sprag then it just goes to show how much underdone Ducati engineered this one for a reasonably higher compression motor. Not forgetting this was the end of the line for Ducati before the bail out and so no improvements were forthcoming.
A pity seeing the rest is an awesome package.