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Cog gear
https://forums.ducatipaso.org/viewtopic.php?f=3&t=8336
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Author:  Simon1068 [ Wed Oct 14, 2020 12:59 am ]
Post subject:  Cog gear

I have replaced the sprag gear .bike started and ran ,for a little while ,then same problem again , would not start ,turns out cog gear is issue , removed and cleaned sanded with 1200 and replaced, now it will start , my question is how do I replace shaft that the cog gear is on ? , does it come out ? Any advice is welcome and greatly appreciated

Author:  Derek [ Wed Oct 14, 2020 10:17 am ]
Post subject:  Re: Cog gear

I presume you mean the starter intermediate gear? As far as I know the shaft is an interference fit into the crankcase half although I can't find any reference to replacing it in any Ducati workshop manual. Short of dismantling the engine you should be able to use a length of tube and suitable washers with a screw into the shaft to pull it out. You'd be best to heat the crankcase it the area of the shaft with a heat gun before pulling it .

Author:  angelix [ Wed Oct 14, 2020 10:58 am ]
Post subject:  Re: Cog gear

on the spare parts catalogue the gear is held with a circlip and the gear pin is bolted to the crankcase trough a long allen bolt.

my guess is that the pin is fitted with a slight interferance, and the bolt does the holding.

Author:  Derek [ Thu Oct 15, 2020 9:11 am ]
Post subject:  Re: Cog gear

angelix wrote:
on the spare parts catalogue the gear is held with a circlip and the gear pin is bolted to the crankcase trough a long allen bolt.

my guess is that the pin is fitted with a slight interferance, and the bolt does the holding.

Ah. That makes sense and explains the length of the bolt.

Author:  higgy [ Thu Oct 15, 2020 3:19 pm ]
Post subject:  Re: Cog gear

Sprag has to be the most troublesome part of these engines. I keep a supply of new springs and end up replacing them every other year. I have replaced the idle gear and shaft when experimenting with readily available springs I ended up welding the idle to the shaft during this trail. Yes the shaft is removable.In the end I found a guy in England sells the proper spring. I have also tried other types of sprags with no luck so far. Recently a new updated spag has become available From a source in Italy and I have one to try as once again it is slipping

Author:  Mc tool [ Fri Oct 16, 2020 6:23 am ]
Post subject:  Re: Cog gear

Hi Higgy , do you think the sprag failures maybe oil type related. When I was still riding my Paso ( been near 15 years now ) I did about 60k kms on it and never had a sprag problem , did make some awful noises if it backfired when starting tho . I used valvoline xld oil . Just thinkin :-)

Author:  higgy [ Fri Oct 16, 2020 3:34 pm ]
Post subject:  Re: Cog gear

I think it is heat that sacks the spring so yes oil would have its part to play. Dont know if the st type oil slinger would help

Author:  Mc tool [ Fri Oct 16, 2020 8:58 pm ]
Post subject:  Re: Cog gear

I had a sprag "reverse" itself in an auto trans on my car (ZF 4hp22 ),pain in the arse as car wouldnt move off in drive , had to put it in L to move off then shift to D and then all was normal till next time I stopped .

Author:  du907 [ Fri Nov 06, 2020 4:35 pm ]
Post subject:  Re: Cog gear

higgy,
Surprised you have had to put so many sprag clutches in.
When I bought mine in 1992 it had 3,000 miles on it. I brought it home on a trailer, changed the oil and filter, wash and polished it, ready to ride. Push the starter button and the starter spun but didn't engage. Damn, brand new bike and I was ready to ride. I figure with new oil, everything was just more slippery. After research, took the side cover off and inspected the sprag clutch and spring was stretched and the blocks showed some flatting. Put a new sprag clutch in and it started fine. After 60,000 miles I am still on the same sprag clutch!
Seems the quartz clock takes a lot of electrical power. Most bikes would sit waiting for that weekend ride. You go to start the bike and the battery is low and this wears on the sprag clutch. It seems it doesn't get that full kick to engage as it does with a fully charged battery. After time and multiple "weak" starts it wears the sprag clutch. Some would use rubber washers and remount the clock to disable it keeping it from running the battery down.
I installed the Hicap battery cable kit and wow. The bike starts in their guaranteed one revolution. Really, what a difference, and my engine has been rebuilt, balanced, blueprinted,ported, the works and it takes more to spin it.
Just thought I would share this.
du907

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