Ducati help needed...

[Fly]

I posted this on a www.ducati.ms but no answers yet. Any help would be welcome. I'm planning on replacing the 15 tooth front with a 14.

"My ST3 has one large (22 or 24mm i'm guessing) bolt holding the front sprocket on the spline.

Questions:

1. is this bolt a regular thread or "left handed"?
2. torque spec?
3. any tips or tricks here...I'm assuming I'll need to engage the rear brake to keep the engine from turning over.

Thanks."

[Arby]

Fly

So, no new dual sport or super moto after all, huh?

My nephew made that change on his 749, I'll email him and see if he remembers.

[BobFV1]

Can't help with the torque setting. You will be popping wheelies! You probably know this, but the advantage of going down a tooth on the front is that you probably don't have to change the length of the chain, but that little sprocket will wear out relatively quickly. And alternative would be to go up three in the rear, but that would require some chain work.

May we see a pic of the Duc please - I am sufferring from withdrawl.

[DarthRider]

Going down on the countershaft sprocket will also wear the chain faster as the smaller sprocket is pulling & stressing fewer teeth at any given time.
And you can make "finer" adjustments to gear ratios with drive sprocket changes.

Dave

[DJ Down Under]

Fly...a mate of mine has replaced his 15 front with a 14 on his Duke...no probs..he's very happy..I'll ask him tomorrw..he'll know the answers to your question.

DJ

[Fly]

DJ...I eagerly await your answers.

And yes, the 14 will wear out the chain faster and the swingarm guide as well and it isn't as mechancially efficient as the 15 toother. As delivered the ST3 comes with a 15/42 or 2.8...42/14 = 3...so I could have gone with a 45 rear but being the cheap SOB I am, I didn't want to get a new chain.

Would cheap SOB in this case equate to shortsighted SOB? I haven't got the 14 in yet...just ordered it.

And the dual sport idea isn't dead, just on hold. The devil will certainly make her pitch and I'll probably wind up on a damned full-on dirt bike. She's hard to resist. And she's persistent. Aprilia?

Lastly I will say this: I've only ridden the Duc a short time but this bike is fast! And dangerous! And hard to ride within the legal limits.

Oh well.

I'm looking forward to a hot summer and several (thousand) cold beers.

Regards.

[BobFV1]

Fly - I was at a track day with a guy on a stock ST3 last year and he was really holding his own on that thing - very, very fast and nimble - I was very impressed.

Good luck on the mod.

[DarthRider]

Fly -
If it were me, I'd change the C/S sprocket and use the stock chain.
Then change the chain & both sprockets when the C/S & chain need replacing, and adjust the gearing with the drive sprocket.
I'd rather have another worn out chain laying around than a new, wasted one!

Dave

[BobFV1]

Fly -
If it were me, I'd change the C/S sprocket and use the stock chain.
Then change the change & both sprockets when the C/S & chain need replacing, and adjust the gearing with the drive sprocket.
I'd rather have another worn out chain laying around than a new, wasted one!

Dave:031:

That's brilliant. Dave - we're not worthy!!!

[DarthRider]

Well, different things pass for brilliance with different people, but thanks.
Actually, I'm just cheap...

Dave

[DJ Down Under]

Fly..I checked with my friend...I'm sorry but I must have misunderstood him because what he actually did was leave the front and add a couple of teeth to the rear...:eusa_wall:

He was told that they (Ducati) over gear their bikes to help pass sound tests..most country's (including ours) have a drive by test at 100 kph (60 mph)

By gearing the bike high the rev's are lower and this helps them pass...so the best thing is to change it to what it should be.

You may loose a little top speed but the bike will ride much better.

Lucky they don't do a sound check at idle...geees his bike rattles at idle...I can't hear my bike at all when we stop together at red lights..:003:

He was not able to tell me which way the nut should be turned to undo the front sprocket.

Sorry I'm not much help.

DJ

[DarthRider]

Right on DJ, about why they over-gear chain drive bikes, but...

Logic and other experience would tell you that adding 2 teeth to the rear sprocket would cost you top speed, however, with intentionally over-geared bikes like the Duc you will actually often see an *increase" in top speed.

Why? With the over-gearing to pass sound emissions the bikes will often not be able to reach redline in top gear. By gearing it *down* by *adding* 2 teeth to the rear sprocket it will rev higher and go faster.

My '92 Ducati 900 Super Sport was geared like this and would not pull to redline in 6th. It would top out at ~135. After going up 2 teeth on the rear it ran 140.

My Speed Triple will run over 150 (indicated) in 5th at redline. It will not pull redline in 6th and will only run a little over 140. I'm going to fix that!

An added benefit to "gearing down for higher speed in 6th" is that you pick up more acceleration in the lower gears. Maybe I can get that damn Speedy to do a wheelie then...?

Hoochie Mama!

Dave

[Dallara]

I'll third that...

Common practice when I was production road racing Honda CB-750 and 900-F's was to add one tooth to the rear sprocket to get them to pull redline on the tach in 5th (top) gear. If you didn't do that they would never pull redline, and by adding a tooth you picked up nearly 5 MPH in top end.

On the subject of the countershaft nut...

I don't know about Ducati's, but common sense would dictate that if the chain/countershaft is on the left side of the bike then the nut would thread on normally - i.e. clockwise - conversely, if the chain/countershaft is on the right side, then counter-clockwise. I believe your Ducati countershaft is on the left, so clockwise should be the answer.

Still might want to check, though. Why don't you just call a Ducati dealer and ask 'em?

Cheers!

Allan (Dallara - NAABSCD)