Ducati Sporting Club UK > Model Specific - Discussion, Technical Problems and Help > Sport Touring: ST4 / ST3 / ST2 > 14T sprocket ST4S ?

[cj2]

Has anyone fitted a 14T sprocket (ST4S '03) - i've done this based on items i've read here and other sites, the problem is that i get a sort of 'droning' noise when coasting (clutch-in, tickover) which comes in at about 30mph as the speed drops but disappears below about 20mph.
I've tried alternate chain tension etc. etc. but can't get rid of it. obviously i've re-fitted the 15T standard and it's then o.k. - is this perhaps the chain rubbing on the plastic guide on top of the swing arm since with the 14T the radius is smaller so brings the chain nearer the swing arm (i'm assumming this 'cos in the condition described, the top of the chain is the slack side).
Any help / suggestions greatly appreciated.

CJ2

[Rushjob]

I did this on mine when it had a standard 38 tooth rear on and liked it but
I also had the droning and didn't like that bit.
As I was due a new chain & sprockets anyway I changed over to ST4 gearing - 15/43......
Now that is fun.....
Still geared for about 162 mph at the rev limiter but if you want to it'll lift the front wheel now with ease and is awesome out of the bends....

[BDG]

I did about 19,000 miles with the same 14 tooth front sprocket on, very slight noise but no problem.

I did intend doing what RUshjob did when the chain needed replacing, but sold it.

[Athelstan]

Strange This:
I had a 14T front fitted and kept to the std rear ST4s sprocket size plus new chain and have no "droning" noise. There is also no appreciable extra wear on the top swinging arm rubber guide, and no wear of the front sprocket grey plastic cover. So I wonder what is going on cj2?

[rockhopper]

My St2 used to make a droning noise when the chain was too tight.

[Rushjob]

I think part of the cause as well as the sprocket was the high ride height I have set on mine.......

[cj2]

Thanks everyone for the info - i still can't get to the bottom of this so i'm reverting to the 15T with 40T rear and new chain - better to be safe than sorry (i did like the acceleration though with the 14/40 combination that i also tried)

Cheers

CJ2

[Jools]

Originally posted by Rushjob
Still geared for about 162 mph at the rev limiter but if you want to it'll lift the front wheel now with ease and is awesome out of the bends....

I hope you'll only be riding like that when you're "familiarising yourself with the performance of your machine"

[Rushjob]