63 A10 SR engine sprocket

[worntorn]

Just sayin' that if the spreadsheet shows. 6500 rpm = 108 MPH for a 19" rear wheel , 3.50 tyre and 3.74 to one gearing, the spreadsheet is wonky by a large factor.
108 MPH with that high gearing is just a tad over 5,000 rpm. Unless my arithmetic is wrong, which does happen now and then.

Glen

[worntorn]

I changed the engine sprocket to the 23 tooth today and it makes things much nicer at highway speeds. The bike doesn't have quite as much urge thru the gears as with the 21 tooth, but still feels quite lively and it is very smooth running. It also stays in each gear a tad longer and to a higher speed, which I like.

The old seat, which looked OK but was wrong for the bike, has been replaced with an RK Leighton item. The old seat was the correct  for the earlier bikes, the Leighton one is a good 1" or so wider and is correct for this bike. It is very comfortable, well worth the £.
I also dropped the footpegs an inch so that the footpeg arms run approximately level.  This extra inch of leg room is nice. It's very comfortable ride now  with the cowhorn bars, soft contoured seat and lots of legroom to the pegs. I feel like I'm in a comfortable old TV room chair when I ride it.
Would it be possible to run a small TV from the E3L? I wouldn't necessarily have to use a clicker with it, though it would be nice. 

Glen

[worntorn]

Hi Again Glen,
I forgot to mention that the 23 tooth engine sprocket I bought had quite a pronounced shoulder on the inner face, which would or could alter primary chain alignment 
In my case because I was modifying the clutch at the same time it all worked out ok, but it would not have worked with the previous clutch adaptor

Regards
John

Hi John

The 23 tooth sprocket I received also had a substantial shoulder. I was on the lookout for this (from reading your post) so it was no problem. I cut the shoulder back on the lathe and kept trying it until I had alignment.
Very hard material, as it should be!

Glen

[chaterlea25]

HI Glen
Glad to have been of help,
I have seen several clutch chainwheels well chewed up because of misalignment 

Like below !!!!

Regards
John

[East_Coast_BSA]

The stock/current gearing on my 59' SR is 21/43 on the primary and 19/42 on the Final drive.  I was thinking about bumping up the gearing.  The bike is very responsive for around town riding, but if I have to get on the highway (which I like to avoid) it gets "buzzy" around 50-55 MPH.  I filled the handlebars with silicone RTV and that did help, but I'd really like some more gear.  I see that Draganfly sells the 23t gear and the 70 pitch chain for about half of what SRM gets.  Is there a difference in quality between the two?  I've had good luck with both places.

[Viking]

I changed the engine sprocket to the 23 tooth today and it makes things much nicer at highway speeds. The bike doesn't have quite as much urge thru the gears as with the 21 tooth, but still feels quite lively and it is very smooth running. It also stays in each gear a tad longer and to a higher speed, which I like. 

I found exactly the same. The SR is under geared with a 21T engine sprocket.
3rd gear is newer used.

After changing to a 23T, 3rd gear is fine for town riding ie 30MHP. At 50 MHP the engine is pleasant smooth and “semi slow running” Seat vibration at 50 MPH is gone. 
The bike is designed for winding roads in the 50ies.
Most old roads are straighten op and leveled out, changing the need and use for a low geared bike.
Today the roads are more for cruising.
Motorway use is still a challenge. Cruising hour after hour at 80-90MPH is hard work for the SR and “oil boiling”
With a 23T sprocket. 70 MPH is easy and comfortable, without “cooking the oil”
If easy cruising at 100 MPH is a high priority, buy a “Japasaky” or “Ducaguzzy”

Do it the Don way:

The best twin for overall use  

"A wonderful stabile and reliable machine"
    
http://www.dailymotion.com/video/xpcvc1_don-s-road-test-bsa-a10-golden-flash_sport