Author Topic: 16-18 toothed sprocket? (Read 10326 times)

scooberton · **on:** August 22, 2008, 09:07:13 pm

Could anyone tell me what difference the number of teeth and diameter of various sprockets do for the riding characteristics of motorcycles?A change of low end,mid range,top end speed/power?

Bankerdanny · **Reply #1 on:** August 22, 2008, 09:44:59 pm

More teeth up front = more MPH per engine RPM. Less teeth on the rear sprocket has the same impact.

A number of us here have installed larger fronts.

The standard sizes are:

16T - STD for a 350cc.
17T - STD for a 500cc.

I used an 18 tooth on my 4-speed '02. It shifted the revs down a bit so that 55-60 was a much more confortable speed.

Others here have used 19 and 20 tooth sprockets with stock 500's and reported no issues with hills. Some of the larger sizes can require mods to the primary case and extra links in the chain to fit right.

I think that the 19 and larger sizes make perfect sense if you have upgraded the carb and exhaust because the extra power will make up for the extra effort required to deal with the higher overall gearing.

baird4444 · **Reply #2 on:** August 23, 2008, 03:04:20 am

Quote from: scooberton on August 22, 2008, 09:07:13 pm

Could anyone tell me what difference the number of teeth and diameter of various sprockets do for the riding characteristics of motorcycles?A change of low end,mid range,top end speed/power?

I am told that the 19 tooth can only be used when changed back to RH shift. Xtra cross over linkage is in the way. GO for the 18 if you haven't yet. It isn't much of an increase but it brings the shift points closer to being in line with our speed limits and every little bit helps. Here are some #'s from that disk I sent you.... - Mike
~~~~~~~~~~~~~~~~~~~~~
18T (19/18ths of above RPM)
50MPH-3029 RPM
60MPH-3642 RPM
70MPH-4249 RPM
80MPH-4855 RPM

17T (stock, 19/17ths of 19T readings)
50MPH-3207 RPM
60MPH-3855 RPM
70MPH-4498 RPM
80MPH-5141 RPM

bob bezin · **Reply #3 on:** August 23, 2008, 03:07:37 am

i have left hand shift and a 19 tooth sproket on a 06 delux

baird4444 · **Reply #4 on:** August 23, 2008, 03:13:40 am

Quote from: bob bezin on August 23, 2008, 03:07:37 am

i have left hand shift and a 19 tooth sproket on a 06 delux

is that a 4 speed or 5??

Bankerdanny · **Reply #5 on:** August 23, 2008, 03:28:06 am

He meant the 4-speed need to go back to RH shift. The 5-speed on the 2006 uses a different linkage.

baird4444 · **Reply #6 on:** August 23, 2008, 03:35:49 am

yea BD, that's what I meant...
I keep fergetting bout the 5 speeds. Last year Chris Janes was bragg'n on his
19 tooth so I figured I'd give it some thought... then Chris busts my bubble
telling me I got to do the RH conversion then mumbled sumthin bout how
God and the Queen intended....
- Mike

t120rbullet · **Reply #7 on:** August 23, 2008, 05:46:53 am

I'm still mumbling about how bad that left shift bodge is on the 4 speeds.
My "new" bike is almost imposable to shift. I'm going to get it over on the correct side just as soon as I get my hands on a rt shift kit.

Bankerdanny · **Reply #8 on:** August 24, 2008, 12:18:34 am

I had some issues with shifting after I put the box back together this spring. But once I got use to the peculiarities of my particular bike I found that it shifted very reliably.

clamp · **Reply #9 on:** August 24, 2008, 02:50:49 am

Why do you change the front drive sprocket. This means removing the primary etc and also means that the sprocket will be bigger giving clearance issues and the sprocket is now bigger.

Its much cheaper and easier to reduce the size of the rear sprocket giving no such clearance issues?

I can only assume that the rear does not give any room for the reduction in Dia of the sprocket.

Bankerdanny · **Reply #10 on:** August 24, 2008, 03:30:30 am

The rear sprocket can only get so small because the rear brake drum is on the same side as the chain.

There is much more flexibility available on the front sprocket. But you are right, changing the sprocket is not a simple job, but I the result was worth it.

clamp · **Reply #11 on:** August 24, 2008, 10:31:48 am

Get a 5 speed gearbox ,--mine is perfect,--I wouldnt want any higher where I am.

baird4444 · **Reply #12 on:** August 25, 2008, 01:21:44 am

Quote from: clamp on August 24, 2008, 10:31:48 am

Get a 5 speed gearbox ,--mine is perfect,--I wouldnt want any higher where I am.

The gear ratio of 4th and 5th is the same, just more steps to get there on the 5 speed.
- Mike

clamp · **Reply #13 on:** August 25, 2008, 03:28:39 am

4 speed top gear ratio 5.7228 :1

5 Speed top gear -------4.726:1

Taken from the Royal Enfield hand book delivered with the bike. Both have 2.41:1 primary.

Even first is a little higher.

To calculate your ratio divide drive teeth by driven

20 teeth on the drive sprocket--40 on the rear =2:1 + primary

Total ratio =4.41

LotusSevenMan · **Reply #14 on:** August 25, 2008, 12:19:11 pm

My 500cc right foot shift four speed Classic is just getting to the running in nearly over stage (so now I guess it'll be running out!!!).
It pulls well and I'm letting it rev a bit more.
I think the 18t sprocket change is a viable one as it is only ridden solo and I find I'm basically in top gear at about 25-30mph indicated.

Can someone give a blow by blow account of what is involved please?

This version seems a bit 'simple'. Must be more to it.

It's not too hard, I just changed to a 19t.

]Drain primary chaincase
Remove chaincase gear and clutch (may need a clutch puller tool) When removing clutch make sure you keep order correct. Watch for clutch rod and ball bearing, they may roll out of the mainshaft gear.

Remove chaincase

You have exposed the rear sprocket gear. Remove chain.

Fold back metal folded washer (you'll see what I mean when you get here).
Using a 1 1/2 inch wrench, remove sprocket and replace with new one.

Total job time 1-2 hours

Cheers, LSM

meilaushi · **Reply #15 on:** August 25, 2008, 03:19:22 pm

Don't you have to remove the alternator at the Engine end before removing the chaincase too? I don't think you can remove the chaincase with the alternator in place.

clamp · **Reply #16 on:** August 25, 2008, 04:57:56 pm

The alternator coils are bolted to the chain case, the magnets are in the rotor on the crank pulley.

Even the wires come straight out with a half moon rubber seal and a simple snap conector.

Bankerdanny · **Reply #17 on:** August 25, 2008, 10:54:17 pm

Quote from: clamp on August 25, 2008, 03:28:39 am

4 speed top gear ratio 5.7228 :1

5 Speed top gear -------4.726:1

Taken from the Royal Enfield hand book delivered with the bike. Both have 2.41:1 primary.

Even first is a little higher.

To calculate your ratio divide drive teeth by driven

20 teeth on the drive sprocket--40 on the rear =2:1 + primary

Total ratio =4.41

The top gear difference is because the 5-speed comes standard with the 18-tooth sprocket.

The 4-speed and the 5-speed both have a 1:1 top gear.

Bankerdanny · **Reply #18 on:** August 25, 2008, 10:58:20 pm

Changing the front sprocket is a relatively big job. It's not difficult, but it is definitely an all day or even all weekend proposition.

PhilJ · **Reply #19 on:** August 26, 2008, 12:10:00 am

Dan,

Clamp has an Indian model 350. Do you think that may make a difference in the ratios?
I've never heard either way whether there are differences like that.

Phil

clamp · **Reply #20 on:** August 26, 2008, 01:10:47 am

Bankerdanny is quite right all gearboxes are 1:1 in top gear.

The drive chain ratio is the reason for the differences.

I must pay more attention.

Bankerdanny · **Reply #21 on:** August 26, 2008, 03:14:37 am

The 350 uses the same box as the 500 with the same ratios. However, it uses a 16 tooth front sprocket to give lower overall gearing (higher numerically) to make up for the 350's lower HP/Torque.