Author Topic: Who’s running the 16 tooth sprocket  (Read 3376 times)

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RecoilRob

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Reply #30 on: June 21, 2021, 01:03:18 am
The cam profile on the 650 is so mild that mine will pull without complaint from 2000 rpm in 6th...with the 16T sprocket.   It can't pull hard down that low, but compared to my Suzuki SV1K it's a veritable tractor.   The Suzuki won't have anything to do with any kind of throttling beyond maintenance on level road at 3000 and 4000 is minimum for full WOT.   I believe the Ducati's are much the same...when something is cammed, valved and ported to run to 11,000 rpm the flow just doesn't work well down so close to idle.

I've got the S&S cam ordered and am curious how it will affect the powerband.   Reports say it softens the bottom end below 3500 or so which makes total sense, but looking at the specs I'm thinking the motor will still be very happy to run at ridiculously low rpm without breaking a sweat.   Thinking about it I'm going to order the 17T just for S&G to see if it'll fit and how it runs once we fit it.   Might need a new longer chain but that's no problem...we'll have the stock one for a spare which is always nice to have. :)

Edit:  I just found a 17T-36 combination with chain on Ebay so it'll be on the way soon.   Having multiple sprocket options we'll be able to see how it handles different combinations.   If we want to sneak up on the increases we don't have to jump to the tallest gearing straight away....we'll see how it goes once the package gets here.
« Last Edit: June 21, 2021, 01:35:21 am by RecoilRob »


whippers

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Reply #31 on: June 21, 2021, 01:57:25 am
Please tell us how the cam goes. I am interested in that but maybe with hi comp pistons to compensate for losing the bottom.

Also to those with 16 how is fuel economy same or even better?
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Starpeve

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Reply #32 on: June 21, 2021, 02:10:18 am
The cam profile on the 650 is so mild that mine will pull without complaint from 2000 rpm in 6th...with the 16T sprocket.   It can't pull hard down that low, but compared to my Suzuki SV1K it's a veritable tractor.   The Suzuki won't have anything to do with any kind of throttling beyond maintenance on level road at 3000 and 4000 is minimum for full WOT.   I believe the Ducati's are much the same...when something is cammed, valved and ported to run to 11,000 rpm the flow just doesn't work well down so close to idle.

I've got the S&S cam ordered and am curious how it will affect the powerband.   Reports say it softens the bottom end below 3500 or so which makes total sense, but looking at the specs I'm thinking the motor will still be very happy to run at ridiculously low rpm without breaking a sweat.   Thinking about it I'm going to order the 17T just for S&G to see if it'll fit and how it runs once we fit it.   Might need a new longer chain but that's no problem...we'll have the stock one for a spare which is always nice to have. :)

Edit:  I just found a 17T-36 combination with chain on Ebay so it'll be on the way soon.   Having multiple sprocket options we'll be able to see how it handles different combinations.   If we want to sneak up on the increases we don't have to jump to the tallest gearing straight away....we'll see how it goes once the package gets here.
Excellent! You should get away with the same chain if you’re reducing the rear and fitting the 17 to the front. Can’t wait for the feedback!👍
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Jon_98

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Reply #33 on: June 21, 2021, 02:17:27 am
I live in the Blue Ridge Mountains in western North Carolina. Twisties are my world. The 16 tooth has made a huge difference. I spent so much time shifting between 2nd, 3rd and 4th with the stock 15T, now I can practically live in 3rd gear except for the tightest hairpins or occasional straightaway.
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RecoilRob

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Reply #34 on: June 21, 2021, 07:53:56 am
Please tell us how the cam goes. I am interested in that but maybe with hi comp pistons to compensate for losing the bottom.

Also to those with 16 how is fuel economy same or even better?

Fuel economy is excellent...certainly no worse in my case than with the 15T.   Today's fill-up saw 70.7 mpg's...that's US gallons too.   Can't say I'm not impressed by the frugality of this bike!   Amazing....:)


Breezin

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Reply #35 on: June 21, 2021, 09:46:42 am
The scientific and technical case for 16 teeth is well and truly made.

Also, 'just for S & G'. I had to think about that one!  ;D


YellowDuck

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Reply #36 on: June 21, 2021, 02:21:42 pm
This is definitely a change I will make eventually because 1st is stupid short.  Runs out of revs much too quickly when starting from a standstill, and the bike is pretty much impossible to stall anyway, with so much low end torque and a clutch engagement over a very wide range.

What I don't get though is why the difference from 5th to 6th is so small?  You are turning just over 4k at 60 mph (indicated), shift up, and now you are turning just under.  Like, JUST under.  I think they botched this a little in the design.  According to the manual the difference when you shift from 5th to 6th is 1.040 to 0.962, which is 7.5%.  So at 4000 rpm it drops the revs by 300......from about 4150 to 3850.  I mean, why bother?


Bibbage

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Reply #37 on: June 21, 2021, 02:57:02 pm
https://chainsandsprockets.co.uk/

£9.27 with uk free delivery

Which one did you get, I emailed them they said they didn’t have the fitment info so couldn’t match one up!
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drums4money

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Reply #38 on: June 21, 2021, 03:23:54 pm
Which one did you get, I emailed them they said they didn’t have the fitment info so couldn’t match one up!

same here- the link prompts for vehicle make and naturally RE isn't listed.
i notice the Hitchcock's item has the rubber cushion ring for the chain.  I'm certainly interested after having read the numerous positive experiences from the group.

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CPJS

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Reply #39 on: June 21, 2021, 07:22:15 pm
I have just ordered a 16 tooth sprocket from Hitchcocks, I will report back as and when.
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Hoiho

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Reply #40 on: June 21, 2021, 09:34:36 pm
Are are re-using the bent locking washer?


Jack Straw

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Reply #41 on: June 21, 2021, 10:43:51 pm
Yep, I reused mine.
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RecoilRob

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Reply #42 on: June 21, 2021, 11:11:06 pm
This is definitely a change I will make eventually because 1st is stupid short.  Runs out of revs much too quickly when starting from a standstill, and the bike is pretty much impossible to stall anyway, with so much low end torque and a clutch engagement over a very wide range.

What I don't get though is why the difference from 5th to 6th is so small?  You are turning just over 4k at 60 mph (indicated), shift up, and now you are turning just under.  Like, JUST under.  I think they botched this a little in the design.  According to the manual the difference when you shift from 5th to 6th is 1.040 to 0.962, which is 7.5%.  So at 4000 rpm it drops the revs by 300......from about 4150 to 3850.  I mean, why bother?

The gearing from 5th to 6th wasn't chosen for cruising at 60 mph, it is so at redline or power peak in 5th the revs will only drop down the power curve a little so it doesn't drop clear off and also reduces the speed difference because peak in 5th is really close to top speed...and in some cases it IS top speed and 6th just for cruising at Autobahn speeds.

Pretty much all 'close ratio' gearboxes tighten up as you go up in gears until the top two or three will be pretty close together as you're at a speed that's demanding all the power you've got so only a bit more speed is to be had.   I know...talking about 'top speed' with the 650's sounds a little daft but there ARE people who are interested in getting all that can be had...and the gearbox is made for them.


ATXConti650

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Reply #43 on: June 22, 2021, 03:44:47 pm
Are you able to reuse the stock chain ?

After reading these posts I ordered a 16T sprocket from Hitchcocks. Their site says OE chain can be used with it.
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CPJS

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Reply #44 on: June 22, 2021, 05:12:13 pm
After reading these posts I ordered a 16T sprocket from Hitchcocks. Their site says OE chain can be used with it.
Just fitted my 16t sprocket. Plenty of chain adjustment to spare.
The nut holding the sprocket on was effing tight!
I'm going out for a ride tomorrow to see what the difference is like.
Current bikes.
R E GT650
BMW R1200GS
Honda CRF250L
BSA B25SS

Still young enough not to care, too old to remember why.