Building a 40 tooth for the 1290

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abc
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Building a 40 tooth for the 1290

Postby abc » Tue Jan 06, 2015 11:01 am

Its been raining again here so I have been quietly working away at finding an easy solution to the lack of available 40 tooth rear sprockets for the 1290. Unfortunately I have been unable to find good materials at the right price to make one from scratch so i have had to find a 40 tooth 525 pitch sprocket off another bike and will have to heavily modify that one to suit.
Heres a pic of the stock 38 tooth arrangement
Image

And heres a pic of the comparison between the 2 sprockets - lots of work to be done to get the new one to match the original. The stock sprocket has signs of wear on only one edge which suggests there is some misalignment in the stock arrangement. I will fix that too.
Image

I measured the details of the stock mounting profile and stuck it into cad. I then produced an aluminium sheet profile to check it will fit prior to machining the final gear.
Image

I then made some blanking plates to fill the 6 cut outs in the new sprocket.
Image

From here I will weld prep everything and clamp it down to a baseplate so it wont distort when i TIG weld the blanks into position. These are there because the original sprocket is supported on its diameter where it sits on the cush drive.
Once all the welding is done I can machine the final mounting profile into this new unit. More pic to follow when I have time to make more progress.
Last edited by abc on Sun Aug 06, 2017 3:32 am, edited 1 time in total.
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ktmguy
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Re: Building a 40 tooth for the 1290

Postby ktmguy » Tue Jan 06, 2015 10:06 pm

Nice work!

Can't understand neither why the likes of renthal hasn't got a sprocket out yet.
Aren't there places around who cut a sprocket to order?

So the rear doesn't run very straight if the sprocket wears out more on one side.... Another one to the list.... :roll:
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abc
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Re: Building a 40 tooth for the 1290

Postby abc » Tue Jan 06, 2015 10:15 pm

ktmguy wrote:Nice work!

Can't understand neither why the likes of renthal hasn't got a sprocket out yet.
Aren't there places around who cut a sprocket to order?

So the rear doesn't run very straight if the sprocket wears out more on one side.... Another one to the list.... :roll:


The nice thing about this time of the year is that things at work are quiet so I get payed to work on my bike, the rest of the year makes up for it because it is normally pretty crazy around here. But a quiet week and time to do my own thing is why I didnt order a custom sprocket.
The rear sprocket does run straight but I think there might be a little problem with the alignment offset. Will confirm when I measure it and get to that machining stage.
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SDNerd
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Re: Building a 40 tooth for the 1290

Postby SDNerd » Tue Jan 06, 2015 10:23 pm

ktmguy wrote:Nice work!

Can't understand neither why the likes of renthal hasn't got a sprocket out yet.
Aren't there places around who cut a sprocket to order?


+1

AND

It's easy to understand: The (after-)market for 1290 sprockets is miniscule.

AND

There are - and a LOT of them (this list is far from exhaustive):

http://www.sprocketsunlimited.com/Sprockets.html

http://www.rebelgears.com/

http://sprocketspecialists.com/

http://www.superiorsprockets.com/sprocket_custom.html

http://www.kingssalesandservice.com/mot ... rockets-2/

And on and on ... Don't immediately see what you like - call 'em up, and most of the these vendors will entertain any sprocket whims you may have.

I have to admit, I was hoping to stumble on them here: http://spacely-sprockets.com/

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Re: Building a 40 tooth for the 1290

Postby jmann » Wed Jan 07, 2015 4:43 am

Comrade abc: Very nice as usual :D :D :D

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ktmguy
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Re: Building a 40 tooth for the 1290

Postby ktmguy » Wed Jan 07, 2015 4:46 am

jmann wrote:Comrade abc: Very nice as usual :D :D :D


Hey not too fast I haven't seen the welds yet! :lol:
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DribbleDuke
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Re: Building a 40 tooth for the 1290

Postby DribbleDuke » Wed Jan 07, 2015 5:18 am

With all the rage over cnc machines taking over the planet. I would have thought that a flat disc cut into a fairly uncomplicated arrangement would have been child's splay for more machine shops than meets the yellow pages. It almost feels as if the direction abc is taking this is close to what we here in the states call Okiefied or ethiopian engineering.
Well. carry on, it eats time your paid for, what else should it be used for?
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abc
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Re: Building a 40 tooth for the 1290

Postby abc » Wed Jan 07, 2015 6:24 am

DribbleDuke wrote:With all the rage over cnc machines taking over the planet. I would have thought that a flat disc cut into a fairly uncomplicated arrangement would have been child's splay for more machine shops than meets the yellow pages. It almost feels as if the direction abc is taking this is close to what we here in the states call Okiefied or ethiopian engineering.
Well. carry on, it eats time your paid for, what else should it be used for?


Keep in mind that I couldnt get the material at a decent price (our $ has dropped 20% in the last 3 months) and if I could have found the right material for the right price then I would have cut a complete gear as you so expertly suggested - why didnt I think of that........
AND I would not have waisted machine time CNCing it but would have wirecut it or waterjet cut it.
I also dont get the chance to fabricate stuff much thesedays so its a good chance for me to do things that I enjoy and keep my skill up to scratch.
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Re: Building a 40 tooth for the 1290

Postby abc » Thu Jan 08, 2015 8:31 am

Heres the flange and the inserts after weld prep. Everything clamped to baseplate to reduce distortion during welding and to help with setting up for following steps.
Image

All TIG welded up and being machined back to ensure flat faces.
Image

Because of your fascination with welds this pic is for you KTMGUY. Notice full penetration and no impurities. Shape to be cut out next and is quickly marked on face to ensure weld coverage is good.
Image

Shape cut out and mounting holes machined and all edges broken. Sprocket then chamfered and shot blasted to remove stress.
Image

final comparison for you. Left is new 40T and right is stock 38T
Image

All done and works very well. New sprocket has been offset by 0.3mm (o.o12") to realign the front and rear sprockets because they were out from factory
Image

Bike rides really well and has more punch everywhere and is a crazy blast to ride. Difference is easily noticeable. Stock speedo shows 100klms at 3600rpm. Final drive is -1 front and +2 rear.
Was "the ethiopian method" worth it.......absolutely. Maybe I have the fastest accelerating 1290 on the planet at the moment :roll:
Last edited by abc on Sun Aug 06, 2017 3:34 am, edited 2 times in total.
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Re: Building a 40 tooth for the 1290

Postby Davo-Singapore » Thu Jan 08, 2015 9:08 am

Splendid! Well done mate.

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jmann
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Re: Building a 40 tooth for the 1290

Postby jmann » Thu Jan 08, 2015 10:43 am

Comrade: :D :D :D

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1290Nerd
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Re: Building a 40 tooth for the 1290

Postby 1290Nerd » Thu Jan 08, 2015 10:57 am

Thats some nice work ABC !!!
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Re: Building a 40 tooth for the 1290

Postby kevxtx » Thu Jan 08, 2015 11:25 am

Great job mate, nice to see a man at work. :D

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SDNerd
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Re: Building a 40 tooth for the 1290

Postby SDNerd » Thu Jan 08, 2015 5:08 pm

Nice work.

abc wrote:All done and works very well. New sprocket has been offset by 0.3mm (o.o12") to realign the front and rear sprockets because they were out from factory[/img][/url]

No shit? Add another to the 1290 hit list ...

Was "the ethiopian method" worth it.......absolutely. Maybe I have the fastest accelerating 1290 on the planet at the moment :roll


:lol: Someone over here has a nitrous setup on theirs ... Only a matter of time before someone sticks a blower on a 1290.:wink:

DribbleDuke
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Re: Building a 40 tooth for the 1290

Postby DribbleDuke » Thu Jan 08, 2015 6:09 pm

I was thinking about the direction of adding teeth to the rear and at what point does the add actually start subtracting to the gear ratios optimum values.
I was also wondering if the added benefit of a larger circumference rear sprocket on leverage toward, effectively creating a pull downward force on the rear tyre, add to the creation of easier wheelies :?:
If the ratios were changed to put the motor in a sweeter spot of torque, in regards to speed, why is it always the case that enlarging the rear, or enlarging the ratio, instead of shrinking with a much smaller rear sprocket and leaving the bike in a lower gear is not a direction used.
I too added two teeth to the rear on the 990. It gave me the ability to power wheelie in second gear without going into supersonic speeds. If I were any good at wheelies I could perform the same thing in first gear with a gearing that made first gear reach higher speeds before redline.
With traction control limiting revs that do not coincide with forward motion and a motorcycle that produces the torque figures that the 1290 does. I would be interested in hearing your long term evaluation of this gearing change.
Myself, I went back to the 38 tooth rear as the limited value of the 40 did not add up to the overall value of the 38.
Do you believe that if you did not fill in the area of the sprocket with just the more limited surface around the lugs would have failed?
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Re: Building a 40 tooth for the 1290

Postby abc » Fri Jan 09, 2015 7:37 am

DribbleDuke wrote:.Do you believe that if you did not fill in the area of the sprocket with just the more limited surface around the lugs would have failed?

If I understand your question correctly - I would not just mount the sprocket on the 6 bolts. The supporting area in between the bolts actually centres the sprocket on the cush drive and provides all the axial location. There is 0.6mm clearance in the mounting bolt holes compared to the bolt diameters so there is no real way of ensuring the sprocket runs concentric if you were to just rely on the bolts to do the mounting. That is why I went to the trouble of reproducing the standard mounting arrangement. No point changing this arrangement because its a good design and works effectively. Although I did reduce the mounting bolt clearance from the stock 0.6mm down to 0.2mm to ensure a neater fit.

I very much like the idea of supercharging a 1290 and throwing all the computers away and just running motec but it would cost a pretty penny to do and I would require the help of others with the wiring so I'll let someone else that is "cashed up" take on that little project :wink:
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Re: Building a 40 tooth for the 1290

Postby ktmguy » Fri Jan 09, 2015 10:26 am

abc wrote:
I very much like the idea of supercharging a 1290 and throwing all the computers away and just running motec but it would cost a pretty penny to do and I would require the help of others with the wiring so I'll let someone else that is "cashed up" take on that little project :wink:


Great job on the sprocket there! I put the one tooth down on the front on a while ago and it's defo an improvement, not sure if I could handle a few tooth up on the back too!

On the supercharging thing, not sure if it needs it too, but trowing all the computers in the bin would been an improvement in my opinion.
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Re: Building a 40 tooth for the 1290

Postby DMacL » Fri Jan 09, 2015 5:06 pm

Do you have one tooth less on the front also abc?

And if you come up with the money I'll do the wiring for a s/c 1290 :)

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Re: Building a 40 tooth for the 1290

Postby DribbleDuke » Fri Jan 09, 2015 5:13 pm

abc wrote:
DribbleDuke wrote:.Do you believe that if you did not fill in the area of the sprocket with just the more limited surface around the lugs would have failed?

If I understand your question correctly - I would not just mount the sprocket on the 6 bolts. The supporting area in between the bolts actually centres the sprocket on the cush drive and provides all the axial location. There is 0.6mm clearance in the mounting bolt holes compared to the bolt diameters so there is no real way of ensuring the sprocket runs concentric if you were to just rely on the bolts to do the mounting. That is why I went to the trouble of reproducing the standard mounting arrangement. No point changing this arrangement because its a good design and works effectively. Although I did reduce the mounting bolt clearance from the stock 0.6mm down to 0.2mm to ensure a neater fit.

I very much like the idea of supercharging a 1290 and throwing all the computers away and just running motec but it would cost a pretty penny to do and I would require the help of others with the wiring so I'll let someone else that is "cashed up" take on that little project :wink:

You did understand my very poorly worded question. I can now picture where the fit becomes important. It is not unlike the fit around the inner ring of the 990 sprocket around the cush drive.
Can you feel the traction control more pronounced with the higher torque?
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Re: Building a 40 tooth for the 1290

Postby DribbleDuke » Fri Jan 09, 2015 5:14 pm

Final drive is -1 front and +2 rear.
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Re: Building a 40 tooth for the 1290

Postby bic_bicknell » Fri Jan 09, 2015 6:06 pm

Nice job :D It's always a pleasure to see someone's work that makes me think, "Phew, that's out of my league!"
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Re: Building a 40 tooth for the 1290

Postby prikkie » Fri Jan 09, 2015 6:15 pm

Can I order one ? :D

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Re: Building a 40 tooth for the 1290

Postby guzzi4v » Sat Jan 10, 2015 3:43 am


abc
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Re: Building a 40 tooth for the 1290

Postby abc » Sat Jan 10, 2015 6:30 am

guzzi4v wrote:http://www.chaingangchainsandsprockets.com.au/

That is one of the many companies I contacted prior to ordering the sprocket I had to modify.
Before everyone starts posting links to businesses that say they will make any sprocket to order!
I felt I exhausted all these businesses and the response I received from most was "sorry mate we dont do one for the 1290 yet as they are too new to the market"
So because they cant get hold of a hub or cush drive they cant make one for the 1290 because they need something to measure off. If one of these companies was near to where I live then maybe I would provided my bike for them to measure off.
So not so straight forward to have these companies "make any sprocket for you"
Things are rarely what they seem.......................
Any modifications you undertake are your sole responsibility, I am not liable for any claims relating to modifications or suggestions posted on this forum. If you undertake any modifications you do so at your own risk.

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Re: Building a 40 tooth for the 1290

Postby guzzi4v » Mon Jan 12, 2015 11:34 am

You're right. I didn't actually check them out. I've had some success in the past with this mob with dirt bike stuff.

Admire your efforts.

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