[sf_ds]

Make sure you follow the factory procedure for measuring slack to the letter. Push up on the chain (make it taut) under the swingarm at the largest spline on the swingarm, the distance between the top of the chain at that point and the bottom of the swingarm should be ~5mm. That ends up with a looser chain compared to sport bikes, but not as loose as a dirt bike.

Easy way to check how properly adjusted it is: If it howls, it's too tight. If it rides rough, it's too loose. The Duke is pretty good about telling you when things aren't perfect.

The Duke also has a lot of suspension travel compared to anything other than a sumo or dirt bike: 135mm front and back for non-R, 150mm front and back for R models.

 

[michaelnel]

I have ordered a 15T front and 42T rear. I also have the service manual on order from EBAY but have not received it yet. Can someone tell me the torque specs for the countershaft sprocket nut and the bolts that mount the rear sprocket?

Thanks, Michael

 

[michaelnel]

Pleased and surprised to find the torque specs in the owner's manual. I figured I would need the service manual for that.

Anyway, countershaft sprocket nut, 80nM with Loctite 243
Rear sprocket bolts, 35nM with Loctite 2701

 

[Weldertron]

Just an FYI, all the manuals are available online from KTM.

 

[michaelnel]

Just an FYI, all the manuals are available online from KTM.

I don't believe the service manuals are.

 

[KTMCol]

Just want to say thanks for all the info everybody. I decided to go with this:
.aliexpress.com/item/44T-CNC-Rear-Chain-Sprocket-KTM-EGS-EXC-SX-EXCF-LC4-LSE-RXC-MXC-SMR-125/32439962581.html?spm=a2g0s.9042311.0.0.U72cqM
Couldn't post the full link but just add www
Loving the ease of second gear wheelies and getting lift over rises in 3rd [emoji3]. Bike has a top speed of 180 kph and great drive in the twisties. Better/smoother around town too.

Sent from my NX700QC using Tapatalk

 

[michaelnel]

Good luck with that. I would not be inclined to buy a cheap chinese imitation of a SuperSprox.

 

[KTMCol]

Good luck with that. I would not be inclined to buy a cheap chinese imitation of a SuperSprox.

Yeah, it's a gamble but it fitted up perfectly and the rivets are tight. Only done about 100k's so far. I'll keep an eye on it and time will tell.

Sent from my NX700QC using Tapatalk

 

[Maddog Reynolds]

Chain slack spec in manual seems very small... 5mm / .25" with the bike on a swingarm stand. Is that correct?

As I read it, it's not slack. It's the gap between chain and bottom of swinging arm, when you lift the bottom run of chain.

 

[michaelnel]

Yes, I understand, thanks.

 

[capsella]

related question... I got a new rear (46, keeping stock front) and hence a new chain, the chain came with a clip type master link. I know these are considered "ok" for dirt bikes, but is it safe to use on a duke?


thanks.
-Andrew

Just wanted to post back re: the 46 rear (powerparts supersprox) w/ stock front... LOVE IT! not really missing the top speed losses, gearbox really feels perfect now. It's just always in the right gear. got a rivet link btw

 

[cors187]

+13% torque over stock very nice :smile2:
Front Rear Ratio Torque Speed
16T 38T 2.38 -5.3% +5.3%
16T 39T 2.44 -2.6% +2.6%
16T 40T 2.50
16T 41T 2.56 +2.4% -2.4%
16T 42T 2.63 +4.8% -4.8%
16T 43T 2.69 +7.0% -7.0%
16T 44T 2.75 +9.1% -9.1%
16T 45T 2.81 +11.1% -11.1%
16T 46T 2.88 +13.0% -13.0%
16T 47T 2.94 +14.9% -14.9%
16T 48T 3.00 +16.7% -16.7%

 

[Ingolf Stern]

has anyone done a dyno with various sprocket configurations so we can see an actual torque curve?

and for clarity - does a 16/42 work with the OEM chain?

 

[cors187]

torque
noun
1.
MECHANICS
a force that tends to cause rotation.
Torque is a measure of how much a force acting on an object causes that object to rotate.

Chain and sprockets
Its just a consistant mathematical formula which can be represented in an increase or decrease %.

 

[prometheus]

This has been an enlightening thread. What i've learned:
[Combined charts from thread]

Front	Rear	Ratio	Torque	Speed		Front	Rear	Ratio	Torque	Speed		DIFFERENCE
16T	38T	2.38	-5.30%	+5.3%								
16T	39T	2.44	-2.60%	+2.6%								
16T	40T	2.5										
						15T	38T	2.53	+1.3%	-1.30%		
16T	41T	2.56	+2.4%	-2.40%								
						15T	39T	2.6	+3.8%	-3.80%		
16T	42T	2.63	+4.8%	-4.80%								
						15T	40T	2.67	+6.3%	-6.30%		
16T	43T	2.69	+7.0%	-7.00%								
						15T	41T	2.73	+8.5%	-8.50%		
16T	44T	2.75	+9.1%	-9.10%								
16T	45T	2.81	+11.1%	-11.10%		15T	42T	2.8	+10.7%	-10.70%		0.40%
16T	46T	2.88	+13.0%	-13.00%		15T	43T	2.87	+12.8%	-12.80%		0.20%
16T	47T	2.94	+14.9%	-14.90%		15T	44T	2.93	+14.8%	-14.80%		0.10%
16T	48T	3	+16.7%	-16.70%

optimally keep front large as possible.

So why not go further than this?

17T	38T	2.235294118	-11.84210526	11.84210526		18T	38T	2.111111111	-18.42105263	18.42105263
17T	39T	2.294117647	-8.974358974	8.974358974		18T	39T	2.166666667	-15.38461538	15.38461538
17T	40T	2.352941176	-6.25		6.25			18T	40T	2.222222222	-12.5	12.5
17T	41T	2.411764706	-3.658536585	3.658536585		18T	41T	2.277777778	-9.756097561	9.756097561
17T	42T	2.470588235	-1.19047619	1.19047619		18T	42T	2.333333333	-7.142857143	7.142857143
17T	43T	2.529411765	1.162790698	-1.162790698		18T	43T	2.388888889	-4.651162791	4.651162791
17T	44T	2.588235294	3.409090909	-3.409090909		18T	44T	2.444444444	-2.272727273	2.272727273
17T	45T	2.647058824	5.555555556	-5.555555556		18T	45T	2.5		0		0
17T	46T	2.705882353	7.608695652	-7.608695652		18T	46T	2.555555556	2.173913043	-2.173913043
17T	47T	2.764705882	9.574468085	-9.574468085		18T	47T	2.611111111	4.255319149	-4.255319149
17T	48T	2.823529412	11.45833333	-11.45833333		18T	48T	2.666666667	6.25		-6.25

 

[Frankenschwinn]

has anyone done a dyno with various sprocket configurations so we can see an actual torque curve?

and for clarity - does a 16/42 work with the OEM chain?

I just put a 42 tooth sprocket on this weekend and fits just fine.

Right now, it looks like the 16-42 combo will fit my style perfectly!

 

[The LabPack]

Need a good brand and site info.. im looking to do the 42 rear and 15 front.. Im in US.

 

[majorek]

15-42 is really close to 14-40 where you need to replace only one sprocket.
Is it not advised to use 14teeth front sprocket as it is somehow too small?
Could you please tell me disadvantage of this solution? Does it cause any problems?
Is it too small and cause excessive tension to the chain or make it wear out too fast?
Or there is maybe not enough adjustment of slack on the swingarm?
Have anyone tried it?

I currently have 14 front sprocket on my Husqvarna 610 SM, but I cannot compare it to 15 teeth as I always used 14. And I did only 1,5k km yet so I cannot really say anything about chain wear as it looks brand new and did not stretch at all yet.

 

[The LabPack]

Answer the damn question

Guys i keep seeing the same question what brand and where did yall order it from. I have been looking every where for a 42 15 set up but nothing seems to fit my duke... 2014 690r.... anyone send a good link for parts?

 

[tecknojoe]

I got my 42 by calling Driven Racing. It's not on their site but they had it, and it was only like $35