Front sprocket issues

[Chuck78]

I just wanted to update this thread with some additional info, as our beloved KDX's age and parts sourcing turns unto something a bit more challenging for all but those who are more resourceful.

The 89-06 KDX 200/220 gearbox output shaft is now NLA from Kawasaki OEM. I've got a bit of wear on at least 1 of my 3 KDX220 engines (2 bikes + spare engine), so I had considered machining a bolt-on outer splined flange from a cut down sprocket and drilling and threading it into the actual sprocket from the outboard side, sandwiching the circlip after a little bit of recessing cut into it on the lathe.

Then I saw a kid with a new-to-him KX125/KDX200 hybrid with a 14T and finding it a poor gearing for technical climbs, so he ordered a 13T and said it was skinnier and flopped around left and right and rotationally, and was claiming that he got the wrong sprocket for the bike.

It turns out the early 1980s KX front sprocket is exactly what he had from the dishonest previous owner, the same one described above. '83-'86 KX500 gets you the fitment, although it fits a few other models such as an '82 KX250, KDX420, etc.

I thought this was great to find as wider splines will spread the load out more evenly, and would be nice to run even on a good gearbox driven/output shaft just to prolong the lifespan of the shaft, and not just as a Band-Aid for a shaft that is already worn out.
I ever had to weld up and then machine down new splines onto a shaft, I certainly would be using his wider splines, although these sprockets are somewhat scarce although JT still makes them.

I'll copy and paste links below and specifications.

[Chuck78]

KDX/KX/YZ/Banshee/etc sprocket:

https://www.jtsprockets.com/catalogue/part/JTF569/
(As thin as the chain inner link bushings)

Old Yamaha version with extended splines, 8.0mm thickness:
https://www.jtsprockets.com/catalogue/part/JTF575/


'83-'86 KX500 etc 8.3mm spline section width:
https://www.jtsprockets.com/catalogue/part/JTF507/

I scoured the internet via inage searches looking for JT sprockets of visually identical splines but with a wider "hub" section vs the actual width of the teeth.

Now, I'm wondering if the output shaft seal collar/bushing/sleeve off of the early 1980's KX's would be a match for spacing to fit these sprockets to a 95-06 KDX, or if the 95-06 output shaft seal collar just needs to be turned down in a lathe regardless.


Also I might add that a good solution is to use high moly content paste for CV axles on cars or BMW etc shaft drive motorcycle splines, on the sprocket/gearbox splines, and then degrease the exterior after installing the circlip, and degrease again (rag and cotton swabs &/+ light solvent), & then RTV silicone the circlip area to seal it, as well as the rear of the sprocket. This will seal out dirt/sand/grit and moisture and keep the molybdenum disulfide friction paste captive. High moly content paste (25%-50% molybdenum disulfide, expensive stuff though) is the absolute best thing for moving parts which have high load and very low movement. That's why it is used in CV joint car axle shafts, very high loads but they aren't a wheel bearing that spins hugh RPM, the balls only make small movements back and forth. Same with shaft drive splines on street bikes.
The more common moly fortified chassis and bearing grease typically only has 5% molybdenum disulfide content, but is still soooooo much better than just a dry chain lube or silicone spray. The good 50% moly paste comes in a brush-in-can container and is $40-50 a can, or the 20%-35% moly content paste in a small free single use tear-off package with car CV joints...

[Chuck78]

STOCK KDX etc:

JTF569.png (7.36 KiB) Viewed 545 times

KDX/KX/YZ/Banshee/etc sprocket JT569:

https://www.jtsprockets.com/catalogue/part/JTF569/
(As thin as the chain inner link bushings)
(pro tip, RaceTech Titanium makes these in lightweight anodized titanium advertised for the Yamaha Banshee quads!)





FITMENT as follows.
13 Teeth:
*Kawasaki ATV
KXF250 A1,A2 Tecate 87-88
*Kawasaki Off Road
KDX200 A2-A3,B1-B3,C1-C3,D1-D2 84-88
KDX200 E1-E6 89-94
KDX200 H1-H11,H6F 95-06
KDX220 R A4-A12 97-05
KDX250 SR F1 Japan91
KX250 K4-K5 97-98
*Yamaha ATV
YTZ250 N,S (Tri Moto) 85-86
YFM350 X- T,U Warrior 87-88
YFM350 X- W,B,D,E,F,G,H,J,K Warrior 89-98
YFM350 X- L,M,N,P,R,S Warrior 99-04
YFM350 S,T,V,W,X,Y,Z,A,B,D Raptor 04-13
YFM350 RSE-W Raptor Special Edition 07
YFZ350 T,U Banshee 87-88
*Yamaha Off Road
IT250 D,E,F 77-79
IT250 K,L 83-84
MX250 B 75-76
YZ250 J,K,L 82-84
YZ250 F,G,H,J 94-97
YZ250 K5DJ 98


12 Teeth
*Yamaha ATV
YFA1 W,B,D,E,F,G,H,J,K,L,M,N,P,R,S 125 Breeze 89-04
YFM125 G-S,T,V,W,X,Y,Z,A,B Grizzly 04-12
*Yamaha Off Road
TY350 N USA85

14 Teeth
*Kawasaki Off Road
KDX200 SR F1,F2,F3 89-91
KDX200 SR F2,G3,G4,G5 Japan90-93
KDX250 SR F1,F2,F3 Australia89-91
KDX250 D1-D4,E1-E4 91-94
KX250 E1,F1,G1 87-89
KX250 H1-H2 90-91
KX250 J1-J2 92-93
KX250 K1-K3 94-96
KX500 C1,D1 87-04
KX500 E1-E16 87-04
*Kawasaki Road
KL250 A3-A4,C1-C2 79-85
KL250 G4-G7 Super Sherpa USA00-03
KL250 G9F Super Sherpa USA09
KLX250 R E1,E2,E3 91-95
KLX250 G1,G2 94-98
KLX250 Japan98-16
KLX250 ES Japan94-97
KLX250 SR Japan93-97
KLX250 R E1,E2,E3,G1 France93-97
KLX250 R F1,F2,F3,F4 Japan93-97
KLX250 R D1,D2,D3,D4 93-99
KV250 A3,A4 85-86
KLX300 A2,A3,A4,A5,A6,A7 (KLX300R) 97-02
KLX300 R B1 France97
*Yamaha ATV
YFZ350 W,B,D,E,F,G,H,J,K Banshee 89-98
YFZ350 L,M,N,P,R,S,T,V Banshee 99-06
YFZ350 LE-S Banshee - Ltd Edition Black 04
*Yamaha Off Road
IT250 H,J 81-82
TT250 G,H,J 80-82
WR250 V 89
WR250 A 90
WR250 ZB,ZD 91-92
WR250 ZE 93
WR250 ZF 94
WR250 ZH 96
WR250 ZJ 97
WR250 ZK 98
YZ250 D,E 77-78
YZ250 F 79
YZ250 G 80
YZ250 H 81
YZ250 N,S 85-86
YZ250 T,U,W 87-89
YZ250 A,B 90-91
YZ250 D 92
YZ250 E 93
YZ250 K5DJUSA98
IT400 D,E,F 77-79
YZ400 D,E,F 77-79
IT465 H,J 81-82
YZ465 G 80
YZ465 H 81
IT490 K,L 83-84
YZ490 K, 83
YZ490 J,L,N,S,T,U,W 82-89
WR500 ZE,ZF 93-94
*Yamaha Road
DT250 MX-D,E,F,G,H Australia77-82
SR250


(*ALSO COMES IN 10T, 15T, 16T, and 17T, although none of those sizes would be of interest to us aside from supermoto conversions wanting to keep the same length chain as offroad gearing to swap wheels back and forth)

[Chuck78]

Here's an extended spline version off of a few older Yamaha models, 8.0mm width splined portion:

https://www.jtsprockets.com/catalogue/part/JTF575/

It lists "Available sizes:13, 14, 15, 16" but only shows application listings for 14T and up. The full part number for a 13T JTF575 would be JTF575-13

JTF575.png (8.29 KiB) Viewed 540 times

Applications:
14 Teeth
*Yamaha Off Road
TT250 S,T,W,A,B 89-92
TT350 S,T,W,A,B 86-92
*Yamaha Road
TT600 L,N,S,T,A,B,D 83-92
TT600 E

15 Teeth
*Yamaha Road
XT400 4 Valve 83-84
XT550 82-83
SRX6001XL,1XM 86-94
TT600 E 96-00
XT600 83-84
XT600 85-86
XT600 Tenere 84
XT600 H,N,D,E,Z Tenere 85-88
XT600 L,N,S,T,U,W USA84-89
XT600 C-L,N,S,T,U,W USA84-89

[Chuck78]

...AND... the widest spline sprocket fitment of interest, the early KX/KDX!

JTF507 (Steel Front Sprocket)
Available sizes:13, 14, 15 (JTF507-13, etc)
8.8mm spline width!

JTF507.png (8.03 KiB) Viewed 540 times

Applications:
13 Teeth
*Husqvarna Off Road
250 CR 95-97
360 CR 92-94
360 WR 92-98
*Kawasaki ATV
KLT200 A1,A2,A3 80-82
KLT200 A4,A4A,B1,C1,C2 83-84
KLT250 A1,A2 82-83
KLT250 C1,C2,C3 Prairie 83-85
KLT250 P1 Police 84
KXT250 A1,A2 Tecate 84-85
KXT250 B1 Tecate 86

14 Teeth
*Cagiva Off Road
250 WMX 89-92
*Husqvarna Off Road
250 CR 90-91
250 CR 92-94
250 WR Enduro 92-98
250 WR/CR 90-93
*Kawasaki Off Road
KDX250 B1 82
KDX250 B2 83
KDX250 B3,C1,C2,C3 83-85
KX250 A5 79
KX250 A6 80
KX250 A7 81
KX250 B1 82
KX250 C1-C2 83-84
KX250 D1 85
KX250 D2 86
KX420 A1-A2 80-81
KX500 A1 83
KX500 A2,B1 84-85
KX500 B2 86
*Kawasaki Road
KE250 B1-B3 USA77-79

15 Teeth
*Husqvarna Off Road
360 WR 99-02
*Kawasaki Off Road
KDX400 A1 USA79
KDX400 A2 USA80
KDX420 B1 81
KDX450 A1 82

[Chuck78]

It also occurred to me that Sprocket Specialists or PBI would very likely be readily equipped to make a custom sprocket to our specifications but of the widest splines possible, for a output shaft seal sleeve protrusion of perhaps only 1.0mm or .75mm and the extended splines making up the difference. This would be a nice preventative measure or repair measure as well if enough people got together to get a small group purchase batch made up, and someone turned down a handful of the output shaft spacer seal sleeve collars to the appropriate dimension.

https://sprocketspecialists.com/custom-builds/

https://sprocketspecialists.com/product/front-sprocket/

never heard of this company, but it sounds like they may make custom sprockets as well, perhaps front per their custom order form:
http://www.rebelgears.com/customsprockets.html




I really think this is just a wear and tear issue, although very likely accelerated in wear by a loose fitting aftermarket sprocket as well as too tight of chain tension.
ALWAYS check chain tension baseline with the suspension compressed around halfway - whether you have a heavier person sit on the seat and bounce on the seat while you check the tension when the axle / swingarm pivot bolt / countershaft sprocket are all straight inline with each other , as THAT is when the chain sees it's maximum tension under suspension travel. Checking chain tension with the bike sitting on the side stand or up in the air on a bike stand or center lift is not a good indicator of proper tension, especially if the bike is lowered or has a longer than stock shock etc.

[Chuck78]

Apparently SuperSprox was bought out by All Balls in recent years... They were formerly a fairly high end sprocket maker, perhaps their products are still better quality than JT Sprockets, since Renthal doesn't seem to offer an '83-'86 KX500 front sprocket, although since the sprocket design # seems to be somewhat of a copied almost-industry-standard, I'll look into it, as the JT569 KDX sprocket showed me that SuperSprox made a CST-569-13-1 version that's a direct fit to our KDX's, and also made a 1990's Husqvarna CR version (identical to the '83-'86 KX500 sprocket specs), and I found they make a 13T version by changing their part # to the desired spec using the somewhat standardized sprocket model # substituted in:
Supersprox "CST-507-13-1"

https://www.allballsracinggroup.com/cst ... t-sprocket

718FUhC9a2L._AC_SX679_.jpg (51 KiB) Viewed 535 times

[KDXGarage]

Thank you for researching it!

[billie_morini]

This content above caught my: "...perhaps their products are still better quality than JT Sprockets,..."

I usually buy Sunstar fronr & rear sprockets for my KDX and DRZ. The new sprockets going onto my KDX are JT brand. I've not ever used them. If they are not so good, then I wished I'd not purchased them. I guess I'll find out going through December and new year.

[billie_morini]

Chuck talks about high content moly grease for high load applications like KDX counterpart and BMW shaft drive (and clutch splines!). I've had BMW shafties for decades and have applied & re-applied moly grease at specific intervals. It really does cushion the splines. I also applied moly grease to my KDX counterpart when installing the new front sprocket earlier today.

For those that are not familiar with this grease, it's:
1) very, very thick & very, very sticky
2) has moly content of 60% or greater
3) best applied with a tooth brush - a little goes a long way & the brush is used to really "work" this thick grease into the "nooks & crannies"

The photo below shows the product I have used for years. You can even buy it on Amazon.

[KDXGarage]

Thanks, billie.

[Chuck78]

https://www.partzilla.com/product/honda/08734-0001

[KDXGarage]

$17.56?! Billie, how much for a teaspoon? HA HA

[billie_morini]

For KDXGarage, no charge!

[kdxdazz]

Well done for spotting the wider splines of the kx500, I used this quite a few years ago in my early days of kdx ownership, had to machine down the bushing, it's super tough and made of bearing steel
I used the kx500 sprocket after a failed attempt at welding the sprocket to the shaft , it's almost impossible to do as the sprocket needs to be pushed hard to against the bushing to seal the o rings although admittedly I didn't think about this when i was doing the welding. I should add Tig welding first attempt didn't work, cracked instantly, 2nd attempt was stick welding with stainless rods worked, although now I am older and wiser I now know all hard casing should be done with high nickel content rods which I now own
JT stands for jomthai which is a Thai Brand, they are not great and in my experience not comparable to Japanese quality
Not sure if it's on my YouTube channel but I replace all my front sprockets with original Yamaha wr200 sprockets, the fit is much better than the other brands
When I finally replaced the output shaft amazingly the sprocket was loose again within just a few rides, that particular bike I ended up using Loctite 660 on the splines,Think it is still solid and will do all the rest of my kdx's
As you stated moly grease is a must but the spline design is so bad that the ingress of dirt and water just acts as a grinding paste,I don't think any dirt bikes use that silly design anymore

[KDXGarage]

Jomthai... new to me. Never stop learning. Thanks for the info.