Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[lukec53]

The Goal
To compile all of the required information for anyone to make/assemble their own chain kit with any ratio they choose.


The Data - What we know

Front sprocket spline:
(measured from a 2020, I think it is the same for any 2017+)
Number of teeth: 13
Major diameter: 24.9mm
Minor diameter 21.3mm
(Diameters above are approximate; these are difficult to measure with digital callipers given the odd number of teeth)
Module/Standard: Actual specification unknown, but seems to match JTF565.

Front sprocket spacer:
Ideally 25mm ID x 33mm OD
Length: 16mm (needs to be confirmed, this gives a slight amount of clearance so that the retaining washer does not clamp the sprocket/spacer)

Rear sprocket:
(appears to fit all years?)
Bolt Circle Diameter: 132mm
Bolt holes: 4 holes, 8.5mm diameter (M8 bolts). The Zero chain kit uses countersunk bolts, I just used the same socket heads with washers from the stock pulley.
Center hole: 110mm diameter

Chain:
Chain size (sprocket width): 520
Number of links required: 113-115 (120 links is a common off-the-shelf length)
Gearing options:OEM kit: 65T rear, 12T front (5.417:1)rayivers try #1: 71T rear, 12T front (5.917:1) (he says 71T too big for rear)
rayivers suggestion: 65T rear, 11T front (5.909:1)
rayivers try #2: 65T rear, 10T front (6.5:1) (10T front requires modification to retaining washer)My try #1: 66T rear, 11T front (6:1)

[lukec53]

Useful References

These two posts by rayivers were where I got most of my info.
https://electricmotorcycleforum.com/boards/index.php?topic=4559.0
https://electricmotorcycleforum.com/boards/index.php?topic=6803.0

More clues grabbed from here:
https://zeromanual.com/wiki/Chain_Kit

^ Including this excellent video that shows details of the kit and the install process:


Here was a previous question about the spline for the front sprocket. There is no resolution, but Harlan suggests it may be the same as KX250F and YZ450F.
https://electricmotorcycleforum.com/boards/index.php?topic=7010.0

This sprocket seems to match the spline. Also note the list of bikes that this fits.:
http://www.jtsprockets.com/catalogue/sprocket/JTF565/

[lukec53]

The Story

Hi everyone, this is my first post here. (I wanted the first two posts to be at the top so that I can keep the top post updated with the most recent information). I apologize for a long read, but I am hoping some of you will want to dive deep into this with me. If not, I will think out loud here so someone may stumble upon it later and have some useful information.

I bought a 2020 Zero FX 7.2 (single battery) last year. I am in western Canada. Since I ride mostly offroad in tight forest trails, I want to convert to chain drive.

After a ton of searching, the only kit I could find was the one offered by Zero, and a couple online resellers of that same Zero kit. I contacted my local dealer who quoted $650 CAD (around $520 USD).

I care more about low speed torque than I do about a high top speed. So I knew that I likely would want to swap the front 12T sprocket from the kit for an 11 or 10, and maybe even wanted a larger rear. Therefore, it seemed silly to buy the OEM kit only to keep the "least important" parts.

I have a mechanical engineering degree, and I work in machine design. So as soon as something is not readily available to buy, my mind immediately goes to building it myself.

I was disappointed (but not overly surprised) at the lack of aftermarket options, and (other than the links shown below) the lack of info to build one's own kit. I saw Sprocket Specialists mentioned by a couple people on this forum, so I thought I should see if they could do it. I talked to them and although they did not have a pattern for the newer splined front sprocket, they seemed eager to work with me to figure it out. From what I understand, they had a contact at Zero that they had worked with in the past. They requested the front spline info from Zero, and did not get anything.

This made me think that Zero may be protecting this information. Though I can't really blame them, I don't like the idea of monopolies. So this is when the idea of building my own kit and putting the info out here for all to see was really cemented.


My Build So Far

Using the dimensions listed above, I ordered a 66T rear and an 11T front from Sprocket Specialists. The rear fits perfectly. The front seems to have a bit of "slop" at the spline. I am not sure how much clearance is normal here. I would feel more comfortable with a tighter fit, but it is not enough to make me think that it is the wrong spline.

For the front sprocket spacer, I took a 18mm long piece of 1" schedule 40 pipe, slit along the length and clamped back closed to reduce the ID a bit, then milled both ends flat with a finished length of 16mm. This seems like it will work fine, but it would be cool to find a tube/pipe that doesn't need to be re-sized.

I am working on a design for the lower chain guide. I have access to a CNC mill and a 3D printer, but I am going to try to have it simple enough for others to fabricate with basic shop tools.

For the swing-arm shield it seems I just need to protect the top of the round crossmember from the chain rubbing on it. Seems like any rubber/plastic wrapped around will work for this. Maybe even ABS pipe? I am hoping as I finish assembling the sprockets, something will come to me.


Main Questions (as of 2021-04-20)

Front sprocket spline:
I know this has been asked before, but I want to figure out the actual spline specifications (the information required to put on a drawing and bring to a machine shop with no motorcycle-specific knowledge). At my job I am used to splines being described by diametral pitch, pressure angle, and number of teeth. I suspect this specific spline may be better described by a metric "module".

Hubbed front sprocket:
I am currently in search of a front sprocket with a hub that can utilize more of the spline. It seems silly to me to use only 6mm of the 22mm available spline length. Does anyone know of such a sprocket? I whipped up a drawing and talked to Sprocket Specialists yesterday about it, but they are too swamped right now to make a one-off of such a custom design.

To clamp, or not to clamp?
For the front sprocket spacer, my intuition was to make the spacer short enough so that the sprocket/spacer do not get clamped by the retaining washer. This is based off the way we do it at my job, to avoid fatigue failure of the bolt. However, after I assembled the parts, I was concerned by the amount of movement I could feel when manipulating the sprocket by hand. This makes me second-guess my assumption. Does anyone have any experience here?

[valnar]

I care more about low speed torque than I do about a high top speed.

You find the low-end torque lacking on the FXS?

Edit: You did say FX.  I read that wrong!  Either way, good luck.

[lukec53]

You find the low-end torque lacking on the FXS?

Lol, no, not lacking. The torque on these bikes is amazing. The ability to lose momentum up a steep hill climb to avoid an obstacle, and still have the torque to recover opens up a whole new world. I am used to riding motocross bikes, so this is a situation where a 250 2-stroke would bog down, a high-compression-ratio 4-stroke would stall, and pulling in the clutch would mean restarting the hill (likely after falling).

This being said, by switching to large knobby tires, the useable torque is now a bit lower than factory. People say that the OEM chain kit (65T/12T) brings it back to feeling stock. Personally I wouldn't mind if the front end came up just a bit easier than stock (ex. getting up over a log), so I chose a ratio just on the side of more torque.

If I was riding mainly on-road (you noted FXS), I probably wouldn't bother changing the ratio.

[Red Clay]

Great work! Thanks for researching and sharing this information. Maybe someone with a zero chain kit will let us know if there is play in the front sprocket. You may have it right, every ICE (honda and yamaha) motorcycle that I've owned had play in the front sprocket.

The belt is made by Gates with proprietary sizing and is unavailable other than through zero dealerships. The FX belt works well and it is easy to replace a broken one, BUT $125 for a nothing special consumable product is too much to pay.  Some (dealers) will say "proprietary is common in the motorcycle business" but this is not consoling to me, the customer who feels price gouged.

Thanks again for your hard work and sharing the rewards.
Please post what you learn on to the (built by us for us) unofficial service manual.

Ride On, Red Clay

[Crissa]

Are belts cheaper somewhere else?

Is there a more expensive belt?
https://www.af1racing.com/Zero-Motorcycles-Drive-Belt-ZM30-08084

-Crissa

[Red Clay]

Most machine drive belts of comparable size are in the 30 to 60 $ range.

The belt quoted from af1racing is for prior to 2017.

Is there anything special about the zero belt besides proprietary and the price?

crissa, I appreciate all of the great advice that you share.

[Richard230]

Are belts cheaper somewhere else?

Is there a more expensive belt?
https://www.af1racing.com/Zero-Motorcycles-Drive-Belt-ZM30-08084

-Crissa

If you are looking for a motorcycle brand that sells more expensive drive belts, try BMW.    How about paying around $450 for an F800GT drive belt from a U.S. BMW franchised dealer? The main reason for that high price appears to be because they had (or had) an exclusive sales agreement with the manufacturer of the belt. (I think I heard that the belt is manufactured by Continental where, now that the GT has been discontinued by BMW, you can buy the belt for around $150.  )

[lukec53]

^ Monopolistic control is never good for the consumer. Hopefully we will get an aftermarket option eventually that will force the price down.

Personally, although I have not had any issues with my belt, I have a hard time trusting it fully. There is always a fear in the back of my mind of it breaking and leaving me stranded, that grows the further I get out into the bush.

[lukec53]

In the mean time, I did some digging last night (more like web scraping off the JT website ) and found some better "off the shelf" options for the front sprocket:

JTF1503 has 10.2mm of engaged spline (compared to 5.7mm on my JTF565). It is available in a 12T.
http://www.jtsprockets.com/catalogue/part/JTF1503/
I ordered one of these from Amazon. Although it is not the 11T I am looking for, I think for now it will give me better peace-of-mind that I am not hurting my splines.

The best I found was JTF1307, with a spline length of 13.6mm. Though unfortunately it only comes as a 14T or 15T.
http://www.jtsprockets.com/catalogue/part/JTF1307/
I am going to check in with Sprocket Specialists to see if they can do a custom tooth count on this pattern.

[Crissa]

Ahh, the new belt is like 30% larger.

https://www.af1racing.com/Zero-MCs-Drive-Belt-ex-ZM30-08086-ZM30-08278

Yes, belts for smaller things are cheaper.  Most machine drive belts are smaller and have worse tolerances.

-Crissa

[lukec53]

I just realized that I have somewhat of a treasure trove. Attached is a collection of diagrams for (what I believe to be) a comprehensive list of all JT sprockets with our spline.

I was playing with ideas of taking the hub from another sprocket and mating it to the 11T somehow. Bolting would be preferable, though there is not a lot of meat to play with on an 11T; would likely be dealing with pretty small bolts (even an M4 countersunk head would be tight). Welding would be another option (likely a series of "cold" MIG tacks, to avoid reducing hardness at either set of teeth).

For now, these options will be left as a "last resort" for myself. But there's no point on me holding onto this information if someone else out there has a good idea!

[Shadow]

Brilliant. Moving topic to parts mods and hacks section. Thanks for contributing.

[lukec53]

I have attached some pictures comparing the new 1503.12 sprocket to the original 565.11.

Unfortunately there is a bevel on both sides of the spline which decreases the useful length a bit. Still, it is definitely an improvement. Wiggling both on the motor shaft, the 1503 feels like it moves approximately half as much.

I made a new spacer that feels perfect at 11.6mm.

Overall I am much more confident with this than I was with the sloppy-feeling 565.

PS: I did not use loctite on the pinion keeper bolt when I installed the sprocket the first time (I didn't have any on hand and got excited). During a quick test ride, (maybe 10 minutes in) the bolt spun loose. So be warned that red loctite is absolutely necessary here.

PPS: I emailed sprocket specialists about doing a 1307 as an 11T about two weeks ago and have not heard back. Maybe placing an order for it will carry more weight, and they can contact me if they CAN'T do it. They were responding just fine when I had an active order in.