LC50 Champ Brakes and Wheels

OK, my wheels are rusted out on my Yamaha Champ LC50, I know I can buy used replacements on ebay, but with shipping to my remote Canadian location it was going to be nearly $200 CAD which is insane. Also I was wondering about upgrades or disc conversions I found the idler pulley disc mount method on this forum and it is a decent option on a budget. But, I wanted to make my machine stand out a little and change it up. I have been obsessing over this for weeks and spent hours digitally measuring photos using the Pythagoras theory, counting pixels and gathering specs. Here is what I have discovered.

Yamaha Razz or Yamaha Riva rims should bolt up with out issue to the LC50 Champ. They share the same 16 spline rear drive axle and 10mm front axle. A spacer may be required for the rear wheel as they are designed for the CVT housing. They also use an EBC519 Brake shoe front and rear. I do not own either of these bikes and cannot prove this though.

PW50 wheels will not fit due to smaller spline shaft in the rear and smaller brake shoes. Also they are 3 spoke which I personally don't like. In theory if you love 3 spoke you could use the QT50 rear drive axle assembly with the PW50 wheel. and the whole front PW50 axle and brake assembly and wheel. This would lead to smaller brakes and even worse braking though.

Below are the full specs for the wheels and rims for the champ and Jog R/ZR I was very interested Jog R because there are some aftermarket options for wheels for this bike and the stockers are actually really nice. Note: The new Jog RR rims use the larger 18 spline shaft and will not fit.

Champ Front Rim / Wheel

10mm center shaft (AxleShaft)

10 inch rim x 2.15 inch width

Will fit a 10 x 2.5 to 10 x 3.5 tire

Drum Brake (EBC 519) 95mm Diameter x 25mm depth

Champ Rear Rim / Wheel

10 inch rim x 2.15 inch width

16 Spline count on centershaft

Will fit a 10 x 2.5 to 10 x 3.5 tire

Drum Brake (EBC 519) 95mm Diameter x 25mm depth

Spline diameter 17mm

Yamaha Jog R Front Rim

10 inch rim x 2.15 inch width

10mm centershaft (Axle Shaft)

Will fit a 10 x 2.5 to 10 x 3.5 tire

200mm front disc 57 mm 3 hole mount

Yamaha Jog R Rear Rim

10 inch rim x 2.15 inch width

16 Spline count on centershaft

Will fit a 10 x 2.5 to 10 x 3.5 tire

EBC 503 110mm x 25mm Brake Shoe

Armed with this info I pulled the trigger on some aftermarket Jog R/ZR rims from China and I am please to announce that they fit, but some adaption will be needed.

20191120_134910.jpg
20191120_134913.jpg
20191120_134907.jpg

As you can see from the specs the rear drum for the Jog r has a 7.5 mm larger radius drum brake this means I have 3 options for the rear: figure out how to run bigger drum brakes, install a 7.5mm spacer in the rear drum to make it 95mm again or do the pulley disk brake conversion. I also have to put a small spacer on the axle shaft as the rim wants to rub against the driveshaft tube. Up Front I have to weld up a caliper mount and cut off the peg from the front for that keeps drum assembly in place.

I still have some work to do here, I have not ordered the large 200 or 220 mm disc brake kit yet as my research on this is not yet complete. When I get home tonight I will mount up the whitewalls and the front rim to check clearance for the disc, which I just held up as I didn't have time to mount it.

If you decide to use this information please be very careful. Yamaha scooter rims come in both 10mm and 12mm front axle shafts and the rear splines can be 16 or 18 count. Not to mention the smaller size of spline used on the QT50 and PW50. (edited)

Re: LC50 Champ Brakes and Wheels

Jeremy Homser /

This is very cool! Good luck with your project

Re: LC50 Champ Brakes and Wheels

This is awesome detail!

Usually the shaft diameter doesnt matter, just spline count:

looking into it the spline shape is pretty standardized, so the size of the shaft is basically pre-determined by the number of plines which are like 3.1mm radial spacing (inner). So what winds up happening and this is clever is being about pi in length is that the mm of the inner part of the splines equals pretty much the total diameter

(circumference = 2*pi*r = pi*diameter) then if# splines = circumference / spline width and spline width = pi, then basically # splines = inner diameter

THAT IS FUCKING NEATO!

spline height's about 1mm too

so an 18 spline has 18mm ID, plus 1mm on each side for spline height is 20mm OD

or 19 spline = 21mm OD

etc etc

Point being though, only Spline count matters, anything with matching spline count SHOULD have by default the same diameter.

I was at one point trying to get 10" wheels on an arrow, cuz I think theyd look rad with smaller rims but fatter tires, same final OD but more toy-like. I ordered some scooter wheels cheap but sold the arrow before I got em n had a chance to really dig into what fit.

The arrow is 18 spline and brake is 110x25

Your set of detail here adds to that info nicely.

Re: LC50 Champ Brakes and Wheels

I would see what happens if you just put bigger brake pads on there. you might get lucky, I could see the brake arm/spreader still working on bigger pads.

Re: LC50 Champ Brakes and Wheels

Dirty30 Dillon /

WIllD, technically the spline to diameter correlation is correct, although I think about things like the Kinetic Vs. Vespa Output shaft on the trans' that don't mesh properly, despite being the same OD and spline count.

How the splines are broached onto the shaft can alter the fitment just enough to make it out of whack.

This info is VERY cool, although over coming having to sleeve the brake surface may over shoot the same budget for the stock wheels.

Re: LC50 Champ Brakes and Wheels

Thanks so much for the wealth of information on this topic! I have been sitting on pins and needles wondering if they would bolt up while they were in transit. I think I will order a set of brake pads for the rear to see what happens. I posted this over my lunch break when the rims came in. so I didn't get much of a chance to do anything.

I do believe the QT50 but the diameter of the shaft in smaller. I will look when I get home as I have both rear ends in my shop.

Re: LC50 Champ Brakes and Wheels

Dirty30, you are absolutely right regarding budget I paid $170 for the rims shipped from ali. The 200mm front disk kit I have been looking at is $60 shipped so I am around $30 over the cost of two used rims. but that buys me 2 brand new rims and a big brake upgrade. Granted I have nothing sorted for the back brake yet.

I have put a number of go fast mods on my Champ which makes me want better braking as this was a weak point to begin with. I also have access to a welding shop and some machining equipment which cuts my costs substantially. The other thing I have failed to talk about is the front hand controls and possibly rear will also need to be altered for hydraulic brakes.

Given the better braking, the unique rims and the chance to learn and share some new information I personally think the extra bucks are well worth it. (edited)

Re: LC50 Champ Brakes and Wheels

yea they look sweet too

Re: LC50 Champ Brakes and Wheels

having a chappy i'm interested in how you work things out with a front disc...

Re: LC50 Champ Brakes and Wheels

Dirty30 Dillon /

I helped Doov here in NYC put a disk on his Champ a year or two ago, using a 5-spoke scooter rim that was a really close match to the stock rear. Very simple setup, and worked REALLY well

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