'73 Suzuki GT250 - Part 9 - Front wheel size conversion from 19" to 21"

For this project I decided to change the front wheel diameter from the stock 19" to 21" which is normally used in motocross and enduro motorcycles. I started by masking both sides of GT250 front wheel hub and sandblasting it at our university's workshop. I got it painted with matte black at the same time as few other parts like rear wheel hub and triple clamps for front forks. Before taking those parts to the paint shop I cleaned them with acetone. I left same masking for painting which I used during sandblasting to protect areas I didn't wish to be painted. After that I installed pair of 6302 (DDU 2RS) (15x42x13 mm) front wheel bearings to the hub together with front hub spacer.

Masked and sandblasted GT250 front wheel hub

Hub after after painting

I used a file to cleanup edges of paint

New front wheel bearings 6302 (DDU 2RS) (15x42x13 mm)

#54730-18400 Spacer, front hub,
to go inside the hub between bearings

I decided to replace the stock front axle spacer and speedometer drive with aluminum spacers. I'm gonna use a modern speedometer in this project, which uses a magnet instead of a wire drive. Dimensionwise the front hub is symmetrical so I was able to use same sized spacers on both sides. Only difference is that hubs for axle seals are different and I needed to buy two types of seals (25x42x6 mm and 25x43x8 mm). Otherwise I'm going with stock parts in the front wheel axle assembly. I replaced the old spacers (#09180-15034), which go underneath the axle holders, with new ones. I will use this setup together with GT550 front forks I purchased a while ago. More about that swap later 😎

Front axle spacer (#54740-18402)
and speedometer drive (#54600-18402)

Dimension drawing for new front axle spacers

Turned new spacers for front wheel in a lathe out of aluminum

Pair of axle seals (25x42x6 mm & 25x43x8 mm)

Pair of spacers (15x22x30 mm), #09180-15034

GT250 front wheel axle

Front wheel axle assembly

To achieve the look of a motocross bike and to match the RM rear wheel I ordered a new 36 holed and undrilled 21-1.60 Excel rim (#ICS402U). It had a silver coating on it, but I polished it to match the look of the rear wheel. I only used polishing paste to get rid of the coating, which was quite soft. Only bad side of that method was that it tends to clog up the buffing wheel. Rim itself will not tolerate as much abuse anymore without the silver coating, but for more show than go bike it looks better in my opinion.

New 21-1.60 Excel rim waiting for unboxing

Product data on the box

Stamping on the lip of the rim

Seam...

...and the other side of it

Buffing wheels and polishing paste

After getting the rim polished I packed it with hub, spacers, reference nipple and instructions and send them to Wheel Factory Finland Oy. They designed new spokes for it, drilled the rim and laced it according to my reference. I went with polished stainless steel spokes and nipples. I'm very happy with the result. Only bad thing about the work was that it took 5 months for them to finish it. I send it in beginning of January and got it back during May. It was also quite hard to get in contact with them during those months after initial chat about specifications of what I wanted. If you're thinking to use their services like I take that into account. Luckily my projects aren't in too much of a hurry 😄

Assembled front hub waiting to be packed with spacers,
reference nipple, rim and instructions

Shipping address for Wheel Factory Finland Oy

Finished wheel waiting for unboxing

GT250 wheel hub laced with stainless steel spokes
and polished 21-1.60 Excel rim

Rear wheel bearings and brake shoes - Suzuki T250J

Next thing on the list of many things was to replace rear wheel bearings and fix the wheel fitment. Old owner of the bike had installed a wrong spacer to the rear wheel axle which was a bit too long. I tried to order the correct spacer (part number 09180-25011, dimension 25 x 30,5 x 11,3 mm) from my local Suzuki parts dealer but they told me that it was no longer in production. Instead I  had to order a spacer (part number 09180-25033) with dimensions close to the original one (25 x 32 x 10,7 mm). With a different size spacer I also had to replace the oil seal around it. To get the correct length for the spacer I cut out four shim plates with a laser cutter from a 0,6 mm thick stainless steel sheet.

Here is a list of all the parts I purchased:

  Quantity    Part number       Part                                                                     Dimension [mm]

- 1 pc.          63032RS            Right rear wheel ball bearing 6303                   17 x 47 x 14
- 1 pc.          62032RS            Left rear wheel ball bearing 6203                     17 x 40 x 12

- 1 pc.          09262-25003      Rear sprocket hub ball bearing 6205                25 x 52 x 15
- 1 pc.          09180-25033      Rear axle spacer                                                25 x 32 x 10,7
- 1 pc.                                     Sprocket hub oil seal                                         32 x 52 x 8
- 1 pc.                                     Spacer shim plate                                              25 x 32 x 0,6
- 1 pc.          MCS 904            TRW Lucas brake shoes GT 250 380 500        180 x 28

New rear wheel and sprocket hub bearings for my Suzuki T250J.

Spacer, oil seal and shim plates for the rear axle. 

I removed the right side bearing first with a heat gun by heating the bearing housing from the outside. I didn't want to remove the rubber cushions from the left side. Old rubber cracks easily and I didn't want to break them. To get the left side bearing out I heated the bearing housing from the inside and pushed the bearing out. 

Old rear wheel bearings removed.

I was able to drop the new bearings in place easily after heating the bearing housing with a heat gun.

New bearing in place.

I did the same thing to the rear sprocket hub and installed new brake shoes to the brake hub.

New sprocket hub bearing in place.

Fitting the new spacer and oil seal.

New brake shoes.