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.
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| Masked and sandblasted GT250 front wheel hub |
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| Hub after after painting |
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| I used a file to cleanup edges of paint |
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| New front wheel bearings 6302 (DDU 2RS) (15x42x13 mm) |
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#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 😎
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Front axle spacer (#54740-18402)
and speedometer drive (#54600-18402) |
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| Dimension drawing for new front axle spacers |
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| Turned new spacers for front wheel in a lathe out of aluminum |
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| Pair of axle seals (25x42x6 mm & 25x43x8 mm) |
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| Pair of spacers (15x22x30 mm), #09180-15034 |
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| GT250 front wheel axle |
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| 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.
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| New 21-1.60 Excel rim waiting for unboxing |
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| Product data on the box |
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| Stamping on the lip of the rim |
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| Seam... |
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| ...and the other side of it |
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| 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 😄
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Assembled front hub waiting to be packed with spacers,
reference nipple, rim and instructions |
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| Shipping address for Wheel Factory Finland Oy |
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| Finished wheel waiting for unboxing |
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GT250 wheel hub laced with stainless steel spokes
and polished 21-1.60 Excel rim |
