'73 Suzuki GT250 - Part 8 - Lining up chain and rear wheel

Here's an update of my '73 GT250K VMX build. After getting rear wheel refurbished and rear shocks installed it was time to get the '79 RM125 rear wheel installed to the '79-80 PE/RM250 swingarm. I was missing few crucial of parts needed for the rear wheel axle assembly such as rear wheel axle itself, chain adjusters and rear hub panel spacer which I needed to either buy or make myself. I started by purchasing rear wheel axle out of Rieju RR/Derbi Senda which had the correct 15 mm outer diameter to fit RM chain adjuster spacers and rear wheel bearings. It was advertised as 275 mm long but ended up actually being 285 mm long which meant that it needed add spacers to both ends of it.

Rear wheel axle assembly to fit '79 RM125 rear wheel
to '79-80 PE/RM250 swingarm installed to '73 Suzuki GT250K

15 x 285 mm rear wheel axle Rieju RR, Derbi Senda (#752103)

Chain adjuster assembly

It was quite difficult to find proper sized chain adjuster spacers for '79-80 PE/RM250 swingarm. After asking for crucial dimensions I managed to get a hold on a correct pair. They needed a new surface finish so I decided to use gun blue for them for now. I'm not totally happy with the finish since it tends to build up surface rust for some reason after applying it to a clean metal surface. I'm gonna get few other parts zinc coated later so I might throw these in that patch as well.

Sandblasted and acetone dipped
chain adjuster spacers (#64781-40300)

Surface after applying Perma Blue...

... and after rinsing with warm water and oiling

New nuts for chain adjuster spacers (#09140-22006)

I was missing adjusters for the chain adjuster assembly and couldn't find either used or NOS parts on sale so I decided to make them out of 2 mm stainless steel sheet since they are rather simple parts. Only difficult part is to get the 90 degree bends to correct position. I made few test bends before bending the actual parts. After checking few dimensions for them I came up with 2D model (DXF) to be cut with abrasive water jet cutter located in our University's workshop. After cutting I first deburred them with Dremel and then sanded and polished them. I then protected the polished surface with masking tape and marked the bending lines before bending them with a folding machine. Last step was to tag weld nuts inside of them.

Dimensions for chain adjusters

Preview of DXF-file to be cut

Abrasive water jet cutter
at the workshop of Uni Oulu

Cutter head

User interface, UI

Chain adjusters cut out of 2 mm thick stainless steel sheet

Deburring inside and outside edges with Dremel

Sandpapers from 240 to 600 grid for water sanding

Autosol polishing paste and cloth

After sanding and polishing

Protected outer surfaces with masking tape
and marked bending lines

Bend and welded chain adjusters

Chain adjusters ready

To finish the rear wheel axle assembly I needed to turn out few simple spacers for it. I used stainless steel for the rear hub panel spacer and aluminum for the spacers to align the rear wheel.

Dimensions for rear hub panel spacer (#64213-40300)

New rear hub panel spacer turned out of stainless steel

Dimensions for spacers to align rear wheel

Turned spacers out of aluminum

Rear wheel axle assembly ready!

I decided to use ProX parts for chain and sprockets setup. I found a nice black aluminum rear sprocket which fit to my rear wheel. I replaced sprocket side axle seal with a another one to fit those new aluminum rear wheel axle spacers.

ProX rear sprocket, alloy (#07.RA32080-51)

ProX Rear Sprocket Bolt Set (#07.SBSM825)

Back side of the bag

Rear sprocket bolt set out of the bag

New rear wheel axle seal (22x35x5) to fit 15x22 mm spacers

Rear wheel with new rear sprocket and axle seal

Finding a right sized front sprocket suitable for 520 chain required bit of searching through Google. After some time I came up with #07.FS42094 front sprocket which had the right axle pattern to fit GT250 counter shaft. It is meant for 94-08 Kawasaki KX125.

ProX front sprocket (#07.FS42094-14)

Out of the box

I put together a mockup assembly, which consisted of lower crankcase and counter shaft with front sprocket and bearings, and mounted it to the frame with swingarm and rear wheel. I bought two long enough steel U-profiles to first align rear sprocket and then measure lateral position of rear wheel rim after installing right length rear wheel spacers. I started with shorter mockup spacers and end up with those aluminum ones shown earlier in this post.

Counter shaft assembly for mockup

Lower crankcase, lay shaft and case screws and nuts

Two U-profiles helped with aligning

I tightened a U-profile to rear sprocket with a wood clamp
to find right lateral position for it and measured correct length
for those aluminum rear wheel axle spacers

Closeup of front sprocket

Side view

Checking the rim position after installing
rear wheel axle spaces

Another side view

Used swingarm and engine mounts as a reference and
marked current position of the rear wheel with a pencil
to calculate the new position for the it

Yamaha RD 350 F2 '88 - Part 6 - New rear wheel bearings, seals, X-ring chain and sprockets

While maintaining rear linkage for my RD350 I went and replaced worn out sprockets and chain. The old chain had strained quite a lot during its life time and it was already tightened to its max position. One option would have been to just shorten it but since the old rear sprocket was also in pretty bad condition I decided it was best to just replace all those parts. 

I ended up choosing sprockets made by JT Sprockets and a X-ring chain made by D.I.D. I went with 17 tooth front and 39 tooth rear sprockets. Since the chain needed to be riveted I had to buy a chain breaking and riveting tool also made by D.I.D. There were two types of tools for sale. I bought the cheaper one, which had "02-99" stamped on the side of it. While riveting the chain I found the lower jaw of the tool bending and had to make a cotter out of flat bar to stop it.

I also decided to replace rear wheel bearings while I had the rear wheel out of the bike. I bought a kit which also included right sized oil seal (22 x 42 x 7 mm). I used a gas torch to heat up and expand both bearing hubs in the rear wheel to get the old bearings out and to install the new ones. Depending on the condition (rusty) of the bearings you might need give them a small knock. If you have painted your wheels you might need to use another solution. If you don't have proper tools for the job, there's a lot of shops, which can do it for you. 

Unfortunately I forgot to buy a new bearing (6304) for the sprocket carrier and since it was Sunday and all the shops were closed when I was doing all of this in a hurry to get the bike finished I just ended up greasing the old bearing and replacing worn oil seal with a new one (32 x 52 x 7 mm).

To sum all up here's a list of all parts needed for the job:

-Tourmax rear wheel bearing and seal kit (MCI-WBK-055) 

 or two 6302 bearings (15 x 42 x 13 mm) and oil seal (22 x 42 x 7 mm)

-Oil seal for sprocket carrier (32 x 52 x 7 mm)

-6304 bearing for sprocket carrier (20 x 52 x 15 mm)

-JT Sprockets 17 tooth front sprocket (JTF569.17)

-JT Sprockets 39 tooth rear sprocket (JTR846.39)

-D.I.D 520 VX2 X-ring chain with 106 links

-D.I.D chain breaking and riveting tool (02-99)

There's also one O-ring (93210-40530) in the rear wheel you might need to replace. Since mine was in good condition I just ended up greasing it.

Tourmax rear wheel bearing and seal kit (MCI-WBK-055)
and collar (90387-154A0).

Rear wheel (black) and sprocket carrier (blue) oil seals

Front and rear JT sprockets and D.I.D 520 VX2 X-ring chain.

D.I.D chain breaking and riveting tool.

Parts of the tool... 

...and instructions for it.

Cotter kept lower jaw from bending.

Bearings and other hardware removed...

...and new parts installed.

New rear sprocket and oil seal installed.

X-ring chain riveted and tightened.