900 Cush Drive Question.

[brad black]

i have a customer with a 10/96 m600 just like minnie and it has a carrier which places the sprocket too far out.  it has been fitted with a 5.5 rear wheel, and i replaced sprockets the first time i saw it and have just done so again 15,000km later and the rear sprocket was quite worn on the outer adge of the teeth.  when i replaced them i put the laser aligner on the outside of the front sprocket (flat side out) and it hit the middle of the rear sprocket ish when the rear (axle) had been aligned with the same tool.  as the aligner line usually sits on the chain outer side plate this meant the chain was about 5 or 6mm out of line i thought.  the front edge of the rear sprocket would have been turned in slightly by the aligning process, as you're just pointing it at the front one basically, but sitting the tool on the front sprocket gives you a nice parallel line as it can't move.  when the sprocket is mounted on the cush drive carrier there is a mm or so carrier protruding at the center, just like minnie and the 851 and every other one i could see at the time.

i then noticed on a customer's 01 m750 that it had much more centre protruding, like the carrier was machined to allow the sprocket to sit further in toward the centre of the bike.  i've seen a lot of these on ebay, mostly 25mm axle ones from little engined bikes (nominally 4.5 rear wheel).  but some called m750 00.

i've also seen some of the (i think) 4.5 rear wheel bikes with a much thicker spacer fitted b/w carrier and swingarm.  probably in the order of 5mm.  possibly only st framed bikes, i don't recall the pattern.

anyway, i need the 13.mm offset carrier.  i didn't think of checking that dimension.

the pins changed when they went to lh thread into the carrier.  the early ones that had the nuts come off were rh thread in the carrier, then they went to lh.  when you tighten the sprocet nuts on the lh ones it tightens it all up.  on the rh ones it unwinds the pin if you don't have the pin and carrier fixed.  so while the nut is tight against the sprocket the pin is not tight on the other side and it can wind in (towards the outside) and unload the nut.

[koko64]

Id be happy to swap with him Brad. It's a good one, nice and tight in the bushes and the bearings are good.
What you describe makes sense. He has the big wheel, but he needs the smaller wheel carrier to get alignment with the small case front sprocket/swingarm combo. You can try it and measure it up.

[Blue]

Perhaps it's due to the 748 transmission, but my Monster S4 has the same trans and uses the normal sprocket. 

I had an M900ie in for a chain and sprockets a while back.
I carefully measured, and the alignment was better with a normal sprocket.

Speeddog, I have my Monster in for the winter and would like to measure the alignment of the chain (among other details).  Would you be willing to let me know how you checked the chain and sprockets?  Thanks!

[OzzyRob]

If you've still got the sprocket carrier I'm interested.

[koko64]

Yes I have it, but it suits the 750/600 narrower wheel.

[OzzyRob]

Got the carrier today 

[koko64]

OR, I know you wanted the 750 cush drive/sprocket carrier. Yet you have a 900, so what's your plan with the part?

[OzzyRob]

The cush drive I machined to get the sport wheels to fit was about .15mm - .2mm out on the sprocket mounting face. The 750 is a godsend as I only have to machine for a new circlip, reduce the boss accordingly and throw in some thinner bearings.

Plus if anyone else wants to follow the route I took it'll save having to machine down the cush drives pins and cut the thread. And no need to make a complete new sleeve\spacer just take about 3mm off the inside end and reduce the O\A length.

I know this doesn't make a lot of sense but once I continue in my spoke wheel howto it'll all become clearer.

[koko64]

Picked up cush drive pins from the local dealer for 55 bucks! Thats what the 750 carrier owed me and what I got back for it (thanks Rob).
I fitted them with a light coat of high pressure grease on the pins where they insert into the cush rubbers.
The carrier/cush drive play is gone.
Note that the pins have a left hand thread into the carrier.