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Discussion Starter · #1 ·
In the process of replacing chain and sprockets, and had some questions. Bike has a 4.5" rear, so that means the flat side of the sprocket should go towards the motor, with the little collar on the outside. This is how it is right now, but I feel like it's throwing the alignment off- checking alignment with a straight edge clamped to rear sprocket results in the alignment marks on the swingarm being off by about two notches. I know those can't really be used to set alignmnet, but would have expected them to be closer. The old front sprocket that was removed was installed in the opposite manner- flat side facing away from motor with the collar on the inside. Bike has only ever had a 4.5" rear. Am I missing something here?
 

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Yes if original parts the flat facing away is for a 5.5" rear and flat facing in is for a 4.5" rear. where you need to watch is that there are different cush drives with different spacing if it has been changed then you may mount the front as if the bike has a 5.5".

Simply mount the sprocket then align the rear wheel with the engine, measure both sides from the swingarm pivot to the axle center and make them equal. Then sight down the chain and see if your chain is running at a angle or is straight. If you have the bike on a rear stand and no sprocket retainer you can spin the rear wheel by hand some times (engine off) and the chain will center the front sprocket. If the sprocket is close to where it will be when attached you are good .

As delivered you are correct the question is , Is the bike still as "as delivered"?
 

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Discussion Starter · #4 ·
Yes if original parts the flat facing away is for a 5.5" rear and flat facing in is for a 4.5" rear. where you need to watch is that there are different cush drives with different spacing if it has been changed then you may mount the front as if the bike has a 5.5".

Simply mount the sprocket then align the rear wheel with the engine, measure both sides from the swingarm pivot to the axle center and make them equal. Then sight down the chain and see if your chain is running at a angle or is straight. If you have the bike on a rear stand and no sprocket retainer you can spin the rear wheel by hand some times (engine off) and the chain will center the front sprocket. If the sprocket is close to where it will be when attached you are good .

As delivered you are correct the question is , Is the bike still as "as delivered"?
Interesting, is there any way to differentiate between cush drive versions? Ill check all this next time I'm in the garage, suspect there's a reason the countershaft sprocket was installed the way it was.
 

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i thought the carb bikes would have had the front with the flat side out on both? although i did my 400ss recently and ended up with a centre offset from an m900ie on it as that seemed to align best. wacky as. i thought only the later models used the reversed front sprocket? like the 25mm axle monster models.

confusing myself now.

you can see on some cush drives how much further the centre section comes out in the middle of the sprocket. it's quite obvious. i think the early ones there is no protrusion. would need to look. eric has some to hand.
 

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part numbers are different on the two versions as well as you can see a thickness/offset difference. I am in the middle of inventory right now but if I get the chance later I will see if I have a couple to add a photo. I know I have both it is a matter of finding what box I have them in right now.

Later monster models simply used the version for the 5.5 and added a thicker spacer between the wheel Iirc to make things align.

There also is the early 2000's m900 that used a 5.5 rear and a unique front sprocket that was centered into a sprocket with about 5mm step on both sides, only used on this one model for some reason.
 

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Discussion Starter · #7 · (Edited)
So I actually have a 5.5 rear stowed away for use in the future. I just measured from brake rotor to the sprocket, and both that 5.5 and the 4.5 thats on the bike have the same spacing at just under 7 1/4 inches. Not sure what the deal is with the cush drive that's on the wheel right now as I know nothing about the bike from the PO, but guessing that would explain why he had the countershaft sprocket flipped around.

Also, where does the spacing difference come from between the 5.5 and 4.5? Is the the hub width, or the cush drive? Mines a 96, any chance Ducati changed this later on to standardize sprocket orientation?
 

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Discussion Starter · #8 ·
Ok so end of story I guess. All the measurements between the 4.5 and 5.5 I have are identical- cush drive, hub width etc. Flipped the sprocket over with flat side out and everything lined up as expected. No idea why it's this way, I've read countless times that 4.5 has collar out, 5.5 flat side out. ?‍♂
 

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Nice. Just saw this post but I swapped out the 4.5’’ rear on my 1995 900ss/cr recently for an oem 5.5’’ rear wheel. All measurements around the hub were exactly the same as the 4.4’’ wheel. No other changes required except wider rubber ;)

Cheers


Sent from my iPhone using Tapatalk
 

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Discussion Starter · #10 ·
Nice. Just saw this post but I swapped out the 4.5’’ rear on my 1995 900ss/cr recently for an oem 5.5’’ rear wheel. All measurements around the hub were exactly the same as the 4.4’’ wheel. No other changes required except wider rubber ;)

Cheers


Sent from my iPhone using Tapatalk
When yours had the 4.5 on, sprocket was flat side out too?
 

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So bottom line : Do not assume anything. Start from scratch and do whatever you need to do to get this to line up. It is adjustable at both ends. The only thing that matters is that it’s in alignment when you’re done. Don’t overthink it.
 
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