Chain dragging on tire

[mastershake]

Hi all! Got a problem I honestly can't fix. My 01 Monster 750's chain is eating the tire. I have small gouges all along the side of the tire. Just sitting, the distance between the tire and chain is maybe at most the thickness of two nickels or less and the chain easily pushes up against the tire. The tire is a Dunlop 170.

I have replaced the front sprocket and chain. The axle measures the same difference on either side and I have one inch of slack on the chain. Looking from the rear down the length of the chain, it looks to be perfectly straight from rear sprocket to front. I've had the bike since February but only started doing this about a month ago.

I honestly am at a loss for what could be causing this. So please, any advice is welcome.

[zippsub9]

Could it be loose adjusters perhaps when the chain is under power it torques the rear axle causing deflection?  I would pull of the rear wheel, check bearing and alignment.  It may appear aligned but under power it is drifting.

[koko64]

A few things to check as a routine.
You may have these covered.

The adjuster plates cant be trusted. It may still be out of alignment.
Get the front sprocket cover off and inspect it carefully. Is it a retainer type or big nut holding it on? It may have walked across if the retainer plate failed.
Double check for the correct parts/sized parts for your model.
Maybe the sprocket is on the wrong way if it has a shoulder?
Check the rear sprocket/ sprocket nuts, just in case.
Check what zipps said and axel torque.
Some tyres are wider than others irrespective of the numbers. Dunlop make some wide tyres like Q2s. Q2 170=180 of some other brands for example.

[mastershake]

I used a tape measure and measured from the front of the swing arm to the center of the axle on both sides. The sprocket uses a retaining clip, I'm wondering of the sprocket is installed backwards, I see pictures of them both ways. I've checked the rear sprocket, it has zero movement. When I installed the new chain today I torched the axle nuts to 55ft-lb and the tension bolts to 8ft-lb. I guess tomorrow after work I'll pull the rear end all apart.

The trouble started about a month ago when I took the original front sprocket off to fit a 14T sprocket on. But it ended up being the wrong pitch and I put the original back on. I was looking at Ducati of Omahas parts diagrams and it shows the sprocket facing opposite of how I have mine, it also shows some type of shim behind the sprocket that I don't have.

[Speeddog]

Your front sprocket should have the hub outboard, flat side towards the engine.

Confirm that the retainer plate hasn't worn through, allowing the sprocket to move inboard.
Some models have issues with that.

'01 M750 should have a 160/60 rear tire on a 4.50" rim.

Confirm that the cone shaped spacer on the left side of the rear axle is still there, and is installed flat side out.

Take some pictures and post 'em up.
Here's how: http://www.ducatimonsterforum.org/index.php?topic=109.0

[Howie]

If everything Speeddog says to check is OK ( you might also use a straight edge or lazer to check sprocket alignment too)  and you have a 4.5 inch wheel replace that 170 with a 160.  160 is the correct size for a 4.5 anyway.  If you have a 5'' wheel...ummm...trying to remember, maybe wrong sprocket carrier.

[mastershake]

Thank you all for the suggestions. I will dig into it today after work and give you all a update.

[Dellikose]

I had the same problem and it was the retainer clip, as mentioned by others. If you need a new one, grab a few because they are not that expensive.

[mastershake]

Well to show my ignorance, I measured my rim and came up with 6inches. I measured from the inside not measuring the lip that extends up. It may not make a difference but the frame is a 2001 M750 and the engine is a 900, the owner before me did that and I had no clue till I ran the VIN. He advertised it as a 900 I.e.

[Speeddog]

Look at all the spokes on the rear wheel, one should have lettering like 17x4.50 or 17x5.50 or the like.
What does it say?
Swingarm aluminum or steel?
Bottom left side of the engine has the engine number, first 4 digits are?

[mastershake]

It is a 17x5.50 rim and the first four are RA41.

[mastershake]

What exactly does RA41 signify?

[mastershake]

Is it possible that after I tried changing my front sprocket, I smashed something in the rear carrier? If I measured correctly, there is a 1/16th difference between the front of the sprocket and rear of the sprocket.

[koko64]

If everything Speeddog says to check is OK ( you might also use a straight edge or lazer to check sprocket alignment too) maybe wrong sprocket carrier.

The 750 sprocket carrier on the 900 wheel will have the chain too close to the tyre. I found that out once. There's maybe 10mm difference iirc. Speeddog or Howie will remember. Any part no. on the cush drive/sprocket carrier?

[mastershake]

The sprocket has Z1G00 stamped on it. I'll go to Strada fab tomorrow and pull it all apart. So the sprocket on the 750's sit closer inboard than the 900? If that's the case, could I shim the sprocket to sit more outboard?