Front Sprocket

[750supnorth]

Hi all,

New member and have purchased a 1989 750 sport.

I have a question regarding the front sprocket, spent tonight just checking a few things out and removed the side cover from the front sprocket and have found the sprocket has side to side movement.

Is this normal, I would have expected the sprocket to be relatively solid, does it have movement to allow some misaligment in the chain?

Lookig forward to using your knowledge to get this machine in good order.

[modteepee]

Sounds like the retaining plate is worn. With the two screws and plate removed, the sprocket will slide onto the shaft. Then the retaining plate should slide on and when it gets to the groove in the shaft, you can move it to one side so the screw holes line up thus moving the tabs on the plate to lock the sprocket on.

[ducinthebay]

The front sprocket on the Sport is standard Ducati issue that is common with many other models. There is always some amount of free play in the sprocket. The retaining plate is held on with two 5mm bolts with 10mm heads, or allen bolts. Remove the bolts, rotate the retaining plate just a bit and remove it. The sprocket will then able to slide off the counter shaft.

Clean all the parts. Check the retainer plate to see that the sides don't have big notches in them. It should be smooth, but it will show some wear marks. When you reassemble, put some very heavy grease on the shaft and the inside of the sprocket when you slide it back onto the shaft. Use blue Loctite on the screws the hold the retainer plate.

hope that helps.

[750supnorth]

Thanks for that, I did have a look at the manual but nothing to say how it all goes together.

I will take it apart in the next few days to make sure everything is OK.

I can see if it only held by a plate that it would wear and hence some play. I was worried that the shaft may be damaged, but sounds like that is not possible as the plate is the softer material and hence will wear.

[blaster]

hi, here's a little trick. if the teeth on the retaining plate are wore which they usually are, just flip it over so the fresh surface bares against the splines on the shaft. the worn side just sits against the sprocket face. also, ducati supplied two plates. the original plate has a gold color, these ware quickly. the latest design has a black parkerized finish and they last alot longer. they are pretty cheap too. blaster

[750supnorth]

Had another look last night and realised that my setup is different

The end of the shaft has a bolt screwed into it with a plate bolted between the bolt and shaft end, this plate is thin to allow the bolts of the retaining plate on the sprocket to be removed and longer on the 90 degree the the bolts holding the plate to the sprocket, this plate does not touch the sprocket.

It does look home made.

Any idea why this has been done?

I was thinking maybe as insurance to stop the sprocket coming off the shaft.

My concern now is it a left or right hand bolt, had a try to undue but was worried I might try the wrong way and shear the bolt, but thinking about it I would think it would be a convensional thread

So still thinking about it, not rush as the sprocket is not that loose, but will have to tackle at some point.

[blaster]

hi, sounds like you have the early verson like the paso. i never messed with the early verson but i'm sure there are plenty of people here that can help you. blaster

[ducinthebay]

Look at your motor mounts on the right and side. Is there a 3mm spacer inbetween the motor and the frame? If not, you probably have an earlier version of the frame, and the sprocket needs more offset to clear the rear tire. I had a sprocket that had a very thick washer welded onto the side and used the threaded hole in the countershaft to hold it on. the threads are normal right hand threads, but you need to put loctite on it to keep it in place. When I opened mine up, the bolt was backing out.

Best thing to do is check the chain alignment to see what front sprocket you need. Some of the Paso ones had a deep dish to offset them correctly. those sprockets are rare, but they can be found. First center your wheel in the swingarm. Measure from the wheel axle to the swing arm pivot axle on both side to make sure that it is square. Then use a laser to see where the rear sprocket is pointing. Its a bit tedious, but essential to get a good chainline.

If you could post a picture of what you have, we might be able to tell you what you've got.

Cheers,

[750supnorth]

Thanks for that I will try and get a couple of photo's this weekend.

[Tamburinifan]

It does look home made.Any idea why this has been done?

Maybe to fit a sprocket not made f your bike?
I have done that & many others.

[jcslocum]

the threads are normal right hand threads, but you need to put loctite on it to keep it in place. When I opened mine up, the bolt was backing out. Cheers,

There may be loctite in there so as a precaution, heat the head of the bolt a bit with a propane torch to melt and loosen any loctite.

[modteepee]

Speaking of front sprockets, does anyone have a part number and/or source for it? ('90 750 sport) I'm seeing several numbers for Paso.