Chain wear - help please

[chasio]

Cheers for all the tips.

OK, with the assistance of 13 year old Chasiette, the string method showed up that the notches on the swingarm are out by about 1.5mm, meaning the right front edge of the tyre was cocked in a bit. That hadn't shown up by the lie down and squint method or countin threads, somehow. Lesson 1: don't be a lazy git. I've marked one face of each adjusting nut so I can keep them in sync.

Also using the tip of the ScottOiler as a reference, it appears to me that the rear sprocket has actually got a bit of lateral variation i.e. either it's not perfectly flat or the fitting is a bit out somehow... It's around 0.5mm variation I'd guess.

Now I just need to find a large friend to check tension and I'll check it again in another few hundred to see if it seems any worse.

[cobber]

Hi all

Thanks for all your replies There's a heap of good stuff here that I will get into today.

The DID O ring chain has (now) only done about 600kms on brand new JT sprockets. I'm pretty easy on the throttle (I think), I've never waterblasted it and it hasn't been off road (even on metal) yet.

I've used kerosene and a rag to clean it a couple of times and a bit of WD40 as a light lube afterwards, then just left the Scottoiler to do its thing, tweaking the delivery rate up during heavy rain. When I have inspected the chain between cleaning, both sides of the chain have looked lubed OK to me, maybe the outside (scottoiler side) a bit better.

I'll have a ride and a tinker today and let you know how it goes.

Cheers again - Chasio

To align your sprockets borrow a gizzmo used by competive gokart racers , it is a clip on or magnetic laser attached to the rear sprocket and pointed onto the drive sprocket with the chain removed pretty fool proof and simple if you want to be very presice

[YellowDog]

Sounds like you are doing great in getting to the bottom of this. I sold my XF650 (not to a KBer) before solving very similar problems.

[XF650]

Chasio - have you checked your cush-drive rubbers?

[puddytat]

Cheers for all the tips.

OK, with the assistance of 13 year old Chasiette, the string method showed up that the notches on the swingarm are out by about 1.5mm, meaning the right front edge of the tyre was cocked in a bit. That hadn't shown up by the lie down and squint method or countin threads, somehow. Lesson 1: don't be a lazy git. I've marked one face of each adjusting nut so I can keep them in sync.

.

After seeing the damage a misaligned rear did to new tyres, I did the string thing & found that although the marks were exactly the same, over the length of the wheelbase my rear was 12mm out of line with the front...

[rogson]

There is a bearing in the sprocket carrier of the cush hub assembly. If it gets flogged-out it will lead to a wobbly/misaligned sprocket and result in increased chain and sprocket wear.

[chasio]

Chasio - have you checked your cush-drive rubbers?

There is a bearing in the sprocket carrier of the cush hub assembly. If it gets flogged-out it will lead to a wobbly/misaligned sprocket and result in increased chain and sprocket wear.

When I looked at the sprockets that came off, the front was a lot more worn than the rear and that sounds like it could match the above.

This sounds like a job for the PDF workshop manual and a long weekend at the speed and skill level I work at. I'll have a read and see if I'm feeling brave!

To align your sprockets borrow a gizzmo used by competive gokart racers , it is a clip on or magnetic laser attached to the rear sprocket and pointed onto the drive sprocket with the chain removed pretty fool proof and simple if you want to be very presice

This sounds clever. I'm not too close with any kart racers, but I know my boss's boss's boss's boss's boss is quite into it. Might be a stretch to ring him and ask to borrow his tool, though.

Sounds like I should check the cush drive area first.

Cheers to all for your input

Chasio

[YellowDog]

If anyone doesn't have the XF650 PDF Manual - PM me and I'll send you a download link.

[warewolf]

When I looked at the sprockets that came off, the front was a lot more worn than the rear and that sounds like it could match the above.

No, that's normal. At roughly 3:1 gearing the front sprocket is doing 3x the work, they almost always wear out first despite being made tougher. My 640A goes through 2-3 fronts per rear and chain; leaving the front on too long flogs out the rear and chain, as the most-worn component brings the other 2 down to its level in short order.

[chasio]

That makes sense now I stop and think about it!

[cobber]

No, that's normal. At roughly 3:1 gearing the front sprocket is doing 3x the work, they almost always wear out first despite being made tougher. My 640A goes through 2-3 fronts per rear and chain; leaving the front on too long flogs out the rear and chain, as the most-worn component brings the other 2 down to its level in short order.

Totally agree with this as Ive done 78,200 kms on my dr650 since 2002 and getting near the end of the second chain and rear sprockets life though I change the front sprocket around 10,000kms using genuine Suzuki ones and a Scott oiler

[chasio]

Right, I took front sprocket cover off to have a look at it.

I noticed that there seemed to be a fair bit of play both around the axis as well as lateral "wobble". Reading up, a bit of lateral play seems to be OK but maybe not the axial play...?

I also noted that two of the three bolts were not tight. I read they need only 6Nm plus thread lock, but they were moving freely either way using a 10mm socket on a short handle with virtually no torque. I managed to get those two out with a bit of prying and the threads are full of alloy, so I am assuming that the bushes they're going into are stripped.

So my working assumption is that 1 tight bolt and two loose ones makes for a wobbly sprocket and increased chain wear. And I doubt it's especially safe, either.

What next? My thought is to refit with some thread lock and hope that makes it safe enough to ride until sorted out.

Anyone know what kind of mission sorting the stripped threads is likely to be? Maybe replace the stripped part or get a shop to fit helicoils... or is there another option worth looking at?

Cheers - Chasio

[NordieBoy]

Most re-fit with some e-clips instead of the plate/bolts.
lots of float but not whilst under load.

Even a good tight plate/bolt setup floats.

[chasio]

Thanks Nordie, I've had a read up about using the e-clip and I'll get one sorted and take it from there.