Triumphrat

Husk01

My bike have always had a tendency to turn right when I let go of the bars. Rear wheel alignment marks are spot-on. Tried the string method and all seemed OK, but the margin of error seems large given the string may or may not touch the rear tire just right and mess up the results.
Decided to play with the rear wheel this afternoon and see how changes effect straight-line hands-off stability. Seems that I found a neutral position that has the index marks off by almost one complete mark. Very strange. The other interesting thing I have found is that now the distance between the tire edge and the swingarm is identical on both sides (I used a 32mm socket to check the distance rather than a tape measure since it is such an awkward spot).
If anyone has a set-up known to be true, please have a quick look and let me know if your rear tire edge is the from your swingarm. Mine has never been, and I attributed that to the design of the swingarm as not being symetrical. Now I am not so sure. It would make a very handy way to align the wheel if it works correctly.
Steve

alfacliff

On our old xs650's, we finally setled on centering the front of the tire in the swingarm. the alignment marks on the adjusters just didnt make it. just setup for the same spacing between the front of the tire and the swingarm on both sides.
cliff

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2006 Bonnie Black
1980 Yamaha xs650

Weasel Pete

I've done this
I've also used flourescent light tubes instead of fishing line.
I hope your frame or swingarm arent bent.

uzidzit

I have seen very few bikes that the marks were on. The important thing is now when you adjust the chain to do each side evenly, I would trust the handling before all else but watch for wierd tire wear, and any evidence of sprocket wear on the sides of the teeth. If that is not in evidence don't worry, if it is, you will need to straighten the chain alignment and adjust the spacing on the front so it will go straight. You can check for frame warp with a cross test level on the rear disc, and when the bike is dead vert. then check the front disc, with the wheel straight this will show major warpage . The other thing to try is to loosen all the bolts in the front end and retighten, to allow the forks to re align if the front has racked a little, The tubes are hard to bend but the trees are easy to tweak out of alignment.

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"Peter, It seems like you have been missing a lot of work recently, well Bob I wouldn't say that I've been missing it"
ENOUGH, go out and ride!

Husk01

Thanks for the info n578md. Your bike is aligned and the tire to swingarm is off by 5/16". That's a significant amount.
Intially the left side of my tire was closer to the swingarm too.

Went for a little ride just now and it seemed to handle just fine with the tire centred on the swingarm. The tendency to turn tight is still there but not quite as bad. I've tried both sides of the road (brit side) to allow for crown and results are similar.

I'm going to get the string out again and see what it says with this setup. Also going to measure the swingarm centre to axle center on both sides and compare.

Steve

raproe

Like Weasel Pete, I prefer something more substantial than string or fishing line. I use some aluminum angles and a couple of spacers (to clear my "center stand").




I align the wheels by putting the spacers and angles firmly against the rear wheel, making sure they are parallel. Then I turn the front wheel until it is parallel to the angles. If the wheel is centered between the two parallel angles, it is aligned with the rear wheel. If not, I tweek the adjusters until it is. You can measure the gaps but eyeball seems to work just as well.

Any good straight piece of something (fluorescent light tubes if you don't drop them, pieces of pipe etc.) can be used instead of the aluminum angles.

Rich

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"....by its very nature, a single-tracker is in unstable equilibrium, i.e., it cannot, when stationary, stand up by itself."

Husk01

Raproe,
You've got a great setup. I don't think you can get any more accurate than that.
Mind having a quick look at your tire-to-swingarm clearance? Wondering if it happens to be centered or not.
Looked everywhere for a good straight-edge but found nothin' yet. Those flourecent tubes on the ceiling are starting to look tempting.
Well, I'm off to get the string out...
Steve

raproe

It's hard to say. The tire-to-swingarm distance changes a lot depending on where you measure fore-and-aft. Also there is a brake cable and tie-down on the left and the chain guard on the right so it's hard to get a good measurement in the same location.

Rich

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"....by its very nature, a single-tracker is in unstable equilibrium, i.e., it cannot, when stationary, stand up by itself."

Husk01

Raproe,
I hear you. What I did was slid a suitable socket along the swingarm till it touches the tire (my battleaxe has a nice ridge) and checked to see if it worked on the other side.
So here's what I just discovered on my bike: The rear wheel was grossly misaligned when centred on the swingarm, verified by using the string alignment method. The strings brought everything back to exact alignment with the alignment marks (guess they are accurate). Measured the tire to swingarm clearance with a measuring tape, and the best I could get given the brackets and other things in the way was:
left side 1 3/4"
right side 1 5/8"
Not really an exact measurement but it seems that the tire does not ride in the middle of the swingarm.
More disturbing is that when I rode the bike misaligned, I ran great ,implying that either my bike is bent, or I am.
Next step is to measure the axlepivot to swingarm pivot. Looks like covers and mufflers in the way.
Time for a beer, or two.
Steve