Hi everyone,

I took apart the swing arm of my DT100 expecting to find worn bushes. Instead, I've found the through holes in the frame with which the swing arm pivot runs through is worn laterally fore & aft. However, if I tighten the shaft too much, the swing arm doesn't move.
What could I do? Drill out the frame (no idea how to keep it straight) and pop in a spacer? Try find needle bearings to fit?

I'm surprised at this set up, I wonder why Yamaha changed it from the prior year? It seems odd using the frame as a wearing surface!

Looks like they're the common stretchy bonded rubber/steel a lot of smaller bikes use. Basically they last forever, So i'll guess that the bolt has been loose enough to turn in the frame for most of its life & just plain worn out the frame holes from turning. Give it a try in locking the bolt up tight with the arm about the angle where the shocks bolt up the see if you can pull up an inch or two & push down the same--pushing pulling against bonded rubber. If that shows things are normal then i guess come up with a plan for the worn frame holes. I guess it's pretty bad & pic would be great if possible by using a hosting site. People use imgur & i just use google photos i think it is. imgur.com/ www.google.com/photos/about/
If it tightens up & you can get it pointing straight i'd be tempted to just leave it & keep it tight. Otherwise can you shorten the ends of the worn cross piece a little & make caps to sit over each end so its a firm fit over the outside with a central hole the right size then bolt it up & carry on. Caps would need clearance so they don't touch the outer part of the rubber steel where its pressed into the arm, so it can rotate it's slight amount. They don't stretch far but slight stretchy movement at the bush relates to quite a lot of arm movement at the wheel axle end. Another test is to clamp the arm in your bench vice one bush at a time & see if it move springy rubbery. I guess its possible now that the bonded steel center of the bush has worn shorter & should stick out slightly past its outer bonded bit to have clearance to stretch/turn its small amount. Ok that's enough woffling--now i'll edit my mistakes lol. & i keep adding bits. Hope its understandable. Oh, & welcome from NZ if you're new. Sorry i see ya not new but welcome back.

www.partzilla.com/catalog/yamaha/motorcy...00d/frame-side-cover

www.partzilla.com/catalog/yamaha/motorcy...r-cushion-chain-case

You were spot on, all I had to do was tighten up the swing arm axle and she pivots well in the bushings. This bike will barely be ridden so I'm not too fussed at the worn out holes, the bushings are now doing their job!

I was basing my feelings of it being too tight when I didn't have the shocks or wheel attached - I'm used to modern dirt bikes which are silky smooth.

P.S. When I win the lotto I'm buying a little house in Wanaka

You'd almost certainly need to win lotto for that .

'One' lucky person won 23.5 million last week. [nz so low dollar value compared to usa] That'd do 'me'. Buy a New DT1. Must be one still in a crate unassembled somewhere--if only.