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Discussion Starter · #1 ·
I am doing some restoration work on a 40 year old Honda CM450. It is in excellent condition, except for most obviously the old tires. The front is 27 years old, and I think the back is even older than that, and both are in real rough condition. When I first got it I put a few miles on it to see what I was in for. It rode like it had one it more flat spots in the tires. Stands to reason since it has been idle and parked for decades. 1994 was the last time it was registered. I had the rear wheel re-spoked and trued, and put a new Kenda Challenger on it. Took it for a spin, and the front still had the flat spot in the ride. I figured, oh that should go away when I clean up the front wheel and put a new tire on it.

Today I disassembled the wheel, cleaned, repacked the bearings and speedo mech, and put a new tire on. Took it for a spin, and the bump in the ride is still there. Using crude methods with a milk crate as a guide, the side to side alignment seems fine, but there is an ever so slight gap in the up/down rotation. In other words, if I jack the front end up a bit, and spin the wheel with a milk crate up against the middle of the tire, it rubs the tire about half of the way, but then there is a little gap for a while of about the thickness of a heavy cable wrap, or 1.25mm.

Is this enough offset to make the front ride like this. If not, what could it be? BTW, the bearings are original, and seem fine, so I cleaned them up and repacked them.
 

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Before you go any further replace the bearings, they only cost about 18 bucks each for quality name brand ones and are available at any decent bearing supply or farm supply outlet. ... don't buy the 7$ ones, they have fewer balls.
It's not even hard to do, you press them out and in, don't hammer them.
 

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Before you go any further replace the bearings, they only cost about 18 bucks each for quality name brand ones and are available at any decent bearing supply or farm supply outlet. ... don't buy the 7$ ones, they have fewer balls.
It's not even hard to do, you press them out and in, don't hammer them.
good place to start.
 

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Discussion Starter · #4 ·
As I said, I already pulled, inspected, and thoroughly cleaned the bearings They had no play and I could spin them with my air compressor in both directions before I re-packed them. They are OEM bearings with less than 5K on them, I believe.

I did not mention the wheel is not balanced. After I replaced the tire I checked it with nickles (all I had) to be not very far off, about 3 nickles or 15 grams or .5 oz. I should mention I did this both with the axle and a short 1/4" metal rod between two stools. Not the most accurate method, but they both gave similar results.
 

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there is an ever so slight gap in the up/down rotation. ................ about the thickness of a heavy cable wrap, or 1.25mm.
Is this enough offset to make the front ride like this
Probably.
Where I went to school the spec for max 'hop' was .020". I've seen .040" listed in a manual or two. You're over both at 1.25mm.

S F
 

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Just to put it in perspective, I get about 4 years on a set of wheel bearings if they don't get water in them and rust. Then they have sufficient free-play in them to start messing with the brake.
The new bearings will be too close in tolerance to easy spin them with the air compressor
 

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Try taping a pencil to a fork, so that the point just touches the rim, and spin the rim. This will tell you straight off it it is the rim that needs truing, or if the tire is defective.
 

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Randall, 27 year old tire...lol. They turn to wood after 20 years. Sounds like the bead of the new tire has seated a bit off center. If your out of round on the surface of the tire by 1.25 you will feel that. If while your rotating the wheel with the tire on it does the wheel run tire but you see a out of roundness on the tire, or does the wheel actually have a "flat spot"? Check the bead of the tire where you see the flat spot. Does the bead ion the tire in that area go into the wheel just a bit more than other areas?

I'm pretty sure the OEM spec is .080 that applies to radial and axial directions. There are professional services (Woody's Wheel Works) that can get your wheel to .040 T.I.R (Total Indicated Runout). They charge about $100 for their service but they do amazing work.
 
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