1977 Bonnie front wheel. Mounted a new Dunlop K81 and tube over a year ago. Bike was stored for shipping for one year in garage. Now that I am riding, the front wheel starts to hop at 40 MPH. Any and all comments would be appreciated.
Sitting on its wheels? Provided the wheel was balanced when you fitted the new tube and tYre (tire!) it sounds like you have flat spotted the tyre. It should round out after a few miles once it has warmed thoroughly. You can speed up the re-shaping by running it slightly soft for a couple of careful miles before inflating to spec. If the wheel has never been balanced it will patter as it tries to loop the loop!
Thank you for your replies. The tire was refitted and the hop remained. The bearings were replaced and there is no stickiness in the rotation of the axel. I'll try running it on low pressure for a short distance and balancing the front wheel.
Long shot I know but is the wheel true? Raise it and spin it and look for any deflection at the rim. Unlikely if cast wheels but shelling out for a new tyre when it's the wheel would be a kicker and it only takes a few moments to check.
Wouldn’t have thought it would be the wheel cast or spokes unless it was deformed before the bike was stored. Wheel bearings should be ok unless the bike was stored on a vibrating surface. I’d go for a wheel balance problem, them tyre.
Update: New front tire replaced the new tire that was out of round. Front end balanced, wheel checked for roundness, fork oil changed, wheels aligned and still there is a bit of vibration in the front end above 40mph. Could it be the front brake disc? Replaced the dsc last year, new from Baxter's Cycle which was warped and had to be turned. Thought about removing disc and running without front brake to see if it smoothed out. Note: Rear tire was also replaced and balanced about the same time. Please keep the suggestions coming in. Old bikes are like old people. Every morning I wake up, there are pains I did not have the day before. Ps: Watched a video about aligning the front wheel only on a 50s Triumph. Loosen fork nuts, sit on bike with center stand, then tighten the nuts back. Is this an issue for a 1977 Bonnie?
Yes, with old tires and old front disc there was no vibration, but who wants to keep running on 25 year old tires and tubes. See my most recent, and thank you for your reply.
Seems like you are narrowing things down! I assume the wheel was balanced with its new tyre on a ‘standard’ static balance stand? It begs the question whether the disc was on the wheel or not. It would be simple enough to re-check the balance with the rotor in place (gee, I am talking American already!) and that the disc/rotor is centralised properly. Beyond that, if the whole rotating assembly seems ok static but acts up at road speeds I would suspect wheel bearings but you might find an auto shop with a dynamic balancer that can centralise (on cones) and spin up a motorcycle wheel in a way that will identify any oddities. I am thinking of thick rim portion that induces wobble and hop. And the fitter did know the dot on the tyre wall goes opposite the valve stem?
Update: Have done everything but remove the front bearings and check for wear. This will be my next step, but I am finding the wobble comes and goes on a consistent level, smooth for about 2 seconds, wobble for 4 seconds. I am beginning to think the guy who pressed in the ebarings might have left out the dust cover on the right inside and the full bearing housing is rotating. Any thoughts?
