Front end hop/vibration 37 mph-44mph only, HELP!

[Ncstatecamp]

Im having a bit of an issue with the front end of my 72 CB750 having a bit of the shakes, like a addict quitting cold turkey. I only get the movements between 37ish/44ish (gps speedo). Its both a shake (side to side) and a hop (up and down)

New tires - Avon Roadrunners
New Seals/rebuild forks
New progressive fork springs
2 part Progressive rear shocks
New clean/aligned chain
New swing arm bushing
New neck Allballz bearings/seats (Checked for square, no binding)
Has fork brace (OEM front fender, chopped)
New Spokes (Trued to within spec)
Forks are even in tree
Air Pressure Good

My first instinct was lacing was improper but why would I get such a small range of hop
Second Instinct was that I was hitting a resonance in the fork springs or something so I went ahead and got progressive.

Im going nucking futs trying to figure this out, its really irritating b.c its at traffic cruising speed only. Above or below and I glide along smooth.

 

[mlinder]

Balanced? And yeah, could quite possibly be out of true or bad lacing. Centripetal force does different things at different speeds.

Hold up the front end and spin the wheel, visually inspect for true and even radius, flat spots, etc. Tap each spoke, do they ring at similar tones?

Do the same for the back.

Also make sure the beads are seated all they way around.

I did have a defective avon once. Was terrifying.

 

[chillinfellow]

Had similar experience avon tires too, the bead was uneven, was more hop if anything. brought it back to who I had mounted them they corrected it, believe they ended up having to use a bigger tube and pump a ton of pressure into it to get the bead to seat proper / evenly. been fine since put them on 1 1/2 yrs ago * once bead was even they adjusted to correct air pressure

 

[HerrDeacon]

That's what's happening on my MB5 front tire, can't get the tire even all the way around, problem area is right where the valve is. The Gazelles I have are notoriously hard to install, I've tried a number of times with no luck. I can feel it a bit at lower speeds but is really noticeable at 40 mph.

 

[mlinder]

How are you installing the tires?
A little soapy water and a lot of pressure (80+ psi sometimes) will get the bead to pop in correctly.

 

[Scruffy]

Deflate the tire, pack the bead with Vaseline, reinflate. Almost guaranteed to get it seated correctly. I even have to do that to bicycle tires on my stock 1937 rims. Clean up the residue with lacquer thinner, denatured alcohol, etc.

 

[mAd mOrdigan]

How are you installing the tires?
A little soapy water and a lot of pressure (80+ psi sometimes) will get the bead to pop in correctly.

we did this at america's tire company when beads wouldn't seat.. put a bunch of lube on it and put it in a cage and fill it up with LOTS of air. Car tires.. but sort of the same. Sometimes the bead will be not quite seated fully.

 

[Hoosier Daddy]

Did you line up the paint dot on the tire to the valve stem?
That is the heavy part of the tire and should be aligned to the lightest part of the rim (valve stem hole)

 

[Ncstatecamp]

I just upped the air pressure a bit and my wobble is gone. Im going to get it rebalanced monday, so hopefully thatll help the bounce. I had a mechanic put the tire on, he said no problems there, and I'm assuming he lined up bead/weight, and seat it right.

 

[Scruffy]

Never assume, on a front tire it can get you killed. I've been installing mc tires for longer than a lot of the forum members have been alive, and still get fooled occasionally. Especially with Dunlop 401/402/404, and Avons. They'll look fine on the rack, the bead makes a nice popping sound while inflating... install on the bike, go for a ride and the damn bead rolls under. Low price tires at least do you the courtesy of blatantly being garbage so you don't waste any time/money trying to get them seated if they are bad.

 

[Ncstatecamp]

So do I just hyper inflate it or what? How do I check to make sure it's seated? It looks even all the way around?

 

[xb33bsa]

you need to get the wheel off the ground and spin it and carefully look at it and the runout(crookedness/up and down uneveness)

 

[Scruffy]

If there is a big V shaped kink in the sidewall above the rim shoulder, the bead is bad from sitting on the shelf improperly for too long. No V? Even all around? Do like xb33bsa suggests. Do that anyway, sometimes a spoke or two loosens up and it isn't caught during the tire swap.