middling speed wobble

[ambrose78]

My bike has developed a bit of a wobble. It only happens if you take hands off the handlebars (not that I do this a lot but when checking for the tracking of the bike). Put the hands back on - wobble dissapears.

It only happens between 50km/h- 80km/h (30-50mph). Below and above this range the bike tracks true.

I've had a look at the tyres (Metzlers) and they appear to be in reasonable knick. No obvious flat spots on either front or rear.

Could this be wheel balance?

[nhmaf]

I'd re-check the tightness of your steering head bearings, but first, check that your tire pressures are up to where they should be (at least 32 PSI -or 2,2 Bar in the front tyre).  I once had a wobble in my front tyre that seemed to happen exactly between 40 - 45 MPH.  I started looking into head bearings etc, but stopped myself to recheck the tyre pressure... there was only 23 PSI in the front tyre.   I normally ride with 35-36 PSI.    Pumping it back up solved the problem.

[ambrose78]

Checked the Tyre pressures 32psi in both. I'll try 36psi next time.

How exactly do you reckeck the steering head bearing tension? Will i need to pull the top of the triple clams off?

Otherwise the steering feels smooth, and there is no lateral movement if rocked front brake aplied back and forth.


cheers

[montmil]

Try a quick check for correct preload of the steering head bearings. With bike on centerstand and front tire clear of the ground and pointed straight ahead, note how the wheel falls off to either side when encouraged by a gentle nudge.

Wheel does not want to lay over smoothly? Bearings are too tight. Flops over rather briskly and with some impact with the stops? Too loose. This is pretty much what the BMW manuals advise.

You mentioned wheel balance. This is worth checking, too. Doesn't sound serious but little niggles such as this are indicators of... something. All we have to do is find that something. Check back in.

Monte My freshly painted R65 wouldn't start because I forgot to fill the tank Miller :-?

[Justin B.]

If everything checks out then revisit the front tire.  I have bought two bikes with front Metzlers that looked great but had a head-shake at about 45 MPH.

[DgM]

Replace the tires...

[MrRiden]

Tire pressure, head bearing preload, swing arm centered and bearing preload, rear and front wheel bearings, rims true, wheel balance, drive shaft play, fork alignment, frame not bent from any mishap with crash bars, sliders not binding. Just throwing out anything and everything I can imagine on top of a dodgy front tire.

[ambrose78]

Okay well the steering does have some impact on the stops. I'll tighten the head bearings a little and see if that improves the situation.

The mention of a bent frame is a little alarming. I've had a look near the crash bars bolt on to the loops frame and it appears that there is more room between the engine and the frame on the left side than there is on the right by about 5mm (by eye measurements). Is the engine supposed to be symetrical in the frame? Is this normal for an r65?

[nhmaf]

Hmm. I think that the engine is supposed to be centered and symmetrical about the front frame down tubes, I guess that I haven't measured then to be sure - might it be an optical illusion if the crash protection bars aren't mounted exactly the same?   Remember, one cylinder is further forward than the other, which might be messing with your visual image.

[ambrose78]

Well I'm trying to tighten the adjuster nut. It is as tight as I can make it by hand. There is no fore/after play and the steering is smooth but it will still hit the stops "with some impact".

Does it need to be any tighter? And if so what would one use on the knurled adjustment nut to tighten it further?

[ambrose78]

As for the frame - when viewed directly from the front the gap to the engine on the left hand side is larger than the gap on the right hand side. Is this normal?

[Justin B.]

Use some big "Channelock" pliers with a few wraps of duct tape around the nut.  As far as spacing I suppose if somebody had replaced the stock steel spacers on your motor mount bolts with the aftermarket rubber ones (supposed to help the 4.5k buzz) they could be deteriorating and letting things flop around a bit...

[nhmaf]

I wouldn't tighten them much further - mine will still make a "clunk" on the stops when nudged to either side, though the wiring loom on the left hand side slows the turn out a bit, and I'm pretty sure the steering head is an appropriate tighteness.

[weasel01]

I went to the local MC shop and checked the preload on several different brands of bikes as well as BMW for a reference.

You might want to go ahead and service the bearings there if you havent already, it's not that hard to do ...only took me a couple hours and the bike feels more connected to the road and stable for it.

There is a nice instruction thread on the "how to" part of this forum.

The engine to frame spacing on my bike is the oil filter cover side is closer to the frame than the gear shifter side.
Oriented towards the drive shaft side which I am sure is normal.

[Justin B.]

If you choose to torque the adjustment a bit more and get it a tad too tight then the bike will exhibit a "slow speed weave", IIRC.  At this point just back off just a hair and re-do the test ride until the "weave" just goes away and you can't induce shake by smacking the end of the bar.  When I take my hands off the bar and smack one end (on all my bikes) it will oscillate maybe 2-3 times and then go rock steady.  If to loose you'll have to grab hold to get the shake to stop.

At least that's been my experience...