the disks were fine 2 years ago, which is when the problem first occurred.
replacment bolts are on my wishlist of things 
I have titanium rocker cover bolts to fit already as the originals get furry every winter
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If its fine until you reach a certain speed then starts shaking the bars it points to a front wheel out of balance.
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Firstly what do you mean by high speed? above 110mph or above 50mph or?
But I agree with Royston and I would want the wheel rebalanced first before any other investigation. - if they do it on a machine it balances axially and radially so will allow for any disc imbalance.
True that the rear shocks are unlikely to have any useful damping by 30k and as the rear spring is too high a rate .it is possible that the springs are now entirely overpowering the dampers but while that may worsen any oscillation in the frame i cant see it causing it
over 100 is progressively worse.
the front wheel was balanced twice around time the problem started, once before bearings changed and once after, on the old wheels.
most likely balanced again on new wheels but I wasnât there when they were swapped over, the rear has been changed since at my usual tyre place and balanced then.
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I tried a .5 bar increase front and rear this morning, I need more testing but it seems to have improved things very noticeably.
Have you ever changed the fork oil?
nope, that and the rear shock both probably need replaced.
Have you checked to see if the tyres are on the correct way round, many years ago I put my front wheel back in the wrong way (V65 Lario) this caused a weave at speed.
The torque specs for the stock ball bearings would be too tight for taper roller bearings. Theyâre a different type of bearing. The only way to set them correctly is with the forks out and set them just tight enough so you canât feel any play.
This would all be a lot easier if Moto-Guzzi actually greased the bearings at the factory. They should last at least a decade and 100k miles. Maybe they donât want to stain their designer overalls with grease.
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yes itâs worth checking that, mine are definitely right way round.
Iâm thinking now it might just be these particular tyres on this bike, at recommended pressures⌠never had an issue with any other tyres.
next on the list of things is new shock, replace fork oil, and possibly finally change back to standard bearings.
Have you fitted tapered rollers? Are they too tight?
tapered rollers, theyâve been checked twice at two different guzzi service places, second time i asked them to loosen them off a bit, first place said they were a little tight but not enough to cause issues.
Did you fit them yourself or a dealer? I fitted mine with plenty of grease and tightened them down as tight as theyâd go and then backed the bottom collar off half a turn. It steers so much better now and doesnât tip into corners now, the handling is very neutral. No play detectable when trying to push the forks forward and pull them back so the clearance feels right.
The steering is so nice and very easy to manoeuvre at walking pace. Iâm sure Iâve been riding round for the last two years with overtightened stock bearings and by the looks of the locking collar and tab washers theyâd never been touched since it was built.
Iâm running Bridgestone A41 tyres as a new free one came with the bike from the previous owner, I havenât been a fan of Bridgestone on other marques but they really seem to suit the Guzzi and last ages
dealer fitted, the mechanic there recommended them as both cheaper and stronger than stock bearings.
however opinions differ, the mechanic in england who checked them, and who races aprillias, said he wasnât a fan of taper bearings.
I donât believe bearings are the issue since an increase in tyre pressure had a noticable effect. they have probably got 6-7k miles left in them so I wonât be changing them until next year most likely, but Iâll go back to metzler road tec after that.
Taper rollers should last indefinitely if checked, greased and adjusted fairly regularly, thereâs a much larger contact area with the rollers against the races unlike caged ball bearings which these days are only used on bicycles or ancient clunkers like my AJS 650 twin. Strange choice to fit them as stock but it is Italian.
Taper rollers are superior to ball races provided that they are fitted correctly. If they havenât been seated home fully then they will cause a front-end wobble. Has anyone ever told you how to do the tap test? Iâd guess yes. Iâll go through it just in case anyone else doesnât have a clue what Iâm talking about.
- Be absolutely sure that the outer race is fully home in the top and bottom of the headstock. The old outer race makes a good tool for blatting with a hammer. Generally (but not always) âfully homeâ is just below the rim of the bearing seat. Occasionally it might be level with the top of the rim of the bearing seat but it should never be above it. There is a very distinct change of tone as the new race seats home.
- Tighten the taper rollers bit by bit until the forks wonât move if you tap the end of the handlebars. If you canât fit the handlebars while adjusting the taper rollers (BMW Iâm giving you the hard stare), tapping the wheel will do. Otherwise youâll need to bruise your fingers on the fork legs
- Back off the taper roller nut until a gentle tap will allow the front end to swing cleanly from side-to-side. It shouldnât go suddenly (too loose) and it shouldnât slow down or stop before hitting the lock stop (too tight).
- Grab the bottom of the forks and rock them gently forward and back. Youâre feeling for the slightest movement in the new bearings. If there is any, take a tiny turn on the nut and repeat until you can no longer feel any rocking movement. For this stage be sure to tighten the nut a tiny bit at a time otherwise you risk overtightening and binding
- Reassemble as much of the front end as you can.
- Do the tap test again. Depending on how much clutter is on the handlebars, you may not reach full lock before something slows it up.
There used to be a good description in the Haynes manuals (which is where I got this info from originally) but as updated manuals were issued, it vanished. I guess it was a victim of Mr. Elf Safety and Mr. Legal Advice.
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excellent guide, no i didnât know that test. thanks for posting it.
bike passed MoT today, but over the summer Iâll be getting a few more unexciting goodies for it like fork seals and possibly a rear shock, bearings may have to go on the endless list too.
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