Bullet 500 - 'wobble' through front.

[arry]

After some advice on a little handling issue that's showing itself on my Enfield.

First off, I should say that I believe the issue has always been there to some degree, but I am noticing it more now having fitted some new, and different to stock, rubber. Ordinarily I'd point towards wheel balancing but on this one I'm not so sure - so any second opinions welcomed.

On a straight road travelling at ~27 to ~31 mph, and whilst on a consistent throttle, I'll get what I'd say is a 'wobble' at the front of the bike. It's not a tank slapper by any stretch of the imagination; there's nothing to fight and it's not like you have to hold on for dear life, but I can feel this vagueness and slight left/right in the bars. It's ever so slight - but does get worse on occasion, notably:
When the road surface is more rough.
When there's weight on the back - if I pillion my wife around, it's far more noticeable.

I have tried tyre pressures up, tyre pressures down - that doesn't seem to affect it; it's still there running 20psi or 30psi.

I have checked for play in the head bearings / swing arm and there's no notchiness or jiggle in either.

There's no dive or unusual movement from the front forks.

Yet this issue is there. It was there on the old tyres, and it's there on the new tyres, too. I wouldn't say it's getting worse, but it's more noticeable now on the RoadRiders than it was on the RoadSmarts.

Does BCF have any what do's?

Cheers

[Nobby the Bastard]

What torque are the head bearings done up to? You would be surprised at just how tight they are supposed to be...
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[sickpup]

[UncleFester]

Spokes out of kilter / disc not true?
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Module 1 and 2 passed - October 2014. Happy owner of a 2017 Z1000SX, ex owner of a YBR125 / CB500 / VFR800.

[stinkwheel]

UCE or iron barrel?
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[arry]

[arry]

[arry]

[Easy-X]

Putting weight on the back end lightens up the front end making the effect more pronounced I suppose. Do you notice anything if you try to accelerate in this "wobble zone" ?

If I were to guess the areas to look at would be the head bearing tightness. From my experience of old bikes there's a Goldilocks zone of "not too tight, not too slack, but just right."

After that I'd be looking at the forks: are they 100% lined up on the yolk TBF having 2 mm more sticking out of the yolk on one side should be pretty obvious but hey, if it's a proper old Indian Enfield maybe that's to account for a really dodgy casting. Also, are the forks 100% in parallel or slightly twisted.

Then there's the wheel. If the hub/spoke dishing isn't centred relative to the axle and whatever spacers it'd make little odds a low speed. Finally I'd hoist up the front and a spin the wheel and just see if any obvious things jump out with the rim shape.
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[stinkwheel]

Make sure it hasn't cracked the axle clamp on the front fork. Also check the mudguard is all clamped up firmly, it acts as a bit of a fork brace, heavy steel with three stays either side.

Also inspect the engine mounting plates for cracks because the frame has all the ridgidity of cooked spaghetti without the engine firmly bolted in place.

The swingarm is mounted on nylon bushes. Not bearings so beware of play. If in doubt, they are a fiver each.

I'd have a good look at the rear hub. Make sure the bearings are all ok. That includes the one in the sprocket/brake drum which stays attached to the bike and is heardly ever looked at. Make sure all the spacers are in and in the correct place. Cush drive doesn't have too much play.

Check the rear wheel alignment, the position of the snail cams adjusters is pretty spurious/random. Just because they are set the same does not mean the wheel is in straight.

Parts diagrams here: https://www.hitchcocksmotorcycles.com/partsbook/314/2016-500cc-bullet-efi-b5

I find the standard rims can be a real sod to get the beads up onto. Check they are correct.

Umm. Check it has the right length shocks. The EFI should have 320mm ones. Too short is going to do silly things to the rake angle.

To an extent, it's worth remembering they are quite a "sporty" bike geometry-wise, despite how they look. They have a comparatively short wheelbase and a realtively tight rake and trail. Comparing it to, say a TZR250, the wheelbase on a bullet is an a good 20mm shorter, rake angle is identical and trail is 20mm shorter. The leading axle calms things down a touch on the steering but it can also feel slightly weird.

Both my bullets do have a slightly "wobbly" feel at lower speeds
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[stinkwheel]

[Easy-X]

Yeah, now I see why ppl think these bikes have "character"
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[arry]

Thanks for the input. That's a lot to check up on and some good places to start

[blurredman]

[Polarbear]

I have nothing to add to what people have said above except I wouldn't shout

When there's weight on the back - if I pillion my wife around, it's far more noticeable.

too loud or a wobbly front end might be the least of your worries.
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Triumph Trophy Launch Edition

[Tdibs]

Ive always had the same thing very pronounced on a divvy, running roadriders too, any load in the topbox/anything on the rear = front end wanting to tank slap if I keep my hands off the bars. Higher tyre pressures help, to a point.
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Previous : 09 Vanvan 125| 02' Sv650s || Current: 1999 Xj600n | 1992 DR650 RSE | 2005 Fazer 1000

[MCN]

Drastic changes to tyre construction can present a substantial change in the profile meeting the road.
It's difficult to see but is noticeable when riding the beast.
Tyre pressure can affect the profile as mentioned.
I had issue with new tyres I fitted to a bike due to the way the tyre manufacturer changed from Michelin to Dunlop. It went away after a while or perhaps I just became accustomed to the difference in handling from old to new.
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Disclaimer: The comments above may be predicted text and not necessarily the opinion of MCN.

[pepperami]

Didn’t read/to long.
Has anyone mentioned a squared off rear tyre?
Or worn wheel bearings?
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I am the sum total of my own existence, what went before makes me who I am now!

[Robby]

To sum up the thread, if it isn't notchy head bearings then you need to check everything else on the chassis. It's an Enfield, so there are a lot of things to check due to the, erm, artisanal nature of their construction.

Only other useful bit to add is that front end symptoms are often causes by rear end problems, and vice versa.

[stinkwheel]