Stark Varg “weave” (steering wobble)

[texanate]

I picked up a Stark Varg MX a couple months ago and have put about 20 hours on it so far, trailriding.

I mostly love it, but from that very first ride around the neighborhood after putting it together, I noticed it doesn’t like to stay pointed in a straight line. It kinda weaves, slaloms on its own, or “swims” like a fish. It’s most noticeable on pavement and gravel transit sections but on the trail it’s hard to put the front wheel exactly where I want it - it feels like the front wheel is loose somehow. At first I thought it was just brand new dirt tires on pavement, but the issue persisted.

Things I have tried that have not seemed to help the issue:
- Changing the tires (I wanted to run Tubliss /
gummy tires anyway)
- Tightening the following to spec: Steering head nut (loosening the associated pinch bolt first), fork leg pinch bolts (upper and lower), front axle nut and axle pinch bolts, rear axle nut, docking station (handlebar) bolts, handlebar mount lower bolts.
- Adding rear preload to get proper race sag (I am 240lb, so will install a stiffer spring soon too).
- Checking wheel bearing play (no play)
- Checking front wheel spacers (it would be obvious if these were in there backwards right?)
- Checking the front end for play (i.e. standing in front of the bike, locking the wheel with my feet and trying to pull the handlebars left and right) - no clunking or abnormal play that I could tell.
- Checked front wheel spoke tension. I don’t have a spoke torque wrench but I tapped all the spokes and they all sounded fine.

My next ideas:
- Maybe loosen the steering head a lot and see if the issue is noticeably worse? This same bolt on my Tenere is like 140Nm, is it possible the Stark spec (I forget if it’s 12-14Nm) is way too low?
- Stiffer rear spring (in case this is a geometry issue)
- Get a spoke torque wrench and actually torque the spokes up properly?

After that it might be a trip to the mechanic, and/or finding someone else local with a Varg who would be willing to swap bikes to see if they’re all like this. My benchmark is mostly Yamaha 4-stroke dirt bikes, which are renowned for being very stable, but I feel like no bike would weave like this.

 

[OpaTsupa]

Do you only notice it on asphalt and at higher speed?
If so try balancing the wheels using spoke weights. I've seen reports of as much as 100g needed.

If you are noticing understeer or oversteer than try to check the fork legs alignment using this device:

ForkTru™ - Fork Alignment Tool - Motion Pro

Motion Pro - High quality cables, tools and controls for motorcycles, ATVs, snowmobiles and personal watercraft.

www.motionpro.com

My test for problem in this area is to ride perpendicularly on the steep incline. If the front slips or bucks than there is malalignment somewhere.

Also check the chain/axle alignment.
If you like gizmos, there are laser alignment tools for not much money.

You could also try lowering the forks in the triples. That should settle the front end assuming the rear geometry is correct, but there are tradeoffs.

 

[texanate]

Thanks for the tips. The weave is apparent at low speeds - like 15-20mph on asphalt - it’s not a high speed wobble like I’ve seen on YouTube (but thankfully never experienced). At very low trailriding speeds it manifests as vagueness in the front end. I ordered in the MotionPro fork alignment tool - seems like a more systematic way to confirm front end alignment vs bouncing and guessing like I usually do. Will be useful on my other bikes too, even if it doesn’t solve my immediate issue with the Varg.

 

[Philip]

Try sitting more forward.

Also, tighten that steering stem nut as hard as you can. This is your steering damper and stabilizer. I run mine pretty tight, it gives me a calmer front end at all speeds.

 

[texanate]

So I did an experiment today - I tried the steering nut at 3 different torque settings: 2nm,
12nm and 20nm, and rode the bike around the neighborhood at each of the settings, trying to replicate the conditions of that initial test ride when the issue was so prominent. Unfortunately, the weave wasn’t super apparent today at any of the settings. I did feel some tightness / resistance to turning at the stiffer torque setting, which I didn’t like. So, mission accomplished?

Maybe, maybe not. After I packed away the tools it occurred to me that low tire pressure might mask the issue on pavement, ugh. That or some of the digging around torquing random front-end bolts to spec yet again fixed the issue. Or maybe some steering components have finally broken in?

When I googled around for the issue generically (across all dirt bike makes and models) I heard that leaving that steering stem nut too loose OR too tight can cause weaving - if it’s too tight the bike can’t self-straighten with the steering.

When the issue surfaces, riding on the front or back of the bike doesn’t make a difference.

New supermoto wheels should come in the next few weeks, and I’ll move to a stiffer shock spring soon too - so maybe those changes might shed light on the cause too.

 

[markhamr]

tyre pressure and ride height both at the front and rear
are the main factors to consider
suspension adjustment too.

 

[markhamr]

Soft spring soft tyre add some torque =wobble wobble
A bit like taking high speed weave out of the front of any dirt bike.
Start by running higher tyre pressure.
I switched to a 14 front sprocket it actually caused some spring wind up in the rear.(pitching)
Balance is the key .The bike does struggle with that being so overweight.
The more I soften it the more it is all over the place.

 

[AbnormalWrench]

I have dirt tires (original) and street tires. The dirt tire has a bit of a wobble on the road. There is no wobble at all with the street tires. I just assumed it was the relatively aggressive nobbies on the front tire. I don't ride on the street very often with the dirt tires, so never looked into it. I would expect lowering your front tire pressure would help.

 

[MotoxXxMan]

When I googled around for the issue generically (across all dirt bike makes and models) I heard that leaving that steering stem nut too loose OR too tight can cause weaving - if it’s too tight the bike can’t self-straighten with the steering.

This is where my mind was going. Especially after that guy above said tighten the steering nut as tight as possible. NOOOOOOOOO, that is the WORST thing you can do! To any bike!
Different bikes have different ways of doing it, but whatever tensions the two conical steering bearings is supposed to only be SNUG, tight enough to have some light tension and not have any play, but loose enough to not allow it to stick at all. If it's even the slightest bit too tight causing the steering to stick, yes, it will weave. Because it will stick and drift til it gets beyond whatever force cracks it loose to turn the other way, then sticks and drifts the other way, and just repeats back and forth nonstop. This is always the very first thing I check, especially when buying a used bike, because theres a LOT of people out there that crank that nut down way too frickin tight thinking its supposed to be tightened like a fastener and not a tension device.
After that; Fork alignment, torque specs, and tire pressure.
And when aligning the forks, theres a specific order it all has to be tightened in, otherwise it will often cause it to be out of alignment. Doing the right order typically aligns itself too, meaning no tool or anything else needed. Start with all bolts loose, backed out several threads from touching. with front wheel off the ground: Torque the axle nut. Torque lower steering clamp bolts. Hold the front wheel between your legs and give the bar a small wiggle back and forth, see if you feel it moving or not. Hopefully not. This causes the self alignment simply due to pressure on the flat surfaces. Then torque the upper steering clamp bolts. Then tighten the steering pinch bolt. Then tap the fork legs with a hammer to settle the axle centered in the clamps (the axle should be greased so it cam move freely in the clamps), then tighten the axle clamp bolts.

Considering your weight, and that you mentioned you properly adjusted rear sag, there's also a chance the front end is sagging too low, which would have the same effect as raising the forks too far up in the clamps. So until you increase the front spring weight, it'd be good to test various fork heights too, starting with stock setting, and lowering them from there 2-3mm at a time. Just don't go beyond flush at the top, because that could start to cause some other issues, maybe. I'm wondering if perfectly flush will end up being the best setting for your weight with stock springs.

Another thought; I've seen a number of people complain about how there was nearly zero grease in any of their bearings throughout the bike. A lack of lubrication can cause all sorts of weird issues too. One of which would be the steering sticking even when torqued properly. I would suggest disassembling the steering and packing the steering bearings with as much waterproof grease as possible. There are very specific ways to pack conical bearings, and unfortunately nearly none of them work once pressed onto the steering parts. One way I have found that works well is to have a grease gun dedicated to only using waterproof bearing grease, and get a needle attachment for it. They are a very small very sharp hollow needle used for piercing the rubber boot of tie rods and balljoints to grease them when they don't have a grease fitting. You can stick the needle down into the race of the conical bearing and inject the grease from the inside until it pushes out between the rollers. Then move over a few rollers and repeat, and go around the full circumference of the bearing doing this until its completely full. And apply liberally to the outside of the bearing as well as the race before assembling again.

 

[MotoxXxMan]

Oh also, have you spun both wheels while on a stand to make sure they're both still perfectly true and straight? If a wheel is canted a little, it'll definitely cause a weave back and forth, though it'd be a higher speed wobble than a low frequency weaving.

 

[DaveAusNor]

I've seen a number of people complain about how there was nearly zero grease in any of their bearings throughout the bike

I have a few questions here. Isn't "nearly zero grease" very subjective? Some people's "zero" might be another persons "loads".

I asked an LLM and got this response for different bearings:

• Wheel bearings: Typically packed with a high-temperature grease, and the amount is often specified in grams or by visual inspection (e.g., "fill 2/3 of the bearing cavity").
• Swingarm and linkage bearings: Should be fully packed but not overfilled to avoid attracting dirt.
• Steering head bearings: Usually require a generous but not excessive amount—enough to coat all surfaces.
• Axles and bolts: A thin layer is enough, often specified as “light coating.”

and also

• Over-greasing: Can lead to problems like attracting dirt, causing seals to pop out, or interfering with torque specs.

I would say the parts I've dealt with so far (EX model) have been adequate, more than other OEMs. I'll wait until the winter month tear down to do a more thorough assessment.

Has anyone found any particular parts that have required immediate attention?

 

[Theo]

AJ Catanzaro says that you should tighten the steering bearings a lot:

But this is one of the few of his tips that I disagree with, mainly because I want my bikes to take as little maintenance as possible and I believe that this will reduce the bearings lifespan. According to the guidance read on websites of bearings manufacturers, tapered bearings should have some preload just to compensate for their limited, but still existent, elasticity, that would generate play under load with 0 preload. I also think that some preload prevents the rollers from sliding instead of rolling.
Too much preload, though, will surely reduce the lifespan of the bearings. In the company I work for, they once needed to compress a component by 1.000 kg for R&D purposes and they achieved that just by turning a nut on a threaded rod with a wrench. The dimensions of the thread of that rod were similar to those of a steering stem thread, so when you apply force to those bearings you will be crushing them a lot. Theoretical formulae also suggest that you could achieve such forces.
Besides, what if you successfully hide some wobble with a stiffer steering? What if then the wobble is still there while airborne and all of a sudden the bike is free to rotate and it destabilizes the bike?

 

[MotoxXxMan]

I have a few questions here. Isn't "nearly zero grease" very subjective? Some people's "zero" might be another persons "loads".

Pictures were posted, I (a retired performance auto master tech and powersports mechanic) can verify, there was truly nearly zero grease in/on the bearings. And it has happened to a LOT of people, and it was almost always all the bearings throughout the entire bike when it did happen; not just one or two random bearings here and there. They literally looked almost completely dry. As if someone had a dot of grease on their fingertip, and just smudged a thin coating across the needles/rollers and thought that was enough, just enough to give a wet sheen and thats it.
If you've had any bearings open or apart and they had an ample amount of grease, I'm going to assume your steering bearings have enough grease, just based on the pattern from what happened to the people commenting in the thread about nearly zero. Meaning all bearings were greased correctly, or none were. There didn't seem to be an in between.

Has anyone found any particular parts that have required immediate attention?

Grease in all the bearings... lol.

 

[MotoxXxMan]

AJ Catanzaro says that you should tighten the steering bearings a lot:

But this is one of the few of his tips that I disagree with, mainly because I want my bikes to take as little maintenance as possible and I believe that this will reduce the bearings lifespan. According to the guidance read on websites of bearings manufacturers, tapered bearings should have some preload just to compensate for their limited, but still existent, elasticity, that would generate play under load with 0 preload. I also think that some preload prevents the rollers from sliding instead of rolling.
Too much preload, though, will surely reduce the lifespan of the bearings. In the company I work for, they once needed to compress a component by 1.000 kg for R&D purposes and they achieved that just by turning a nut on a threaded rod with a wrench. The dimensions of the thread of that rod were similar to those of a steering stem thread, so when you apply force to those bearings you will be crushing them a lot. Theoretical formulae also suggest that you could achieve such forces.
Besides, what if you successfully hide some wobble with a stiffer steering? What if then the wobble is still there while airborne and all of a sudden the bike is free to rotate and it destabilizes the bike?

Keep in mind he started that video by saying "some people run their steering really really tight. And that he used to run his loose, until he learned there can be some positive effects of steering tight enough for it to stick a little.
Also notice the way he was describing it, wasn't referring to it being torqued to hell and back, just being tight enough to stick. Not so tight that it binds up.
Also keep in mind, the people he's referring to are sponsored pros who mostly don't wrench their own bikes, and which get completely overhauled practically every race. People that literally run brand new tires for every single race, and then toss them and install a new tire for the next race.
And now that I'm thinking about that, where do all those tires end up? And how much wear could they actually have after a single moto? Can I get some for dumb cheap? Now I'm OT, back on topic... Lets help the OP figure out his steering issue.

 

[MotoxXxMan]

Has anyone found any particular parts that have required immediate attention?

I would suggest checking other threads. There are some specifically regarding that topic. This thread is about a steering wobble issue, lets try to stay on topic, myself included

 

[Theo]

Keep in mind he started that video by saying "some people run their steering really really tight. And that he used to run his loose, until he learned there can be some positive effects of steering tight enough for it to stick a little.
Also notice the way he was describing it, wasn't referring to it being torqued to hell and back, just being tight enough to stick. Not so tight that it binds up.

I've watched more than a video in which he suggests to tighten those bearings a lot, not just slightly, like in this other one:

I can't find it right now but I remember having watched one in which he said that he learnt that from the Lawrence borthers.

Also keep in mind, the people he's referring to are sponsored pros who mostly don't wrench their own bikes, and which get completely overhauled practically every race. People that literally run brand new tires for every single race, and then toss them and install a new tire for the next race.

That surely makes a difference; if I had the support of a team willing to replace them often, I would try that.

 

[Chaconne]

As others have suggested tire pressure and type of tire would be first on my list. I would swap out the front tire before I did anything to settings and work my way from the wheel up. Next spokes and balance.

Hacking at steering bolts, torques, and suspension before you eliminate the contact point is a mistake I made with my WR450 which tended to "float" at certain speeds on asphalt.

I would also suggest using a standard tube in any test rather than mousses or other non --only suggesting to test and I am figuring you don't rider knobs on asphalt regularly.