Register a SA Forums Account here!
JOINING THE SA FORUMS WILL REMOVE THIS BIG AD, THE ANNOYING UNDERLINED ADS, AND STUPID INTERSTITIAL ADS!!!

You can: log in, read the tech support FAQ, or request your lost password. This dumb message (and those ads) will appear on every screen until you register! Get rid of this crap by registering your own SA Forums Account and joining roughly 150,000 Goons, for the one-time price of $9.95! We charge money because it costs us money per month for bills, and since we don't believe in showing ads to our users, we try to make the money back through forum registrations.
 
  • Post
  • Reply
Renaissance Robot
Oct 10, 2010

Bite my furry metal ass
It wasn't a nail



Given the blunt end it's entirely possible the tube is fine; I'll do a leak check tomorrow

Adbot
ADBOT LOVES YOU

SSH IT ZOMBIE
Apr 19, 2003
No more blinkies! Yay!
College Slice
Could a larger pit bike, like a Kayo tt 125 or 140, function OK as a trail bike? A bunch of people are liking the local ATV park. I have been taking my Versys X 300. I can only deadlift it so many times before I am tired. I don't want to bite the bullet on a CRF300, and like a real tall bike might be tough in atv tire tracks. My stepfather kept dumping his Crf450rl. On my bike in real dicey areas I can waddle with it.

Hm, maybe would be better served by a KLX140 or CRF150.

SSH IT ZOMBIE fucked around with this message at 04:18 on Jun 3, 2023

TotalLossBrain
Oct 20, 2010

Hier graben!
How much do you weigh? My kid (150 lbs) rides a Kawi 140 and it's honestly too slow for him now. You can make it work and it's pretty fun, but you have to ride it like you goddamn mean it. And then the suspension will bottom out all the time.

I'm not sure I'd trust the class of bike you're suggesting in a trail. They may be fine, I don't know. Maybe someone else can chime in.

A 125 2-stroke would work. An XT250 would work, or a TW200, any 250 4T

Verman
Jul 4, 2005
Third time is a charm right?

SSH IT ZOMBIE posted:

Could a larger pit bike, like a Kayo tt 125 or 140, function OK as a trail bike? A bunch of people are liking the local ATV park. I have been taking my Versys X 300. I can only deadlift it so many times before I am tired. I don't want to bite the bullet on a CRF300, and like a real tall bike might be tough in atv tire tracks. My stepfather kept dumping his Crf450rl. On my bike in real dicey areas I can waddle with it.

Hm, maybe would be better served by a KLX140 or CRF150.

Short answer. Yes.

Long answer, it will depend on the trails. Are they just flat dirt/gravel or more like western technical trails?

I would feel more comfortable on a reputable brand than something that's seen as relatively disposable but parts are cheap and they usually run forever. The smaller bikes will get the job done on most normal trails. A lot of the trails out here (Washington state), are rarely fast and open enough to go any faster than 3rd gear so high speed isn't really super important. The benefit is that you'll likely be able to flat foot anywhere obstacles might be tricky. The difficult part will be that the smaller wheels might have trouble rolling over things like rocks, logs etc. The other issue is suspension. Those bikes aren't generally designed for adults so the suspension is often way too soft. I would look at stiffer springs. They also won't have quite the same amount of clearance but unless you're hopping logs and stuff it's not a big deal. To make the smaller bikes more comfortable I see a lot of people put taller bars on (like you would see on a BMX bike).

I see a lot of people ride a wide variety of bikes on the trails and the 140-230cc bikes are generally being ridden by beginners/wives/kids. They're very approachable and give people a lot of confidence. They should be fine to ride some trails.

TotalLossBrain
Oct 20, 2010

Hier graben!
You might consider a used SurRon electric bike or a clone

SSH IT ZOMBIE
Apr 19, 2003
No more blinkies! Yay!
College Slice

TotalLossBrain posted:

How much do you weigh? My kid (150 lbs) rides a Kawi 140 and it's honestly too slow for him now. You can make it work and it's pretty fun, but you have to ride it like you goddamn mean it. And then the suspension will bottom out all the time.

I'm not sure I'd trust the class of bike you're suggesting in a trail. They may be fine, I don't know. Maybe someone else can chime in.

A 125 2-stroke would work. An XT250 would work, or a TW200, any 250 4T


155, 5'8. The place has a speed limit of 20, it's basically hill climbs and descends, lot of roots. They have crushed rock placed through the woods for some semblance of traction in mud.

I am leaning against the pit bikes after seeing some videos, the suspension will probably get damaged.
Kawi 140 might be the smallest doable thing.

A lot of dirtbikers complain about the lack of trail maint and singletrack.

Toe Rag
Aug 29, 2005

Not knowing anything in particular, I would get a TTR125L.

SSH IT ZOMBIE
Apr 19, 2003
No more blinkies! Yay!
College Slice
I have had like real bad luck lately. Do you think it is safer to trail ride on a dirt bike vs adv bike? Like my suspension was upgraded on the ADV. On some of the harder trails there have been a few moments where I wasn't in 100% control, like falling into deep ATV tracks or out and hitting a root. If the bike is at some point going to fall on me, 380 lbs could hurt, 200 lbs is nothing.

And like the thought of the potential of breaking my bike which is my ride to the ATV park and bring stranded isn't great.

I kinda want to stop doing it on the ADV. Offroad nearly flat adv trails aren't a problem at all. This ATV park might kill me.

I kinda am starting to feel like I just got lucky twice not breaking any bones.

SSH IT ZOMBIE fucked around with this message at 15:26 on Jun 3, 2023

TotalLossBrain
Oct 20, 2010

Hier graben!
I think you'd be much, much better off with a smaller, much lighter dedicated trail bike or maybe a small dual sport. 380 pounds is ridiculous on the trail.
Imo a 300 lb bike is still too heavy.*

You want something you can easily control and wrestle around. A 140cc bike like the Kawi or SSRs you're thinking of are around 200 lbs.
It's a huge difference. Once I started riding my VStrom, my KX250 felt like a mountain bike with power, and the KLX140 like a very fun toy.

If you want something small, light, with great suspension - look for 65-125cc 2 stroke MX bikes. Probably a little above your price range. Those suckers are surprisingly expensive even used.

*Unless you just ride fire roads, i.e. easy dirt roads in the forest.

TotalLossBrain fucked around with this message at 16:22 on Jun 3, 2023

knuthgrush
Jun 25, 2008

Be brave; clench fists.

On the topic of trails: what's the best way to climb a relatively steep gravel hill? I usually just put it in 2nd gear, get a little bit if speed, sort of squat and hang my butt over the back of the bike but once in a while I'll just get slapped in the nethers. Effective but it doesn't feel the most controlled of approaches.

TotalLossBrain
Oct 20, 2010

Hier graben!
I'd be going in fast so that most of the speed and momentum is already there and you don't have to build it on the way up.
Move body position forward to keep the front down.
Accelerating uphill lifts the front easily. Moving weight backwards will make that worse.

Edit: what I'm describing is more dirt bike appropriate.
Don't let the seat slap your nuts. Sit down to keep firm contact with the seat and the bike. The suspension should be able to handle this. Still lean forward though.

Slavvy
Dec 11, 2012

He's on a dirt bike so standing up and gripping with the legs makes sense to me, idk how bumpy is bumpy though

TotalLossBrain
Oct 20, 2010

Hier graben!
My own technique is that I try staying seated. If the suspension can't do the work for me, I'll stand up. Knees bent will still leave me higher than just hovering above the seat.

The only time I really smash my balls is when I try wheelying and come back down too hard. Oof

Edit. Actual example with me on the bike going on a pretty steep climb. I'm seated but leaning forward.

https://www.youtube.com/watch?v=8XFxRaFYuFc

Double edit: watch to the end to see me pop into neutral unexpectedly and almost fall over


TotalLossBrain fucked around with this message at 21:18 on Jun 3, 2023

GriszledMelkaba
Sep 4, 2003


Sands different!

Beve Stuscemi
Jun 6, 2001




Gravel you want to be pretty far forward so the rear end can move around without moving you around too much

Also as mentioned hit it as fast as you can to let momentum do as much work as possible

SSH IT ZOMBIE
Apr 19, 2003
No more blinkies! Yay!
College Slice

knuthgrush posted:

On the topic of trails: what's the best way to climb a relatively steep gravel hill? I usually just put it in 2nd gear, get a little bit if speed, sort of squat and hang my butt over the back of the bike but once in a while I'll just get slapped in the nethers. Effective but it doesn't feel the most controlled of approaches.

In my own personal experience, lotta gas, low gear, lean forward, let the back end do whatever, might kick sideways a lil but the forward momentum keeps the bike upright. If there's roots and stuff maybe you can be out of your seat a lil.

SSH IT ZOMBIE
Apr 19, 2003
No more blinkies! Yay!
College Slice

TotalLossBrain posted:

I think you'd be much, much better off with a smaller, much lighter dedicated trail bike or maybe a small dual sport. 380 pounds is ridiculous on the trail.
Imo a 300 lb bike is still too heavy.*

You want something you can easily control and wrestle around. A 140cc bike like the Kawi or SSRs you're thinking of are around 200 lbs.
It's a huge difference. Once I started riding my VStrom, my KX250 felt like a mountain bike with power, and the KLX140 like a very fun toy.

If you want something small, light, with great suspension - look for 65-125cc 2 stroke MX bikes. Probably a little above your price range. Those suckers are surprisingly expensive even used.

*Unless you just ride fire roads, i.e. easy dirt roads in the forest.

Yeah. The bike I have is totally fine for backcountry "adventure" riding. These trails I am hitting feel like play stupid games win stupid prizes. Another friend just got an ATV so it is time for a dirt bike.

Kayo makes a 140. It's better than the SSR. I was looking at it, steel brake lines, shifts nice. 160 lbs. My other friend just got a track bike by them. Works actually really well.

They aren't comparable to the $900 chinabike I got. Company is run by an ex honda engineer. US parts. Several local KTM dealers will also service Kayos but won't touch Baodiao\XPRO\etc.

The Kawi 140 also crossed my mind. I want to keep it to like slightly shorter dirtbikes. A lot of dirtbikers complain about the place I am going to as the trails are beat up by ATVs or unmaintained.

SSH IT ZOMBIE fucked around with this message at 22:21 on Jun 4, 2023

Fluffs McCloud
Dec 25, 2005
On an IHOP crusade
How does this happen:


Spotted this yesterday morning, after having had a new rear tire put on a week or so ago. Haven't been riding too many miles since then. The last persons to touch the rear wheel was a local independent shop, but I suppose that doesn't preclude some really egregious error on my part from adjusting chain slack a week or so before that, I can say for a fact that I tightened up that locknut and now it's finger loose.

Additionally, I'm obviously gonna need a new chain puller, but what else do I need to check, no way the axle or the bearings in and around that could be very happy, right?

Fluffs McCloud fucked around with this message at 01:02 on Jun 6, 2023

Slavvy
Dec 11, 2012

1. The shop hosed up, no further questions at this time

2. The bearings will be fine, the axle will likely be fine but I'd check it's straight, have a good look at the sprocket and its bolts when you get the wheel out, the alloy axle carrier part will likely be hosed also

Fluffs McCloud
Dec 25, 2005
On an IHOP crusade

Slavvy posted:

1. The shop hosed up, no further questions at this time

If you'll bear with my amateur mechanic brain for a few more seconds, could you expand on how they likely hosed it up? Missing or incorrectly assembled parts, not tightened to spec?

quote:

2. The bearings will be fine, the axle will likely be fine but I'd check it's straight, have a good look at the sprocket and its bolts when you get the wheel out, the alloy axle carrier part will likely be hosed also

You willing to tell me the part number from here that corresponds with the alloy axle carrier? Like I said, pretty limited mechanical knowledge.

https://www.partzilla.com/catalog/yamaha/motorcycle/2021/xsr700-xsr700mcw-b2gl/rear-wheel

Captain McAllister
May 24, 2001


Should a bushing running between the two bearings in a front wheel spin with the bearings? I feel like the answer should be 'no'.

I'm still trying to track down an intermittent issue with my bike, and think I've at least narrowed it down to the front end.

The issue only seems to come up after riding for a while, and the bike drags and feels like I've gone into a headwind or am riding over hot tar or something.

All of the wheel bearings have already been replaced with SKF bearings front and rear, but I don't have any paperwork for when.

When the issue happens, I've coasted in neutral to a stop without using the brakes, and none of the rotors or hubs are even warm to the touch.

I'm running out of ideas.

SSH IT ZOMBIE
Apr 19, 2003
No more blinkies! Yay!
College Slice

Captain McAllister posted:

Should a bushing running between the two bearings in a front wheel spin with the bearings? I feel like the answer should be 'no'.

I'm still trying to track down an intermittent issue with my bike, and think I've at least narrowed it down to the front end.

The issue only seems to come up after riding for a while, and the bike drags and feels like I've gone into a headwind or am riding over hot tar or something.

All of the wheel bearings have already been replaced with SKF bearings front and rear, but I don't have any paperwork for when.

When the issue happens, I've coasted in neutral to a stop without using the brakes, and none of the rotors or hubs are even warm to the touch.

I'm running out of ideas.

What bike, how is your chain maintenance? What kind of chain?
Where is your clutch engagement point? Is the clutch slipping? How many miles, what kind of bike? What makes you say the problem is in the front? Actually neutral, or holding in clutch neutral? If actually neutral, I think you can cross off the clutch checks.

How do the calipers and brake pads look? If you prop up the front wheel immediately when it happens does it spin freely?

Did you tighten the wheel out of spec to the forks? Could be compressing the bearings depending on the bike.

SSH IT ZOMBIE fucked around with this message at 03:10 on Jun 6, 2023

SSH IT ZOMBIE
Apr 19, 2003
No more blinkies! Yay!
College Slice

Fluffs McCloud posted:

If you'll bear with my amateur mechanic brain for a few more seconds, could you expand on how they likely hosed it up? Missing or incorrectly assembled parts, not tightened to spec?

You willing to tell me the part number from here that corresponds with the alloy axle carrier? Like I said, pretty limited mechanical knowledge.

https://www.partzilla.com/catalog/yamaha/motorcycle/2021/xsr700-xsr700mcw-b2gl/rear-wheel

I don't think you should gently caress with your axle without a torque wrench, thread lock, and basic mechanical knowledge. Partzilla has explosion diagrams for all the parts. This is honestly a lot to diagnose over the internet, because it requires putting the bike on a stand, and disassembling the back end for inspection and maintenance. Can't the shop fix it under warranty? The only way that can happen is if they didn't torque the axle to spec or didn't lock it in some way(cotter pin, thread lock, other mechanisms)

If you want to pull the back end apart and lay like the axle, chain tensioners, etc out maybe can get part numbers. But like are YOU going to fix it right? Do you want to buy the tools and learn?


Or did you not ride it like that? You checked it, felt it was loose, and undid it? If you didn't ride it like that, the wheel is probably just out of alignment. Align it, torque and secure to spec, tighten second nut on chain adjuster.

SSH IT ZOMBIE fucked around with this message at 03:08 on Jun 6, 2023

Captain McAllister
May 24, 2001


SSH IT ZOMBIE posted:

What bike, how is your chain maintenance? What kind of chain?
Where is your clutch engagement point? Is the clutch slipping? How many miles, what kind of bike? What makes you say the problem is in the front? Actually neutral, or holding in clutch neutral? If actually neutral, I think you can cross off the clutch checks.

How do the calipers and brake pads look? If you prop up the front wheel immediately when it happens does it spin freely?

Did you tighten the wheel out of spec to the forks? Could be compressing the bearings depending on the bike.


Edit:

Bike is a 2013 F800GS, with 26,000 km.

I don't think it's a clutch issue, coasting was in neutral, no use of clutch lever).

All wheel bearings pass the lateral wiggle test.

I did rear brake pads last summer, and front fork seals over the winter prior. I tightened everything to factory specs with a torque wrench.

Chain I clean and wax every 4-600km or so (try for every 400km, sometimes when I'm getting close to that a longer ride takes me over.

No kinked links in the chain.

I've tried cleaning the calipers and slide pins, everything seems to move ok.

SSH IT ZOMBIE
Apr 19, 2003
No more blinkies! Yay!
College Slice
If it was my bike I would ride around till it happened, get it home, put it on paddock stands(Moto D are OK, Pitbulls are amazing), and see which wheel isn't moving right.

If you have a center stand that works too.

Slavvy
Dec 11, 2012

Fluffs McCloud posted:

If you'll bear with my amateur mechanic brain for a few more seconds, could you expand on how they likely hosed it up? Missing or incorrectly assembled parts, not tightened to spec?

You willing to tell me the part number from here that corresponds with the alloy axle carrier? Like I said, pretty limited mechanical knowledge.

https://www.partzilla.com/catalog/yamaha/motorcycle/2021/xsr700-xsr700mcw-b2gl/rear-wheel

There are two options. Either you left the adjuster loose when you did your chain and they didn't see it, or they loosened it when they did the wheel and they didn't tighten it. Either way it's their fault, that is not something you should miss when you're doing a tyre.

Looking at the diagram and your bike doesn't work like I thought it did, I would just get 23, 24 and maybe 31 if it's damaged

Captain McAllister posted:

Edit:

Bike is a 2013 F800GS, with 26,000 km.

I don't think it's a clutch issue, coasting was in neutral, no use of clutch lever).

All wheel bearings pass the lateral wiggle test.

I did rear brake pads last summer, and front fork seals over the winter prior. I tightened everything to factory specs with a torque wrench.

Chain I clean and wax every 4-600km or so (try for every 400km, sometimes when I'm getting close to that a longer ride takes me over.

No kinked links in the chain.

I've tried cleaning the calipers and slide pins, everything seems to move ok.

You may have an issue with the ABS putting pressure on the front brake because of an internal fault, I have seen this happen on those bikes before. You could test for it by line clamping one of the brakes and carefully riding around using only the other one until the problem appears or doesn't. I think what you're experiencing can only be explained by a brake issue.

SSH IT ZOMBIE posted:

If it was my bike I would ride around till it happened, get it home, put it on paddock stands(Moto D are OK, Pitbulls are amazing), and see which wheel isn't moving right.

If you have a center stand that works too.

I'm gonna need you to really step back and stop handing out 'advice' while you're still glistening with egg yolk please and thank you

That said it's worth figuring out which wheel is binding when the problem occurs

e: wait to clarify, did the wheel bearings get replaced to fix the issue or did it start happening after they were done?

Slavvy fucked around with this message at 03:53 on Jun 6, 2023

SSH IT ZOMBIE
Apr 19, 2003
No more blinkies! Yay!
College Slice
Outside of like chasing specific mechanical issues - does anyone have any holistic bike maintenance plan outside of vendor service intervals and normal stuff like chain and oil, tread?

I am watching videos on youtube...husq shipping new bikes with dry steering head bearings in the tripple tree...then I had a weird cooling issue on my new Kawasaki, weird sediment and metal filings in the coolant...flushed it and it hasn't happened again...

I was surprised by the catastrophic cush drive failure on the china bike I have, and the frozen wheel bearings upon disassembly.

It's not necessary to disassemble bikes looking for problems, is it? If so, what problems are normal to look for? Should I bash apart my tripple tree on the china bike to inspect for bearing lubrication, or just wait till it handles funny? Rip off the front wheel to look at the bearings?

My kawasaki should be much better, right?

I am...worried about the mechanical soundness of my bikes. So far I am just reacting to stuff. Kawasaki next to nothing has gone wrong outside of the coolant.

Or, for the most part, stuff like wheel bearings inspect or have the shop inspect when changing tires? You'll notice stuff degrading with normal maintenance?

I am mechanically inclined enough to react to stuff and fix without youtube. I definitely do not have the experience to know what to expect ahead of time.

SSH IT ZOMBIE fucked around with this message at 06:11 on Jun 6, 2023

Captain McAllister
May 24, 2001


Slavvy posted:

You may have an issue with the ABS putting pressure on the front brake because of an internal fault, I have seen this happen on those bikes before. You could test for it by line clamping one of the brakes and carefully riding around using only the other one until the problem appears or doesn't. I think what you're experiencing can only be explained by a brake issue.

That said it's worth figuring out which wheel is binding when the problem occurs

e: wait to clarify, did the wheel bearings get replaced to fix the issue or did it start happening after they were done?


I haven't done the wheel bearings. I thought they might be the most likely culprit, so I ordered the replacements before I tore into everything (good thing, because one of the rear wheel seals needed to be replaced and didn't survive removal.)

Once I cleaned up under the seal, I found that they've already been replaced with SKF bearings (which is also what I had ordered).

They spin OK (no gritty or notchiness), and with the wheels off the bike I partially reinserted the axle and wiggled it around to test for lateral play.

I bled both front and rear brakes at the beginning of May before going on the most recent test ride. I went about 80km issue free, stopped, walked around, and the issue returned maybe 1km into my return trip. I think it's the front wheel because when I got up to speed and coasted to a stop, there was almost a rhythmic 'whumming' noise from the front wheel, that I was able to get on video.

Slavvy
Dec 11, 2012

To me that sounds like the front brake is sticking on

Toe Rag
Aug 29, 2005

I asked about this before, but now I have some specific numbers, so I am back. My fork has 118mm of travel, per the FSM (although it calls it "front axel travel"). The air gap is 111mm, per the FSM. Then you put the spring in, which reduces the gap even further. In my mind, fork oil is incompressible, so how do I have 118mm of travel? Or is that the maximum possible amount based on the fork design, and the actual amount is tuned by the oil level?

Slavvy
Dec 11, 2012

The oil level has no bearing on fork travel. Travel is 'hard' limited by how far the stanchion will go into the lower (or vice versa on usd's) before hitting the bottom out stop, then soft limited by the spring (usually the spring rate is too soft for this to happen so you just bottom out anyway).

The air gap just gets compressed when the fork compresses because air is compressible. As the air gap compresses it is basically adding to the spring rate. Bikes that experience frequent rapid fork movement and have relatively fast damping (so dirt bikes) will tend to cavitate and suck air in past the fork seals with every extension, eventually this builds up a lot of pressure in the air gap causing the fork to feel harsh. These bikes usually have an air bleed screw on the fork for this reason.

Toe Rag
Aug 29, 2005

I understand conceptually how a telescoping fork works, but maybe not in actuality. Let's say I have 150mm of travel but only a 90mm air gap. What happens once I'm 120mm into the stroke? In my mind there air is probably entirely compressed, and now you're running into the oil, which has nowhere to go, but as I am writing this, I realize maybe there has to be room inside the cartridge for oil to go into so you have any damping at all?

Slavvy
Dec 11, 2012

You simply wouldn't have that short an air gap with that long a fork travel is all, if you find a conventional fork (so no special chambers MX bullshit) with numbers like that I'd be interested in seeing it. I honestly have never thought that deeply about it lol

Sagebrush
Feb 26, 2012

Every shock absorber has three key parts: the slider (or linkage), the spring, and the damper.

The slider is the part that allows the wheel to move relative to the frame and track over bumps and holes in the surface. With no moving parts, you cannot have suspension. This should be obvious.

The spring is the part that keeps the slider or linkage suspended in the middle of its travel, and which responds to forces by pushing back in the opposite direction. Without the spring the slider would just collapse. (Hopefully this is obvious too).

However, springs don't absorb significant amounts of energy. When stretched or compressed and then released, they oscillate. If all you had on the front of the bike was a slider and a spring, the first bump would start it bouncing up and down like crazy. In addition to moving in response to forces and returning automatically to center, the suspension needs to absorb the energy behind those forces somehow. This is the purpose of the damper.

In most shock absorbers, the damper is a piston that moves in oil. The piston is not fully sealed! It has a small hole(s) in it that allow the oil to flow past it at a controlled rate. When the suspension compresses, the oil -- which can be considered incompressible -- prevents the piston from moving any faster than the oil can flow through the hole. This slows down the motion of the suspension. Similarly, when the spring returns the slider to center, the oil slows down the spring and absorbs its force so it doesn't overshoot and oscillate.

Here is a nice picture of what's going on inside:



So as you can see, because the oil flows around both sides of the piston, there is no situation where the piston hits a hard "wall" of oil and stops moving. The end of the travel is when the mechanical system bottoms out.

The reason the oil level matters is because the air space above the oil forms another sort of spring that changes how the system behaves under compression. Too little oil and the fork will be too soft, too much and the fork could hydrolock and blow out your seals.

Fancy suspensions have clever mechanical systems that change how the oil damper behaves in different circumstances. For instance, you usually want your suspension to be pretty hard when braking so that the fork doesn't dive too much, but if it's too hard it won't rapidly respond to small bumps in the road. Those would seem to be at odds. Old designs just kind of split the difference and called it a day. New designs will have a system where (for instance) the fork is normally damped through a small hole, making it stiff under slow, consistent compression like braking. However on a sudden shock, like hitting a pothole, the compressed oil forces open a spring-loaded valve and blasts through, allowing the fork to rapidly compress and track the surface. As soon as the force is gone the valve slams closed and it's back to firm and well-damped. Cool stuff.


So to answer this more directly,

Toe Rag posted:

I understand conceptually how a telescoping fork works, but maybe not in actuality. Let's say I have 150mm of travel but only a 90mm air gap. What happens once I'm 120mm into the stroke?

It would depend on the diameters of the tubes and the volume of oil that fits in the bottom versus the top. If it were designed so that 120mm of travel at the bottom raises the oil level at the top 120mm as well, you'd hydrolock and blow out the seals. If the top tube were significantly larger in diameter than the bottom tube, so that 120mm at the bottom is only 60mm in the top, it would be fine.

In your specific case, where it's only a matter of a centimeter or so, I bet there is a difference in volume of oil vs. height in the top and the bottom, and that's why it works.

Sagebrush fucked around with this message at 08:47 on Jun 7, 2023

Captain McAllister
May 24, 2001


Slavvy posted:

To me that sounds like the front brake is sticking on

What did you mean by clamping the lines? Like, front or back? Or one side of the calipers up front, then the other?

Would taking the pads out have the same effect?

Slavvy
Dec 11, 2012

Taking the pads out is not a good idea.

I mean clamp off the front or rear brake near the MC, doing it to one caliper at a time on the front can help if you're trying to narrow down which caliper is the problem.

Start by actually identifying the issue properly first. Make it occur, work out which wheel is dragging, go from there.

Phy
Jun 27, 2008



Fun Shoe
Having starting issues on the ZRX, not sure what the culprit is.

  • I push the starter button with the killswitch closed, bike in neutral and stand down or bike in gear with clutch in and stand up, and the starter does gently caress-all. No clicks, nothing.
  • picking the bike up and moving it a few inches seems to do the trick most of the time
  • I did have to bumpstart it once last week, that worked fine
  • Starter gets the engine turning promptly when it does engage
  • Battery may have issues due to going a month or more uncharged while I dealt with COVID last fall, but I had a dying battery in this bike a couple years ago and it presented more as being very anemic starting the bike.
  • my kickstand bolt was alarmingly loose, like not even finger tight. Bad Phy.
  • However, so far no issues with having the engine cut off once it's running, which to my mind implies that it might not be the kickstand switch.

E: by the owners manual, I shouldn't have to clutch in on start if it's in neutral, and I think the wiring diagram agrees but I'm not 100% positive.

Phy fucked around with this message at 17:36 on Jun 7, 2023

Sagebrush
Feb 26, 2012

I have never owned a bike with a kickstand cutoff so idk anything about that one.

No clicks means there is no power getting to the starter relay. So it's either a bad connection somewhere in the chain that goes battery -> starter button -> relay -> ground, or one of the cutoff switches is not working properly and the relay is not getting energized (or grounded, depending on system layout).

The fact that it works when you roll the bike a few inches suggests it might be connected to the neutral cutoff, since rolling it around is rotating the output shaft and some other elements of the transmission.

Going on memory here but I believe the neutral switch is closed and connected to ground when the bike is in neutral. So I would suggest maybe disconnecting the neutral switch wire and clipping the wiring harness end directly to battery ground with an alligator lead. If it starts reliably that way, there is something wrong with the neutral switch. If it still doesn't, then you've eliminated that from the equation and can look at the other parts of the circuit.

SSH IT ZOMBIE
Apr 19, 2003
No more blinkies! Yay!
College Slice

Captain McAllister posted:

What did you mean by clamping the lines? Like, front or back? Or one side of the calipers up front, then the other?

Would taking the pads out have the same effect?

I also think it is the brakes, was in the list of potentials posted earlier. The INTERNET has me believe that your bike has an ABS sensor on the front fork that is easy to damage if not removed during front wheel removal\installation. Additionally there is a way to disable ABS it looks on your bike, again according to the internet. Try that. If it is that, you could start trying things like replacing the sensor or cleaning it. It's a BMW though. Angry electronics for not following weird esoteric dealership stuff?

Adbot
ADBOT LOVES YOU

Slide Hammer
May 15, 2009

Phy posted:

Having starting issues on the ZRX, not sure what the culprit is.

  • I push the starter button with the killswitch closed, bike in neutral and stand down or bike in gear with clutch in and stand up, and the starter does gently caress-all. No clicks, nothing.

My bike is outside all of the time, and the killswitch just recently needed to be jostled to allow current to pass through what are probably corroding contacts. No current going to the starter at all sounds like one of the safety mechanisms, like that loose kickstand bolt possibly misaligning the kickstand from the plunger switch it's supposed to hit when it's raised (sounds like the most likely culprit).

I would check those contacts. When batteries are too weak to spin starters, they will actuate the solenoid (the starter click) and then not have enough power to actually turn the engine.

  • 1
  • 2
  • 3
  • 4
  • 5
  • Post
  • Reply