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 Swingarm eaten by chain

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Akasy




PostSubject: Chain slider wear   Wed Jun 22, 2011 9:51 am

I think you are running yours about where mine is or just a tad tighter.

Your assumptions on no slack topside under power is correct--counter pulling on rear sprocket.

However, don't think you will see wear as you envision. The top of the chain slider will wear as the slides across it under deceleration or it can slap up and down if too loose. I see this all the time on my KTM where I run the chain extremely loose.

I agree with your assumption on chain wear on the bottom from too tight a chain.

Also concur with your statement on suspension compression.

It would be interesting to see exactly what position the swing arm wear has occurred by looking at where the swing arm would have to have been postioned for the chain to do the damage. That is would the swing arm have to have been under comprssion for the chain to make the marks or could the loction of the marks been accomplished while the swing arm was in a "normal" position?


motokid wrote:
I just went out ("non-smoking smoke break") and checked my slack with a non-calibrated eye and a pretty hefty push on chain. I got to roughly a half inch-ish from chain to swingarm. Looked a little less than a true half inch but not much.


Thinking more about this:

Would swingarm wear on underside of swing arm be a symptom of chain to tight, and swingarm wear on top be a symptom of too loose?


The tension on the chain under load (acceleration) would be on the top part of chain between sprockets right?
The slack would be under the swingarm during normal operation.

But when the suspension compresses the chain on the top move away from swingarm and the chain underneath moves closer, or even into the swingarm.

Just trying to figure out cause and effect here while sitting at desk.

What would too loose versus too tight chain conditions look like on swingarm protector?

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KLRchickie




PostSubject: Re: Swingarm eaten by chain   Wed Jun 22, 2011 10:47 am

motokid wrote:
Old, original spec:





So how different is the new "chain spec" with the 8mm from swing arm to the original?

Is the new spec tighter, or looser?



After realizing that with different sized sprockets from stock the "new" measurement of chain to swing arm would be whacky, I measured total deflection. With the chain at 8~9mm from the swing arm I found I had 52mm of total chain deflection. This is now the measurement I use on our chains when adjusting them.
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pbnut

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PostSubject: Re: Swingarm eaten by chain   Wed Jun 22, 2011 9:41 pm

With all this talk about chain-to-swingarm clearances I'm going to 14/49 sprockets when the time comes. That should give a bit more clearance from the swingarm in all areas.
This should be less of an issue then.
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motokid
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PostSubject: Re: Swingarm eaten by chain   Mon Jun 27, 2011 6:45 am

So what's going on with all this Jager? What are your thoughts now that some time has past and you've been able to think more about what happened.


What's the plan forward?

_________________
2008 WR250X
Gearing: 13t - 48t
Power Commander 5 / PC-V
Airbox Door Removed - Flapper glued - AIS removed
FmF Q4
Bridgestone Battlax BT-003rs
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Jäger
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PostSubject: Re: Swingarm eaten by chain   Mon Jun 27, 2011 1:39 pm

The plan forward is to sit watching the driveway and hope my swingarm slider shows up sometime today after I paid for 2nd Day Air. Or tomorrow. Because I have to be back in the sticks after that and my ride back to work is no good after tomorrow night and I am not going to walk 250 miles.

New sprockies and chain have arrived from Rocky. A Supersprox front sprockie put me at $100.72 and free shipping.

I was thinking of just gooping some JB weld in there without taking the swingarm off. I thought of then running the old chain/sprockies for a while, checking to make sure the swingarm slack was factory spec every day, and see if it still hit the swingarm/JB weld properly adjusted. Then doing a really nice JB weld fix after the swingarm was taken off.

Nixed that as I realized it wouldn't mean anything because the factor of the swingarm slider essentially not being there anymore can't be eliminated. So I really wouldn't learn anything unless I had another, almost worn out slider laying around to replicate conditions prior to my screwing up somehow and letting my swingarm get munched.

So assuming the slider gets here today or tomorrow, I'll just switch the slider out for now, throw some Prussian Blue on the swingarm chewed up area, and see if I'm still getting contact with a new slider. Check chain tension every single day because from what some Yamaha techies have told me, when a chain goes bad it can go bad really, really fast, and that super slack chain in conjunction with a mostly worn out slider probably was the cause of that. Why the chain didn't skip on the sprockies with it that loose, however, I have no idea. Possibly because the sprockies still look to be in very, very good shape, so they wouldn't skip like a worn sprocket? I don't know. I'm pretty sure I didn't adjust to a tight/loose spot in the chain, given how I adjust chain tension.

Assuming the new slider stops further damage, I'll check chain tension every day and accept what will probably be some accelerated wear on the slider for a few days - they're cheap. When my mechanic brother gets here in about ten days, then we'll tear the swingarm off where he can see the same thing as me and supervise my being turned loose with tools on bearings and such. His input will be interesting. At that time I'll do the best JB Weld fix I can, try and match the original contours, and possibly fit a piece of hardened steel into what I think would be the initial point of contact from a chain starting to hit the swingarm. I'd rather wear a chain out running it on hardened steel than chew through JB Weld if this should ever happen again and start munching on my swingarm again. THAT is not inexpensive to replace.

Anyone who has discovered they were just starting to get initial contact with the swingarm, can you give me a good descriptive "map" of where it was on the swingarm? Otherwise, I'll just assume somewhere around the center part of the wear is where to look at putting in a hardened piece of steel.
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motokid
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PostSubject: Re: Swingarm eaten by chain   Mon Jun 27, 2011 3:57 pm

Where did you order swing-arm slider from?

Any such thing as an aftermarket swing-arm slider for the wr that might last longer?




_________________
2008 WR250X
Gearing: 13t - 48t
Power Commander 5 / PC-V
Airbox Door Removed - Flapper glued - AIS removed
FmF Q4
Bridgestone Battlax BT-003rs
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0007onWR

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PostSubject: Re: Swingarm eaten by chain   Mon Jun 27, 2011 4:34 pm

I had a good look at mine (12t spkt) and I have absolutely no contact with the front end but there is noticeable wear on the rear
Downhill, down shift and general decel might be the reason for this
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trav72

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PostSubject: Re: Swingarm eaten by chain   Mon Jun 27, 2011 5:44 pm

I ordered a new slider last Monday and received it on Friday. I installed it and went riding on Saturday. It took 8500 miles, 2000 of which I was running a 12t front, to wear through. I'm not really going to worry about for the next 7,000 or so miles.

All of these posts on various forums about slider wear make people paranoid. Consider it a wear item, check it every once in a while and plan on replacing it at some point. Besides that, just ride. thumb
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motokid
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PostSubject: Re: Swingarm eaten by chain   Mon Jun 27, 2011 8:43 pm

trav72 wrote:
I ordered a new slider last Monday and received it on Friday. I installed it and went riding on Saturday. It took 8500 miles, 2000 of which I was running a 12t front, to wear through. I'm not really going to worry about for the next 7,000 or so miles.

All of these posts on various forums about slider wear make people paranoid. Consider it a wear item, check it every once in a while and plan on replacing it at some point. Besides that, just ride. thumb

Ordered from where? Online or stealership?


_________________
2008 WR250X
Gearing: 13t - 48t
Power Commander 5 / PC-V
Airbox Door Removed - Flapper glued - AIS removed
FmF Q4
Bridgestone Battlax BT-003rs
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trav72

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PostSubject: Re: Swingarm eaten by chain   Mon Jun 27, 2011 8:55 pm

Service Honda
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Arkmage




PostSubject: Re: Swingarm eaten by chain   Mon Jul 04, 2011 4:04 pm

Akasy wrote:


I would be interested to hear if any of you still have your old slider--and swingarm damage--was that aft lower rear worn and if so how much? I'm guessing it would wear to about 1\2 inch and then the front would start to wear rapidly--just my guess.


You're correct. It's worn to about 1/2" thick. I just noticed last night that my bike also suffers from this little "issue". I'm convinced it's from being too tight as this bike is a 2008 and up until 8500 miles was set to the original spec (which was tighter).

More pics: http://www.flickr.com/photos/42226511@N04/sets/72157627116215582/


Swingarm Damage 2 by Noah_K_T, on Flickr


Worn out guard by Noah_K_T, on Flickr

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0007onWR

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PostSubject: Re: Swingarm eaten by chain   Mon Jul 04, 2011 10:34 pm

Hmmm, that looks like it's not in the same place as Jager's
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Arkmage




PostSubject: Re: Swingarm eaten by chain   Mon Jul 04, 2011 11:24 pm

0007onWR wrote:
Hmmm, that looks like it's not in the same place as Jager's

Nope, it's the same place... look at where the weld seam is in his picture.
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Arkmage




PostSubject: Re: Swingarm eaten by chain   Wed Jul 06, 2011 4:18 pm

Talk about insult to injury... no idea when I'll be back on the road now. The slider is back ordered for an unknown amount of time.

"Greetings:
Thank you for using Service Honda for your parts needs. The following part number(s) are backordered from Yamaha and have no current release date as of now."
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Akasy




PostSubject: Slider   Wed Jul 06, 2011 5:48 pm

Arkmage wrote:
Akasy wrote:


I would be interested to hear if any of you still have your old slider--and swingarm damage--was that aft lower rear worn and if so how much? I'm guessing it would wear to about 1\2 inch and then the front would start to wear rapidly--just my guess.


You're correct. It's worn to about 1/2" thick. I just noticed last night that my bike also suffers from this little "issue". I'm convinced it's from being too tight as this bike is a 2008 and up until 8500 miles was set to the original spec (which was tighter).


Kind of what I expected. If the chain is run too tight when the swing arm makes it arc upwards the chain first contacts the lower aft end of the slider. My supposition is that it then takes a while for that lower aft end to wear--dependent on two factors, chain tension and angle of attack from sprocket\counter sprocket changes. These two variables result in significant variations in reported slider wear. Third variable is rider use--every time I ride I max rear suspension compression--if I were easier on the bike the chain would not contact the slider nearly as much.

Using my calibrated eyeball I estimated that when the chain wears into the lower aft edge of the slider to about 1\2" the chain now rubbs along the full length of the underside of the slider and begins to eat that lower front edge which is not as thick and wears quicker.

My choice is to run the chain at the new specs and if I err it will be on the loose side. My second move is going to be to a 13-48 gear ratio which in my estimation will get the chain a bit further from the slider--I'm currently running 12-stock.

Since I will be running the TAT on the WRR this summer and I plan on making the ratio change prior to departure I should know by the end of the ride if my ratio change reduces the wear on the slider.

Good luck on the fix and on getting the new slider--luckily I ordered one just after I bought the bike based on Yamaha making the chain tension change.
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Will B




PostSubject: Re: Swingarm eaten by chain   Thu Jul 07, 2011 9:58 am

OK this got me worried so I decided to go and check it out, there does not appear to be any damage, I snapped some photos of the guard to show you guys to see what you think of the wear. This is a 2008 WR250X with 2100 miles.

Photobucket

Photobucket

Photobucket

I'm still not quite sure how to adjust or really check the chain tension, I took this photo as well and maybe someone could help me out. Also don't mind the dirt, I have to wash the bike and clean the chain hide

Photobucket
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Arkmage




PostSubject: Re: Swingarm eaten by chain   Thu Jul 07, 2011 10:02 am

You're fine. That's what I'd consider normal wear. It's going to get a little scuffed from normal use, that's why it's there. Take a look at the back part of it (out in the middle of the swing arm) and see how deep the wear is. That will give you a better indication of how fast the front will start wearing, or at least we think it will :)

Your chain looks too tight to me though. I'd put it closer to the low end of the spec for swing arm distance (8mm).
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Will B




PostSubject: Re: Swingarm eaten by chain   Thu Jul 07, 2011 10:12 am

OK so not trying to derail the thread but where do you measure to 8mm from? The bike was on the side stand if that makes any difference, also is there a thread that you or someone else could point me to with instruction on checking the chain?I assume that the spec you are talking about is from the TSB? I'm new to all this so please bare with me haha.
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Arkmage




PostSubject: Re: Swingarm eaten by chain   Thu Jul 07, 2011 10:24 am

Will B wrote:
OK so not trying to derail the thread but where do you measure to 8mm from? The bike was on the side stand if that makes any difference, also is there a thread that you or someone else could point me to with instruction on checking the chain?I assume that the spec you are talking about is from the TSB? I'm new to all this so please bare with me haha.



Try that out. Most of us just push up with our finger... the fancy fish gauge is just a funny joke yamaha plays on us.
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Will B




PostSubject: Re: Swingarm eaten by chain   Thu Jul 07, 2011 10:41 am

Just checked it and it is between 12mm and 13mm. So I guess I should loosen it or will that chain start to loosen on it's own? I also checked the back of the guide and there is a little more wear there than the font but not a lot more wear. To loosen the chain I adjust it towards the front of the bike correct? Is there any special way to keep the wheel aligned?
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0007onWR

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PostSubject: Re: Swingarm eaten by chain   Thu Jul 07, 2011 11:30 am

Next time you are at the grocery store or a shipper or something push on the scale with your finger so you can get an idea what 36lbs feels like, it's a lotta pushin for one finger
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Rule292

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PostSubject: Re: Swingarm eaten by chain   Thu Jul 07, 2011 11:56 am

Will B wrote:
Just checked it and it is between 12mm and 13mm. So I guess I should loosen it or will that chain start to loosen on it's own? I also checked the back of the guide and there is a little more wear there than the font but not a lot more wear. To loosen the chain I adjust it towards the front of the bike correct? Is there any special way to keep the wheel aligned?

Motion Pro makes a tool to keep the chain aligned. It's cheap so I bought one and I think (at least for a nOOb like me) it's worthwhile. Especially when sorting out things like "is this too tight or too loose"... Very happy

http://www.rockymountainatvmc.com/productDetail.do;jsessionid=49C9DDCE99ABC1A0FA75FDBA3ABC7B10?webCatId=9&webTypeId=35&navTitle=Drive&navType=type&prodFamilyId=17145&stockId=142934


And when I changed my sprocked I decided to spring for the tension tool - well, of course I used the "old" tension specs from the online manual and guess where I bought the tool at? The HARLEY dealer! wings Of course, the 2010 manual specs call for a different tension, and the Harley gauge doesn't work (but a car belt gauge now does). So now I have a belt gauge for a Harley and no Harley..... YET! Sleep
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jeffpack1957




PostSubject: Re: Swingarm eaten by chain   Wed Jul 13, 2011 10:43 am

what about machining a small delrin block for a slider?
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Arkmage




PostSubject: Re: Swingarm eaten by chain   Wed Jul 13, 2011 1:26 pm

jeffpack1957 wrote:
what about machining a small delrin block for a slider?

That's what the stock piece is...
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Jäger
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PostSubject: And Now It Can Be Told...   Wed Jul 13, 2011 6:25 pm

So... the rest of the story...

Let's start with a few pics... the sad sight I was shocked to see:







Figured I let the chain get so loose it was throwing and rubbing on the Sandman case protector...



So I parked the bike, kicked my ass a whole bunch for being so incredibly negligent I didn't notice that happening while doing regular chain maintenance, posted about it here, etc. Couldn't believe how I had been such a moron to allow that to happen - especially after I thought I was being wary of that after seeing it happen to others. But didn't understand either, as I run my chain a bit on the loose side of the adjustment range and check it regularly while doing chain lube chores. This is supposed to be caused by tight chains. Or 12 tooth sprockets if you prefer that reason. Neither of which applies to me.

Turns out nobody seems to keep these "seal protectors" in stock. Eventually, my fast-as-possible delivery "seal protector" arrived via 2nd Day air once the seller got it from Yamaha - just one, because after I got it fixed I was going to see if somebody would soon make a better aftermarket one.

Had to go to town to make an appointment with the lawyer the same day the replacement slider arrived. So I left off replacing the sprockies and chain - because they still looked more than acceptable and the chain didn't seem to have any tight or loose spots - for the next day. With a properly adjusted chain, and a new chain slider, how bad could 20 miles be?



Well, as it turned out, this bad:





After my wife told me to quit screaming and brought a crowbar out and pried me off the roof of the garage, I checked the chain tension: 8mm spacing while on the sidestand, perfect Yamaha adjustment. WTF, over?

Screw waiting for my brother to show up, I started tearing my wounded little bike apart to try and figure out what the hell was going on. Tore swingarm, linkies, shock, Yamalink etc off to check for seized bearings or collars or something. Didn't know exactly what I was looking for, as a mechanic I ain't. But I'm a jackleg machinest and I figured something had to be seized or bent or something. Everything moving and lubed. Even started measuring stuff up with micrometers and dial indicators, trying to find something that wasn't right. Didn't have the courage to throw calipers in the worn slot to see how much material was left... I figured this would be one of those cases where ignorance is bliss.

No luck with any of that, but it did allow a closer view of the damage:





Couldn't find anything wrong. I was goin' crazy here. Until I decided to check and see if I should be ordering a new rubber insert for the rear chain guide while I was ordering a couple of dozen chain sliders. And then I saw what at first seemed like a rubber part had peeled up and come adrift.





And then I suddenly realized what I was looking at:



A damned rock! Well worn in by now.

Talk about The Golden BB taking you out. What are the chances of a rock coming up off the front tire, and being perfectly aligned with the opening of the chain guide when it hit it. And not only being perfectly aligned and arriving at an instant when the chain was high enough in the guide to let it enter, but being big enough to stick and not small enough that the chain simply pulled it out the back?

To make The Golden BB effect even better, it wasn't just any kind of rock. No, it couldn't be one of the softer sedimentary rocks around that would have been quickly fractured or ground down. See that kind of waxy look? That rock is chert. For those who have never worked underground in a hard rock mine, chert is the kind of rock that makes drillers cry when they find their worksite is in chert; they drop their lunch pails so they can carry an extra bag of drill bits. It ain't as hard as steel, but hard enough - another name for chert is "flint".

Yes, what are the odds? The perfect Golden BB.

So I threw the new sprockets and chain I had on hand (14/49, 112 link chain). Once I get over being pissed off, maybe I'll go examine the old chain to see just how badly it is worn, measure the gullet on the sprockies, etc. Or maybe not...

So now the cause of what happened is solved, patch the swingarm. Toyed briefly with getting a skilled welder to fill it in, then thought of what doing that would entail, possibility of things going bad, etc. Decided to skip that idea. Filed out the damaged area and fitted a small piece of round stock that would fit in the resulting notch to provide a hard point to stop further chain wear on the swingarm should this ever happen again. Hardened it up and then fitted it in and filled the notch with JB Weld.



I had intended to take a Dremel and shape the repair to match the curve of the swingarm. Then I noticed it was close already (didn't want to shape more of the hardened JB Weld than I had to) and didn't interfere with where the swingarm slider sat, even when it was a little bit proud. So I left it and called it good.

Now I had a fixed bike (I hoped... by this point I was pretty gun shy). But while I had ordered two more swingarm sliders, they wouldn't get here for a week and I was back on foot and mountain bike again. So I decided to try my luck and see what would happen: repair the damaged "new" slider. Grabbed some Tech Plastic, a plastic/fiberglass stick I use in gunsmithing that you activate by kneading the two component parts together. I thought about JB Weld briefly, but wondered if it would be too hard or inflexible when the slider flexes, etc. So the finished repair to the slider looked like this:





I left it a little bit proud when moulding it into what remained of the front of the slider, held together by a last few bits and pieces. Thought about dressing it down to the original contours, but then decided to let the chain do that and use the wear as a bit of an indicator on what kind of contact I was getting.

So, bike back together, swingarm and pivot rod and linkage bits and pieces all cleaned up with mineral spirits and regreased with Belray Waterproof grease. Used up the inch of lowering in the rear shock while I was at it, something I've been meaning to do. I am such a shortass, my legs barely reach my feet.

Sidebar Note: HighFive isn't kidding when he says that plastic matrix the needle bearings sit in is fragile - I tore some bits and pieces out just rubbing them back and forth with a gloved finger while cleaning with mineral spirits. Not picking at them with a fingernail like HighFive did. Wife had to come out and pry me off the garage ceiling with the crowbar once again, etc. I mean, they damage REAL EASY - almost effortlessly. Nothing about that in the Service Manual...

Like HighFive, I put the bits back as best I could and hope the grease, the remaining matrix around the damaged parts, and the fit will keep all them needles where they're supposed to be. If not....

Loaded some tools up and headed out to hit some potholes and washboard to see if there would be any more instantaneous damage to the slider. But, bigger sprockies... chain tension first... hmmm.... I'm in a hurry. Yamaha says 8 - 13mm distance between chain and swingarm on sidestand. I decided to use 6mm distance between chain and swingarm with minimal pressure. With bigger sprockies and lighter pressure, closer than at the loose end of the stock adjustment range, that should be a safe chain slack setting for now. Will explore that with Sarah at a later date as I think her drive and suspension setup is pretty comparable to mine.

Link to that day trip is here.

Anyways... the good news is that everything now works as expected. Stopped to check after 5 miles, 15 miles, and 30 miles. Just a bare amount of wear on the proud parts of the repair to the slider. 300 miles later, the wear doesn't feel any different. I suspect I could use this repaired slider for thousands more miles (but I'll swap it out once my new sliders get in and keep it for a spare and a memory).

Other notes related to the repair (aside from confirming HighFive's warning).

First, I really, really like the 14/49 setup. Might be my imagination, but the drive feels a bit smoother than the stock 13/43 I've used to date. It definitely ISN'T more vibey. And the power is much more usable over the entire transmission range. I don't notice much difference in 1st as little of my riding makes use of first gear grunt. But where before I found 6th (and often 5th) useful only for low rev slab motoring with insufficient power to even pull a hill or make a smooth pass, now I find them much stronger and more useful on the highway. For true 50/50 dual sporting, I think 14/49 is pretty close to perfection. Maybe 14/48 - if I could discern a difference.

Second, mileage. Just before I put the bike away last year, I posted Hey! Where did my mileage go?. Well, it didn't come back this spring despite all the theories, and I hadn't had the time to try sorting it out after trying the usual suspects. With the rock out of the chain guide, my 50/50 dual sport ride up Redding Creek netted me 85mpg Imperial/71mpg US. Which took care of that question. How much had to do with the rock and how much with the worn (but NOT worn out) sprockies and chain? Hard to say. On the one hand, given how fast my new chain slider got eaten, I would think I got lucky because I caught it before it ate right through the swingarm in a number of days. On the other hand, perhaps the majority of the wear happened immediately when that rock was biggest, and then decreased as the rock got worn down by the chain. Until it wore on the chain enough that it went suddenly, significantly, slack.

But, in either case, my mileage is back as well. I did a steady 60mph run until the fuel light came on, ended up refueling at exactly 100 miles. Worked out to 66mpg Imperial/55mpg US. So losing the low rev, low grunt 6th gear will cost me a bit in high speed slab riding, but those higher gears are also more useful on the highway and for dual sport riding the entire gear box is much more useful.

Total cost of this little adventure: about $200 and three weeks of mostly being afoot so far. And a damaged swingarm that I really, really hope won't end up needing to be replaced.

Pan to Paul Harvey... And now you know... the rest of the story.

Won't help to identify the root factors in why some swingarms get eaten and some don't, however.

One..... Freaking... Rock. The Golden BB.
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