Forum input? Swing arm chain "slider" modification:

I'm a bit concerned about the swing arm eating abilities of the wr250R/X's  drive chain...i've read many explanations... too small counter sprocket...chain too tight...chain too loose... rider to slack in  maintenance /chain slider replacement...riding conditions / style { mega street use/miles}
  i've been making my own chain sliders for other bikes using nylon that "slides" instead of rubber like some or many models have.. HERE is an example of a simple chain slider build.

All that being said I've read on this fabulous site about maybe using a metal finger under the chain slider as a last ditch effort to buy more time/save the WR's aluminum swing arm in the event of the chain burning through the chain slider material and on into your swing arm..or "maybe"...larger counter sprocket..etc etc

to the forum:
I'm thinking about trying to concoct some kind of roller to ward off chain damage. It would maybe mounted on the same plane as the lower chain slider so that it would only be in contact during the chain eating "moments" and not full time contact.{in conjunction with a slider}    I will have my bike in the shop before spring to address this and "will" implement something..my bike will be the guinea pig {it has 4000 kms on it}.

ok enough rambling you get the picture...

input on this design would be great in case you can think of something i'm not getting.. but it seems even in the cave man days,,, the wheel..prevailed over sliding anything.
If you post and have seen or have an  idea.. how about scanning or loading a picture of something you would like to contribute ,,, as one picture sometimes spawns more idea's from the gazillion hours of riding time experience all the forum readers have.


To get started here is a viewing of the chain path in relation to the swing arm..the best one i could find..


ctp11 by freewillieklr, on Flickr

Please see my last post in "SA eaten by chain"--and the standard diagram you've shown says it all when you view my slider damage and the location of the marks in the SA--they are right around the front!!. From the diagram if the chain behaved itself then there is no way that it would contact this far around the front. I might add that my bike was run with a knackered and loose chain at fairly high speed--previous POLICE owners!

I think running a loose chain and/or with the odd tight link allows it to "hang on" and to be thrown up to the front face of the SA. This particular slider is both expensive and odd in that its open at the front asking to be picked up and chewed off by a misbehaving chain accelerating the exposure---just about all other sliders are thinner here and wrap around the front edge--much less likely to be chewed off?

When I install my new (and expensive) yam slider I'm at least going to look at adding a titanium strip that wraps around the front a bit--and also reprofile the front edge so that its less likely to be pulled out and ripped off.

Good luck with a cure--in all the bikes I've had I've never had to replace a slider as they bed in--on mine after 8k on the clock the wear on the top and the rest of the slider looks "normal" and would go on for some considerable time.

My 2 cents

I dont see where you can put a roller to help.

When the suspension gets close to bottomed out the chains path runs right into the bottom side of the swingarm, the wrr/x has its swingarm lower than normal in relation the the sprocket, its the nature of the beast.

Put a 14 tooth sprocket on it, replace your chain the second it looks like it has a kinked link, keep the chain adjusted properly, keep the shock stiff and high so the bike will be further from bottomed out and you will never have an issue in the first place.

I've been doing those things execpt for the 14 tooth sprocket, I've run the stock 13 for 2 years and my slidier is fine.

My 3 cents.

It's a "normal wear item". It's meant to be there and do what it does. It's designed to wear out and require replacing.

Trying to prevent it from wearing is sort of like trying to stop your break pads from wearing. Or trying to prevent your tires from wearing.

Just keep an eye on it. Check it once every 500-1000 miles. Keep your chain adjusted properly.
Buy a replacement slider and have it handy for when the time comes to change it.
Hell, it's easy enough to check almost every time you take bike out for a ride.

I went about 10,000 miles before I changed mine.
For at least a 1000 of those miles (maybe closer to 2,000) I even had a 12 tooth front with stock rear.

All this worrying about something that's designed to wear and designed to protect your bike seems too over-the-top for me.

The slider is easy to see. Easy to replace. Relatively inexpensive, and it does what it's designed to do.

Adding something to the bike that would prevent the chain from contacting the slider might induce MORE problems and reduce the bike's power or responsiveness. Plus, you'll then have to replace the "something" you've added because that will surely be worn down faster than the slider. It might also induce excess wear on the chain and require changing your chain more often. You're talking about toying with the direct line of power.

All that being said - I love guys that tinker and invent and think outside the box, so if nothing else I'd love to see what the possible "fix" might be.
I probably wouldn't bother to employ it myself, but I'd like to see what such a thing might look like.

I believe it comes down to having enough slack in the drive chain, especially when riding off-road when dirt will get caught between the chain rollers and sprocket teeth which tends to reduce slack.
Most riders will adjust their chains with too little slack and readjust it often.

I haven't conducted a scientific experiment to prove this sentence, but it would not surprise me at all if the recommenced slack-adjusting procedure shown above results in insufficient slack under certain conditions.
How?
Why would they?
Well, how can the Owner's Manual list a recommendation of servicing the air filter once every six months?
Maybe that's just fine on the street or in the photo studio.

If you have things set so the drive chain is forced into the front bottom edge of the chain slider under tension, it will eventually band-saw it's way through whatever you place there, or the chain, itself, will eventually wear away.

My guess is that a roller down there would require a longer chain to clear it as well as coming under high tension if slack is insufficient.

good info folks... the first thing i am going to do is unhook the rear shock and get the counter sprocket centerline/ swing arm center/ pivot and rear axle center all in a straight line then raise the wheel to see if the swing arm pivot may be the lowest point when the rear suspension is under compression. ..and of course where the slider is on all this.

Question.. the WR has an x number / amount of rear travel.. would you folks consider the available travel starts to be measured upward on ..a side stand.. a bike jack or what? \

I would need to understand this before i could raiise the wheel to its "highest point" while doing the centerline check.

I had a comment on another site about sliders in general... and that is if the material is slick like nylon or teflon the chain roller would actually work with the slider.... to put it in perspective snowmobiles with slide suspension had a kind of steel cleat that surrounded the track drive bar... this bar or many of them were in direct contact with the slide suspension[ yes the snow was the lube... but still a similar dance]

anyways i may not move the world with this.. but it will be interesting to see what comes about.

Claimed wheel travel is how much travel is available from the fully extended position with no weight on the rear suspension (uncompressed).
Yamaha claims 10.6 inches, and having the bike sit against the side stand uses some of this travel up by supporting the bike's weight, and when you sit on the seat, more travel is used.

Let us know what you learn.

I would love to see an aftermarket supplier like TMD make a slider for our bikes out of better material like they do for the more popular machines. That said, improper chain adjustment/maintenance is only part of the issue IMHO. Many bikes I have seen that have extreme wear on the leading edge of the lower slider have never bother to check & correct their sag.

YZEtc wrote:

Claimed wheel travel is how much travel is available from the fully extended position with no weight on the rear suspension (uncompressed).
Yamaha claims 10.6 inches, and having the bike sit against the side stand uses some of this travel up by supporting the bike's weight, and when you sit on the seat, more travel is used.

Let us know what you learn.

ok thanks I'm going to make a fixed "point" 10.6" above the rear wheel when the wr is lifted on the bike jack and use that as the full compression spot with the rear shock removed .


From there i will update this thread when i get everything in order..it may take a while... but before spring riding.

In the meantime i hope some folks jamb a few pictures in here of slider idea's that may be debated for use into the design ....like the benefit of the TMD design 4play mentioned

thanks again for the input

From my post above this is my contribution(while I await delivery of my new slider)..
I cut up a strip of titanium and formed it to just cover the bottom weld--this is JB welded in place after a thorough solvent clean--pics attached. I note from the inner form of the slider that they actually make cutouts to accommodate the welds on the SA making it particularly thin in this area such that when its worn through a bit the whole nose will get chewed off--my strip adds about a mm but wraps over the weld. If its good enough for Valentino then its good enough for me !!

looks good!The titanium may buy valuable time from what the chain can do.

Thats the idea--there really isn't much scope for anything--and you'll note the large gap between the chain and the bottom of the SA--I firmly believe that its a "chain hanging on to the gearbox sprocket" issue . In my case I had to scrape away the grease and chain lube to expose the bottom of the SA. In other words the damage was done during previous ownership and in my hands with a new chain and non hooked sprocket--and reasonable adjustment--- the chain hadn't been "up there" and the grease had built up.

Just had another look at the set up and I have an additional possible reason for the problem--the distance between the SA pivot and the gearbox shaft is about 75mm. The equivalent distance on a 2015 KTM exc is about 60 mm--in other words there is more space on the Yam for the chain to follow the sprocket round before its forced down by the front edge of the guide--best described as more chance of a "wave " being generated on the yam--and therefore more rubbing action on the front edge of the guide--the KTM guide stops the chain FOLLOWING the sprocket much sooner.(just corrected spilling mistook!)

rarepartbuilder wrote:

looks good!The titanium may buy valuable time from what the chain can do.

good point about the longer distance  between the counter sprocket and swingarm end .. maybe the  bottom chain slider just needs to be longer {towards the counter sprocket} that way no type of chain wave could get near the swingarm .

Edit: what does a WRR chain slider cost ?

Here in the UK its 35 GBP--in the US about 35 USD?--in other words half as much again and much more than say an "F" replacement from an aftermarket supplier (I can't find an aftermarket version?)--too expensive to ignore as for me its nearly the price of a new chain at approximately the same mileage--shouldn't happen!--we'll see how I get on as I'm a new owner.

rarepartbuilder wrote:

good point about the longer distance  between the counter sprocket and swingarm end .. maybe the  bottom chain slider just needs to be longer {towards the counter sprocket} that way no type of chain wave could get near the swingarm .

Edit: what does a WRR chain slider cost ?

HERE is an interesting slow motion video... where a new rear tire is tried out on a WR250... The amount the chain was bouncing near the swing arm got my attention.. albeit we dont know if the chain was properly tensioned.. still the thing is really flopping towards the lower side of the swing arm..

That's not what causes the chain to saw through the slider and then the swingarm.
The chain is being pressed into it via force, not merely slapping around as will happen on any other model of motorcycle in the same situation.

Take another look at those photos taken by owners who were shocked to see damage, and take note of the angle the wear marks are at.

I understand

i thought the slap was excessive for a bike that has a chain tensioner /roller under the chain. One theory i gravitate to is a possible chain kink and front sprockets worn with the hook teeth.

It would be cool to see a slow motion video of the chain action with the front chain guard off.... better yet on a bike due for a new chain and sprockets.

I concur on the worn/kinking chain and hooked sprocket--did about 100 miles at highway speeds today (65/70)---and checked my new slider--not a mark (but chain and sprocket are pretty new and the chain is well lubed and "free".)
CB

rarepartbuilder wrote:

I understand

i thought the slap was excessive for a bike that has a chain tensioner /roller under the chain. One theory i gravitate to is a possible chain kink and front sprockets worn with the hook teeth.

It would be cool to see a slow motion video of the chain action with the front chain guard off.... better yet on a bike due for a new chain and sprockets.

it would be awesome if someone with a worn chain and sprockets could remove the counter sprocket /guard  cover and video the chain sprocket action on different terrain using some kind of mount for a gopro or the like...any offers??...
youtube has a feature that can slow a video down to 25%