New swingarm thread - I reckon I need a new swingarm...

Pardon my new thread to this topic but I know the old one has quite a bit of dust on it.  I'd like some healthy feedback on this thread, if you guys will be tolerant.  :)

I just got off the Transamerica Trail (stopped mid Nevada due to non-bike related issues) but not without nearly cutting my swingarm in half and throwing the chain in nowhere-ville Utah.

I started the TAT on from TN with a brand new chain, and maybe my preload was a bit soft but not tremendously.  4" sag with TAT kinda load.  I weigh 170 even.  Admittedly, I probably ride the bike like a dirt bike, not easy going.  I have 13/47 sprockets on, both new.  I was following what I "think" was Skeird's advice of 3 fingers of slack ABOVE the swingarm...does this sound right?

About in OK I noticed the chain was eating into the swingarm a bit, and I was at a Yam shop, they didn't have a new slider but thought the swingarm would be fine till the end.  I pressed on.  In UT I noticed some noise but I guess being an idiot I didn't realize it was my chain going slack.  eventually caught it hundreds of miles later.  I mean hundreds.  By this time the chain slider at the front was completely gone and the rollers were sliding on the swingarm (I could see where they had been sliding, that is).  Several chain adjustments day after day...no good places for chains way out in nowhere's ville NV you know... After getting to mid-Nevada and having to divert back to SLC UT for another issue, I threw the chain.  The chain was obviously in terrible shape, all stretched out.  Thank goodness for a Good Samaritan passing by with a dremel and chain, generator, and patience.

SO, I'd like to rebuild the thing so I can do the TAT again...  this time I want it to be right...learning from my experiences.  Soo..... a host of questions I guess:

1) I see some "lightly used" swingarms on ebay, some for $70 some for $300, I know I can ask for photos of that area, but could anyone suggest a better way to get a good swingarm for a decent price?

2) What other parts do I need to rebuild the swingarm?  Bearings, chain slider, and what else? (I see some rebuild kits out there, which is best?)

3) In reading a multitude of posts on this, some people say "loose is better", some people say "Yam spec is better" and I can't make heads or tails of the right answer.  I just know I don't want this to happen again to me, especially mid TAT.  So, 6 years these bikes have been out (since 2008) do we have a good idea of which is really better now?  

Please try to answer all three questions in this thread if possible.    ;)


Thanks!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

1) Please post pictures of your damaged swing arm.  

2) Buyer beware, especially on ebay. Try to find one close enough you can go hold it in your hands and inspect it before you buy it.

3) I'd replace all seals, bearings, and what not. Since you have to do a rather large job, do it right.

http://www.partzilla.com/parts/search/Yamaha/Motorcycle/2011/WR250R+-+WR25RAL/REAR+ARM/parts.html

4) The "three fingers on top" method isn't the prescribed method of setting chain slack.
    Push up from bottom of chain, and chain should come to within a half inch to a quarter inch of touching the swing arm.

5) Yes - loose is far better than tight. - Remember, you have 10 inches of suspension travel.

I can't post a pic..the bike is still in SLC awaiting shipment.

And thanks for the partzilla link.


With prices like that i will take advantage of the time i have and wait for a part out.

Unfortunately i work overseas so getting my hands on a part is really difficult.

Jäger wrote:

This is the Yamaha recommended method.

OK back to my 3 questions,

IF I'm able to get a good used swingarm, what is the "Whatnot" of replacement? just go through the partzilla page and replace everything that moves or slides? I see a couple of bearing kits online (like form Moose, or one from a Walmart page (?)...the one on the Walmart page actually has more parts... http://www.walmart.com/ip/Moose-Swingarm-Bearing-Seal-Kit-Fits-08-11-Yamaha-WR250X/30026728 but I never know if they're the best parts or not... would be nice to get a kit rather than piece-meal it all though...

Lastly, seeing what Motokid posted, does that seem to provide the most insurance against this? Is that the new rule of thumb? (I know as WR owners we've gone though many revisions of what is "right" in chain slack)

What chain did you have?

Did you have a steel rear sprocket or aluminum? aluminum doesnt last long and will destroy a good chain.

Your chain shouldve went the whole trip without needing adjusting.

My 2 cents, once a chain gets worn or kinked it eats the slider and swingarm, your chain tension was close enough and close to what I run.

I pull the bike down untill the swingarm is straight back from the pivit then set it so I have a 1/2 inch of slack there, as this is its tightest point, when adjusted like this you can fit 3 fingers between the chain and swingarm above the swingarm when the bikes on its side stand.

Get the best used swingarm you can off ebay.

I reccently put a used swingarm on a used mx bike I bought with a cracked swingarm all I needed to buy extra was a lower shock bearing and seal the rest were fine... If your in a rush and you dont know if the bearings and seals are good in it buy new ones. If you have time get the swingarm than check the bearings they might be fine, this will save you close to 150 bucks as getting all the bearings is expensive, the kit in your link doesnt include linkage bearings which cost about the same as that kit.

Honestly the chain was "nothing special." It was from a local bike shop...they have a big reel of o-ring chain and it was cut off that.

I think it stretched due to many bottom-outs thus the chain was stretched across the bottom of the swingarm.

Do i need the linkage bearings too? Why? 14k miles on the bike,,,

My chain ate into my swingarm a little bit once. Since it didn't go all the way through, I just had a local shop weld up the slots that were cut in by the chain. Probably didn't even need that as mine wasn't very bad. I caught it before it did a bunch of damage.

If yours wasn't eaten all the way through, I probably wouldn't worry about it.

If it was and you're dead set on replacing it, I'd recommend -

- Swingarm
- (2) oil seals 93106-22019-00
- (4) bearings 93317-22262-00
- (2) collars 90387-18013-00

Everything else should swap over and just need to be cleaned and re-greased while you have it apart.

Note that these recommendations are based on not having seen any pictures and simply a wild, educated guess based on what you've told us.

Now on to why it happened . . . I think I've seen enough evidence (my own included) that I'm pretty certain it is caused by one of two possible things.

1) chain run too loose. I know on most dirt bikes looser is better. The WRR is a little different. It likes its chain to be run "just right". With 13/47 on my bike, it seems to be best right about where Biglake suggested. Right at 3/8" gap between the top of the chain and the bottom of the swingarm when pressed up.

2) kink in the chain. A worn chain tends to get kinks in it. Any kink at all with eat through the slider in a matter of miles.

I run a decent X-ring chain and keep it right at 3/8" gap and my sliders have been lasting me a while now.

One more note . . . if your bike was starting to give you fits in Oklahoma, you should have contacted me. I've got an extra slider (and usually a new chain/sprocket set) in the garage at all times

Always be prepared

the bike should arrive from the shipper on or about Tuesday. I will try to take off the swing arm and get a photo of it for you guys as quickly as possible.

for what it's worth I just ordered three, yes three! Sliders along with a new chain and set of sprockets!

sr1 wrote:

3) In reading a multitude of posts on this, some people say "loose is better", some people say "Yam spec is better" and I can't make heads or tails of the right answer.  I just know I don't want this to happen again to me, especially mid TAT.  So, 6 years these bikes have been out (since 2008) do we have a good idea of which is really better now?  

motokid wrote:

Jäger wrote:

Look at the diagram that motokid posted.  The tightest the chain will EVER be is when the center of the front sprocket, front swingarm nut and rear axle are in alignment.

Disconnect rear shock, jack up swing arm to proper height to acheive this alignment and then adjust your chain so there is a little slack.  Done.

Now bolt things back up, put you bike on the side stand and push down on the rear several times to let it settle in.  Pick a point on the swingarm that you can reference easily again and again and push up or down (whichever way is easier for you to take a measurement from your reference point) and take a measurement.  There you go.  From now on, use this reference point and measurement to set your chain slack.  Easy peezy and repeatable.

Hint - Find a reference point that allows you to use a two or three finger width and you won't need a tape measure when you bolt everything back up when you have to fix a flat in the woods.

That's exactly what I'll be doing once I get this swingarm back. I am planning to do the drill rod sections like Jaeger did inserting them into the swing arm and see how that work. I will receive the bike on Tuesday I think and I will be able to look at the swing arm and make a determination then.  since I live in Korea I think I'll be spending the swingarm back to Korea to meet me there and I'll do all the work there and then send the swingarm back to the u.s to be ready for my next adventure

sr1 wrote:

Honestly the chain was "nothing special."  It was from a local bike shop...they have a big reel of o-ring chain and it was cut off that.  

I think it stretched due to many bottom-outs thus the chain was stretched across the bottom of the swingarm.  

Do i need the linkage bearings too?  Why?  14k miles on the bike,,,

I wouldnt buy that chain again, hard to say what it is or how good it is.

Bottoming out doesnt stretch the chain as its tightest point is when the swingarm is straight back from the front srocket, the chain is kinda loose when the shock is bottomed out.

I am having a hard time figuring that out. ..I'll have to see it to understand. How it can be looser bottomed out than inline.

Think about it. The CS sprocket and swingarm are in fixed locations relevant to each other; the rear sprocket's arc of rotation is in relation to the swingarm, not the CS sprocket. So it's true it's always the same distance from swingarm to the rear sprocket no matter what point in the rotation arc. But as the sprocket moves up under full compression, it rotates closer to the CS sprocket in doing so as the distance from the axis of the CS sprocket to the axis of the rear sprocket is now closer.

Draw three points on a piece of paper and it'll immediately become pretty obvious.

:)

I understand that part, but I'm thinking of how the chain has to make the turn round the end of the swingarm when the suspension is completely compressed. The chain is more slack but the swingarm pivot prevents the chain from going in a straight line on the bottom.

But, it's all academic. There are so many variables...like are you on the brakes (rear) when the suspension is compressed, or under power, or both, or is there good traction, etc. Many things could affect whether the chain is pulled taught against the swingarm pivot but having good slack as you guys have described is the best insurance.

I've decided to rebuild the swingarm like Jager didbut also got a fair price on a very good replacement swingarm. Kinda belt and suspenders I suppose. Again, it's comlpetely academic right now because the bike STILL hasn't been delivered and I'm back in Korea anyway. At least when I get back to the US for my next trip I will have a game plan or two, some options, and it won't take that long to get either in place. I also got two 114 link chains and a 14/51 sprocket setup. The destroyed chain (btw, when it was thrown, it actually broke. it was not still in one piece) and the swingarm damage scared the shit out of me quite frankly and I will do everything I can to prevent this in the future. I was even considering changing bikes, but the rest of it performs so well...

If I had gone further into Nevada that day, rather than turning back toward SLC, I'd have been screwed royally. Mostly my fault for not taking action on that chain when I saw it looked bad. Now I know. I bought two chains (and an extra seal guard(slider) for a reason...the next time I do the TAT I might just send a chain and guard to Moab just in case, ahead of time. I can always send it back, but it only takes 10 minutes to put one on. Never again will that thing get me if I can help it. Never again. Nevada and eastern Utah are way too remote and exposed to play around. You can probably tell by this message it got to me, and maybe rightfully so. I should have been paying better attention.

Thanks for all the help guys. I've taken all of your advice and also saved this thread so I can refer back to it in front of the bike, and on the trail should the need arise.