2007 crf250r chain snap damage assessment

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12/2/2017 3:35 PM

Well the other day i was out riding and i came down off of a table hard on the throttle and low and behold, the chain snapped and got locked up between the sprocket and the case.
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Then i noticed that i was dripping oil, and i thought well crap there goes my left side case. There does appear to be a decent sized hole in the case, so im most likely getting a new one to replace it.


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my problem comes from what made the chain snap. It was an oring protaper chain, had about 26 hours on it. One ride day before it snapped, i noticed that it was loose (like 4 fingers between the swingarm and chain behind the end of the guide) so we tightened it up to 3 fingers (again, behind the chain guide. hope that was the correct move) and it didnt seem excessively tight through the stroke at all and got rid of an annoying rattling noise. I just checked the sprocket bolts and they seem pretty tight, so im kinda stumped as to what went wrong here. Any help is appreciated!

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Mediocracy is my middle name.

12/2/2017 3:42 PM

Shouldve said this before but i forgot: right before it snapped i was trying to shift mid air (clutch in, shift, clutch out) but i was still on the throttle. It didnt want to shift, so i let go and tried again right as i landed and it shifted. Then, when i got on the throttle a bit more it snapped.

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Mediocracy is my middle name.

12/3/2017 12:34 AM

First of all, you're front sprocket bolt and washer looks to be incorrect installed, it looks crooked but it may be the picture?

Did the chain snap, or is it the chain link that fell off? End of chain looks so nice on the pic..

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12/3/2017 5:23 AM

Where was your chain guide and case saver?

Paw Paw

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12/3/2017 8:39 AM

Kawasaki-rider wrote:

First of all, you're front sprocket bolt and washer looks to be incorrect installed, it looks crooked but it may be the picture?

Did the chain snap, or is it the chain link that fell off? End of chain looks so nice on the pic..

Sorry, the front sprocket being crooked was from us trying to get the chain out, we took it out and then hastily put it back in. But you're right, it does seem like it was a link that fell off. What could that mean?

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Mediocracy is my middle name.

12/3/2017 8:42 AM

Paw Paw 271 wrote:

Where was your chain guide and case saver?

Paw Paw

The lower bolt hole for a case saver was broken off when we got the bike, so we didn't think the case saver would stay in place and didn't want it moving around a bunch with the chain right there.
What do you mean by chain guide?

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Mediocracy is my middle name.

12/3/2017 11:16 AM

Rexblaster wrote:

The lower bolt hole for a case saver was broken off when we got the bike, so we didn't think the case saver would stay in place and didn't want it moving around a bunch with the chain right there.
What do you mean by chain guide?

Chain guide is the guide on the bottom of the swingarm, just ahead of the rear sprocket.
It doesn't sound like your chain was overtightened, and it doesn't look like the chain snapped. It looks like your master link came apart.

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Many thanks to everyone helping me out this GNCC season: SRT Offroad, Acerbis, FCR Suspension, O'Neal Racing, Evans Waterless Coolants, Rekluse, Twin Air, Braking Brakes, Carbsport

Profile image credit Ken Hill Photography

12/3/2017 11:23 AM

Paw Paw 271 wrote:

Where was your chain guide and case saver?

Paw Paw

Rexblaster wrote:

The lower bolt hole for a case saver was broken off when we got the bike, so we didn't think the case saver would stay in place and didn't want it moving around a bunch with the chain right there.
What do you mean by chain guide?

harescrambled wrote:

Chain guide is the guide on the bottom of the swingarm, just ahead of the rear sprocket.
It doesn't sound like your chain was overtightened, and it doesn't look like the chain snapped. It looks like your master link came apart.

Ah okay yeah that's what I figured. The chain guide seems to be okay, I'm just stumped on what made the master link come apart after a year of riding. I'm assuming operator error? Is there anything specific I need to do to take care of an oring chain? I dont use chain lube and hit it with wd40 after every wash as I recall seeing that as advice on here a while back. Could I just have installed the master link incorrectly?

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Mediocracy is my middle name.

12/3/2017 1:08 PM

If you had installed it incorrectly, I doubt it would have lasted a year. On my O-ring chains, I use chain lube just to keep the O-rings from drying out.

The master link retainer clip closed end has to face the direction of drive. If the master link is on the top chain run, the closed end faces the engine sprocket. If it's on the bottom run, the closed end should face the wheel sprocket. Also, the retainer clip can get worn down during its service life, and if it wears too thin it will lose tension and come off. Not sure if that's what happened in your case, but it's something to be aware of and to keep an eye on

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Many thanks to everyone helping me out this GNCC season: SRT Offroad, Acerbis, FCR Suspension, O'Neal Racing, Evans Waterless Coolants, Rekluse, Twin Air, Braking Brakes, Carbsport

Profile image credit Ken Hill Photography

12/3/2017 1:12 PM

It’s possible you put the clip on backwards (ie with the open end towards the rotation direction). Given that it’s an o-ring, it’s also possible your outer plate on your master link wasn’t fully seated, causing the clip to not fully seat in the grooves. I’ve seen that happen in the past, especially if the master link hasnt been on and off a few times.

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12/3/2017 1:57 PM

Due to the extra width of the oring chains, it will wear out the clip on the master link in short order. THus they need to be replace from time to time.
FYI: The chain guide I was speaking of earlier is also the case saver. With it in place damage is reduced with a chain break. Also, chain sure looks to have much more than 26 hours on it.

Paw Paw

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12/3/2017 2:11 PM

Paw Paw 271 wrote:

Due to the extra width of the oring chains, it will wear out the clip on the master link in short order. THus they need to be replace from time to time.
FYI: The chain guide I was speaking of earlier is also the case saver. With it in place damage is reduced with a chain break. Also, chain sure looks to have much more than 26 hours on it.

Paw Paw

Ah, I see what you mean. Thanks paw paw! And could the extra wear be due to improper maintenance? I will be the first to admit that while I keep up with my engine maintenance I may not have done my research with what I needed to do with this chain. I heard that they were more durable, but I don't really see too many people running these chains for moto only. Would you advise against buying another oring? And if i do what would proper maintenance call for? Thanks again!

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Mediocracy is my middle name.

12/3/2017 5:07 PM

I have always used o ring chains as they do last a lot longer. Change the clips regularly and keep the chain clean.

Paw Paw

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12/4/2017 10:38 AM

...I'll add that you should still lube the chain occasionally. As stated above, it keeps the o-rings pliable so they can do their job and keep the grit out.

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Braaapin' aint easy.

12/4/2017 12:37 PM

I would bet my paycheck your master link clip worn out and that is what caused your problem. I have had the master link last a little longer by putting the clip on the inside of the chain and it seems to last longer but must still be checked regularly because they do wear. Wd40 is a waist on a chain and it doesn't last, you want to use a chain lube for better chain life. I don't like chain wax because it gets on everything and I've liked Maxima chain lube

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