m4i2k2e2

Member
Oct 8, 2007
344
0
hey, today i was riding my bike a 99cr250r. i went to the top of a hill got a little air and i heard a pop i landed and the bike just reved up. so i looked and the chain snapped. no damage was done. it was a d.i.d 520 o ring chain. i tend to follow my manuals as much as i can. so my chain was a little loose so during the week i tighted it and i rode saturday and today. im wondering if i overtightened it. i read the manual to get the exact tension that i should run. it was sort of vauge. i put the bike on a stand in neutral tightened it up and right at the end of the swingarm chain gaurd i had about an 1"-1 1/2" of play.
i rotated the tire and checked and a couple other spots and had the same tension. the chain a bit old. its been on the bike for a long time. can i get some advice on a good tip on how to set up the chain tension. and also how ofter should the chain be replaced? i dont do any racing i ride trails and pits, alot of hill climb and some jumps. thanks for the advice guys.

-mike.
 

Ol'89r

LIFETIME SPONSOR
Jan 27, 2000
6,961
45
Sounds like it may have been too tight or just simply worn out or both.

When you adjust your chain, have someone press down on the back of your bike and compress the suspension ALL THE WAY DOWN. You will notice, the chain starts out loose and gets tighter at one point of the stroke. Adjust your chain at the tightest part of the stroke and make sure you have the proper amount of play at that point. All bikes are different. Some, the chain will start out tight and get looser. Some start out loose and get tight at the end of the stroke. Some start out loose and get tight in the middle of the stroke and then get looser at the end of the stroke.

How often the chain is replaced is up to you and how you ride and maintain the bike. Conditions such as mud or sand will wear a chain out sooner. Try lifting the chain off of the rear sprocket with your fingers. A new chain will stick close to the sprocket. If the chain is worn, you will be able to lift the chain up off of the sprocket teeth. Your manual should show you how to do this.
 

mihm82

Member
Apr 6, 2009
26
0
My guess is it was just worn out and had no integrity left to it. i'd say just replace the chain and sprockets and then adjust to spec like matt90gt said
 

m4i2k2e2

Member
Oct 8, 2007
344
0
im gonna replace the chain. i rode the bike for about a year and a half and the original owner had it on there before me. which brand do you perfer for a chain, a D.I.D or an RK chain? thanks for the help guys.

-mike.
 

_JOE_

~SPONSOR~
May 10, 2007
4,697
3
I've had good luck with both of those brands. The D.I.D. I have now is an X-ring with 75ish hours on it and it hasn't stretched hardly at all. The stock sprockets still look new, no hooking.

Make sure you replace the sprockets as well or you'll likely ruin the chain in a hurry.
 

Matt90GT

Member
May 3, 2002
1,517
1
I dont like any of the ring chains. They always get dirt in them and then kink which means at that point you need to replace the chain or do some serious cleaning.

Just good MX roller chains. The EK MRDs are super tough. Best ones I have run and are cheaper than other brands. You will have to grind the rivets otherwise you will not be able to use a breaker tool. It will just break the pins until the rivet is ground flat.
 

julien_d

Member
Oct 28, 2008
1,788
0
I'm using an RK 520HD that was cheap. I was nervous about how cheap it was actually. It seems to work very well. Had it out for the first 6 hour trip and didn't need to adjust it during the day or afterwards. I agree on roller chains / x chains. Waste of money on a dirtbike. Once water/dirt/grit gets behind those o-rings there's no easy way of cleaning it out.
 

whenfoxforks-ruled

Old MX Racer
~SPONSOR~
Oct 19, 2006
8,129
2
Merrillville,Indiana
Running an o ring chain on a mx bike is the same as adding weight to the flywheel, bye bye power, imo. Most stock oem chains stretch fast and wear sprockets fast. A mid priced name brand chain and sprocket combo should be fine. How are the sliders and guides? After the slack is properly set, sight from the rear to front sprocket to double check alignment, you may have to have someone sit on it to get the chain off the swingarm.
 

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