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XRGUY79

Chain Tension!

6 posts in this topic

This is the first Season for me riding my BRP

and I was abit unsure about chain Tension. What is a good way to judge if its too tight or too loose. I have read the owners manual but just wanted some input from experts.

I also wondered do you check it with the bike in the air or at normal sag. Please help! :)

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XRGUY,

Put the BRP on a stand and get the rear wheel off the ground.

Some people remove the rear shock linkage and bring the swingarm up parallel to the ground and then measure the chain tension.

With the rear wheel off the ground and linkage connected, I adjust the chain tension to the extreme maximum limit recommended. Some say even this is too tight. They say that after you adjust to the extreme limit, if you disconnect the shock linkage and raise the swingarm parallel to the ground you can see that it is too tight. Check this out for yourself.

I don't take big jumps on my XR, so I don't keep mine as loose as others would recommend.

I would NOT recommend measuring the tension with the rear wheel on the ground or adjusting to the minimum recommended limit.

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I've been racing my BRP for over a year and a half and I set my tension about a half inch tighter than spec. and have never had a chain or sprocket related failure. Some of the scrambles in my state range from extreme tight woods to almost wide open MX style.

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Hey man!! Don't run your chain too tight no matter what anyone says! Too tight will cause damage to the sprockets, chain, and the countershaft bearing. Too loose could cause a de-rail. Check the chain tension with your weight on the bike. It should have at LEAST a half inch of slack at this point, and up to an inch is ok.

Remember, too tight increases friction at all points, and is not good. Never, ever run the chain tight. As the suspension is compressed, the tension will only increase more, and at the highest level of the swingarm arc , there should still be no less than 1/2 inch of slack.

Chain tension settings are extremely important not only for reducing wear and tear, but also for proper rear suspension action, which will be seriously compromised if the chain doesn't have the correct slack setting.

Check a Honda shop manual, or any off road bike's shop manual, and you will get the same advice.

Hope this helps you out!

L.L.

P.S... Please note there is NO known benefit to running the chain tighter than the manual recommends. None at all!! I'm picky about this because I have seen firsthand the expensive damage that is done by running a tight chain. It makes no sense to do it. None at all. The chain guide, buffer, and roller, are there for a purpose, to keep the chain from de-railing. And if you're running it tight to save those parts, forget it, the buffer and roller still wear the same, you're only helping the guide, and that's a cheap part compared to chains, sprockets, and especially shaft bearings. You don't gain power, or anything at all, from running a tighter than normal chain setting. In fact you lose power to excess friction.

If you wonder why the timing chain is kept tight all the time, then why not the drive chain? Then, note: the timing chain first of all is not as tight as you might think, even with the tensioner functioning properly. It's a small, short chain which is under fairly minor stress, and the plane of operation does not vary at all, as the drive chain varies from swingarm movement. Also, the cam chain is driving a relatively minor force which consists of the valve train assembly. There is really no comparison, but I have heard people argue this point.

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there's a lot of voodoo and speculation regarding chain tension. The bottom line is that the chain is tightest when three points allign: rear axle, countershaft, and swingarm pivot. This is not neccesarilly when the swingarm is parallel to the ground, or when you sit on the bike, etc.!! actually, most measurement specs are derived from this reference point.

One method that works on some bikes is to stand on the right side of the bike, no kick or center stand, put your chest as far back as you can on the seat/fender and your left hand on the rear of the swingarm. Pull up on the swingarm, while using your right hand to feel the chain tension. On some bikes it is possible to actually go "over center" to where the chain gets looser. Try to find the point of rear suspension compression where the chain is tightest, and at this point you want a bit (but not much) slack in it.

Guess I better put a disclaimer at the end here: on some bikes there are rollers that increase chain tension as full compression is approached. The best way to see what's going on with your particular bike is to unhook the shock or linkage with the bike on a stand and check it out. It never hurts to take good notes on reference points.

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