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Chain Tension on the WR250X

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How do you measure the play in the chain? With the bike on the swing-arm stand, I rotate the wheel to the point where the chain feels the tightest. I place a small framing square on the bottom of the swing arm with the chain just behind it. Then I press the chain down with about 5 pounds of force and I make a pencil mark on the framing square where the center pin of the closest chain link is. I then push the chain back up towards the swing arm and make another mark on the framing square next to the nearest link's pin. I take the chain slack to be the distance between the two marks that I've made on the framing square.

My question is this: should I be measuring from the link pins or from the top/bottom of the links themselves?

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I measure from the top of the chain link, you can also measure from the pins or top of the link, the measurement should be the same provided you measure from the same fixed point.

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I guess what I was asking was if I was supposed to push the chain down and make a mark on the ruler where the bottom of the link rested and then push the chain up and make a mark where the top of the link came to rest. I don't want to sound like an idiot because I know that if you take measurements at the same point on the link then that point can me anywhere on the link and you will get the same measurement. Geeze, I've never had anything that was this hard to explain.*laugh* It's such a simple thing and yet it's almost impossible for me to describe it.

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It's a good question. You don't sound like an idiot. I understood what you were asking in your first post.

You want to know if the chain slack is measured "outside to outside" or "center to center" in other words (words that may not be any clearer than your own).

The owners manual does not say, and it does not indicate it in the drawings either.

The chain is about 1/2" in height, so measuring it outside-to-outside makes your slack measure 1/2" more than center-to-center.

I assume Yamaha means center to center, but I have no reason to think that is correct.

If the rear sprocket is stock and new, I suggest you use the tight end of the recommended range. 40mm in the case of the X.

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I understood your question and that is why I used the phrase: "the measurement should be the same provided you measure from the same fixed point."

You always want to adjust chain slack using the same reference point.

i.e: if you take your upper measurement from the top of the chain then you also want to measure the top of the chain when you press it down to the low point, you can also measure the bottom of the chain so long as you use the bottom of the chain as reference for both the high and low; the measurement will be the same either way.

The thickness of the chain is not a factor in adjusting chain slack.

A common mistake is to push the chain upward and mark where the bottom of the chain is then push the chain down and mark the top of the chain, this will usually result in a chain that is too taught.

The manual (if you look very close) shows a reference line drawn through the center of the chain, not exactly sure why as the center point is difficult to actually use as a reference since the chain would be in the way when trying to mark the point on your measurement stick.

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Guys, thanks for the responses. You cleared it up for me. Thanks for being patient. I really appreciate that. I'm so used to getting flamed for asking questions like these.

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So long as you don't mention your second amendment rights, synthetic oil and use proper spelling and grammar; you'll be OK around here.

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So long as you don't mention your second amendment rights, synthetic oil and use proper spelling and grammar; you'll be OK around here.

I think that's actually pretty close to right - and maybe not so bad. My positions:

2A: Outside the "Yamaha Dual-Sport" forum scope IMHO. I'll stay mute on this topic in the future.

Synthetic oil: IMHO someone who thinks they know more than Yamaha does about what oil works in Yamaha drivetrains is mistaken. IMHO. Beyond than that, everybody has an opinion.

Grammar and spelling: When I see something well written marred by one or two things, I have mentioned it to be helpful. But I've noticed in the past week or two that people are sensitive about it, so I'll add speeling and grammer to my "speak no evil" list. I really appreciate that most people here seem to take some care in what they post, and IMHO we all benefit from that.:D

The only controversy not on your list that comes to mind is the relative efficacy of the FMF vs PCIII fuel controllers. And please don't take mention of this as encouragement in any way to re-open the subject. Let sleeping dogs lie, as they say.:worthy:

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The only controversy not on your list that comes to mind is the relative efficacy of the FMF vs PCIII fuel controllers. And please don't take mention of this as encouragement in any way to re-open the subject. Let sleeping dogs lie, as they say.:worthy:

I thought that once the FMF guys saw the PC-III LCD screen that debate was put to bed. :D

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