Setting proper drive chain tension.

On a 06 WR450, the factory manual states to raise the bike on a stand, measure from the chain guide screw to the middle point of the chain. Roughly 1.9” to 2.3” of slack should be obtained. I set mine to 2” and found the chain to be very tight once I sat on the bike. I’m clocking in at 190#’s so I don’t think it was my weight but the chain seemed very tight to me. It makes me wonder how it would be if jumped like this. Anyone have a trick for setting chain tension? I don’t believe the manual to be correct. I must have measured it 4 times, just as the book states to do. I does not seem correct to me. Thanks.

this measurement should be at the tightest point on the chain, what you should do is take a measurement, spin the tire some, take another etc. etc. - at the tightest, it should be 1.9, I prefer to set mine towards the looser end of the allowed.

once you sit on the bike, you need to get someone else to measure the play (keep bike in Neutral), because it probably will "look" tight to you but there will likely be slack on the bottom portion of the chain - chances are you're fine, but better to measure twice that be wrong.

The manual is correct. My 07' manual says the same thing. "1.9 to 2.3"

I used to worry about it too when I first got the bike. I played around with the tension a bunch, and what seems good in the garage always made chain clanking noise on the trails. I now keep the marker on the axle blocks always somewhere between 4 and 5 lines from the rear. Never been a problem. (at least for me :lol: )

............ bahhh :banana:

I cut a piece of plywood into a "high tech measurement devise" to check mine. I cut it to 2-1/8" tall and about 4" long. It makes it easy to spin the wheel and check the tension at several different places on the chain.

Mike

Rather than looking for the chains "tight spot". I have been checking after a hard ride. Chain is heated and loose. Are you saying to check cold?

I cut a piece of plywood into a "high tech measurement devise" to check mine. I cut it to 2-1/8" tall and about 4" long. It makes it easy to spin the wheel and check the tension at several different places on the chain.

Mike

Do you have a pic of this to share? Great idea.

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Here's my high-tech chain tension gauge:

WR450F_chain_tension_gauge.jpg

If you don't have access to the materials/tools I can make you one if you like.

Say $10 plus shipping?

Greg

mine always looks a little tight compared to what everyone else runs but i have always set mine to spec and never had problems , my chain even lasts a really long time .

First three fingers right behind screw on slider. Works great....yes please factor in little teeny tiny and huge mongo ape hands in this method.

.

Here's my high-tech chain tension gauge:

WR450F_chain_tension_gauge.jpg

If you don't have access to the materials/tools I can make you one if you like.

Say $10 plus shipping?

Greg

What's with the numbers on the side?

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What's with the numbers on the side?

Millimetres.

Max recommended is 58 and minimum is 48. The others (51 and 54) are just incremental ones. The gauge slips under the chain better this way rather than in one big 10mm step anyway.

On a 06 WR450, the factory manual states to raise the bike on a stand, measure from the chain guide screw to the middle point of the chain.

Interestingly the '08 manual shows the measurement from the top of the bolt to the underside of the chain.

Greg

It's not 2" of true slack, it's 2" from the raised chain to the rear chain slider bolt. As the swing arm swings up into a position where the centers of the output shaft, swing arm pivot, and rear axle are in line with each other, the axle will be at its maximum distance from the output shaft, and the chain will be at its tightest point. If you checked it there, you should have 1/4" of true slack (up and down) per foot of the chain run, or about 1/2".

This looks loose to most people, especially when the bike sits on the ground with no one on it, but it's extremely important to run at least the minimum slack to avoid breaking hubs, etc.

My gauge block is a simpler, two step, go/no-go sort of thing:

http://www.thumpertalk.com/forum/showthread.php?p=7243089#post7243089

Nice to see we all use the same high tech measuring devices!

I started having too many measuring blocks littering the track toolbox, so now I have one stepped block - color coded to the Min/Max of our 4 bikes

grayracer513 is right. when the output shaft, swingarm pivot and rear axle are in a straight line with each other, the chain is at it's tightest point. it will never be tighter because as soon as the suspension compresses past that point, the rear axle starts coming back towards the output shaft making the distance shorter. i find that that amounts to about 3 fingers worth of slack.

I cut a dowel rod to the right length. When you check your chain tension, do you do it before or after you tighten your axle bolt. On my bike the chain will get quite a bit tighter when I tighten my axle bolt, so I have to leave a little extra.

Austin

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Interestingly the '08 manual shows the measurement from the top of the bolt to the underside of the chain.

Greg

In my 06 manual, it only shows a diagram with an arrow pointing to the chain, and it's hard to tell if it is pointing to the middle or the bottom. Based on the design of all the measurement devices I see on here, I assume most people are using the bottom of the chain. I have always wondered which one it is, so I just try and set it at a point where both are within the range.

It's not 2" of true slack, it's 2" from the raised chain to the rear chain slider bolt. As the swing arm swings up into a position where the centers of the output shaft, swing arm pivot, and rear axle are in line with each other, the axle will be at its maximum distance from the output shaft, and the chain will be at its tightest point. If you checked it there, you should have 1/4" of true slack (up and down) per foot of the chain run, or about 1/2".

This looks loose to most people, especially when the bike sits on the ground with no one on it, but it's extremely important to run at least the minimum slack to avoid breaking hubs, etc.

My gauge block is a simpler, two step, go/no-go sort of thing:

http://www.thumpertalk.com/forum/showthread.php?p=7243089#post7243089

When you use the block, is the bike off the ground?

i would say it's worth it to use gray racer's method once, and then record how tight the chain is when the bike is just standing.

use a strap going from the swingarm over the seat and down to the swingarm again and crank it down until the output shaft, swingarm pivot and axle bolt all line up. then leave about a 1/2 inch slack. then take the strap off and measure the slack in several places with the bike just standing there. then make a block or remember the measurement and always adjust it to that.

If you leave enough slack for when the shafts all lign up, you will be safe. that's what i did, has worked good so far.

When you use the block, is the bike off the ground?
Absolutely.
i would say it's worth it to use gray racer's method once, and then record how tight the chain is when the bike is just standing.
Absolutely not. Too many variables. The only way you know for sure is to know exactly where the swing arm is in its arc, which you do know if the bike is on the stand.

Your tie strap method, however is valid, to the extent you can tell when all three shafts line up, and that is really what the numbers the manual calls for are based on.

Note that the '07 and later WR will require more slack than the '06 and earlier, mostly due to the placement of the lower roller, which hits the chain sooner in the downward travel on the older bikes.

After the first ride on my 08 WR and the Sub Frame was already nicked, I knew I had a problem...

I followed Gray's advice, adjusted the chain per the spec's in the manual.

I also measured from the center of the swing arm pivot to the center of the rear axle on both sides and found that my axle blocks are less than perfect...since I have started doing this, all is well with no issues :p

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