Am I running my chain too tight?

[Dan_187]

I run 1.3 inches of slack on my 06 yz450. I know the manual says to run way more than that but when do that all i hear is the chain slapping around. I got 1.3 inches by straightening the swingarm (with shock disconnected) and measuring 1 inch at the tightest point. I read this from a suspension expert from transworld. Is this too tight? Even though its tighter than the manual it always has at least an inch of play in its entire travel so I think its ok. I've been running this for about a year and had no problems because of it.

Please share your opinions. And cut me some slack if im wrong (full pun intended)

[Ga426owner]

This subject has many opinions. Here is what I have done on Yami400/426/450s since 1999. I have never had any issues what so ever.

It is not rocket science:

behind the top chain guide (on top of swingarm) I use my 3 middle fingers between the chain and swingarm approx 1 inch from the end of the middle finger to measure chain slack. This equates to approx 1.9 - 2.1 inches. I do not get chain slap or wear on subframe/frame or any hub problems what so ever. My Sprockets and chain last very long time.

I also suggest ditching the stock Axle blocks for others that have decent marks on both sides. I use GYTR. The Stock axle blocks are known to be problematic in correct measurements on each side.

Also if you ride in wet or muddy conditions - make sure you increase chain slack - these conditions will make the chain slack tighter.

I would say 1.3 inches is not enough slack period

[sidewinder2]

This subject has many opinions. Here is what I have done on Yami400/426/450s since 1999. I have never had any issues what so ever.

It is not rocket science:

behind the top chain guide (on top of swingarm) I use my 3 middle fingers between the chain and swingarm approx 1 inch from the end of the middle finger to measure chain slack. This equates to approx 1.9 - 2.1 inches. I do not get chain slap or wear on subframe/frame or any hub problems what so ever. My Sprockets and chain last very long time.

I also suggest ditching the stock Axle blocks for others that have decent marks on both sides. I use GYTR. The Stock axle blocks are known to be problematic in correct measurements on each side.

Also if you ride in wet or muddy conditions - make sure you increase chain slack - these conditions will make the chain slack tighter.

I would say 1.3 inches is not enough slack period

I would also say 1.3 inches is wayyyyy to tight!! I don't drop below 2 inches!

[grayracer513]

Yes, you are running the chain far too tight. You're begging for a broken hub or worse.

One of the reasons the '06+ models need so much slack on the stand is that the lower roller is lower on the bike in relation to the swing arm than in earlier models, so it doesn't take as much slack out when the wheel is fully extended. But the needs of the bike haven't changed. A roller chain needs to have no less than about 1/4" per foot of real slack, and it's roughly two feet between the front and rear sprocket, so the least you can have is 1/2" of total up/down movement in the chain at its tightest point. That point is not where the suspension is with the bike either on the ground or sitting on the stand, but at the point where the swing arm is in the position in which the centers of the output shaft, swing arm pivot, and rear axle are all lined up. That position puts the axle as far from the front sprocket as it will get at any time, and it is there that the chain tension should truly be set. If you have any doubts, have two of your friends sit on your bike and check your current setup.

The factory realizes that you can't be expected to haul down your rear suspension every time you set the chain tension, so they have done it for you. They aligned the 3 centers and set the chain up, then set it on a stand so that the reading they would provide you with would be repeatable (the swing arm will always be in the same position on the stand regardless of springs or other adjustments). Then they took the measurement as given in the manual and found it to be a minimum of 1.9". If you doubt it, check it yourself.

https://www.thumpertalk.com/forum/showthread.php?p=3704580

[Hempstead]

hes talkin about when his swingarm is parrallel with the ground you guys are talking about when its on a stand or sitting on the ground..theres a difference

[rmzRacer293]

loosen it up a bit, just to be safe.... Yamahas bust hubs...there expensive.

[IDAHOBALLER]

I always set the chain slack and then put the bike back on the ground and bounce the rear suspension up and down to make sure that there is still some slack in the chain when the rear suspension is compressed. It tightens up quite a bit when the rear suspension is compressed.

[grayracer513]

hes talkin about when his swingarm is parrallel with the ground you guys are talking about when its on a stand or sitting on the ground..theres a difference

Ah, yes. However, "Parallel to the ground" is also not the correct way to check it, since that may or may not put the 3 shaft centers in line, and the tension at the correct 1/2" minimum. If he makes the check at the point of alignment, or on the stand using the factory specifications, he will be running the correct tension.

[Dan_187]

Thanks hempstead, I might not have been clear enough; I took the shock off and moved the swingarm up so the countershaft, swingarm axle bolt and the rear axle are all aligned and then took my measurements. With 1.3" slack the chain still had an inch at the tightest point (where all 3 axles are aligned). So is my chain too tight? An inch is an inch, it seems to me that its ok, if not i have to go back to a chain slapping 1.9 inches of slack.

[CaptainKnobby]

I have ran my 06 with 50mm of slack from the screw at the top of the chain slider to the bottom of the chain and I have never had any issues.

[ben_suhard]

Thanks hempstead, I might not have been clear enough; I took the shock off and moved the swingarm up so the countershaft, swingarm axle bolt and the rear axle are all aligned and then took my measurements. With 1.3" slack the chain still had an inch at the tightest point (where all 3 axles are aligned). So is my chain too tight? An inch is an inch, it seems to me that its ok, if not i have to go back to a chain slapping 1.9 inches of slack.

You may get away with setting your chain as you do, but a couple of things to be aware of is that the chain stretches unevenly(it will be tighter in one section of chain compared to another, so measure the distance between your chain and swingarm slider at different points on the chain - turn the wheel a bit each time, then measure), and that if you get mud in the chain, that can also makes the chain tighter. Setting your chain to factory spec. will pretty much guarantee you against shattering your hub(as long as you keep those sprocket bolts tight) or bending your counter shaft. Chain slap can be annoying(and the chain can grind on the frame on '06 upwards), but it's highly unlikely that you'll throw your chain off if it's at factory spec..

[grayracer513]

With 1.3" slack the chain still had an inch at the tightest point (where all 3 axles are aligned). So is my chain too tight? An inch is an inch, it seems to me that its ok, if not i have to go back to a chain slapping 1.9 inches of slack.

1.3" measured at that point is too loose. Instead of going through all the unnecessary hassle of dropping the shock and jacking the swing arm, try it by the book once. Set the bike on the stand and set the chain at 2" above the rear slider bolt, as shown in the manual. Then pull the shock and run the swing arm up and check the slack again. It will be close to 1/2", and that's what it should be.

The 1.9" called for is to be measured on the stand, and not with the swing arm centered.

[Dan_187]

1.3" measured at that point is too loose. Instead of going through all the unnecessary hassle of dropping the shock and jacking the swing arm, try it by the book once. Set the bike on the stand and set the chain at 2" above the rear slider bolt, as shown in the manual. Then pull the shock and run the swing arm up and check the slack again. It will be close to 1/2", and that's what it should be.

The 1.9" called for is to be measured on the stand, and not with the swing arm centered.

Oh, I understand what your saying. I only took the shock off once and now I just measure 1.3 with the bike on the stand regular. I was saying that even at 1.3 it would still have an inch if I were to take the shock off and put it to the tightest point. So I ask again, should I still run it at 1.9 (with the bike on the stand as normal of course)???

[Ga426owner]

Oh, I understand what your saying. I only took the shock off once and now I just measure 1.3 with the bike on the stand regular. I was saying that even at 1.3 it would still have an inch if I were to take the shock off and put it to the tightest point. So I ask again, should I still run it at 1.9 (with the bike on the stand as normal of course)???

yes at minimum....1.9-2.3 should be the range.

And to Bens point, Chain tension can be different on each side of the swingarm top and bottom.

[ben_suhard]

And to Bens point, Chain tension can be different on each side of the swingarm top and bottom.

I actually meant to measure at the same point on the swingarm(above the slider bolt), but to move the chain through a bit by turning the rear wheel and measure at different points(different links) on the chain. I've edited my post to be a bit clearer on that.

[grayracer513]

... I was saying that even at 1.3 it would still have an inch if I were to take the shock off and put it to the tightest point.

I'm sorry, but based on what I have seen in the past, I have quite a lot of trouble buying that. I haven't checked either of my own '06's, but now I think I will when I have time.

1.9" on the stand is the absolute least I would run.

[BASSic]

I also suggest ditching the stock Axle blocks for others that have decent marks on both sides. I use GYTR. The Stock axle blocks are known to be problematic in correct measurements on each side.

I think you just answered one of my questions I asked in another thread regarding odd sprocket wear - only the inside is showing wear, yet my axle blocks appear to be aligned properly on both sides.

[grayracer513]

This is why one verifies wheel alignment by measuring from pivot to axle, or even more accurately, by running a straight edge from the rear sprocket to the front. Even when the marks are wrong on either the swing arm or the blocks, once you know how much the error, if any, is, you can compensate for it.

[Ga426owner]

I think you just answered one of my questions I asked in another thread regarding odd sprocket wear - only the inside is showing wear, yet my axle blocks appear to be aligned properly on both sides.

yes sprocket and chain wear will affect tension on chain. Check tension then turn rear wheel so that the bottom of chain now is on top - a worn chain will show either more or less tension for different parts of the chain

[ww44wrf450f]

if you have a bad chain or its binding at the links it can slap?