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Discussion Starter #1
I just got my 2002 Monster 750, two months ago, you can read about it on my only other post.

Chain tension is specified in the owner’s manual, around 25-27 mm of slack.
My questions:
What happens when the chain is tight?
What happens when the chain is loose?

I understand that some slack is needed to adjust for geometry changes as the swing arm moves up and down. I would think that the slack also helps prevent wear on the teeth of the sprocket.

As soon as the weather gets warmer, I’ll be taking it to have the 6k miles service, where the chain will be tighten, and maybe change since I notice the o-rings looked cracked and the chain had sticky links. However the slack on the bike is about 45 mm (I can hit the swing arm if I push hard the bottom part of the chain up). I asked at a dealership where I’ll be taking my bike, and they said is better the chain to be loose than tight. Is the chain going to be ok as long as I don’t ride my bike hard?

My previous motorcycle was shaft driven, and old Virago, so I never dealt with a chain, and have no experience with chains at all. well my bicycles but I never let them get dry or dirty.

Thank you for your help, maybe this is a very simple subject, but I just don’t have the experience of what to expect to happen.

lgg
 

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Luis said:
What happens when the chain is tight?
What happens when the chain is loose?
Too tight = un-designed for stress on output shaft bearings = expensive motor repairs

Too loose = noisy

(and way way too loose might lead to the chain skipping teeth, but thats somewhere near "dragging on the ground" loose)

Your dealer was right, too loose is _way_ preferable to too tight.

Personally, unless I'm working on the bike for some other reason, I'll usually only tighten up the chain if it's loose enough that I can push the bottom run of chain up into the bottom of the swingarm while its on the sidestand in neutral...

big
 

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Discussion Starter #4
bigiain said:
Too loose = noisy

(and way way too loose might lead to the chain skipping teeth, but thats somewhere near "dragging on the ground" loose)
Personally, unless I'm working on the bike for some other reason, I'll usually only tighten up the chain if it's loose enough that I can push the bottom run of chain up into the bottom of the swingarm while its on the sidestand in neutral...

big
And that's the case with my bike, on the sidestand, in neutral, I can push the bottom run of the chain up into the swingarm.
I tried with my fingers to grab the excess chain and try to pull it of the sprocket, but the slack is not enough to come close to jumping a tooth. however, as soon as possible, I'll take it to be serviced and tighten then chain.

or, has anyone ever had a chain jumping teeth, or causing some damage to the gears, a cause of a loose chain?

Thanks for your help.
lgg
 

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As noted +

Too tight:
Added strees chain links, decreased chain an sprocket life.

Too loose:
'Lash' which leads to a jerky feel and added wear on the drive line

If your chain has kinks/sticking link or dead rings it's probbly past due fora new one. Bad links will rob power and wear on sprockets more than links in good shape. Also, if the chain does fail you'll be very un happy. If it breaks loose odds will be that you'll need a new engine case as a result. It's not unheard of that a breaking chain will punch a hole in the case as it gets whipped around the drive sprocket.
 

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A good friend of mine with a 900SS was VERY pedantic/anal with his chain tension, i think he adjusted the chain on the side stand. I think this what is said in the owners manual, can't recall?

He is a BIG boy and one day while riding a horrible noise came from the gearbox.
We stopped and had a look, the gearbox outer bearing had totally disintegrated.

What i think happened was when he sat on the bike the slack was taken up in the suspension settling, therefore tightening the chain to such an extent that it put large tensions on the output shaft bearings. The repair was very expensive. :'(
All his suspension sag settings were correct, he had all his suspension worked on by a suspension guru here in OZ.

I think the moral of the story is check the sag on the sideastand but also jump on and take up the suspension sag and have quick look at the tension then as well.

Just a note on checking the life of the chain by pulling off the back of the rear sprocket. If you can see daylight in between the chain and the sprocket when you pull it rearwards, time for a new chain. Always replace the sprockets and chain together. if you don't the old part will wear out the new part quicker.

Cheers
 

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I've run a chain to the point of jumping a tooth. It broke 2 teeth off my front sprocket and nearly gouged a hole straight through my crank case cover. Luckily the gouge in the crank case cover didn't go all the way through and luckily I didn't throw the chain. When you run it so loose that it jumps a tooth you'll feel it slip when taking off from a stop or other higher torque situations. You'll start moving and then suddenly will lose power and the engine will rev up like you hit a false neutral or something and then it will suddenly grab again. You'll also hear a loud noise that rivals your dry clutch coming out of the left side of your bike. $20 or so for a nice piece of steel to protect your shiny aluminum crank case from DesmoTimes. You can also get it through CA-Cycleworks. If you keep good track of your chain tension you shouldn't need it but if you tend to forget it can save you a LOT of money.
 

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erkishhorde said:
I've run a chain to the point of jumping a tooth.
I've done that twice (yeah yeah, I know, the first time may be just carelessness, the _second_ time was stupidity...) but both times it was more the fault of spectacularly badly work front sprockets more than the chain slack...

(When it did it on the monster I didn't touch the case either, I wonder it thats an unexpected advantage of the 14t front sprockets?)

big
 
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