Chain Sag with 14t

[AfroStar]

I had a friend install a 14t sprocket, and now the chain seems to be sagging just a bit.  I'm about to go on a long trek, and doing my due diligence.  I'm thinking geometric wise, this could be normal. smaller sprocket, and same chain length.

When parked and on a rear stand, the chain is resting on the chain support on the top swing arm.  I haven't measure the slack yet, will do it tonight. 

is this common?

Thanks DMF

[Spidey]

Going to a 14T will pretty much always affect your chain tension.  Tighten that make the beast with two backser up.

[Slide Panda]

I had a friend install a 14t sprocket, and now the chain seems to be sagging just a bit.  I'm about to go on a long trek, and doing my due diligence.  I'm thinking geometric wise, this could be normal. smaller sprocket, and same chain length.

Correct, you've got the same length of chain wrapped around a smaller perimeter with the 14.  Since the chain length is fixed, and the center point of the two circles (sprockets) is fixed, somethings gotta change - and that's where you get slack. 

So snug up lest you get chain slap and drive line lash

[Armor]

Do you check and adjust your chain?

[AfroStar]

I will try to before my trip, It was adjusted when we put on the 14t. so it should be snug tight with the 14t.  anybody got CM numbers for this?

[Slide Panda]

You adjusted it after you installed the 14t? 

You check the slack under the swing arm, not above.  It's not uncommon for the chain to be touching the swing arm guard with a 14T and no rider on the bike.  W/o a rider on it, the swing arm's going to be a different angle and the sprockets won't be lined up as they are when the bike is loaded.

CM? 

[AfroStar]

You adjusted it after you installed the 14t? 

You check the slack under the swing arm, not above.  It's not uncommon for the chain to be touching the swing arm guard with a 14T and no rider on the bike.  W/o a rider on it, the swing arm's going to be a different angle and the sprockets won't be lined up as they are when the bike is loaded.

CM? 

We adjusted after installation.  Cm is suppose to be for centimeter    .  What you said makes sense. so maybe I should be OK. because the dude, who helped me install the 14t, he is well known and respected on Ducati  Monsters.  Thanks for the input.

[JetTest]

Proximity of the chain to the top of swingarm will be closer due to the smaller diameter of the 14t sprocket, but you would still want the same measurable amount of deflection between the chain and the bottom of the swingarm as you should have with the stock front sprocket, otherwise you will have either too much tension, potentially damaging the counter-shaft bearing and seal, or too little tension causing excessive lash and potentially slinging the chain off the sprockets while driving. Not good, either way.

[AndrewNS]

I think too tight a chain on the S*R bikes would probably kill the rubber cush drives at the wheel sprocket end before it would hurt the output shaft bearings, but that's just a guess - I really don't know for sure. Anyway, a chain is always better being too loose rather than too tight.   

[JetTest]

Yes, the rubber bushings in the rear sprocket carrier would probably go quickly too, but I have seen counter shaft bearings go suprisingly fast on dirt bikes with the chain too tight. Lose would be better than tight, but why not adjust it right and be done with it?