How to know if spark plugs are tight enough?

[tsdexter]

How can you tell if the spark plugs are tight enough? I was a bit worried going too tight so I did the 1/2ish turn past finger tight.

If they're too loose will it make a significant/noticeable decrease in power?

They're supposed to be 9.5 ft lbs torque... I have a 10-70 ft lbs wrench, is it safe to turn the dial backwards from 10 a bit and tighten until it clicks? It felt like they were getting too tight and I didn't want to break them. How 'over tight' do you really have to go before breaking? They don't turn easily anymore with a short wrench, but again still didn't click the 'slightly below 10' torque wrench...

Lastly, can I loosen them out again and retorque after driving about 20 miles (they have the metal coating that acts as anti-seize - will that be ruined pulling them out) or if I really feel they need to be redone just pay the $10 for 2 more?

[k-os]

You're torque wrench is going to be most accurate in the middle of its torque range. I wouldn't trust it set below 10 at all.

[Whiskey]

Accuracy slightly outside the indicated torque should be reasonably ok, afaik reputable brands test at 25% outside the marked range, if you have one with a calibration cert it should say what it was tested at, and what it actually torqued

[tubarney]

Originally Posted by tsdexter

Lastly, can I loosen them out again and retorque after driving about 20 miles (they have the metal coating that acts as anti-seize - will that be ruined pulling them out) or if I really feel they need to be redone just pay the $10 for 2 more?

You can retorque them as much as you want. Just do them up snug. a 1/4 turn more than hand tight is enough.

[Felipe the Ant]

they fall out when they're too loose, just snug them and don't worry about it. a little tighter than a drain plug

[tsdexter]

Originally Posted by tubarney

You can retorque them as much as you want. Just do them up snug. a 1/4 turn more than hand tight is enough.

You sure about that? I only ask because this bulletin from NGK says the protective anti seize coating comes off on removal... Unless it only comes off when removing them after awhile of usage when they would normally be seized up...

http://www.ngksparkplugs.com/pdf/TB-...1antisieze.pdf

[ninjamunky85]

I think you're over thinking things here. I've never used a torque wrench on my spark plugs. Just always used the 1/4 turn past finger tight rule. I've also taken out and put back the same spark plugs many times with no noticeable difference.

[tubarney]

Originally Posted by tsdexter

You sure about that? I only ask because this bulletin from NGK says the protective anti seize coating comes off on removal... Unless it only comes off when removing them after awhile of usage when they would normally be seized up...

http://www.ngksparkplugs.com/pdf/TB-...1antisieze.pdf

I would say that is just manufacturer talk. There is no need for anti seize, maybe a little oil on the threads would be better. Just don't get oil on the electrode( not that it really matters)

The ones I have in my bike at the moment have been removed at least 10 times.

[Motofool]

Originally Posted by tsdexter

How can you tell if the spark plugs are tight enough? I was a bit worried going too tight so I did the 1/2ish turn past finger tight.

If they're too loose will it make a significant/noticeable decrease in power?

They're supposed to be 9.5 ft lbs torque... I have a 10-70 ft lbs wrench, is it safe to turn the dial backwards from 10 a bit and tighten until it clicks? It felt like they were getting too tight and I didn't want to break them. How 'over tight' do you really have to go before breaking? They don't turn easily anymore with a short wrench, but again still didn't click the 'slightly below 10' torque wrench...

Lastly, can I loosen them out again and retorque after driving about 20 miles (they have the metal coating that acts as anti-seize - will that be ruined pulling them out) or if I really feel they need to be redone just pay the $10 for 2 more?

This may clarify some questions:
http://faq.ninja250.org/wiki/Changin...d#Installation

In my experience, which goes back to the times before torque wrenches were invented, the big no-no has been torquing the plugs with the aluminum threads of the head being hot.

The approach changes for new or used plugs: new ones will use some of the torquing for deforming the seal washer.

Aluminum and steel tend to make an electrolytic bond with time: that is the reason for the anti-seizure agent.

[1LoneWolf]

Hand tight + 1/4 turn for me as well. I went 1/3 turn once and felt that I might have overtorqued it. I used anti-seize too.

[tsdexter]

Originally Posted by tubarney

I would say that is just manufacturer talk. There is no need for anti seize, maybe a little oil on the threads would be better. Just don't get oil on the electrode( not that it really matters)

The ones I have in my bike at the moment have been removed at least 10 times.

Well, the bulletin seems to agree with what you're saying. They say you don't need anti-seize on first installation because of the zinc (I think?) coating, which on removal will come off... Subsequent installations of the same plug would use anti-seize/oil, but don't torque to spec in that case.