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+--- Thread: Tightening the spark plugs (/showthread.php?tid=73020)
Tightening the spark plugs - Freza - 25-06-15
Recently I changed the spark plugs.
Upon installation, I tightened them fairly by hand, but not too much.
After riding a bike for few days, I went to check them and found out they were loose. By loose I mean they could be unscrewed easily.
I suppose it happened because I tightened them while they were cold, then they expanded during riding, then shrunk again after cooling.
My question is, should I re-tighten them now, while they're cold? Will they cause problems once they start expanding again?
Re: Tightening the spark plugs - bandit - 25-06-15
Tighten them when cold.
Re: Tightening the spark plugs - BBROWN1664 - 25-06-15
finger tight then 1/4 turn is the way I was always taught with spark plugs.
Should always be cold too.
Re: Tightening the spark plugs - Nightfury - 25-06-15
(25-06-15, 01:26 PM)BBROWN1664 link Wrote: finger tight then 1/4 turn+1.
1/4 to 1/2 a turn after finger tight. And always when cold.
Re: Tightening the spark plugs - Freza - 25-06-15
I tightened them while cold, but they got loose after the first ride. I'll re-tighten them.
Re: Tightening the spark plugs - Freck - 25-06-15
Why not get it right, torque them up to the correct torque listed on the plug manufacturers website, or look in the Haynes manual which is in the Downloads section on here if you don't have one.
As an engineer I'm amazed at how many Heath Robinson bodges and ideas people come up with when the right information is readily available! :rolleyes
Re: Tightening the spark plugs - sinto607276 - 26-06-15
(25-06-15, 11:30 PM)Freck link Wrote: I'm amazed at how many Heath Robinson bodges and ideas people come up with when the right information is readily available! :rolleyes:agree
I'm not an engineer though
Brilliant idea for a thread though :think
Re: Tightening the spark plugs - Nightfury - 26-06-15
On the box there is normally a little diagram that shows either a 1/4 or a 1/2 turn.
I am an engineer, and I have spent years trying to find another engineer with the name Heath Robinson. All the childish comments that could be made!
Re: Tightening the spark plugs - BBROWN1664 - 26-06-15
Quote:torque them up to the correct torque listed on the plug manufacturers website
The only spark plugs I have ever used a torque wrench on were fitted to aircraft engines and were even lock wired into place after torqueing up.
On cars and bikes, especially where access is awkward, finger tight then 1/4-1/2 a turn has always worked and is what it says on most plug boxes.
Re: Tightening the spark plugs - Jules-C - 26-06-15
The 1/4 or 1/2 turn only applies to new plugs when the crush washer has to be compressed. It you try 1/2 turn the next time you risk stripping the thread in the cylinder head.
Torque wrench or calibrated hands that know when to stop before something breaks are the tools to use
Re: Tightening the spark plugs - Neon Knight - 26-06-15
Maybe the threads are already buggered and thats why they keep coming loose again ? Just a thought.
Re: Tightening the spark plugs - Freza - 26-06-15
Nope, they're fine
Re: Tightening the spark plugs - Freck - 26-06-15
(26-06-15, 10:04 AM)BBROWN1664 link Wrote:Quote:torque them up to the correct torque listed on the plug manufacturers website
The only spark plugs I have ever used a torque wrench on were fitted to aircraft engines
I take it you've never read your bikes owners manual then, that specifies the tightening torque for your spark plugs too......RTFM :lol
Re: Tightening the spark plugs - BBROWN1664 - 27-06-15
Freck, I know what the manual says but having worked on many vehicles, I have never used a torque wench on a motorbike or car as experience tells you when things are about right for spark plugs. (That and I cant get my 1/2" torque wrench in the gap under the tank on most motorbikes)