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8V spark plugs torque

Greyo

Greyo

Cruisin' Guzzisti
Joined
Jul 21, 2011
Messages
227
Location
Clemson, SC
Hello, I'd need a quick check on the spark plug torque value for the V8 engine; the Griso shop manual says 30Nm - Molikote. Does this sound right to you? (I assume "Molikote" stands for "put some anti-seize crap on the threads").

I'm asking because I've heard that info on Guzzi shop manuals is not always reliable.

Thanks much in advance for your reply.
 
30Nm doesn't sounds right to me either.

I removed and reinstalled the spark plugs of my G8V not less than 5 times. I torqued them to 12Nm, based on NGK’s recommendation and cross-reference with random bikes using the same size spark plug.

I coated the threads with nickel based antisieze every time I reinstall the spark plugs.

Phang

416uJQvrfdL._SL500_AA300_.jpg
 
Greyo said:
Hello, I'd need a quick check on the spark plug torque value for the V8 engine; the Griso shop manual says 30Nm - Molikote. Does this sound right to you? (I assume "Molikote" stands for "put on some anti-seize crap").

I'm asking because I've heard that info on Guzzi shop manuals is not always reliable.

Thanks much in advance for your reply.
Click to expand...

I think Guzzi wants to sell more heads. Excellent that you questioned what seemed to be a bad specification in the manual, because it is. Another reason to use wrench art instead of a torque wrench except where critical.
 
I'm no expert, but in most situations all you really need to do is feel that the compression (?) washer is mashed down and then just give a wee bit more, about an 1/8 to a 1/4 turn as I remember. As as long as there is no compression loss, It's tight enough.
Got to be gentle on this stuff.
 
[Edited version:]

The same plugs are used for the Griso 1200 and for the inside plugs on the Griso 1100. That is, the NGK PMR8b. The 1100 engine service manual specifies 13-15 Nm for those plugs. This suggests the 30 Nm spec in the Griso 1200 manual is wrong.

The spec for the larger NGK BPR6ES model used for the outside plugs on the Griso 1100 is 20-30 Nm; perhaps the manual for the 1200 copied the larger of those figures in error.

(Insert your favorite Luigi joke here.)
 
Plugs turnig loose?

Phang said:
...I torqued them to 12Nm, based on NGK’s recommendation and cross-reference with random bikes using the same size spark plug.
Click to expand...

So, I have been tightening the plugs on my Griso 8V at 12 Nm, but I have noticed that they tend to turn loose; after a few hundred miles I have to tight them again.

Is this happening to anybody else?
 
Mine doesn't back off at 12Nm, your torque wrench may need calibration :mrgreen:

As stated by moto, Guzzi suggested 13~15Nm for PMR8B, you might want to try 15Nm instead of 12Nm.

or the good old half a turn method.

Phang

sparkplugtorque.jpg
 
We recently had a case of a spark plug shearing off on a Stelvio. The bits were retrieved and sent to NGK (UK)
http://motoguzziclub.co.uk/forum/forum_posts.asp?TID=12011 (You have to be registered to see it).
Response was that it had been over torqued, they (NGK) recommend 8 - 10 Nm. plus 1/3 turn on a new plug, or 1/12 turn on an old one. Guzzi seem to recommend anything between 20 and 30Nm.
 
Brian UK said:
We recently had a case of a spark plug shearing off on a Stelvio. The bits were retrieved and sent to NGK (UK)
http://motoguzziclub.co.uk/forum/forum_posts.asp?TID=12011 (You have to be registered to see it).
Response was that it had been over torqued, they (NGK) recommend 8 - 10 Nm. plus 1/3 turn on a new plug, or 1/12 turn on an old one. Guzzi seem to recommend anything between 20 and 30Nm.
Click to expand...

I just experienced the same thing today. I should learn to trust myself better. When I did the initial service, I used the Stelvio Torque Guide which I got from the downloads section. The value it has for spark-plug torque is 30 Nm or about 22ft/lb. This seemed way high to me but I didn't listen to that little voice in the back of my head.

Well, why riding, my bike started kicking and running like crud. Got home, and tossed her on the lift. After some investigation, I decided to "sniff" around the motor, literally for a leak someplace. Upon getting my head down by the side-relief cut into the cylinder, I smelled both unburnt fuel and the nasty smell of burnt fuel/chemicals. Hmm.

Took off spark plug cover, and went to remove spark plug which came out in about 2 secs. What the Hell!!!

GuzziBrokenSparkPlug003_640x480.jpg


GuzziBrokenSparkPlug002_640x480.jpg


The threads were still in the head when I lifted out the plug with it's naked insulator! Luckily, I was able to use an extractor and a long thin socket bar to twist out the broken thread. Luckily nothing broke off and fell into the engine.

Of course, tomorrow is Sunday, and I have a snowball's chance in hell of finding this unique plug here in Northwest Ohio. lol.

Word to the wise, use NGK's torque specs sheet. The Guzzi torque sheet is WRONG WRONG WRONG at least in this case! Could have been disastrous!

476_695x900.jpg
 
Yup...2 ft-lbs way to high. Pulled my plug last week just to take a gander at things and also read the 22 ft-lbs. Started to torque it to 22 ft-lbs and I got lucky and listened to that little voice. Felt the plug get tight then loose again and stopped. Never got anywhere near 22 but may pull the plug today to inspect it based on your situation.

Anti seized it and put it back in at 12 NM based on a 10mm thread, or which turned out to be my usuall stand by...."sensible wrench tight"

No longer trust torque specs from the manual. I try to verify everything now if the engine is concerned.

Hope you find a plug today.
 
Been through that as well...
Busted a plug on my first try, even though it didn't seem right, I wasn't smart enough to listen to the logic.
Plenty of wrong specs wrong in the manual, I simply don't trust it.
Like the torque specs on the rear wheel lug nuts, lol. This ain't a Caterpillar!!

I just use BMW boxer specs from now on... B)
 
BMW calls for 60Nm or 44 lb-ft on a M10 bolt for the R1200RT. Guzzi's use M12 bolts, so I would use the R1100 series specification of 105 Nm or 77.5 lb-ft. as max setting. I personally torque rear wheels to 70 lb-ft so if necessary you have a chance to get it off on the side of the road with the tools (such as they are) in the tool kit.
 
john zibell said:
BMW calls for 60Nm or 44 lb-ft on a M10 bolt for the R1200RT. Guzzi's use M12 bolts, so I would use the R1100 series specification of 105 Nm or 77.5 lb-ft. as max setting. I personally torque rear wheels to 70 lb-ft so if necessary you have a chance to get it off on the side of the road with the tools (such as they are) in the tool kit.
Click to expand...
So, Guzzi's spec (110Nm) doesn't look that far off (in this case, at least). I've been torquing mine at 80 lb-ft with no issues so far (have sailed through 7 sets of tires already :S ).

I like your rationale for the 70 lb-ft: do you need to re-tighten the bolts every now and then?

Thanks John!
 
Greyo said:
Pascal said:
...I just use BMW boxer specs from now on...
Click to expand...
What are the rear wheel lug nuts specs for, say, a current R 1200 RT?
Click to expand...

Oops, forgot to mention the year Beemer I base myself on...
It's of my buddy's 04 1150 RT but I torque them at 65lbs so it's easier to undo on the side of the road if need to be, like John mentioned...
It's a good idea to check them periodically (front and back), or before a long ride...
 
Pascal said:
Greyo said:
Pascal said:
...I just use BMW boxer specs from now on...
Click to expand...
What are the rear wheel lug nuts specs for, say, a current R 1200 RT?
Click to expand...

Oops, forgot to mention the year Beemer I base myself on...
It's of my buddy's 04 1150 RT but I torque them at 65lbs so it's easier to undo on the side of the road if need to be, like John mentioned...
It's a good idea to check them periodically (front and back), or before a long ride...
Click to expand...

you guys are going to make me paranoid and make me start drilling and safey wiring :whistle: my guzzi like my race bike. that's a simple solution for the lugnuts.

Just remember to make sure the pull on the twist direction is tightening not loosening when you do the wrap.
 
Phang said:
30Nm doesn't sounds right to me either.
I torqued them to 12Nm, based on NGK’s recommendation and cross-reference with random bikes using the same size spark plug.

I coated the threads with nickel based antisieze every time I reinstall the spark plugs.
416uJQvrfdL._SL500_AA300_.jpg
Click to expand...
Is that a wet or dry torque spec? If dry, you're over-torqueing to attain the spec clamping. I do the same thread lube routine but snug it up by feel only.
 
Goodvibes said:
Is that a wet or dry torque spec? If dry, you're over-torqueing to attain the spec clamping. I do the same thread lube routine but snug it up by feel only.
Click to expand...

12Nm should be the dry torque spec.

Judging from the spark plug gasket state of compression, I am not too worried about it.

Torque wrench is not a must, the reason I use it because I have one in the tool box (three actually) :)
 
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