Sprint 1050 ST valve cover bolts over-tightened

SteveSmith · Nitrous Nuisance Joined: 08 Nov 2012 Karma :

Hi, I checked my valve clearances last night but when I put the valve cover back on I trusted my torque wrench too much and over-tightened them (my head was saying "that feels like more than 14Nm", but no click so I kept going). I'm now left with one sheared off in the cylinder head, and one with a partially stripped thread.

The cover feels like it's on firmly, and the seal looks OK, but I assume there are six bolts in there for a reason, and now only four of them are doing anything. The two dodgy ones are in opposite corners.

How big a problem do I have?

Thanks,

Steve.

Meatybeaty · World Chat Champion Joined: 10 Apr 2016 Karma :

Possibly the least you will get is an oil leak, did you put on a new gasket and have you got a service manual Thumbs Up

SteveSmith · Nitrous Nuisance Joined: 08 Nov 2012 Karma :

Pete. · Super Spammer Joined: 22 Aug 2006 Karma :

14 mm is just 10 foot pounds which you can achieve with a normal spanner and 2 fingers. The snapped fastener should come out easily enough, the torn threads will need an insert.
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132.9mph off and walked away. Gear is good, gear is good, gear is very very good Very Happy

SteveSmith · Nitrous Nuisance Joined: 08 Nov 2012 Karma :

Meatybeaty · World Chat Champion Joined: 10 Apr 2016 Karma :

Hi Steve , you could try putting sealer around where the bolts are missing and see if the other bolts will hold the cover down and seal the cover, but that's only a bodge fix, the broken bolts really need extracting to make a good job , and the torque should have been 10nm not 14nm, but really like Pete says a good nip up with the spanner is a better feel Thumbs Up