[lucky phil]

Two bolts broke off inside of the head. Amazing. This. sucks.

Here's a tip. 12nm or 9FT/LBS is the torque for a grade 8.8 M6 bolt and you are correct, that is what the manual recommends. However in my experience none of these "specialised" bolts that are unique to a manufacturer such as the rocker cover bolts on the 650 engine are ever grade 8.8 material, more likely a grade 4.6 material which puts the torque at 4.1NM or 3 FT/LBS or 36 inch pounds.
So in my view the manual torque for these bolts is wrong.

Ciao

[drums4money]

Here's a tip. 12nm or 9FT/LBS is the torque for a grade 8.8 M6 bolt and you are correct, that is what the manual recommends. However in my experience none of these "specialised" bolts that are unique to a manufacturer such as the rocker cover bolts on the 650 engine are ever grade 8.8 material, more likely a grade 4.6 material which puts the torque at 4.1NM or 3 FT/LBS or 36 inch pounds.
So in my view the manual torque for these bolts is wrong.

Ciao

Maybe the tech editor omitted the decimal in the factory manual. . . 1.2Nm seems closer to the mark than 12. 

[6504me]

Here's a tip. 12nm or 9FT/LBS is the torque for a grade 8.8 M6 bolt and you are correct, that is what the manual recommends. However in my experience none of these "specialised" bolts that are unique to a manufacturer such as the rocker cover bolts on the 650 engine are ever grade 8.8 material, more likely a grade 4.6 material which puts the torque at 4.1NM or 3 FT/LBS or 36 inch pounds.
So in my view the manual torque for these bolts is wrong.

Ciao

Ornamental style bolts rarely approach even grade 4 as they are often cat and not rolled and threaded.

[alex12342]

Western cycle supply should have some in stock, saw them on his website a little while ago

[lucky phil]

Ornamental style bolts rarely approach even grade 4 as they are often cat and not rolled and threaded.

Won't argue with that.

Ciao

[clachcik]

Western cycle supply should have some in stock, saw them on his website a little while ago

I'll check it out. They are one time use bolts and this would've been the third time I took the head off to do valve adjustments. The place I bought it from is sending me the parts and I will rip her apart and remove the 3 bolts that are stuck in the head and just hand tighten this time. 9 ftlb seems a little over kill

[6504me]

I'll check it out. They are one time use bolts and this would've been the third time I took the head off to do valve adjustments. The place I bought it from is sending me the parts and I will rip her apart and remove the 3 bolts that are stuck in the head and just hand tighten this time. 9 ftlb seems a little over kill

Get all new bolts, all new seals, and a new cam cover gasket.

[lucky phil]

I'll check it out. They are one time use bolts and this would've been the third time I took the head off to do valve adjustments. The place I bought it from is sending me the parts and I will rip her apart and remove the 3 bolts that are stuck in the head and just hand tighten this time. 9 ftlb seems a little over kill

For the purposes of clarity and factual information do you have an official reference for this statement or is it an opinion? 

Ciao

[Starpeve]

For the purposes of clarity and factual information do you have an official reference for this statement or is it an opinion? 

Ciao

I don’t believe they are, from other readings on this forum

[zimmemr]

I'll check it out. They are one time use bolts and this would've been the third time I took the head off to do valve adjustments. The place I bought it from is sending me the parts and I will rip her apart and remove the 3 bolts that are stuck in the head and just hand tighten this time. 9 ftlb seems a little over kill

I don't believe they are. There is nothing to that effect in the shop manual, they aren't critical fasteners and if they were one time use they'd probably come n the same package as the VC cover gasket. 

[6504me]

Not single use but this type of shouldered bolt, seal, gasket for cam covers arrangement has been around for a very long time and works fine when new, soft gasket and seals are used then the bolts NEED NOT BE THAT TIGHT to seal.

When squashed and hardened gasket and seals are reused the odds of a broken bolt increase dramatically because you don't FEEL the soft seals and gasket seat (give?).

If I were the OP I'd get all new bolts, seals, and a new gasket then choke way up on the wrench when tightening.

[zimmemr]

Not single use but this type of shouldered bolt, seal, gasket for cam covers arrangement has been around for a very long time and works fine when new, soft gasket and seals are used then the bolts NEED NOT BE THAT TIGHT to seal.

When squashed and hardened gasket and seals are reused the odds of a broken bolt increase dramatically because you don't FEEL the soft seals and gasket seat (give?).

If I were the OP I'd get all new bolts, seals, and a new gasket then choke way up on the wrench when tightening.

+1

[Karl Fenn]

This does appear to be a common problem on the 650, use a left handed drill if that does not work try an extractor in the hole they should take that torque no problem, use a vacume cleaner hose to suck up any swarf whilst drilling, these are badly engineered and the wrong torque provided no more than 5 absolute max. If you have to drill and put helicoil inserts in that won't be good sounds if the internal threads are still OK.

[clachcik]

Thanks for the suggestions, I used a little bit of everything but I went at it for a few hours tonight with extractors drill bits and even dental picks. Finally got the 3 broken nuts out of the threads. From what it looks like, the threads are ok? But I tore up the area around the holes. It looks ugly but I made sure to cover the head very well and had a magnet picking up the broken bits and shavings.

[gizzo]

Really great work! Well done.  If you're worried about the ragged edges of the holes, you could knock it smooth with some wet and dry, use kerosene not water to lubricate the paper. But it most likely be fine without bothering.

Take it easy on the new bolts, huh?