I've just snapped 2 bolts, why ?

Glad I stopped at 16...... they felt good and solid but remember them and was holding my breath even at that.

Nerdy wrote:

Buxvan wrote: They just kept doing up & I was wondering when I was going to hear the click

Well, I suppose you did hear a click of sports.

Then I heard swearing , I'm sure it wasn't me though.

Just one small thing . I know it's wrong, but if a 10mm socket fits a nut or bolt, then I call it a 10 mm

By Buxvan: Just one small thing . I know it's wrong, but if a 10mm socket fits a nut or bolt, then I call it a 10 mm

Two broken bolts isn't exactly a small thing.
If you used a 10mm wrench, the bolt isn't 10mm, but smaller. You should get in the habit of knowing exactly what size the bolts are before tightening. and knowing the general torque values for the various sizes of fasteners is good too.

Then I heard swearing , I'm sure it wasn't me though.

Heard the same sort of thing in my shop. Must be poltergeists or something.

Nice Beeza! You might be branded a heretic for posting it here, though.

The bike in my avatar pic is actually a KZ400. It looks (slightly) like a mini Norton and it will never do 100mph, so I called it the 'No-ton'.

Nerdy wrote:

...................
Nice Beeza! You might be branded a heretic for posting it here, though.

Not by me. Ed

That is where you will make mistakes in calling a bolt the wrong size. The torque difference between for example a 8mm bolt and an 6mm bolt are disproportonately larger. It is the shank of the bolt and not the head size that determines the size of that bolt. If you go up further on Ed's chart you will see the size (6mm) for the cam cap bolts that have a torque setting of about 100 in/lbs......I cannot tell you how many times i have heard the poltergeist swearing in so many of our shops when we strip out or break those cam cap bolts. 100 in./lbs translates to only 8 ft/lbs. I do however agree with both Ness and Z1only in that bolts this thin should be done by feel
My .02

You are not the first one to snap these bolts and even here in a land of metrics I have snaped them, striped them, helicoiled them and now days I routinely change them when I take the top off.
Just this spring I swap the head gasket on the bike that I bought a year ago and use as my daily rider.
I was not surprised when I lifted the top and found that both bolt were shaped and only the threaded parts was left in the cylinder. Of course the threads was striped as well.
Lacking my helicoil kit, I put it back and is running the bike over the summer without them.
It's not worse now that it was before and I will do a complete rebuild this winter.
Yeah right, it dosnt leak oil a round the can chain tunnel much to my surprise

/A

I'll blame the Kawasaki manual then ! I only did the bolts up to what it said.
Anyway, ordered the bolts from my local Kawasaki dealer today for £6.28 for the pair. Collecting them Thursday & will NOT use the torque wrench again !!
Thanks for all your help.

Got my new bolts & kept well away from the torque wrench this time!
Worked out my valve clearances & did the shims got all back together & found I'd put one shim size up instead of down . My cockup, All apart again. Weather here is raining so I'm not bothered.

Here's an update on my engine.
Got everything back together again. Fired up the bike. After 40 seconds there's bloody oil appearing from the cylinder head again. There is a tiny hairline crack in the head.
I have a spare head which needs cleaning & the valves grinding in etc.
My dead head has only done 16,000 miles & the valves look great. I think I will swap them over with the spare head.
Problem is I took all the shims out & used some on the cracked head so will have to start from scratch with the valve clearance again.

Where is the crack?
Steve

Steve. you can't see any cracks & neither can I, but it just starts to appear . Put ore JB weld on but no good. It's also weeping from underneath ski think something must have happened to it in an earlier life!
Anyway, I'm getting quicker at stripping it down & putting back together again!!