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[Himself]

Great suggestion Bullet Whisperer. Something I'd not thought about at all. I must say when I was torquing the rocker nuts up to the recommended 9 ft lbs I was worried the threads were going to strip on the studs. Possibly my torque wrench is dodgy.

[Himself]

Further to my post of a few weeks ago, I can confirm the problem was caused by a tight rocker arm. Gwilly and Bullet Whisperer were spot-on with their comments. With the pushrod removed, I put the rocker box and arm back on the engine and tightened the four nuts to discover the rocker arm was very stiff indeed. I wonder if the previous owner experienced the same problem and slackened off the four nuts. I'm going to try to get rid of the stiffness so that the nuts can be torqued to the right level.

On a completely different subject, I was concerned the dog or lug on the alloy fork leg wasn't fitting in far enough to the slot on the front brake shoe plate. I filed quite a bit off the nut that holds the brake plate in position so that the dog or lug goes into the slot further. Alternatively, the inside of the botton of the fork leg and wheel clamp could have been filed but a new nut is a lot cheaper than a fork end if a muck-up is made.

[ChrisD]

Hi Himself.
You tension the rocker bolts to 9ft-lb? I know that’s what the book says but I stripped 3 doing that before this message board made it clear that 5ft-lb is all you need. And that’s what I’ve been doing for the past years successfully, with no rockers breaking free and escaping.

If the head gets too hot, the exhaust valve will stick, losing compression and maybe allowing the pushrod to escape from the rocker arm.

As an aside, I wanted to know what compression was made between two plates when I torqued a bolt joining them. I had googled that already and didn't believe the massive compression from even modest torquing,so I mounted a bathroom scale between two boards with a single bolt to compress the scale. I found that ~4ft-lb on that single bolt gave a compression in excess of 110kg on the scale. The rockers don’t need that much.
Cheers, ChrisD

[Exile]

Nie to get a feedback when a problem is solved. Thanks to Himself..

[Dennis C]

Yes as Exile says, thanks for the feedback always good to know when you are given good advice. ChrisD yes the amount of force comes as quite a surprise, also the finer the thread the greater the force will be.

[Himself]

Thanks ChrisD. I'll try torquing to 5ft lbs and see if the rocker arm is free. Incidentally, I see in Technical Notes - Decoke your Bullet 9 is recommended while 5 for Samrat alloy rockers, but 9 seems way too high for steel ones.

[papasmurf]

Just in case anyone is confusing Ft Lbs with Newton Meters:-

http://www.protoindustrial.com/en/suppo ... x?chart=18

[ChrisD]

Guys - whether the rockers are the OEM iron ones or Samrats, the torque affects the cylinder head into which the rocker studs screw. test the rockers clamped in a vice to see if they are really tight or just skew. The cylinder head is made of rather crap alloy and at 9ft-lb (~13Nm) torque the studs will eventually pull out. They will for sure pull out if you seize the rocker (usually the exhaust) because of overheating. If you plan on riding the bike at high revs (cruising at 4000 rpm), ensure the mixture and ignition timing are correct and that you have lots of heat dissipation. Think alloy barrel, metal-metal head joint, high capacity oil pumps etc.