Barrel Off NH

[MikeHenstock]

Newbie question again. I have the head off my NH to change the gasket. The bike was running very rich so the cylinder head and valves are a sooty mess (see pic). I'm thinking of taking the barrel off to paint it as it's showing some rust and otherwise check all is well underneath. It also occurs to me that the oil purifier bung will be easier to access from the top. The handbook advises against taking the barrel off when de carbonising as you will loose compression once reassembled as, I think the piston rings will not be quite as snug. The question then is it worth doing, is the loss of compression likely to be that bad? Could I mitigate the potential problem by acquiring new piston rings?

[Bob.Murphy]

The oil sludge trap is easy to access with the barrel off, but I found I had to turn-down the diameter of a suitable six-point socket to get a decent fit on the hex.

With the barrel off - remove the piston rings and test the gaps (as a guide . . 0.005" per inch of bore diameter) and replace if worn (mine were at 0.064 ). I usually give the bore a light hone with one of those three-legged sprung hones on a drill (slowly) to de-glaze the bore. Don't aim to take anything off the diameter !

A careful methodical approach and all should be well. If you re-grind the valves as well the compression should be good .

Bob.

[MikeHenstock]

Many thanks!

[MikeHenstock]

Many thanks! All went well but just to check the bolt in the centre of the pic below is the sludge trap? I got a socket on it without adjusting buy its very tight and don't want to damage the flywheel. Is it a standard thread?

[MikeHenstock]

Pic attached

[MikeHenstock]

Socket I'm using is 3/16 WW which seems to fit...

[simon.holyfield]

Is it a six sided socket? If so, give it a go, that's the sludge trap. Pictures here:

http://ariel-square-four.blogspot.com/2 ... r.html?m=0

[chris.shearwood]

I got a socket on it without adjusting buy its very tight and don't want to damage the flywheel.

As with many bolts like that (old Volkswagen wheel bolts come to mind) a sharp blow on the head of it will loosen the threads enough to allow unscrewing.

[cmattina]

I have an impact screw driver in my tool box because so much of what I work on is rusty. I dont typically use it on my bikes, but would be perfect for this job.

They are cheap online and many tool stores sell them.

[will_curry]

If it comes to new rings in an old barrel some care is needed. A ridge develops
particularly at the top worn by the top ring. The new ring can hit that ridge and
break. At one time special rings were available as 'Ridge Dodgers' having a
lower outer top edge. I've used two base gaskets in the past when I've
been concerned about the amount of clearance. Bob's advice on honing the
bore is well worth following to as it really helps new rings bed in.