Forum

[Rex Piekarczyk]

Do you guys really run these with the service manual spec of 0 clearance cold? I just had to get the valves and seats ground after only a few hundred miles since both valves were leaking badly even after the rockers were removed. I suspect the valves weren't closing completely. This is the upgraded head with Kibblewhite valves. Don't have hydraulic lifters in this one.

[Duke of Wybourne.]

Never had any bother whatsoever with factory settings, and my bike did get thrashed. I always did a compression check every oil change (1500 miles) and the occasional leak back check as well, so any issues would have shown up early.

[stinkwheel]

Zero clearance cold on the 350.

One ballhair on the exhaust and half a ballhair on the inlet cold on the 612.

That said, my 350 ran perfectly acceptably for about 6 months with the exhaust valve seat rattling loose in the head.

[Wheaters]

I use the recommended technique on my 350 Bullet, but I do make sure the pushrods spin quite freely. The engine is quiet and the tappets don’t seem to need adjusting at all. They certainly don’t close up, at least not since I had a new, hardened exhaust valve seat fitted. Before that the exhaust used to close right up and the bike lost compression completely after only 50-100 miles.

[Rex Piekarczyk]

"Close up" meaning the clearance would decrease?

[Wheaters]

Yes! The valve moves upwards into the cylinder head. In my case enough to keep the valve from seating properly causing loss of compression.

I got very good at resetting the clearances at the road side. Thankfully a new seat insert and Hitchcock’s stainless valve cured it completely and 10,000 miles later the clearance never varies.

[Rex Piekarczyk]

That may be what we're experiencing also. The seat and valve surfaces were a uniform dark brown on the contact surfaces.