[cyrusb]

The Neway cutters very accurately cut your 3 angles. You do it by hand with a T bar, so it happens under control. Google it, you'll see the system. The kit is around $350, so I do not personally own one. But I bring my heads to someone who does.There is also no lapping when your seats are done this way. That grey finish that grinding and lapping produce are microscopic pits that form the nuclei of the larger pits to come.

[Adrian II]

These:

http://www.newaymfg.com/parts/cutter-kits_motorcycle

A.

[cyrusb]

Holy cow! those are expensive! The sets I saw were on eBay and were $400 to $600 range. They also were not bike specific. My pals set can do air cooled vw's to Shovelheads. I believe it will fit the bullet also. But certainly not the multivalve engine valve sizes.

[ddavidv]

Not to be a contrarian, but hand lapping valves was common back in the day these engines were designed. Why can't one still do it today?

[Adrian II]

You still can, just that some modern methods claim to be better.

A.

[cyrusb]

Have you ever noticed that most engines almost never need valve jobs anymore? Most engines go to the junkyard with the original heads, and that is with a shitload of miles on them. This was not always the case. That is the difference between the old way and the new way(no pun intended). When you cut a valve seat as opposed to grinding you leave a polished surface that is  less likely to burn. But as mentioned lapping still works and is cost effective.

[ace.cafe]

All the top quality valve seat machines today use cutters, not grinding stones.
They have cutters with multiple angles for flow, besides the seat contact angle, and they are all cut at the same time with these cutters.

All the Fireballs and heads we have done had seats done with these types of multi-angle cutters.

[ddavidv]

I don't doubt cutting is superior. It just seemed like we were dismissing home grinding as something that shouldn't be done.

We don't do valve jobs anymore on modern vehicles for a myriad of reasons. Different fuel, better oil sealing and significantly better metallurgy--particularly compared to that on Iron Barrel Enfields.

[ace.cafe]

I don't doubt cutting is superior. It just seemed like we were dismissing home grinding as something that shouldn't be done.

We don't do valve jobs anymore on modern vehicles for a myriad of reasons. Different fuel, better oil sealing and significantly better metallurgy--particularly compared to that on Iron Barrel Enfields.

You can stilll use stones if desired.
Especially if you need to do stuff at home.
But, the state of the art for commercial valve jobs has moved on.

[axman88]

Have you ever noticed that most engines almost never need valve jobs anymore?

And what manufacturer puts periodic de-carbonization into their maintenance schedule, other than two strokes and Royal Enfields?

[cyrusb]

I don't doubt cutting is superior. It just seemed like we were dismissing home grinding as something that shouldn't be done.

We don't do valve jobs anymore on modern vehicles for a myriad of reasons. Different fuel, better oil sealing and significantly better metallurgy--particularly compared to that on Iron Barrel Enfields.

  Grind away if that is what you want to do. As mentioned earlier it works and is cost effective. But when it comes to burning valves, the fuel now has no lead (bad news for valves) , Stellite is still Stellite,and Stainless steel is still stainless steel. It's just a tip, you are free to do what you like. 

[Paul W]

I presume this was resolved? The fault sounds very similar to that on my 350. The fault with mine was a soft exhaust valve seat and a burned valve edge. The engine lost compression every 100 miles or so and to get any compression I had to loosen off the tappet adjuster.

I had a new seat fitted and rebuilt the engine with a stainless exhaust valve. I’ve done about 13,000 miles since and the problem hasn’t recurred.

[Bilgemaster]

I presume this was resolved? The fault sounds very similar to that on my 350. The fault with mine was a soft exhaust valve seat and a burned valve edge. The engine lost compression every 100 miles or so and to get any compression I had to loosen off the tappet adjuster.

I had a new seat fitted and rebuilt the engine with a stainless exhaust valve. I’ve done about 13,000 miles since and the problem hasn’t recurred.

I suspect my hunch about the decompressor valve just being gunked up and not seating properly may have been correct. But whether disassembling and cleaning the decompressor assembly (with a small handheld brass wire brush after its parts had marinated a few hours in SeaFoam) or my subsequent SeaFoam induction and steam treatment with a little handheld steam cleaner both shot into carb throat while fast idling actually cured the issue I cannot say for sure. But over a year on and with nearly 4,000 miles on the clock, that loss of compression has not recurred.

The spark plug also seems a bit cleaner whenever I pop it out every couple-few weeks for a quick dressing. So perhaps a combination of those techniques has put off a proper "decoking" for a bit

[Paul W]

It might also have been a sticky piston ring, your efforts to de-gunk the cylinder could well have freed it off by softening carbon deposits.

[AzCal Retred]

A "partial seizure" can give the same effect, a common two-stroke issue, wiping a bit of aluminum into the ring grove. Cooling down sometimes brings them back to life. The factory piston is a poor part.
I like the "flake 'o carbon on the exhaust valve" theory. If that's it, you should have no more issues after decarbonizing. If not, it's a pushrod motor & you have the head off anyway...   

"No problems that Cubic Dollars won't fix!!" - Some Ancient Wag -