The Queen said off with her head!

I bought this MK III about 4 years ago with gearbox and wiring problems. It always smoked at start up on left side. If you started it and just backed it out of the garage, shut it off more than a minute or two, and restarted it really smoked! It didn't foul the plug so I put up with it until it started leaking around the push rod area. It misted the left side of the bike if run aggressive. Front center head stud was loose and the small studs were not sealed and one was into the push rod "tube". After disassembly I was surprised that it had a fresh bore .040 over. At this point I should mention that it is a RH 4 head that has been ported. It looks like the left intake seal was moving up and down with the valve. With all the rumors involved with these heads I'm thinking of replacing the left valve guides in case this is also where the oil is seeping from. The valve guide support in the head has been shortened from the porting. See pics, the first head is the ported RH4 and the second is a RH 10 for comparison. I hate to put a good RH 10 on an everyday rider. Trip to the machine shop tomorrow and ask his input and check things for cracks. And yes that is a crack in the barrel. Apparently dropped. I don't see that it will be a problem.

Even the smartest people make mistakes, and over-porting the cylinder head must be the most common. We all tend to copy what has been done to fast motorcycles without understanding how changes affect power characteristics. There are many ways of skinning a cat. You can build the biggest most powerful motor and still be slow because you cannot use it properly.

I see 32 mm for the rh4 and 30 mm for the rh 10? These are the factory sizes for the inlets on those heads.
Is the porting work on the rh4 farther in?

Glen

mean gene said:

I bought this MK III about 4 years ago with gearbox and wiring problems. It always smoked at start up on left side. If you started it and just backed it out of the garage, shut it off more than a minute or two, and restarted it really smoked! It didn't foul the plug so I put up with it until it started leaking around the push rod area. It misted the left side of the bike if run aggressive. Front center head stud was loose and the small studs were not sealed and one was into the push rod "tube". After disassembly I was surprised that it had a fresh bore .040 over. At this point I should mention that it is a RH 4 head that has been ported. It looks like the left intake seal was moving up and down with the valve. With all the rumors involved with these heads I'm thinking of replacing the left valve guides in case this is also where the oil is seeping from. The valve guide support in the head has been shortened from the porting. See pics, the first head is the ported RH4 and the second is a RH 10 for comparison. I hate to put a good RH 10 on an everyday rider. Trip to the machine shop tomorrow and ask his input and check things for cracks. And yes that is a crack in the barrel. Apparently dropped. I don't see that it will be a problem.


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Gene,
I don’t understand why you would not use an RH10 head for a daily rider.Please elaborate.
Thanks,Mike

Yes the guide is further exposed and the bowl is blended.
Went to my friendly machine shop and he verified the bronze guides are in spec. Everything is Kimble-White. What he didn't like was the pics of the cylinder bores. They are heavily glazzed from the oil getting by the intake valve seal and possible improper break in, not to mention I run stuff a little on the rich side. Suggest I pull the jug and hone them. I won't pull jug till I get another set of +.040 rings I thought this would be a two or three day job!

To me the RH 10 is a better head if you plan on doing any porting. RH 4 stories are that it is porous and thin I think in the valve spring seat area

Keep going: time for a Fullauto head...

There are lots of thing my wife will tolerate but not that kind of money for my hobby! A little at a time she "doesn't " notice!

This is turning into a "Project". Where do I stop.

mean gene said:

This is turning into a "Project". Where do I stop.

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Well it should keep you away from things like Guzzi gearboxes…

But it was just to be a head gasket change, one maybe two days! Oh well it is winter and if I get bored I'll just buy some "other" piece of junk to work on! LOL

mean gene said:

This is turning into a "Project". Where do I stop.

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You’re asking US !?!

mean gene said:

But it was just to be a head gasket change, one maybe two days! Oh well it is winter and if I get bored I'll just buy some "other" piece of junk to work on! LOL

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My friend Dan Stone called Nortons , " Really neat pieces of Junk ! " . Wahoo ! , Off to 10 Isabella St . in a few hours for the CVMG x-Mas party !

mean gene said:

This is turning into a "Project". Where do I stop.

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Good luck!

Richard Tool said:

Well it should keep you away from things like Guzzi gearboxes…

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Or Ducati bevels - what started as a simple repair of a bad thread is now a completely stripped motor on my bench. There's a _lot_ of shims in there....

Thank God I do not have the funds to own a Ducati bevel drive! Do own a 996 that's bad enough

My advice to any Norton owner is not to plan for a simple fix!!! Found a bad connecting rod on drive side. Thought about not removing the timing side and just removing the drive side engine case, but have been advised not to do it that way. Cleaned up the head, I blast with walnut shell, and see pic. I have a RH 4 head with poursity in the exhaust port side. SOOOO complete redo!!! Powder coat the frame, polish cases and Greg has agreed to rewire in April/May. My wife's honey do list just got torn up!

mean gene said:

My advice to any Norton owner is not to plan for a simple fix!!! Found a bad connecting rod on drive side. Thought about not removing the timing side and just removing the drive side engine case, but have been advised not to do it that way. Cleaned up the head, I blast with walnut shell, and see pic. I have a RH 4 head with poursity in the exhaust port side. SOOOO complete redo!!! Powder coat the frame, polish cases and Greg has agreed to rewire in April/May. My wife's honey do list just got torn up!


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Don't you mean that this will cause her to add to the honey do list like a wild woman to get you back?

mean gene said:

My advice to any Norton owner is not to plan for a simple fix!!! Found a bad connecting rod on drive side. Thought about not removing the timing side and just removing the drive side engine case, but have been advised not to do it that way. Cleaned up the head, I blast with walnut shell, and see pic. I have a RH 4 head with poursity in the exhaust port side. SOOOO complete redo!!! Powder coat the frame, polish cases and Greg has agreed to rewire in April/May. My wife's honey do list just got torn up!


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BTW, probably an illusion but that rod looks bent in the picture. If so, I wonder if that's what caused the small-end problem.

It almost seems to me that it is twisted!?!? I'll check it while in engine, then when it's out, Randy Long and I will figure what's wrong. Not worth doing but has anyone bushed the small end?