Norton Villiers Commando 1968 Re commissioning an adventures at 30

More pictures on previous page of the exhausts ones which are the worst ones

Heres the inlets

Norton Villiers Commando 1968 Re commissioning an adventures at 30

Norton Villiers Commando 1968 Re commissioning an adventures at 30
 
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Valve seats only replacing if they’ve dropped out, or are no longer serviceable.

What makes them no loner serviceable is being worn and recut, and worn and recut, so much that the valve is now ‘recessed’ into the deeply cut valve seat.

The main problem with recessed valve seats is that the valve is still partially ‘masked’ when fully open, thus hindering performance.

IMHO, your valve seats are no where near that above description. I therefore believe they simply need re cutting properly, then lapping in with your new valves.

The main question mark over the head is whether or not the ports have been butchered. Although not a comprehensive test, measuring the ports will most likely be good enough for a stock, road use engine. So if the ports are still under 30mm, I would not worry if I were in your shoes, I’d fit new valves and guides and enjoy !
 
Thanks Eddie really appreciate the information learning all the time from you guys, whos everyone use for sticking new guides in be good to get some alternative prices, the other issue with the head was the lack of interference fit on the rockers they pretty much fell out by hand. Could always consider putting the end cap mod on I did with the 650ss actually got a brand new set.

I missed that nos head the other week on ebay was perfect for 300 quid removed from a new engine. So thats sort of my benchmark at the moment between replacing the head or getting the guides re done. That's good to know about the seats though Eddie give me options :) the worst damage is on the pictures on the previous page guys
 
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Fitting guides and cutting seats is a very common job so there should be an engine specialist near you who can do it. Just make sure they have the right cutter though as I’ve seen heads before with lots of the head cut away too!

If in doubt, send it to Norman or Mick.
 
I would go for guide liners over new guides, less chance of ending up with a scrap head from cracks in the guide bore but in your case the guides need changing. So use Norman or Mick who do know what they are doing.
 
I was wondering why the seats after seeing the first pics...... Don't like the snicked guides though. You've a lot of projects laying in that money basket. I'd pick one get it done and catch another in the line to keep my morale and motivation high.
 
kommando said:
I would go for guide liners over new guides, less chance of ending up with a scrap head from cracks in the guide bore but in your case the guides need changing. So use Norman or Mick who do know what they are doing.
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Are you sure liners will work given the butchered guides? One has a large chunk missing already and I imagine that opening them out for liners would do similar to the others.
 
Thanks guys just waiting to hear back about a head this week then I'll make a choice all the chassis is back together now going to fit the new wiring loom this week when the double ended connectors turn up an the spade ends.
Both the exhaust guides have quite big chunks out of them the two pictures looking from where the exhausts mount on the previous pages show it quite clearly.
Should be having the 16h running in March/April my main aim is to get the commando finished by the end of March once I've got the head done she should be mostly back together I am planning on getting a new oil pump I think.

Does anyone know which holes the loom runs through on the battery tray i can't remember for the life of me
 
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The guides obviously require changing so why not do it yourself? First turn or buy a stepped drift then make sure there is no hard carbon on the port side of the exhaust valves, which can score the bores as the guides come out. Next, heat the head to 360*F/180*C in the oven for twenty mins & drive out the guides. When they have cooled measure them & order a new set of the same dia. Fitting is done in the same way. You may not want to recut the seats yourself as the cutters are rather expensive, so take it to your local engine machine shop. Fitting guides is really quite easy, & I feel certain you will be happy when you have done it.

Martyn.
 
Fast Eddie said:
Are you sure liners will work given the butchered guides? One has a large chunk missing already and I imagine that opening them out for liners would do similar to the others.
Click to expand...
Re read my post and you will see

but in your case the guides need changing

I was referring to liners as the preferred option, but not in this case where it looks like the ends have been ground away during a porting job.
 
kommando said:
Re read my post and you will see

but in your case the guides need changing

I was referring to liners as the preferred option, but not in this case where it looks like the ends have been ground away during a porting job.
Click to expand...
Quite right. You did say that!
 
One quick question guys, someone pointed it out on one of the Facebook groups with the (edit) cylinder being skimmed at tdc it looks like the pistons are slighlty above the cylinder. They reckoned it would smack the pistons an id have to get a compression plate whats the correct method for working out what size i would need.
 
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750's (pistons) are like that, 850's not. (You might note the cylinder head is recessed around the combustion chamber)

I doubt you could plane the head surface enough to have a problem.
 
Quite normal on the 750. (There is still the thickness of the head gasket)
Looking at the previous pictures the head does not look planed but one 3/8" stud is not fully screwed in.

Edit.. That should have been, does Not look planed.

I can't see the cylinder head (RH1) being different from 1968 to 1971 so measured a spare one and the recess / counterbore was around 1/8" deep.
That would soon tell you if the gasket surface had been planed / fly cut reducing it.
 
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Thanks mate it was the cylinder barrel I had skimmed not the head made a typo ill double check that stud though we found the head gasket had been blowing when we took it apart. Am I right in saying its referred to as cylinder to piston deck height on a 4 stroke? :)

Its measuring up at about 0.039 -0.050" Above deck height at the moment gonna buy a new vernier tomorrow.
 
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You’ve measured the piston protrusion. Now measure the ‘step’ in head that TW referred to, and add the thickness of the head gasket to your calculation and add it all up (I usually assume .025” for a ‘crushed‘ composite gasket), let’s call this your ‘head step total’

Then subtract your measured piston protrusion from your ‘head step total’. What’s left is (roughly) your piston to head clearance.

I think you’ll find you have LOTS of clearance.

Remember the factory shaved 1mm off to get the Combats up to 10:1 compression ratio.

Pretty sure you’re gonna be fine.

Don’t need no stinkin’ decompression plate !
 
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