Aluminum cylinder ?

azvintage · Aug 23, 2013

Picked up a '69 Commando awhile back and looking it over, noticed it has what appears to be an aftermarket cylinder of some sort.

Can anyone identify this cylinder manufacture ? I don't see any markings or logo on it.

Could be a big bore ?

Bike is rough but complete, good compression, has the bobber treatment of the '70's, 16" wheel, etc.

Thanks in advance ....

nortonspeed · Aug 23, 2013

Looks like a Dunstall 810cc cylinder.

L.A.B. · Aug 23, 2013

dunstall-cylinder-use-t13114.html

dunstall-810-cylinder-with-broken-lining-t16747.html

azvintage · Aug 23, 2013

Thanks for the quick response !

Dunstall 810, huh ? Are you sure ? Looks identical to the other pics you posted but mine doesn't say Dunstall on the base like yours.

Here's a pic of the bike

Here's another one of a '73 Moto Guzzi I restored

I'm going to part the bike out but I might want to keep the engine for my '72 Commando project.
First I have to get it running so I know if there are any engine issues.

Thing is, I have another fresh, never run Commando engine all gone through by Colorado Norton Works which was going to be used in the ' 72 but now I wonder if the 810 might be even better. The CNW engine is a 750 .040 " over ( 770cc ) with a Webcam, updated breather system, and other updates ( I have the full build sheet )

Maybe I can run the 810 cylinder on the CNW engine and have a real hot rod.

Rohan · Aug 23, 2013

azvintage said:
Picked up a '69 Commando awhile back and looking it over, noticed it has what appears to be an aftermarket cylinder of some sort.

.

Where this is getting murky is that '69' has an inboard tach drive, and points-in-the-timing-case-ignition.
Is this right for 69 ?

Interesting system of holding the cylinder down too - studs with no nuts ?!

comnoz · Aug 23, 2013

That doesn't look to me like a Dunstall barrel. There have been a few good aluminum barrels made for the Nortons over the years. The Dunstall barrel was not one of them. You may have a good one but until you have it off for some pictures it is hard to say for sure. Jim

bwolfie · Aug 23, 2013

That is a Dunstall barrel. I know because I have currently have and have sold a few in the past.
They use special nuts for the hold down as seen in the pictures.
Some of them are unmarked.

You could know for sure once you pull it off and see the lifters.

DogT · Aug 23, 2013

Rohan said:
Where this is getting murky is that '69' has an inboard tach drive, and points-in-the-timing-case-ignition.
Is this right for 69 ?

Yes, I have a 69 production date with points in the timing cover and tach drive off the spigot by the barrels. I think it was 69 when they went to 2M3S with the S model. But mine's registered as a 70.

RennieK · Aug 23, 2013

Here's an upside down shot of Dunstall barrels you can compare to:

These are the fasteners which match yours.

Some of the earlier Dunstall barrels didn't have the "Dunstall" embedded in the front base so you may have an earlier set. Some of the earlier barrels had square cut outs in the cylinder liners for rod clearance which was a problem as the liners cracked in the corners. The round cut outs you see in the top photo were to address that problem. The earlier barrels also had heli coils for the head bolts and not inserts which the latter versions had.

You should keep the CNW motor in tact as a nicely rebuilt motor and play around with this motor as you see fit.

Here are some front shots to help id your barrels:

azvintage · Aug 23, 2013

Thanks very much.

Yeah, I already decided it would be better to not mess with the CNW engine.

I'll get this one running tomorrow and we'll see what's up.

azvintage · Aug 24, 2013

It lives

No smoke at all and sounds strong w/no abnormal noises. Oil leak is from one of the lines coming from the remote filter.

I think I'd like to sell this engine as it is but It would be nice to know just what is inside it .

I guess there's really no way to know w/o tearing the top end off which I don't want to do.

Rohan · Aug 24, 2013

Have a look through the spark plug hole ?

At least you will see if its got pistons with big mountains on top (ie high compression lumps).

RennieK · Aug 24, 2013

Sounds good! Love those cadilac pipes! Were you able to discern if the barrels were Dunstall? I can't see those 2 lower fins in (the bottom center) in your photo. As was said there were a number of makers of these and they all had the same bolt pattern to work around so should look fairly similar in many ways.

BrianK · Aug 25, 2013

RennieK said:
Here's an upside down shot of Dunstall barrels you can compare to:

These are the fasteners which match yours.

Some of the earlier Dunstall barrels didn't have the "Dunstall" embedded in the front base so you may have an earlier set. Some of the earlier barrels had square cut outs in the cylinder liners for rod clearance which was a problem as the liners cracked in the corners. The round cut outs you see in the top photo were to address that problem. The earlier barrels also had heli coils for the head bolts and not inserts which the latter versions had.

You should keep the CNW motor in tact as a nicely rebuilt motor and play around with this motor as you see fit.

Here are some front shots to help id your barrels:

Now that's SERVICE!

I don't have any Dunstall parts but I still enjoyed that.

RennieK · Aug 26, 2013

LOL! One of the benifits of free web picture hosting services. We accumalate an archive of photos there and it only takes seconds to repost them when needed.

azvintage · Sep 1, 2013

Got the engine pulled and the head off to get a better look at the pistons.

Use the photo "IMG" link code (L.A.B.).

I believe it is indeed a Dunstall 810, bore measures 76.25 mm which equals 812 cc's or thereabouts. Looks like compression pistons - from what I have seen, stock compression pistons are flat top. Can anyone shed some light on this ?

Bores look real good, no scoring or noticeable wear. I don't plan on removing the cylinder - I'm just going to decarbonize everything, lap the valves, reassemble, and clean it up. The head is a RH6, which according to the Atlantic Green site, is from a '72 or '73 so I don't think it is the original engine.

RennieK · Sep 1, 2013

Yep, those look like stock Dunstall pistons. I don't recall the compression ratio off hand.

Can you post a photo of the head showing valves/combustion chamber?

azvintage · Sep 1, 2013

Here ya go

RennieK · Sep 1, 2013

Thanks, I was wondering if it had been Dunstallized but it appears to be stock.

Aluminum cylinder ?

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