Dominator 88

Glen writes: "My Mercury is an SS."
Is it a Mercury or an SS? Can't be both: they are two different models.
This is for dynodave: Perhaps Glen meant his Dominator is an SS.

Back from hospital stay...

Stephen Hill said:

Glen writes: "My Mercury is an SS."
Is it a Mercury or an SS? Can't be both: they are two different models.
This is for dynodave: Perhaps Glen meant his Dominator is an SS.

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Glen's explanation is believable . Factory offers for sale"Mercury" and no category for 650SS exists. Order "mercury" with request for "special build" same as 650SS sounds entirely reasonable. If the hardware is 650SS, I accept it. As a small barrel NHT, I accept it as a domi. SS on it's own is not describing anything in particular, it is an adjective attached to a noun, that describes an end item whole bike 88SS 99SS or 650SS as containing the engine also as SS upgrade.
YRMV lol

I totally believe Glen. I am in the middle of putting my 1970 Mercury in SS trim: Black and gray paint, twin carbs, and the "optional" tachometer.
I am having some fun here. But I will add that my bike will still be a Mercury when I am finished. In 650 SS trim.
Is it more of a 650SS if it was sold new as a Mercury, but left the factory in SS trim?
We may need a philosopher to answer this burning existential question.

Glenn/Steve
originally magneto or rear points on these late bikes? I doubt any other difference from earlier engines except carbs and later longer valves /shorter push rods

worntorn said:

My bike was ordered and built in 1969. By then Norton had replaced the 650SS model with the single carb Mercury.
Harry Firth at Firth Motors in Ontario felt he could sell the Dove Grey/Black/Chrome twin carb SS models but wasn't keen on the single carb plain Jane blue Mercury.
So he ordered 5 " Mercuries" but asked that they be built as 650 SS models. On the official Norton register these bikes show up as Mercuries, however they are identical in spec to the last run of 650ss bikes.

Glen

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And all this proves nothing without proper mesuerments you can put a long bolt through a Atlas Barrel just the same so you proved nothing

Not trying to prove anything, just relating how Harry Firth ordered the five bikes. Not sure what an Atlas or measuring things has to do with it?
It doesn't take much to make a Mercury into an SS, a carb and some paint. In order to keep a longtime dealer happy and clear out five bikes in a model they planned to eliminate asap, Norton obliged.
The bikes are all listed as Mercuries on the Norton register.
I have spoken with the original owner who purchased the bike new from Firth Motors. It was in SS form. Others have confirmed this to me as well. Just an interesting bit of Ontario Norton trivia.
But it's totally fine if you don't believe it!

Glen

worntorn said:

Not trying to prove anything, just relating how Harry Firth ordered the five bikes. Not sure what an Atlas or measuring things has to do with it?
It doesn't take much to make a Mercury into an SS, a carb and some paint. In order to keep a longtime dealer happy and clear out five bikes in a model they planned to eliminate asap, Norton obliged.
The bikes are all listed as Mercuries on the Norton register.
I have spoken with the original owner who purchased the bike new from Firth Motors. It was in SS form. Others have confirmed this to me as well. Just an interesting bit of Ontario Norton trivia.
But it's totally fine if you don't believe it!

Glen

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Glen,

I believe she's taking a swipe at the reality that the barrels are not moved rearward on the cases on 600 and 650cc motors, easily debunked by those of us currently residing in said reality.

Not sure why the response was to your statement, but reality must be confusing to those who only visit occasionally.

dynodave said:

Glenn/Steve
originally magneto or rear points on these late bikes? I doubt any other difference from earlier engines except carbs and later longer valves /shorter push rods

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There is Boyer ignition at the rear now, it must have had points originally. 30 mm Concentric carbs. Big carbs for a 650, but that is what Norton put on there when they made the change to Concentrics.

Glen

Well Guys I logged in again to give some feedback on the old Norton and saw quite a lot of discussion regarding crankcases! Apologies for not being able to contribute! So my last update was probably in October where I took the old bike for it's first proper ride after being allowed to after lockdown, and apart from a few small issues, it actually ran really well - no great ball of fire (but then I was also being sympathetic to a freshly rebuilt engine) but the handling is superb - I had reservations about the Honda NSR250 forks and yoke (the Honda yoke has quite a lot of offset so the wheelbase is a bit longer than standard) but it all seems to fit together quite well. However..........unfortunately, the head and barrel are off again. This time however I cant really blame anyone but myself. The first issue was with the head - I should have checked but I did not notice that the RHS plug hole thread was damaged when we had the head rebuilt and as luck would have it, the thread stripped when I removed the plug to check the condition of the electrode. The second issue was directly related to the head - when I came back from the long ride I noticed a fine mist of oil blowing out the joint where the barrel meets the crankcase - just above where the oil pipe union is on the crankcase. It had made its way to the rear tyre during the test, so understandably I couldn't leave it. What had happened here was again just my inexperience with Norton engines - the leak was from the small hole in the crankcase which I'm assuming feeds oil up through the barrel into the head, and ends in the RHS Inlet Valve pocket, under the valve spring seat. When I stripped the head, either the previous owner had got it wrong, or I didn't take notice, but one of the valve spring seats has a hole in it, which I am assuming should coincide with the hole in the head - I had mine on the RHS exhaust valve side. So my guess is that with the hole blocked (or severely restricted) there was too much pressure, which blew the side of the gasket away and resulted in the leak. I suppose I should be grateful that it blew to the outside and not to the inside, otherwise I would never have noticed the leak!

So question time - am I correct in assuming that the valve spring seat with the hole goes with the RHS Inlet valve above the hole in the head? What happens if the valve spring seat rotates and the holes no longer line up - or does this not happen? I must add here that the head is in having an insert so I'm talking from memory here when I say RHS inlet valve - it might be exhaust - please correct me if I am wrong.

What does that oil passage lubricate? if the rockers are lubricated by the line from the oil pump return, what purpose does that oil feed serve?

I'll keep an eye on the answers!

worntorn said:

My bike was ordered and built in 1969. By then Norton had replaced the 650SS model with the single carb Mercury.
Harry Firth at Firth Motors in Ontario felt he could sell the Dove Grey/Black/Chrome twin carb SS models but wasn't keen on the single carb plain Jane blue Mercury.
So he ordered 5 " Mercuries" but asked that they be built as 650 SS models. On the official Norton register these bikes show up as Mercuries, however they are identical in spec to the last run of 650ss bikes.

Glen

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This statement is interesting, it might explain the difference of opinion there is amongst the Norton aficionados. Are you reading this anna?

Andymann said:

What does that oil passage lubricate? if the rockers are lubricated by the line from the oil pump return, what purpose does that oil feed serve?

I'll keep an eye on the answers!

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It sounds like you are describing the oil return passage from the head to the crankcases. That drilling by the right side intake valve is the drain. It's not under pressure.

The "fine mist of oil blowing out the joint" sounds like a blown cylinder base gasket?

Peavey Jeltz said:

It sounds like you are describing the oil return passage from the head to the crankcases. That drilling by the right side intake valve is the drain. It's not under pressure.

The "fine mist of oil blowing out the joint" sounds like a blown cylinder base gasket?

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Yup it definitely blew the gasket out - you could see it clearly when I lifted the barrel. What I also failed to mention is that the gasket that came with the kit I ordered from the UK must have been for a different model because while it fitted perfectly, it had two holes punched in it, for what I now know must be drain holes - I'm assuming later models has two drain holes? Anyway, neither of the two on the gasket aligned with the one on my crankcase, so I carefully punched a third hole which I guessed would be ok. Unfortunately, I see now there was not enough meat left on the gasket where I punched the hole, and it blew there. We live and learn I guess.

Andymann said:

Yup it definitely blew the gasket out - you could see it clearly when I lifted the barrel. What I also failed to mention is that the gasket that came with the kit I ordered from the UK must have been for a different model because while it fitted perfectly, it had two holes punched in it, for what I now know must be drain holes - I'm assuming later models has two drain holes? Anyway, neither of the two on the gasket aligned with the one on my crankcase, so I carefully punched a third hole which I guessed would be ok. Unfortunately, I see now there was not enough meat left on the gasket where I punched the hole, and it blew there. We live and learn I guess.

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I suspect the two holes were there in case some mechanic put it on upside down !

norton bob said:

I have heard that a 650ss engine and a Mercury engine are different in many ways and many parts do not swap . Someone who tried to build one good engine from one of each.

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More rumor BS or just incomplete data?
It's actually true

1 early 650SS spigoted block/head later no spigot
2. early short valve stems/long push rods vs late long valves/short push rods
3. Later 06-0380 head casting
4 . early dual carbs VS later single manifold carb
5 high VS low pressure rocker shafts and narrow VS wide rockers
just a sample...

Certainly a "knows nothing" mechanic could be challenged. We see here all the time ....

Hi Dave , Do you have a Mercury engine then?.

norton bob said:

Hi Dave , Do you have a Mercury engine then?.

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No I don't own a mercury bike, I own 2 early 650 engines, but I do talk to a lot of folks on all topics especially where I have interest.
All NHT small bolt pattern heads and engines get a lot of my attention. The parts dealers have inventory of long stem valves 1.4" like in a late 18 engine variant used in the late 650 and mercury bikes. I don't have the SN cross over in front of me.
It's some time tough researching and then describing where a bike like atlas uses a 20 engine and a 88 bike uses a 122 engine but a 650SS, DL or mercury bikes all use a 650 engine.

Counter that with Commando bike uses 20M3, 20M3S, 200000, 300000, 325000+ engines. This is without even getting into body styles LOL

norton bob said:

Hi Dave , Do you have a Mercury engine then?.

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I've got a very low mileage Mercury motor, where it seems like the head gasket blew, the motor was removed and set aside. I don't have a complete original 650ss motor to compare, but I'd be happy to peer into the Mercury to try to answer any comparison questions.

t ingermanson said:

I've got a very low mileage Mercury motor, where it seems like the head gasket blew, the motor was removed and set aside. I don't have a complete original 650ss motor to compare, but I'd be happy to peer into the Mercury to try to answer any comparison questions.

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Just the head alone would answer 4 questions.
1-2-5 above possibly #3

dynodave said:

No I don't own a mercury bike, I own 2 early 650 engines, but I do talk to a lot of folks on all topics especially where I have interest.
All NHT small bolt pattern heads and engines get a lot of my attention. The parts dealers have inventory of long stem valves 1.4" like in a late 18 engine variant used in the late 650 and mercury bikes. I don't have the SN cross over in front of me.
It's some time tough researching and then describing where a bike like atlas uses a 20 engine and a 88 bike uses a 122 engine but a 650SS, DL or mercury bikes all use a 650 engine.

Counter that with Commando bike uses 20M3, 20M3S, 200000, 300000, 325000+ engines. This is without even getting into body styles LOL

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Yes LOL

And this is why despite the fact I have owned a Commando over 40 years and raced my Dommie for 15 years I generally do not comment in "what do I have threads".

Its a nightmare.

For example I tried to get a 500 SS head for years. Now I have two SS heads. But i certainly would not put my hand on heart and say they were original 500 SS's. They fit 500 barrels and have the full SS shape. That's all I know.

I had guys send me heads that they were honestly certain were SS but were not. Always take a 500 head gasket with you for a start.