Brought the 73 750 home last night

Well did a little more negotiating to a price more comfortable given the condition - pics in an earlier post. All went well until I backed it off the pickup in the dark, alone and it tipped over and broke the left lever mount, not the lever itself, but the adjustment nob and mounting point for the mirror. I was in a hurry as the Giants were about to take the field. If anyone has a used replacement part please let me know. Anyhow at lunch today went home and got out some fine steel wool and wax and was pleasantly surprised how well the rusted chrome bits cleaned up - not as bad as I thought. The weekend will tell much more. Unfortunately the PO lost the ignition key, but I see replacement key and lock are available - can you jump the switch in advance of getting a new one - since I'm impatient? Also needs a battery - what do you guys suggest?
Lastly, I mentioned previously has a single Amal - 932 - is this likely 1 of the originals? I want to go back to dual so need the correct manifolds, but have learned there are 30/32 sizes, but I don't know what I would need? Any ideas here?
Thanks

My local locksmith tells me he can probably make a key for about 25 bucks if I take the ignition in to him. Might be worth checking around assuming the original is in fine shape.

Russ

hockeylife said:

can you jump the switch in advance of getting a new one

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Connecting the Ign.Sw. White and Brown/Blue wires together will (hopefully) give you "ignition". And adding the Brown/Green and Blue wires to the Brown/Blue and White should give you "ignition and lights".

hockeylife said:

I mentioned previously has a single Amal - 932 - is this likely 1 of the originals?

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Possibly, and the build number stamped next to the "932" on the small raised pad at the R/H side of the carb would verify if it is the original 932 (L or R) carb number or not?

[Edit]The '73 parts book lists the 32mm carbs as "L18" and "R19" (however R19 and L20 appear to be the correct numbers, but for 1972). For 1973, 932/R26 and L27 seem to be correct.

L.A.B. said:

hockeylife said:

can you jump the switch in advance of getting a new one

Click to expand...

Connecting the Ign.Sw. White and Brown/Blue wires together will (hopefully) give you "ignition". And adding the Brown/Green and Blue wires to the Brown/Blue and White should give you "ignition and lights".

hockeylife said:

I mentioned previously has a single Amal - 932 - is this likely 1 of the originals?

Click to expand...

Possibly, and the build number stamped next to the "932" on the small raised pad at the R/H side of the carb would verify if it is the original 932 (L or R) carb number or not?

[Edit]The '73 parts book lists the 32mm carbs as "L18" and "R19" (however R19 and L20 appear to be the correct numbers, but for 1972). For 1973, 932/R26 and L27 seem to be correct.

Click to expand...

Well the carb reads L 932 - underneath this there is the number 27. The number 932 is cast, whereas the L and 27 appear to be punched, not cast. In trying to be original, is it likely this is one of the the carbs, so I should just find a R 932 or do I need 2 930's? And what does this all mean for tracking down the correct manifolds?
Though I've read as much as possible it's still unclear, to me anyway, what should be there for my NOV 1972 750.
Thanks again!

The safest thing would be to measure your intake ports and match those with manifolds and carbs. of the same size. The standard was 930 (for 30mm intakes) but the combat head for 1972 had 32mm ports and carbs. The combat head has a "C" stamped on the top front center just under the top motor mount.

Why are you watching baseball, this is hockey season!

hockeylife said:

Well the carb reads L 932 - underneath this there is the number 27. The number 932 is cast, whereas the L and 27 appear to be punched, not cast. In trying to be original, is it likely this is one of the the carbs,

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As it's "NOV 1972" then L932 27 (and R 26) may still be correct.

hockeylife said:

so I should just find a R 932 or do I need 2 930's?

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Measure the intake ports and/or look for an "RH" number stamped on the cylinder head?

A 30mm carb head has 28.5mm diameter inlet ports.

"RH6" or "RH5" heads take 32mm carbs.

hockeylife said:

And what does this all mean for tracking down the correct manifolds?

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30mm carb manifolds - 062819 (30mm-28.5mm)
32mm carb manifolds - 062711

RennieK said:

The standard was 930 (for 30mm intakes) but the combat head for 1972 had 32mm ports and carbs. The combat head has a "C" stamped on the top front center just under the top motor mount.

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But by late 1972 "30mm" heads/carbs can no longer be regarded as "standard" only standard 30mm.

The Sept 1972 N3/23 service release which covers the introduction of the 32mm RH5 and RH6 cylinder heads lists them as "Standard Commando 1972/3 (32mm)".

L.A.B. said:

[

RennieK said:

The standard was 930 (for 30mm intakes) but the combat head for 1972 had 32mm ports and carbs. The combat head has a "C" stamped on the top front center just under the top motor mount.

Click to expand...

But by late 1972 "30mm" heads/carbs can no longer be regarded as "standard" only standard 30mm.

The Sept 1972 N3/23 service release which covers the introduction of the 32mm RH5 and RH6 cylinder heads lists them as "Standard Commando 1972/3 (32mm)".

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Thanks for pointing that out. I was remembering back when I bought my 72 in around june and had those 2 choices. And I guess there's no telling what is actually on the bike now until it's verified.

RennieK said:

Why are you watching baseball, this is hockey season!

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isn't that something they play in that big pink area on my map thats above the USA ?

If there's a letters and numbers character string engraved on the lock, someone in the UK could get you a replacement key ready cut using that character string. I think they were either two letters and three numbers or three of each. At our gas station in Leyland, we had a big rack of pre-cut keys. I think the engravings were discontinued in the early 70s because it was too easy for thieves to get a key for any vehicle they wanted to steal.

Just got in from the garage to watch the Giants, Sabres fan in hockey but that must wait. While out cleaned everything, took the tank off, removed the 3 bolts from the head steady and just at the very edge read "RH6". Does this mean the 932/27 is likely original and I need to hunt down a 932/26? This also confirms the manifolds or should I still pull the carb/manifold and measure the ports?
Thanks for all the help, but in general is this a typical configuration for a 73? Does this make for a more powerful engine?

hockeylife said:

took the tank off, removed the 3 bolts from the head steady and just at the very edge read "RH6". Does this mean the 932/27 is likely original and I need to hunt down a 932/26?

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I think you can safely assume that the 932/27 carb is one of the originals. (as the '73 parts book info appears to be wrong)

The /** "build" number generally refers to a particular combination of jet sizes, needle type, and throttle slide number, so a "/26" carb could be built up from practically any R/H body 932 carb [Edit: although it will be necessary to remove some metal from the inner "blank" throttle stop boss, if it's not an original Commando carb body] so you don't have to hunt down a 932/26. And you really need to check the specification of your 932/27, as changes to the jetting or slide could have been made for "single carb" use?

hockeylife said:

This also confirms the manifolds or should I still pull the carb/manifold and measure the ports?

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Your decision I think, it's always a good idea to double-check, but an RH6 head should be "32mm"

hockeylife said:

but in general is this a typical configuration for a 73?

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Yes.

hockeylife said:

Does this make for a more powerful engine?

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If you are comparing it to the 30mm carb/head, then the the 32mm carb/RH6 setup probably gives a little more power at the top end.

You could also add a 2s camshaft. The 72 combat commando had the 932 (32mm) intakes/carbs and the hotter 2s cam as well as a planed head that lowered compression to 10:1. I think the inner valve springs were a little stronger too. This would bring it closer to the combat spec which was a bit of a hot rod.

RennieK said:

You could also add a 2s camshaft. The 72 combat commando had the 932 (32mm) intakes/carbs and the hotter 2s cam as well as a planed head that lowered compression to 10:1. I think the inner valve springs were a little stronger too. This would bring it closer to the combat spec which was a bit of a hot rod.

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I believe the double S combat camshaft was replaced with the original Commando camshaft from the 1973 model year for both 750 and 850. I've owned both '72 and '73 750s and know the '72 combat has more top end performance than the '73.

If you need a key made just take the tumbler out of the housing by depressing the little button in the hole on the side. Then if your old time bike shop has a key maker they can cut you one by dialing up the three numbers on the tumbler and punching out the key. Or any competent locksmith can reset the tumblers on yours and make a new key from there.
I have a shop near me that can make them if you have trouble finding someone.


Tim_S