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750 Commando Valve Clearance Specs #560042
08/25/14 7:38 am
08/25/14 7:38 am
Joined: Aug 2013
Posts: 84
Iowa, USA
1
1958superrocket Offline OP
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1958superrocket  Offline OP
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Joined: Aug 2013
Posts: 84
Iowa, USA
Have a 73 750 Commando and am going to check valve clearance this week. Is there a difference ins settings between the standard 750 and the 750 Combat head? I have a Haynes manual that says the Combat settings are different? What exactly should the spec be for both set ups? Thanks for the insight. Also, where can I find a reliable place to find std. jetting specs?

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Re: 750 Commando Valve Clearance Specs [Re: 1958superrocket] #560052
08/25/14 8:36 am
08/25/14 8:36 am
Joined: Mar 2006
Posts: 3,655
Norfolk, UK
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Posts: 3,655
Norfolk, UK
Originally Posted By: 1958superrocket
Have a 73 750 Commando and am going to check valve clearance this week. Is there a difference ins settings between the standard 750 and the 750 Combat head? I have a Haynes manual that says the Combat settings are different? What exactly should the spec be for both set ups?


If
it is a true 1973 model (and not a later '72 titled as a '73) then it shouldn't be a Combat, as Combat production officially ended during 1972 at serial 211110.
A '73 model 750 cylinder head usually has 'RH5' (std. comp.) or 'RH6' (high comp. but not as high as a Combat) stamped above the RH exhaust rocker inspection cover, if so, then it isn't a Combat head, Combat heads usually have a 'C' stamp in the area beneath the head steady bracket, however the extra valve clearance is to suit the Combat 2S camshaft, and again, is something a '73 model wouldn't normally be expected to have as standard.

However, valve clearances are .006"In/.008"Ex for all standard models, and .008"In/.010"Ex for the Combat model.

http://www.classicbike.biz/Norton/Repair/70up_Commando/70upCommando.pdf


Originally Posted By: 1958superrocket
Also, where can I find a reliable place to find std. jetting specs?


If you can give the carb build number (R/L 93? ??) that you should find on the raised pad of each carb, then I will probably be able to give you the original specification, as the manual data is incomplete regarding the '73 specs.

Re: 750 Commando Valve Clearance Specs [Re: 1958superrocket] #560071
08/25/14 10:47 am
08/25/14 10:47 am
Joined: Aug 2013
Posts: 84
Iowa, USA
1
1958superrocket Offline OP
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1958superrocket  Offline OP
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Joined: Aug 2013
Posts: 84
Iowa, USA
VIN # 210783
Motor Number 210783 Must be a 72 titled as a 73? Nothing stamped on the inspection covers. Previous owner days "C" stamped on head below stay.

Carbs are brand new 932's

Thanks for the help.

Tim

Re: 750 Commando Valve Clearance Specs [Re: 1958superrocket] #560079
08/25/14 11:09 am
08/25/14 11:09 am
Joined: Mar 2006
Posts: 3,655
Norfolk, UK
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Norfolk, UK
Originally Posted By: 1958superrocket
VIN # 210783
Motor Number 210783 Must be a 72 titled as a 73?


Yes, it's a '72 and likely to have been a Combat model originally.
The month/year date of manufacture would normally be stamped on the frame certification plate attached to the headstock (assuming the plate is still there?).

Re: 750 Commando Valve Clearance Specs [Re: 1958superrocket] #561165
09/01/14 4:43 am
09/01/14 4:43 am
Joined: Nov 2011
Posts: 257
terra Australis
P
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terra Australis
A Combat Cam is crankey , works well wound up - and pulls harder after 3 or 4 thou .Its a Early P.R. Cam .

The STANDARD Cam pulls pretty much from 1000 revs ands not too finicky on throttle position at
lower revs , so you can tell ' from the saddle ' , if it is either .

others run .012 & the 3S runs .016 both .

Ex C.V. carb types should note theyre not C.V. carbs , & being coarse on the throttle isn't the
best way to go . Going W. f. O. at low revs can hammer the rings n things .

Continually maintaining the Ign. and clearances sees em and their best & ensures reliability .


Moderated by  Dave Comeau 


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