CARBURETORS HOCHPOCH SOUP

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searunner

searunner

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on my 850 Mk2 early 1974-recently acquired for restoration, I have find one carb L 930 31 and one R 930 20
Inlet manifold are also different - but with internal same diameter 31mm (30.70)
engine start at the second kit and run and take easy rpm ( on stand only. haven't put it on the road )
Is evident that time and PO have operated on it-
suggestions to return to the origin or one acceptable status ???
https://picasaweb.google.com/lh/photo/z ... directlink
https://picasaweb.google.com/lh/photo/B ... directlink
https://picasaweb.google.com/1127708198 ... directlink
 
Dang it I got useful things to do w/o putting myself in your shoes, ugh. First thing that popped to my mind is whether to continue to be as cleaver expedient as the DPO or just throw money at two new carb.
 
searunner said:
on my 850 Mk2 early 1974-recently acquired for restoration, I have find one carb L 930 31 and one R 930 20
Inlet manifold are also different - but with internal same diameter 31mm (30.70)
engine start at the second kit and run and take easy rpm ( on stand only. haven't put it on the road )
Is evident that time and PO have operated on it-
suggestions to return to the origin or one acceptable status ???
https://picasaweb.google.com/lh/photo/z ... directlink
https://picasaweb.google.com/lh/photo/B ... directlink
https://picasaweb.google.com/1127708198 ... directlink
Click to expand...
whatever you do with this bike do not ride it until you have put a proper head steady on it! or it may spit you off! get a dave taylor one or the original box type one regards baz
 
OMG! Baz i missed that vital detail and you may have saved tossing another Commando. Radius rod is best but by golly anything is life saving compared to no steady which seem just fine until slight crossing double yellow or a bit extra road lumps or some wind gusts by a semi etc, >>> HINGE CITY Morgue. Best wishes on filling up your money hole faster than leaks down.
 
searunner said:
R 930 20
Click to expand...

Are you sure it is R930 20 as 930 20 would appear to be a left hand (L) carb.

Do the jets, throttle cutaways etc. all match?
 
A few things in the pics look out of place, the pic with the carbie sitting on the primary looks wrong, it has a paper gasket on the motor side of the manifold and the insulated gasket is on the carbie side of the manifold, as for the carbies I throught the 850s came with 932s also it does have a head steady but not the nomal one it looks like a homemade one and only using one bolt to fix to the head, don't know what the idea is about that, maybe have a better look at the pics and we might find a few other things out of place.

But looks like a good project bike to pull apart and get everything right before you ride it.

Good luck

Ashley
 
whatever you do with this bike do not ride it until you have put a proper head steady on it! or it may spit you off! get a dave taylor one or the original box type one regards baz[/quote]

Its funny. I saw that photo some months ago and advised the same thing. has the bike changed hands?
Dereck
 
Tanks to all,
oldest Head steady was removed --and NEW one is arrived just today (photo follow ASAP)
so the permanence in hospital will be saved !
Also spare parts to rebuild the old Air Filter are arrived-- but I wait to solve the CARBS problem before
My intention is buy two NEW from AMAL, 932/35-36 (regular on 850 MkII 74) or in alternative 932/42-43 following the last mounted on 850Mk III 75
what is the better choice??

For the inlet, I have the intention, temporary, to stay with the olds-- and look around (ebay??)to find the right two- wait it out
 
searunner said:
My intention is buy two NEW from AMAL, 932/35-36 (regular on 850 MkII 74) or in alternative 932/42-43 following the last mounted on 850Mk III 75
what is the better choice??
Click to expand...

932/35 & 36 should come with 260 main jets to suit your MkII with its peashooter exhaust system and perforated metal airbox, whereas MkIII carbs are likely to have 220-230 main jets. It would appear from previous discussions that Burlen (Amal) only machines the necessary inner flats for clearance on the MkIII carb bodies. Why they do this only on the MkIII carbs I don't know (unless they have since changed their policy) as all twin Amals fitted to Commandos require this.

searunner said:
For the inlet, I have the intention, temporary, to stay with the olds-- and look around (ebay??)to find the right two- wait it out
Click to expand...

To suit the 932 carbs and the 'RH10' (your photo 43) 30mm inlet cylinder head, ideally, you need a pair of tapered (32mm at carb - 30mm at head) 06-5196 inlet manifolds, but note there are also inlet manifolds made in the same style which are 32mm - 32mm (06-2711).
 
searunner said:
on my 850 Mk2 early 1974-recently acquired for restoration, I have find one carb L 930 31 and one R 930 20
Inlet manifold are also different - but with internal same diameter 31mm (30.70)
engine start at the second kit and run and take easy rpm ( on stand only. haven't put it on the road )
Is evident that time and PO have operated on it-
suggestions to return to the origin or one acceptable status ???
https://picasaweb.google.com/lh/photo/z ... directlink
https://picasaweb.google.com/lh/photo/B ... directlink
https://picasaweb.google.com/1127708198 ... directlink
Click to expand...

Looking at the slide in pic2 the evidence of wear is apparent even from that distance... Save yourself grief and time and melt them down and make clutch levers... Two new carbs is the only way to go. Plenty around this site for sale... Make real sure you two manifolds are a pair and have not been "customised" by inexperienced persons...
 
I am ready to solve the carbs problem with my credit card on hands-
inlet manifolds probably L.A.B. reply are right, my RH10 head require the 32-30 manifolds -
and sure I must invert the gaskets with paper gaskets near the carbs and the insulated near the head

This Forum help me a lot - good suggestion with good humor sentences, give a boost to continue in my efforts -Thanks

Yesterday I have reassembled the new (original) Head Steady
https://picasaweb.google.com/lh/photo/K ... directlink
I have assembled it with only one stud,(the second stay in my box)- the purpose is increase the effect size in the vertical movement and limit the amplitude of the horizontal
any opinion ??
 
searunner said:
I am ready to solve the carbs problem with my credit card on hands-
inlet manifolds probably L.A.B. reply are right, my RH10 head require the 32-30 manifolds -
and sure I must invert the gaskets with paper gaskets near the carbs and the insulated near the head

This Forum help me a lot - good suggestion with good humor sentences, give a boost to continue in my efforts -Thanks

Yesterday I have reassembled the new (original) Head Steady
https://picasaweb.google.com/lh/photo/K ... directlink
I have assembled it with only one stud,(the second stay in my box)- the purpose is increase the effect size in the vertical movement and limit the amplitude of the horizontal
any opinion ??
Click to expand...

I would put both studs in, you're allowing movement where it is not desigend to be, so things will wear.

Regarding your manifolds, LAB is of course correct, you should have tapered manifolds 32-30mm. However, if you search on here you'll find many commenting that this is not necessary. Some say a 32-30mm step is better as it creates turbulence in the port. Even Mr Comstock (resident gas flow guru on this site) says a 32-32 manifold fitted to a 30mm port works best simply by radiusing the edge of the port slightly, and that this flows better than a tapered manifold. This radius can be done by hand, in situ. If you have 32-32 manifolds, it may be worth trying them out first.

More food for thought!
 
Just to test, without-and with the second stud
I have read a lot on this site about the Head movement and learned that vertical movement 5/8 mm must be free (I have added two washers
inside the side plates)
and all horizontal movement of the Head must be damped -this is typical scissors movement
Considering that is easy to add the second stud after
 
searunner said:
Just to test, without-and with the second stud
I have read a lot on this site about the Head movement and learned that vertical movement 5/8 mm must be free (I have added two washers
inside the side plates)
and all horizontal movement of the Head must be damped -this is typical scissors movement
Considering that is easy to add the second stud after
Click to expand...

Plenty of owners around here have tried to "reinvent the wheel". But unless your going to use a recommended after market Head Steady to replace the original i would strongly recommend that you bolt up that original H/S as per factory....

IMO, the factory H/S was a piss poor design from day1. But to even reduce its original capabilities as you have done is going in the wrong direction..
Experiment if you want cos thats what we do...
I think that the bolt removal that you have done may well increase the "port/starboard" movements, which is the movement that is the most undesirable to have..... Please do a bit more research via the top right hand corner of this/home page when you got a cuppla days to read up on H/S's...
 
With Credit Card in hand to order new carbs after choosing which makes then yes "might as well" attitude kicks in and DT Heim joint type headsteady becomes moneys well spent. There just spent a thousand of your dollars. Great Fun ! :wink:
 
Just arrived at the end of story, my Credit card now is very weary -(AMAL close this year,with a lot of profit) but the Norton is ended -
Temporarily I have mounted the Norton Air filter box for the Historic certification - but I want to return to K&N Air filter for the normal run
https://picasaweb.google.com/1127708198 ... 8251764210
https://picasaweb.google.com/1127708198 ... JSzwZr4Iw#
https://picasaweb.google.com/1127708198 ... 8883303938
All right, NOW is time to trimming,
but I need the plates before return on the road again, and in Italy aren't a easy and fast affair
 
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