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Misc: Everything Else Norvin Rebuild



Rixon

Website User
VOC Member
#61
I'm about to order some rear shocks for the bike, probably Ikons. To get the correct spring rate it helps if I know the weight of the bike. Does anyone have a good approximation of what a road going Norvin would weigh ? Thanks
 

davidd

Well Known and Active Website User
VOC Member
#62
I have never weighed a Norvin, but if you have a spring scale you can weigh the back of the bike and then turn around and weigh the front. You need to stack some scrap boards in front of the scale so the wheel rides up the boards and rolls (or drops a little) onto the scale.

You can do it with a digital scale, but it is a little more of a challenge because the scale may act oddly to the brief movement of weight on the scale. It has worked for me. Put some painter's tape on the scale to keep it clean. The wife will notice!

David
 

Rixon

Website User
VOC Member
#63
Unfortunately the bike is currently dismantled with the parts scattered to the four corners. Also I don't have all the bits that are going onto it yet.

JMC list their Norvin at 400lbs. My guesstimate would have been 420 lbs so I'll go with that unless I hear otherwise.
 

chrislaun

Well Known and Active Website User
VOC Member
#64
What you need is the front and rear weights with you on it, anything else is only an approximation, but just out of sheer interest I've weighed mine, on it's own with a chopped motor, belt primary and Norton box and it comes out at 184lb front and 204lb rear which surprises me, I would have thought the front would have been heavier than the rear.
 
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vibrac

Well Known and Active Website User
VOC Member
#65
I think you should block the wheel not being weighed to the height of the weighing machine platform and then I have read that its still not accurate why this claim is made I cannot fathom
 

chrislaun

Well Known and Active Website User
VOC Member
#66
We used take some bikes to the local bus depot (now long forgotten why) for weighing and they had a long plank with the scales in the middle so the bike was at the same height whichever wheel was on the scales.
 

Cyborg

Well Known and Active Website User
VOC Member
#67
Weigh one end without the blocking and then with to see how much difference it makes. I would do it, but flying a flag of convenience (so to speak) for a few days.
 

Rixon

Website User
VOC Member
#68
The inlet ports on my bike are 30mm and I'm thinking to stick with 30mm carbs. Is there any benefit in opening everything up to 32mm, including 32mm carbs ? The bike is for road use only and I don't want to lose any bottom end or flexibility but I note that most of the new builds are using 32mm carbs. My engine will have Mk2 cams and 8.1 CR.
 

Bill Thomas

Well Known and Active Website User
VOC Member
#69
I was pleased with 28mm carbs, On my ex L/ning rep', I thought I would be flat out all the time, But not so,
I can still do 80 mph on 1/4 throttle, My other Bike has 36 mm Dellortos, So I am used to big carb's,
I now have 30mm on the l/ning, Mk2 Amal, But that was what came up for sale.
It's more about the state of tune of the Engine , Mine is 9 to ones, Mk2 cams, Open Armours, Exhaust.
Cheers Bill.
P.S. The spares Company Manifolds, Rubber type stub fitting, Are only about 29 mm, A bit thin to take out much more.
 

timetraveller

Well Known and Active Website User
VOC Member
#72
Mine are copies of the original Lightning and Grey Flash ones except that the outer ends are machined to order to allow three different carb types to be used, stub fitting, rubber mounted or flange. So they are longer than the standard ones intended for type 29 s etc but provided that you have the large tank cutaway the front carb will fit in there OK. They are cast in such a way that they could be machined shorter, but not as short as original road going ones.
 

vibrac

Well Known and Active Website User
VOC Member
#75
I made mine shorter and as it was for a Mikuni I was stuck about the groove for the rubber connector a clever lathe fixture was too much as was hand filing.
in the end I turned up a 'cup' that fitted over the cut end with a hole in the side where I wanted the groove the right diameter of the groove I fitted a drill in a electric drill with a tube to restrict the depth to protude to depth of new grove stated the drill pushed it in and rotated the cup, result one groove for the carb rubber
i must say that part worked well but I still found clearance for the Mikuni VM 34mm very tight on my tank
 

timetraveller

Well Known and Active Website User
VOC Member
#76
The design of the casting patterns, from which the carb adaptors I supply are made, is such that the outer approx. 2" is oversized and thus can be machined to fit different types of carburettor. I have just had a look at one alongside a standard one and there would be no problem shortening them by one inch which would still leave them about half an inch longer than the standard ones. The rear one will fit both front and rear heads fitted to the rear cylinder.
 

chrislaun

Well Known and Active Website User
VOC Member
#77
One thing that has always puzzled me is why the studs are top and bottom, making one always hard to get a nut on and restricting how the bore of the adaptor can be angled.
I've recently considered making cruciform adaptor plates that fit to the engine with countersunk screws and then having horizontal studs to locate home made adaptors giving easier fitting and the possibility of lowering the front carb, The stud centres could also be wider apart making bigger bore adaptors easier to fit.
Thoughts on this idea ?
Chris.
 

Cyborg

Well Known and Active Website User
VOC Member
#78
Not sure if the screws you will need are available through VOC spares. I just ordered some for a similar situation, but I don't recall if they are socket head. I don't have access to the #, but they are listed in the parts book for the lightning manifolds.
 


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