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New Technical Section (just being developed ..these photos are hard to work with.. I give up for now..)

NORVIN (a Vincent engine mounted in a Norton motorcycle frame)
Photos continue to the right for now >>>>













 






Engine Mounting:  Some Norvins, even with complete frames, have been built with substantial upper engine mounts. I think that this is a bit of an over kill, but hey, it probably doesn't do any harm. A sturdy head steady is mandatory though. The Norvin with the lower frame rails removed is still around. Known as the Italian Norvin even though it was built in England and then exported to Australia for the '83 International rally before going to Italy. Whilst removng the lower frame rails does allow you to move the engine/gearbox around, I don't see any further point in it. One may as well then fit the steering head to the top of the cylinder heads and then, oh, bolt the swinging arm to the back of the gearbox and remove the rest of the frame and oh gosh, we have a standard Vincent. Cutting up a Manx frame will
probably result in you being paid a visit by the Norton Club linching crew.  It's equivilant to cutting the gearbox off a Vincent engine.  Besides there is something visually appealing about the Vincent unit being "Framed" by the Norton Featherbed.   Phelps  6/9/07

I built a Norvin a few years ago and found it uncomfortable and top heavy.  The engine necessarily has to sit high in the frame as you can't get it to sit between the lower frame rails (as the manx engine does), so raising the C of G.  The wideline frame makes an uncomfortable riding position and makes kickstarting difficult. I eventually sold it as i found i was not using it. With a standard twin and single in the garage alongside the norvin, i always chose one of the other bikes when going for a ride. The Norvin looked beautiful but I found it not very practical.

If I had the chance again I would build an Egli or probably a Vincati. Much more user friendly for an octogenarian, and there is lots of information out there with the ozzy, and not least, Big Sids, Vincatis.   Les Craggs  5/14/07


Check out the way Dave Dresda does his featherbed for Vincent - the bottom rails are spread to get the engine to sit down low - a nice compromise and the rear lug isnt chopped ! . And of course, use the two piece cylinder studs so you can pull the heads off with the engine in the frame. Terry Prince has some really nice Stainless ones.     http://www.dresda.co.uk/bikes2.asp?CAR=9
Norvin Frame:  If I were to build a Norvin I would cut the tubes connecting the left and right frame loop, spread it a bit apart and start from there.The aim is to get the engine as low as possible as it is so heavy. Even ín the original Egli the engine sits a bit high - on my second frame I lowered it 1,5 inches without any harm or ground clearance issues and was rewarded by a much nicer ride and better handling bike. Don´t know about Vincatis but all the pictures I saw of them seem to have the engine on the high side as well. When building race Nortons etc I always try to get the crank below the wheel hubs - as low as possible and as much forward in the frame as well. The little blue Norton got 78 kg on the front wheel and 62 on the back - with rider this gets an almost even load on both wheels and is noticable when comparing the feeling to an ordinary Atlas. Next plan is a Dunstall frame where the front wheel almost rubs the fins of the motor when fork is compressed....

I would not cut the original Manx frame however - sell it and have a wider featherbed made for that money -might probably leave you with some extra
cash in hand and a better suiting frame.   Hartmut 5/15/07


General Comments: My Egli, Norvin and C Shadow all share the same 56 inch wheelbase, give or take for rear wheel adjustments (a Ducati bevel has a 61 inch wheelbase for comparison).  The Egli and the Shadow both have the crankshaft 24 inches behind the front wheel, the Norvin 26.5. The limiting factor on the forward placement of the Norvin engine was the front exhaust pipe, which still required 'massaging' to clear the front down tube (with chopped cases I need the full frame). The Norvin crank is also a couple inches further back than standard Norton, as I found out when I tried to use a Norton primary cover.  I did make the Norvin gas tank shorter than the Egli's so I can sit further forward.  I thought the Norvin was going to be heavy but it's coming out OK, the AMC box must save some weight.

The Egli and Norvin both have the same length Ceriani RR forks and tires, both sit in the same location in the trees so the steering heads are appx. the same height.
 Paul Zell  5/16/07


General Comments: I lifted the swingarm shaft by 4mm lowered and tilted the engine (not much) and used a smaller rear wheel ( 18"instead of 19"). When upgrading the front brake I had to use a wider/higher tire as the 19"Speedmaster couldn´t handle the braking forces, washed out on many bends and was used up within 500 km. So the front fork was shortened a bit as well. No negative feedback from the slightly different swingarm angle but I don´t ride the thing anymore as the Norton is so much lighter, does the same topspeed and is more fun when it gets twisty.  Hartmut  5/15/07
General: Well , having built both an Egli and a Norvin recently:  I cannot think of a single drawback of the Egli style frame in comparison to the featherbed.  The featherbed has compromises in engine location, carb and exhaust clearance, separate oil tank...  There are however arguments to be made for using what you have on hand and building something nostalgic and eye pleasing.  If it weren't for this we'd all be riding new bikes, no?

I had chopped cases which made sense for a featherbed since the standard Vin twin swing arm pivot is gone, the featherbed obviously has one and also the AMC gearbox is right there already mounted.  With removable cylinder studs the heads and barrels come off in the frame.  A chopped engine also sites a bit lower in a featherbed than a complete.  I thought long and hard about spreading the lower rails but in the end did not because my crankshaft sits just about lever with the AMC gearbox mainshaft already.

With the swing arm pivot on a Vin twin (standard chassis or Egli) incorporated in the design the height of the engine directly determines the angle of the swing arm.  My Egli engine looks high but with long travel suspension (relative to other vintage iron) the swing arm is level when I am on the bike.  There is no way to lower the engine without having the swing arm at a unfavorable angle, tilting the front of the engine down substantially or using 16" wheels.  Paul Zell  5/16/07


Norvin Brakes: (4LS front wheel between Norton Commando forks)  I`m working with a front hub from a water buffalo (Suzuki GT750)  and I`ve milled about as much from the brake plates as possible without removing the speedo drive in order to get it between the forks...still don't have the room between my forklegs. There were different sized Norton steering crowns and I'm wondering if  I`ve got the narrowest one ? Anyone know what the different sizes & models were? Or is this the best reason every for custom aluminium steering crowns ?  Marc Beaudry 4/17/03

Norton Forks:  I always deal with the Norvil Motorcyle Company if I want Norton parts.   Les Emery,  the boss is a mine of information and will give you any information you want.   There are certainly two widths of fork yokes listed in their free catalogue - 7inch and 7 3/8 inch centres.    Contact Les at :+44 (0)1543 278008 or e-mail at  mail@norvilmotorcycle.co.uk.    Derek Peters  4/17/03
Build details of Ken Phelp's Norvin:   I have built both my Norvins (the other is a racer) and have been using my road bike as a daily ride for well over twenty years.  The bike as it is in the photo runs a 250mm 4LS Magnesium Fontana front brake, and a Laverda 2LS rear brake. Norton forks are really early sliders with late internals. 1956 Norton Dominator frame with Koni shock absorbers. The fuel tank is of unknown origin, possibly Dresda and the seat is my own aluminium alloy ducktail and base. Black Shadow speedo and Triumph headlight.   The engine has been detuned of late to cope with the crudy petrol on offer but still runs 36mm Dellorto pumper carbys' on matching long manifolds and ports. Std valves are opened by Lightning cams onto 8.2:1 pistons with ignition by the standard Lucas magneto. The exhaust is my own fabrication using slightly larger diameter thicker wall pipe into a straight through resonator megaphone 'Muffler'. The rest (oil tank, foot controls, bracketry, piping etc.) are of my own construction.

My Norvin has a Yamaha 270(?) mm 4LS front brake in 7" (narrow) Roadholders, not Commando forks, but the sliders are basically the same.  However, you need to measure the center to center distance of your fork tubes, then you will know if you have the narrow or wider triple clamps and what your options are.  If you also look at the bottoms of your sliders you will see that there is an inward projecting shoulder on each one.  You can mill a fair bit off each of those to get more clearance.  I assume you have removed the original brake plate retaining boss on the backing plate side.  David Stein  3/26/03
Phelps Norvin: The bike as it is in the photo runs a 250mm 4LS Magnesium Fontana front brake, and a Laverda 2LS rear brake. Norton forks are really early sliders with late internals. 1956 Norton Dominator frame with Koni shock absorbers. The fuel tank is of unknown origin, possibly Dresda and the seat is my own aluminium alloy ducktail and base. Black Shadow speedo and Triumph headlight.   The engine has been detuned of late to cope with the crudy petrol on offer but still runs 36mm Dellorto carbys' on matching long manifolds and ports. Std valves are opened by Lightning cams onto 8.2:1 pistons with ignition by the standard Lucas magneto. The exhaust is my own fabrication using slightly larger diameter thicker wall pipe into a straight through resonator megaphone 'Muffler'. The rest; oil tank, foot controls, bracketry, piping etc. are of my own construction.  Ken Phelps 3/27/03
Norvin Notes:  www.voc.com.uk/ogri has the photo build history of the bike I am effectively copying, and notes relating to parts and services suppliers (but please note that Asa Moyce of Bartel (Northern Ireland) no longer makes the combined oil / fuel tanks, but still makes fuel-only Manx etc. tanks.  Instead, enquirers can be referred to TAB Engineering (Mr TA Baker of Aberystwyth, West Wales, UK) on tel. +44 1974 821469.

Other items to be borne in mind for Norvin builders using an unchopped Vin Twin engine:  if using a Grimeca rear hub, it's necessary to do transpose the relative positions of the torque arm anchor and brake cable abutment points for left-hand operation, and of course to weld a corresponding torque arm anchor tab on the left hand side of your box-section swingarm.  These Grimeca cush-drive rear hubs come poly coated in black, so I have had all 4 exterior hub component surfaces garnet- then bead-blasted bare to take a nice polish on the bare alloy.  I've also had the alloy wheel sprocket turned down for a 1/4 in chain.

Also necessary on frame:  cut and weld to half thickness the left-hand bottom tube where it blends with the L/H gusset plate, and cut back the gusset plate itself to accommodate the L/H crankcase lug co-axially with the S/A spindle pivot point.  For this you must also mill a 1/4 slot roughly central through the lug on a horizontal miller, but not so deep as to break through into the chaincase.  Also, the chaincase part of the casting has a curious circular projection underneath which must be ground off; in fact you should grind a little further back the metal in that area (i.e. chaincase bottom rear) for best bedding with bottom rail / gusset plate junction..

Photo of my own swingarm attached herewith.  Currently I'm opening out the slots and blocks and making new shouldered sleeves for the wheel spindle, as my Grimeca centre is 17mm, but Pete Lovell who makes the Norvin swingarms built mine for a smaller spindle.  Too bad it was already polished and bright nickel plated, but I'll know next time.

It should be remembered that some Norvin builders dispense with the featherbed frame's bottom tubes entirely (viz. the Itlian Norvin from MPH magazines passim).  They don't bear any load anyway if the head-steadies are effective, and could therefore retain the standard Vincent crank balance factor.  It could be argued that this latter approach allows the engine to be dropped slightly lower at the front for lower C/G and to enhance the handling, but the Ogri Norvin hadled superbly by all accounts.  With bottom tubes in situ, the Ogri engine was as low as it could be consistent with box-spanner access to the sump drain plug.

It would be nice to enquire whether the current owner of the Ogri Vincent (last heard of he was a Swiss gentleman) is willing to
share his experiences with the rest of us.  Phil Blakeley 2/1/03



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