TEMPO from Torgeir.

Picture link

Hello!

Let me first introduce myself.

My name is Torgeir Batnes and I am 25 years old and am a Naval Architect working for a shipyard in Norway Called Brattvaag Skipsverft AS, part of the Aker Yards Group. It was here I met Bob who, besides working for CTC, owns and rides a James motorbike. He came to my office one day and started talking about two-stroke motorbikes, because he had noticed my classic bike screensaver. I mentioned to Bob that I have a “Tempo” motorcycle with a Sachs two-stroke engine and used it to work on some occasions.

Well, I have promised Bob to write some lines about my “Tempo” for your Club magazine.

The “Tempo” is a Norwegian bike, made by Jonas Oglaend AS in Sandnes outside Stavanger. They started fitting engines to their bicycles around 1935. These engines were German made Sachs engines of 74 and 98ccm. In the last years before the war they presented a slightly larger bike, looking more like a motorcycle, with a 125cc Sachs engine. After the war, they couldn’t get any engines from Germany for obvious reasons, so they went for Villiers 125ccm engines, which they got very cheap at the time. These bikes called “Tempo Villiers 125” were a solid and good bike according to my father. He owned a 1949 model for some years, before changing it for a new one in 1954. The bike he bought in 1954 is the bike I am riding today.

This model is called “Tempo Standard 150”. It’s a rigid frame constructed with telescopic “grease damped” front forks. There are two rubber “flap” saddles, which are spring suspended (similar to BMW/DKW). It was fitted with a 150ccm Sachs engine which produced around 6 – 6.5 bhp. This gave the Standard a top speed of about 50 mph (with the wind and sun on your back, going home for supper) and my father regarded this to be a powerful bike compared to the Villiers 125. He rode the bike up to 1964, when he bought himself a car (this was an NSU Prinz, a ridiculous small car which he changed for a Morris 1100 some years later). But in the ten years he owned and rode this bike, he managed to get around 85,000 miles on the counter! (the counter stated 35,000kms and my father told me that it had passed 100,000kms one time, so that adds up to 135,000kms = approx 85,000 miles).

After my father put the bike in the basement, it stood there hibernating for 28 years. Now this can be regarded as a matured bike of a noble vintage, but in truth is that it was a heap of rust and dust. I rolled the bike out of the basement, cleaned the carburetor, checked for ignition and oil in the gearbox and I filled a little amount of petrol in the float chamber. Tried an easy prod on the kickstart, felt a little reaction in the engine, tried again and halfway down the kick the engine fired. “Braam pram pram pram papram prampaparampam........” it said, like it did 28 years before. Now I really got the spark I needed for fixing this bike. The restoration took me about two years,

financed with saved up money and holiday jobs. In 1994 the bike was ready for MOT and license plates with the

original license number (T-13085) were fitted exactly on the day 40 years after it was first registered.

I have done around 10,000 miles on the bike myself since then and I can only say that it is an amusing bike to ride

on small country roads, up into the mountains on roads with lots of bends and beautiful scenery or along the fjords which we have plenty of here in western Norway. But on the highways it is a nightmare. Cars are passing at high speed, big lorries and trucks are almost blowing you off the road......... so I prefer to ride on roads similar to the roads which the “Tempo” was designed for. Curvy, small roads where speed is not limited by speed limits, but by the bends and the narrow passages.

Last year I decided to give my “Tempo” some more power under the cylinder head, so I changed the engine for a slightly newer Sachs 175ccm engine, producing a healthy 10.2 bhp. This engine was in good shape, except for the cylinder which was worn out. I thought that “nothing beats cubic inches”, so I got hold of a piston for a 200ccm Sachs engine (Messerschmitt KR200) and bored the cylinder to 200ccm. Now the “Tempo” kind of lives up to it’s name. It has no problem to keep 50mph as a marching speed on flat roads and the top speed lies around 55 – 60mph. So, that is the story behind my “Tempo” motorbike. You can get more information on “Tempo” from the internet, Just write “Tempo motorsykler” in the search window on AltaVista, and you will find a couple of Norwegian sites with pictures and some ads from the golden years of Norwegian bike industry.

Technical data.

Type Tempo Standard 150

Model 1954

Manufacturer Jonas Oglaend AS

Engine Fichtel and Sachs 150ccm two-stroke (changed to modified 175ccm->200ccm).

Output 6 – 6.5BHP (200ccm 11 – 12BHP)

Ignition system Flywheel magneto, type Bosch.

Lights 6 volt Bosch system, no battery (battery as option for parking lights and horn).

Gearbox 4 speed, left side, 1 down-3 up.

Top speed approx. 50mph (200ccm 55-60mph).

Frame Rigid frame, telescopic “grease damped”, front forks.

Colour Maroon metallic ( I used Honda R43M, it was the closest fit)

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Trials and Tribulations with a Dunelt

The Dunelt, made by Dunford and Elliot of Birmingham in the1920s

made stepped piston 2 strokes. Originally, they had a one piece cylinder

and head in cast iron, then later a separate aluminium head. This latter

type is the one which I now own.

The previous owner, George Ghagan, used the bike whilst at Univers-

ity but later became interested in cars. My cousin Tim got to know Mr.

Ghagan by falling out of a tree(a long story) and noticed this Dunelt

mouldering in the back of the garage. A bodge merchant had started to

crudely decorate this bike with red paint. Mr. Ghagan agreed to let Tim

and myself renovate the Dunelt providing we made a decent job of it. The

last time the bike was ridden was in 1947 by the police chief of Nigeria.

The frame and other painted parts were stripped and taken for

stove enamelling at a local works, likewise the plated parts were taken

to a local platers. The tinwear was all missing apart from the petrol

tank. There were 2 engines, both were wrecks, so I decided to refurbish

the least battered parts. The problem originally being the ring pegs like

steel grub screws threaded all the way through the piston with the result

they became loose when the engine got hot. After sufficient rattling

around there was sufficient sloppiness for the pegs to unscrew themselves

and drop into the crankcase followed by the inevitable scrunch. This is

why both sets of crankcases are bent, buckled and battered.

The Sturmey Archer 3 speed gearbox was no better. Every part of it

was broken. The crankshaft went for refurbishment at Rolls Royce but got

stranded in the works when the receivers were called in. Surprisingly,

the wheels looked in good trim and were just treated to new tubes and

beaded edge tyres after enamelling.

Tragedy struck suddenly. Mr. Ghagan suddenly died of a heart

attack in his kitchen. None of the rest of the family had any interest

in vehicles, his collection of cars being sold or sent to museums. Thus

I was told I might as well keep the motorcycle.

Then I made the mistake of getting married just as the bike was

starting to look like a machine, frame together, wheels in, mudguards in

(from Armours), gearbox and engine. From Gaggs of Nottingham I found

enough bits to make up a gearbox and a brand new gearbox sprocket off the

shelf. The piston was welded by Ray Pettit as all the ring pegs were

missing or loose, a common fault. For ring pegs I inserted roll pins,

which do not seem too secure but they have not fallen out. The bungalow

into which we moved had no garage so the Dunelt was left in a shed at my

cousins. After a number of years I built a garage which filled with water

and several more years to waterproof. When I went to collect the bike it

was looking in a sorry state. The shed was dilapidated, windows missing

and the bike uncovered. All the plating was peeling and rusted, and the

paintwork needed redoing. I was not pleased.

After several more years (I am a slow worker) we were ready to

fire up. The magneto had been overhauled and a friend from the VMCC had

made a pair of chainguards. Petroil was inserted in the tank as I did not

know if the oil pump worked. You read in these magazines of rebuilt

machines starting in a few kicks. I kicked for 3 days with getting no

more than a few revolutions. As my knees were giving up I decided to

delve into the engine and found it to be lubricated with a mixture of

Castrol and metal filings! What I had not realised was that I had fitted

taper faced piston rings(I did not know that such thigs existed) which

were chewing up the bore. Major strip down. Not an easy job, requiring

blowlamp and brute force. Good stuff this Loctite. My friend Roland made

new bushes for the little end and piston (yes, bronze bushes in the

aluminium piston). These took a while as we had to wait umpteen months

for the foundry to cast the right grade of bronze, after which Roland's

lathe snapped a gearwheel. More delay.

From Gaggs I bought 2 new thicker piston rings and sent the piston

and rings to the Clupet Piston Ring and Guage Co. who machined out the

ring grooves which were badly worn and made a new bottom ring, 105m.m.

diameter. They did a fine job, quick and not expensive.

After spannering everything together, I at last kicked the beast

into life, running the engine for several minutes until I was no longer

able to breath in the garage, which I later found to be coated in burnt

oil along with everything therein. There was also considerable drippage

from the crankshaft due to worn outer bronze sleeves. This wear was caused

by the crank ball races working loose many years ago. Another engine strip

to have the crankcases machined to take modern plastic oil seals.

Now the engine behaves reasonably and 2 MOTs have been passed.

Riding is fairly terrifying as the front brake might be best described as

"ornamental" and the rear brake, which is a decent size, has such an

awkwardly shaped pedal it is impossible to use normally. I have had to

stab it with my heel. This is not easy as the hefty flywheel is very close

and I have been suffering boot/flywheel scuffing.

On returning from a VMCC evening run (before darkness as I have no

lights) a loud bang occurred about half a mile from home. The sparking plug

had ripped out and clouted the underside of the petrol tank. Thankfully

I am not a purist insomuch as I had fitted a modern rubber trials type

plug cap. As the next weekend was Barnsley Bikers Festival parade, I had

to hasten repair. I had a spare cylinder head which I had been cleaning,

so on it was spannered. The piston clearance was checked by pouring hot

candle wax down the plughole but it only filled as far as the deflector.

Therefore I thought this method is no good as the wax sets before running

over the top of the defector. What a pillock. After the 3rd parade, the

engine would not kick up and had to be push started. The next week, upon

trying to go to the VMCC club night, the engine refused to start. A bent

cylinder head was discovered upon disassembly, and a mushroomed piston

deflector looking like a well hammered chisel. The pull on the 3 trunion

fixings also buckled the crankcases which leak now even more than they

used to. Thanks to Lenton Engineering for Helicoiling the original head.

The engine seems to have a louder rattle than it used to.

Recent modifications are bodging on a BSA rear brake pedal to

convert to left foot operation and away from the flywheel. I am also in

the process of fitting the Dunelt with electric lighting. That has not gone

100% smoothly – the dynamo is slightly low in voltage and is now at Midland

Magnetos, my local repair specialists. The mounting brackets for headlight,

battery etc I fabricated in stainless steel. No rust, but they vibrate like

mad when the engine runs.

Martin Taylor

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THE NVT RAMBLER - A FORGOTTEN MONGREL

In the late 1970s the Norton Villiers Triumph organisation (which

was all that was left of the British motorycle industry apart

from Les Harris's organisation in Devon who were making Triumph

Bonnevilles and Matchless models with Rotax engines, the

Armstrong concern, formerly CCM of Bolton, who were making

models for the Army, using the same Rotax engines and a few

speciaslist frame builders) were looking for something to market

other than the ageing Commando. They came to an agreement with

Yamaha to supply them with 125cc and 175cc two stroke engines and

the idea of of the Rambler/Tracker was born.

The engines which Yamaha supplied were those from the very

successful DT125 and DT175 trail bike models and around these

engines (which were basically the same except for the bore size),

NVT built, or rather had built, its own trail type motorcycle

which, like the Yamaha, used monoshock rear suspension. Marketed

as the NVT Rambler for the first years of its life, it was later

sold as the BSA Tracker, when the remnants of the Norton Villiers

Triumph organisation became BSA-Regal, a company which is still

in business and now marketing the Yamaha powered Gold SR cafe

racer replica. The idea was plausible enough at the time as it

gave a model which could be sold both as a learner legal machine

in 125cc form and a larger 175cc capacity for those who wanted a

bit more power and didnt mind paying the extra road tax for the

privilege, for those who fancied the idea of a bike with some

British involvement. In reality though the engine and electrics

came from Japan and all the cycle parts from Italy. Only the

actual building of the bike was British.

My son Mark bought a 1979 NVT Rambler from fellow BTSC member

Peter Moorey earlier this year. He already owns a 1979 Yamaha

DT175MX, which he has been riding since he passed his test in

1993 and which many BTSC members will have seen at various events

over the subsequent years. He has a liking for trail bikes and

the idea of a different make of bike but with an identical engine

quite appealed to him, not least because of the flexibility of

engine swaps should problems occur with the power unit of

whichever bike was being used at a particular time. Anyway,

having ridden both bikes I thought that members might be

interested in my thoughts on the differences between the two

models when they are actually on the road.

As they both use the same engine, a six speed reed valve 7 port

conventional air cooled two stroke single of 175cc, the actual

power produced is the same 15bhp for both. The electrical setup

is also the same, with electronic flywheel magneto ignition,

battery powered brake light, pilot light and indicators with

direct generator powered headlights. So there is little point in

mentioning any more about those other than to say that it seems

quite a good unit with adequate performance and very reliable,

provided that it does not become overheated, when disastrous

things can happen to pistons and bores very quickly indeed.

The Yamaha DT175MX had a very good reputation as a useful "off

road" bike, one of the few trail bikes that was actually built

for use off road. This kept it popular with enduro riders and

trail riders long after it would normally have been considered

obsolete and made into a trail bike classic. The DT175MX was the

first trail bike I had ridden. I had never previously liked this

type of motorcycle and almost never ride off road and with no

particular wish to do so. My first thoughts on climbing onto the

Yamaha was how soft the suspension was, it must have sunk down a

good six to nine inches when I sat down and to my mind suspension

that soft did not bode well for stability when cornering on bumpy

roads. The front forks also had long travel and seemed soft,

while the small five inch front brake did not look capable of

stopping the bike in too much of a hurry. Other impressions were

of how narrow and light the bike seemed and how upright I seemed

to be sitting.

I rode off with thoughts of knobbly trail tyres and slippery

bends uppermost in my mind, but in no time at all the sure footed

Yamaha had transformed my thoughts on trail bikes. The soft

suspension was extremely comfortable, but was superbly damped and

even the tyres gave no cause for concern. In fact I found it a

delightful bike to ride and it was not until speeds rose over

60mph that wind pressure became a bit tiring due to the upright

riding position, which was not really a problem on this bike,

where speeds were not usually held at more than 50 for any great

time. The front brake, while not good, was at least adequate and

the only real complaint I had was over a harshness from the chain

drive, which continued to intrude no matter how I adjusted the

chain. Originally thinking it was bearings (it feels like that) I

changed both mains and gearbox bearings, which made no

difference. Two road tests of the bike which I then read, both

mentioned it, as have several other owners I have met. So we just

have to live with it. At least the long chain does have a spring

loaded "jockey sprocket" to take up the slack, so there is no

real fear of the chain "jumping" the rear sprocket. We did find

that being geared for trail use, it was rather undergeared for

continuous road use, which made the engine rather "frantic" at

main road speeds and would easily over rev' in top. This was made

a lot better when we geared it up with a larger gearbox sprocket.

Against the Yamaha's general excellence, unfortunately, the NVT

does not measure up too well. In fact, despite the same identical

engine, same size wheels and almost identical wheelbase, the NVT

actually seems a much smaller bike. The original fuel tank in

fact held a ridiculously small amount, which is why Peter had

changed it for the larger alternative, which gives an acceptable

range. Also whereas the riding position is very comfortable for a

small capacity bike on the Yamaha, it is very cramped on the NVT,

with the footrests far too high for anyone who is rather tall.

On the road the NVT seems rather skittish compared with the

Yamaha, and although it doesnt actually handle badly for a

lightweight it does not inspire the same confidence as the Yamaha

does. Its not all bad though, the front disc brake, which was

ridiculed in road tests as unecessary on a trail bike in 1979,

was actually ahead of its time as all trail bikes have discs now.

Its much better than the Yamahas mediocre five inch drum. The NVT

has also benifitted from gearing up in the same way as the Yamaha

The NVT is not actually a bad bike, it is quite well built and is

probably as good as most psuedo off-road bikes of its day, only

with better brakes. Its just that it can in no way be considered

a serious competitor for the DT175, which was actually built to

be useful both on and off road. I dont know whether the NVTs

frame and running gear was actually designed in the UK or in

Italy, but it was often said in the 1970s/1980s that European

designed bikes generally handled better than their Japanese

counterparts. However, not in this case it didnt, which was why

the Rambler/Tracker was not the sales success that it possibly

might have been if it had only been competing with the offerings

from Suzuki, Kawasaki and Honda. However, it is an interesting

bike to own as a companion to the DT175MX for a bit of variety.

Colin Atkinson

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THE TWO-STROKE LEVIS

My previous articles described the basic operation of the two-stroke engine and pointed out that with modern knowledge its operation is not as simple as first thought. For this reason early attempts to tune two-strokes were not that successful and for the between the war years, four-strokes dominated motorcycle racing. The main exception being the supercharged DKWs in the 1930’s that were developed under a “no expenses spared” racing budget. They were famous for the noise they made and their fuel consumption and it is no wonder that they became the best known pre-war racing two-strokes.

There were other companies who tried their hand with two-strokes and one of them was Levis, an English motorcycle company. The company was owned by the Butterfield brothers and the engineer responsible for development was Bob Newey. The name Levis came from the Latin Levis et Celer (light and fast). In the early 1920’s the company had considerable success in the 250cc (lightweight) class with a simple deflector piston two-stroke powered bike ridden by Geoff Davison.

Through a mutual friend who knows Geoff’s son, Martin Davison, I have been able to loan copies of his late father’s books “Racing Through the Century” and “Racing Reminiscences”. These describe the trials and tribulations of the Levis racing team during their brief successful period. I am sure that these will be of interest to BTSC members and a synopsis follows for your delectation.

The power output of any given engine is given by the simple formula

Power = PLAN (divided by 33,000)

where P = bmep (brake mean effective pressure)

L = Stroke

A = Bore

N = Revs Per Min

You do not have to be a mathematical genius to realise that increasing any or all of the above terms will increase power. Some are obvious, if you increase L and/or A you will have a bigger engine and hence more power. Increasing the revs (without blowing up the engine) will produce more power and this approach was successfully adopted by Honda with their four-strokes. This leaves P which in simple terms equates to getting the most mixture into the cylinder, compressing it and igniting it efficiently which as you can gather is a very important factor.

Put yourself in Bob Newey’s shoes and ask the question how are you going to make your 250cc deflector piston two-stroke produce more power based on the knowledge of the 1920’s? You should bear in mind that Bob was aware of the fact that if you raised the compression ratio above a certain value you got pre-ignition and that experiments with an aluminium piston had been disastrous. They had melted!. So cast iron pistons would have to be used. Bob was under no illusions on the task ahead of him in preparing a winning race engine for the 1922 Lightweight TT. As he told Geoff “I cannot give you the speed of the New Imps or the OK Supremes but I can give you better acceleration and greater reliability”. Geoff for his part concentrated on lightening the cycle parts. By picking the lightest of everything, 10lbs was saved and by using narrow bars, dispensing with footrest rubbers, drilling holes here and there, fitting a bicycle saddle etc, another 10lbs was saved. When finished his bike was 20lbs lighter than the other works bikes. He gave every attention to his attire for the race and he started the race in a cricket sweater, drill breeches, stockings and dance shoes. To stop the breeches flapping at speed he fitted his girl friend’s garters round his thighs. The rules on race wear have changed since then!!

A special cast iron piston was machined with 3 thou clearance at the top reducing to 1.5 thou at the bottom. In order to maximise the “P” term in the power equation, the C.R. was set to be as high as possible without causing pre-ignition. To keep the cylinder temperature down, the top fins of the cast iron barrel were machined off and an alloy finned replacement was shrunk on. Crankcase compression was increased by alloy stuffers which extended right up under the piston so at bdc (bottom dead centre) they almost reached the gudgeon pin. The 1922 racing engines ran on roller bearings and had a bore and stroke of 62.5 x 82.5mm giving a capacity of 248cc. The engine was not a “high revver” having a limit of around 4000rpm but with the attention paid in it’s assembly together with its light weight it was reasoned (quite correctly as it was to turn out) that gains would result in reliability, braking and acceleration. The port timing of this engine would appear to modern eyes to be on the short side with 115, 140 and 128 degrees for the transfer, exhaust and inlet periods respectively. A Brown and Barlow racing carburettor of around 1” bore was employed with a variable jet and the inlet pipe was straight and short with the bell mouth projecting sideways into the air stream. the centrally disposed single exhaust port fed a short pipe of around 1.5 inch diameter which in turn fed a cylindrical box at the front of the frame that had a short exit pipe. The engine was noisy....! Ignition was by a chain driven magneto. Lubrication was by a worm pump with adjustable sight feed which fed the flywheel side cylinder wall and the inlet pipe. Castrol R was the oil used. The crankcase, as it now used roller bearings instead of plain bushes, now needed crankcase seals and this was acheived by long glands machined in the shaft beyond the main bearings.

Though the new TT bike employed nothing in the way of an innovative breakthrough in the art of two-stroke tuning, it did accept the known limitations of the two-stroke and its design and preparation took these into account to end up with a competitive machine.

Geoff did his early TT practice on “a gutless bike” but when the new engine arrived “in a brown paper parcel under Bob’s arm” four days before the end of practice, it was immediately run in with an over rich mixture which caused a lot of four-stroking during practice. When the engine was stripped down they were surprised to find that the plug and piston were covered in aluminium. It was clear that the con rod had been scraping the crankcase stuffer blocks. The con rod had been cut down too much - “not enough H section” was the conclusion drawn. The continual four-stroking during practice had caused it to flex. For the race the mixture was weakened to stop it four-stroking and this cured the con rod problem.

On race day the Levis ran faultlessly to win by over 14 minutes from a four-stroke Rex Acme and in doing so set a record speed of just under 50mph. Max speed of the little bike was about 60mph. With wins in the French and Belgian Grands Prix as well, the Levis-Davison combination cleaned up the Classic events for 1922.

For 1923 Bob Newey decided that the 1922 engine represented very nearly the limit in efficiency for a straight forward two-stroke design. So he thought (like many over the next three decades) that the only way to increase the power output was to force more mixture into the cylinder prior to ignition and the way to do this was by some form of supercharging. He chose to add another piston to the crankcase such that more mixture was sucked into the crankcase and it was compressed higher when compared to a normal two-stroke’s crankcase compression. This extra crankcase piston had a bore of 55mm and a stroke of 50mm (giving 119cc) and was operated by a crank on the offside of the engine shaft. The crankcase had a small aluminium cylinder cast in its side to accommodate the supercharger. Similar crankcase pumps were later developed with considerable success by DKW as their “Lade pumpe”.

The new engine gave an extra 4mph plus considerably improved acceleration. “Little Roger” was the name given to this new development. However it suffered from one major snag, namely vibration. test sessions at Brooklands showed that frames lasted 5 miles before they broke. The extra piston should have been balanced but this factor had been overlooked and as the season had already started, the project was abandoned and the engine ended up under the bench in “The Holy of Holies, the Levis Comp Shop”.

So for 1923, the “standard” engine was re-worked and turned out to be even better than the previous year’s model. Unfortunately it was not ready for the TT but it did win the French GP and was second in the Belgian. At Brooklands it averaged over 65mph before seizing whilst in the lead.

For 1924 it was agreed that the four-strokes were not only faster but were proving more reliable in the 250cc class, so it was unlikely that a balanced “Little Roger” would be competitive. the decision was made to concentrate on a new racer for the new 175cc Ultra Lightweight class. Its tuning “secret” was to employ a much higher compression ratio than ever used before. To cope with the necessity to get rid of the resulting extra heat, copper would be used instead of aluminium for the head and fins. Bore and stroke for this new racing engine were 56 x 70.5mm and it was nick name “Copper Nob”.

In TT practice, the bike went well during the early morning sessions but during the race, after taking an early lead, the motor began to “pink”, it lost its edge and finished a disappointing fourth. The trouble was diagnosed as being due to the copper fins not radiating enough heat. they finished third in the French GP with the same problem since there had been no time to do anything to try to solve the issue. The solution was an application of elementary physics. When the burnished copper fins were painted black it made all the difference to getting rid of the excess heat. Geoff went on to win the Belgian GP by over half an hour and finished third in the 250cc class.

This success at the end of the 1924 season was to be the last for Levis. Two-strokes were losing their appeal for the sporting motorcyclist and in 1926 they launched a 350cc four-stroke. So ended their two-stroke development and for the UK at least, two-strokes became solely associated with cheap, economical utility transport. Foe those of you wishing to know more about the Levis marque I would recommend getting a copy of The Classic Motorcycle of September 1993. the late Brian Woolley’s article features his own racing Levis and historical details of the company.

James Barnett Jnr