Manki – A Marriage of Suzuki and Manx Featherbed

The vision started, not on the floor of the garage where one might expect, but on a PowerPoint slide. That is where Martyn Roberts fleshed out the design for his “Manki” a marriage of a Manx Norton and a Suzuki Savage 650.

Suzuki Savage 650 in Manx Norton

Here’s the finished product–I’m sure you’ll agree, Martyn has found the perfect marriage. Continue reading to see all that went into creating this beauty.

The Manki – with Upgraded Exhaust

 

Martyn set his sights on this truly unique combination and put into play his plan of attack. First on the list was a frame and swing arm. Martyn got his hands on a slimline featherbed frame and swinging arm he bought with a 1959 log book for £900! This, Martyn tell us, remained completely stock except for cutting off the centre stand mountings.

Featherbed frame in a box

Next was the power plant – a Suzuki Savage 650. Martyn amicably refers to this donor Savage as “what a dog.”  He bought a complete, running bike so he could check the motor. He found that it ran OK,  but only used the motor, electrics, exhaust, rear hub and a few small bits. We like to think of it not so much as a ‘dog’ but an engine looking for a new home.

The Donor Bike – Savage “Dog”

Once he got the engine out, early trials were done on the garage floor. This gave Martyn some encouragement. The biggest problem with the donor Savage was getting the belt drive sprocket nut off the gearbox output shaft – he had to grind it off — fortunately Martyn had a spare off a GSXR750 that was identical!

Early engine trials – done on the garage floor

It took lots and lots of dummy builds before he could get the engine in a sensible position. He used simple temporary brackets made from aluminum strips while doing this. Most of the problems were down to the chain line, which is much more inboard on a Norton than the original belt line on the Savage.

getting the engine into position

The chain run was eventually sorted by machining about 25mm off the rear hub and using shorter sprocket bolts to match. He had exposed the bearing in the sprocket carrier, so changed it for a shielded type. The hub was still offset 8mm across the bike which later on meant lacing the spokes up offset to get the rim central.

Rear hub after machining

Cardboard templates were used to develop the engine mounting plates: this is the head steady.

Cardboard head steady

These are the mockups used to develop the main engine plates. All engine plates were made from high strength 6mm aluminum alloy using an angle grinder Martyn bought especially for the job. He then filed and polished them.

Cardboard templates used to develop engine plates

The carb originally fouled the floor of the shiny alloy tank. There was no other answer but to design an inlet manifold to angle the carb lower. He passed the drawings to a pal who machined it from a small billet of aluminum–ending up with 2.5mm clearance!

Carb clearance 2.5mm

Clearing the fuel tap was also a challenge: by using a long hexagon nut as a spacer he can reach the fuel tap from under the frame tube and nothing clashes.

Carb to fuel tap clearance

The exhaust was less of a problem: it almost looks like it was designed for this frame.

Exhaust clearance

The head was more of a problem: He had to grind the fins back a fair bit to clear the frame.

Head to frame clearance

When one puts a modern engine into a featherbed they often end up with a big gap between the engine and frame (the frame was designed to take a primary transmission and separate gearbox).

Gap on drive side

On the exhaust side Martyn filled the gap by locating the battery behind the engine and he made the battery box to fit the donor Savage lid.

Battery box

Believe it or not, the chain does clear the frame, but not by much!

Dry build showing chain run

That’s a 1200 Bandit gearbox sprocket. It looks a bit lonely stuck in the middle of nowhere but at least the chain goes slack as the back wheel rises, so chain tension isn’t really a problem.

Gearbox sprocket position

The drive sprocket position was disguised by an old BSA primary cover, cut off to match the line of the Savage engine.

Primary cover open

After several days of blending and shaping with body filler he had a match. Martyn also made some aluminum covers for behind the engine. It was now time to stop the dry builds and pull everything down for painting.

Primary cover and top panel

There were a lot of brackets to be primed and painted, as well as the frame itself. It was quite nearly a production line going at one point.

Prime and paint, then do it again

Both hubs were primed then painted in matte black to give the style of the proper Manx brakes.

Front hub – primed

Much of the build took place on a Black and Decker Workmate. It creaked and groaned a bit, but survived. He labeled all the wiring as they were removed from the Savage—some leads needed to be lengthened and others shortened.

The trusty Black & Decker Workmate

Martyn made a real effort to route everything nicely around the head so nothing would buzz against the tank. The speedo cable had to be extended but extensions are easily available to suit trike builders. Martyn was dead keen to get the proper 50s look for the handlebars: the silver plate with the button on the right hand bar is the electric start.

Neat and orderly

All the major electrics are hidden behind the engine, set into sponge rubber and protected by the engine plates.

Peek-a-boo with the electricals

A Kettle rear sprocket, home-built chain guard and Hinckley Triumph gear pedal. Both front and rear wheel spindles were made by shortening a pair of Suzuki GS850 rear spindles bought for £1 each (you shouldn’t take chances with unknown material for something like spindles). The footrests are mounted directly on the ends of the Norton swinging arm spindle by using extra-long hexagon nuts that leave enough thread for them to screw into. He made the rear torque arm from a length of stainless channel section.

Chain guard and sprocket

The Triumph gear pedal is connected to the Savage linkage by a length of M6 stainless hexagon. He used a lot of stainless fasteners, probably about 150 quid’s worth!

Gearshift

The rear brake pedal was a challenge: the sweep of the exhaust that he initially thought was so attractive meant the footrest had to go above and the brake pedal below. By now Manki was too heavy for the workmate, so with the help of two strong sons Martyn moved it onto a trolley.

Developing rear brake position

After several unsuccessful trials he used part of the donor Savage brake assembly, mounted from an extended alloy plate that also carried the exhaust mount. The rear brake rod is 6mm stainless threaded rod.

Brake pedal detail

The ignition switch was tucked away under the frame so Martyn bash his leg on the key.

Ignition switch position

Time to start on the wheels. Martyn had never laced a wheel before but he found it easier than expected. This is the Norton front hub and rim, waiting for a nice shiny set of new spokes.

Front hub and rim

This is the rear Savage hub which originally had a 15 inch rim, being laced to a 19 inch. Amazingly, after a couple of false starts, Martyn found a set of 18 inch Norton spokes were just what was needed.

Rear tyre Savage hub

By mounting the wheel spindle vertically in the vice, he could easily check run out on the assembled wheel and tyre.

check rear-tyre runout

Manx Nortons don’t have horns, so he hid Manki’s horn behind the side panel.

Hey, where’s the horn?

The rear tank mount is actually a Hoover belt. The front one is a short length of inner clutch cable inside a plastic sheath. You can also see the engine breather pipe and the front seat mounting hole.

Rear tank mount

Front brake torque arm development: the sums said the front one was strong enough in aluminum but Martyn didn’t like the look of it so he made the second one out of stainless steel. He didn’t like the angle that was necessary so finally he made the one at the back – safe as houses.

Front torque arm development

The front end without the flyscreen: you wouldn’t think those are gpz500 forks. The headlamp ears are from an early 70s Suzuki 2-stroke and the speedo cup is from a 60s BSA. Fitting Kawasaki forks to a Norton frame just required an insert to make the steering head tube a bit longer to match the Kawasaki steering stem. A nice new set of taper roller head bearings finished the job.

The front without flyscreen

The gearing was so far out with the bigger rear rim and new sprockets that he had to recalibrate the speedo. The original 100mph scale was replaced by a 120mph scale printed from Martyn’s computer. Subsequent road tests (against a lad’s R1) showed it was still under-reading by 10mph at 70 so this year he made another one. Actual top speed is about 95 – not bad for a 30hp bike!

Speedo face

Everybody uses the same off-the-shelf seats so Martyn decided to make his own, starting with a fibreglass race seat base.

Seat base

After cutting some foam for the seat Martyn made some newspaper templates of the shape of the seat and cut out the upholstery.

Seat templates

Martyn’s wife’s sewing machine was, uh, off limits, so he had to sew the bits together by hand – the trick (Martyn offered) is to do it inside out so when you invert it the seams don’t show.

The seat

The seat, almost finished, waiting for a trim round the edge to hide the clips.

Waiting for edge trimming

Lots of people run illegal rear mudguards but Martyn wanted to cover the tyre properly so a 60s Triumph number plate and a cut-down plastic mudguard from a trials bike did the job. The front mudguard is a Manx replica in fibreglass, mounted on a home-made stainless bridge.

Mud guard finesse

First time out of the garage, in Feb 2012, 14 months after starting the project, with only the side stand left to make.

Feb 2012 – first time out

First ride in March 2012. The only issue was chain clanking against the primary cover – sorted by taking the cover off and relieving it a bit.

First Ride!

Another shot from that first ride

From the first ride.

After a few rides, the bike started to get slower and slower, until it would only manage 50mph. Martyn traced the problem to this debris found in the fuel filter and carb. It’s flux from the ally tank. Martyn admits that evidently he should have rinsed it thoroughly with water before use (it was a NOS tank made in the 80s). The only cure was another carb, which he managed to find after a month or two and transferred the richer jetting over.

Debris from fuel filter

With performance now restored, Martyn enjoyed a good riding season in 2012, visiting various shows, and made the MCN top 6 bikes at Jack’s Hill Ton-Up Day, including a photo in their paper.

Riding summer 2012

For 2013 the main upgrade was a shinier exhaust pipe and a new mega that was a lot louder than the first one. Manki now roars like a proper Manx, with that huge growl as you shut the throttle. 2014 has been free from any dramas – just enjoying the bike!

Upgraded exhaust – 2013

Well done Martyn. Thanks for taking the time to tell your story to Motorcycle Melee and happy riding!