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Seeley XR05 MK3, Suzuki TR500 replica

The owner of this beautiful TR500 replica was kind enough to send a whole bunch of pictures of his racer he started to build 30 years ago. Enjoy the photos and read the story at the end of the page!

Seeley XR05 MK3 is a very close replica to the last of the TR500 twin race machines.
Click on the images for large format. Courtesy of Dave Maskell, the owner.

Steve Tonkin, a former professional TT racer, on Dave's TR500 replica.

Left: The rider's view of instruments — notably on left EGT gauge , front exhaust. Pipes have sensor probes fitted approx. 100 mm from pistons (see the picture above). This gauge enables rider to determine exhaust gas temperature at full throttle 1100 degrees rich... 1200 lean.

Right: Most other rider's view..

The owner's comments

Dave Maskell tells:

My Seeley XR05 MK3 is a very close replica to the last of the works TR500 water-cooled twin race machines.

My connection with the TR500 model began way back at the start of the 1972 racing season here in England. Colin Seeley started to produce complete racing chassis to take T500 motor. The first Suzuki racing frame produced by Seeley finished 3rd in the 1971 TT ridden by Frank Perris for Suzuki GB, also by the legendary Barry Sheene.

I bought the frame exactly 30 years ago, March 31st 1972. Eddie Crooks of world-renowned Suzuki specialist "Crook Suzuki " supplied me with the bike complete less engine for the sum of £350. The standard new T500 road engine cost a further £250. Eddie (ex. I.O.M. racer) gave help by replacing new stock parts in exchange for the much needed racing items e.g. racing pistons, high comp. heads, close ratio gears, standard cut primary gears, 34 mm Mikuni race carburetors... plus the help and advice from non other than race team top man for Suzuki GB, Mr. Rex White, who I am totally indebted to this day.

Never had anything to do with two strokes let alone racing the mean machines. It was to be a whole new learning curve thing... Started of OK at the beginning of the season but was let down by an ignition system that failed to live up to its name. It would have been better if it had failed to produce sparks (straight into the bin). It never failed to produce sparks but sadly at the wrong time i.e. at full throttle with disastrous results to both engine and wallet (the cost of this ignition unit then was £50) so I was reluctant to scrap the damn thing though on hindsight it would have been cheaper in the long run.

A much used and abused Spanish Femsa of a TZ Yamaha eventually replaced this unit and it never missed a beat. All our troubles ended, no more seizures so continued to develop parts to increase engine performance /reliability that has stood me in good stead to this day. All the lessons I have learnt have been incorporated in the water-cooled model.

I must mention at this point in time, the start of the 1973 racing, I first came in contact with the young (he was then) Steve Tonkin (that’s him sitting on my bike). At that time he was just starting out on a long and rewarding professional racing career reaching the dizzy heights of factory rider and developer for Armstrong, using Rotax engines. He won the 1981 250 cc TT at record speed etc. and has been a close and valued friend to this day, for thirty years.

I thank Steve and everyone who has helped with advice and expertise over this period of time. Their help has enabled me to end up with the finished product after 30 years — as the photos show, a machine to be really proud to have built and race though TFFO... too fast for the owner, at least 25 years to late.

The reason that I was able to build the water-cooled Suzuki in the first place was after reading an advert for works TR500 ignition Unit complete in MCN (Motorcycle News) late 1989. The guy also said he had brand new spares for works w/c racer bought from none other than the famous Barry Sheene. The genuine works XR05 racing parts were underneath boxes of TR750-3 and RG500 racing spares he was selling as he was preparing to leave GB for Australia. I bought up all the parts available so the idea was born.

These were the parts: two barrels (one nicosil plated, the other steel linered), two heads, six special racing pistons. water pump and last but not least a very special crankshaft (this is 10 lbs lighter than my standard T500 crank).

Shorter con-rods are fitted i.e. 130 mm centres, same as the 750-3 kettle road bike.
The crankpins are integral with the inner flywheels so if I run a big-end I have no spares.

First and the most difficult thing was to modify the top crankcase half to take the new barrel. Holding down stud configurations is totally different — this means Tig-welding up all stud holes and filling up with alloy weld transfer port cut-out in crankcase, (the top case is first bolted down on a flat plate to stop distortion through heat during the welding process).

After removing from plate after weld completion I was very pleased to find no distortion had taken place. This was the biggest task to overcome. The transfer cutaways were machined and the barrel stud holes jig bored and helicoil thread inserts were fitted to crankcase, this face was also machined to make sure it was flat and square to crankshaft.

Completion of assembly was routine, even water pump fits straight in where oil pump fits, just needed a spacer to clear top case. Straight-cut primary gears together with
5-speed close ratio plus air-cooled clutch — all these were made by gear specialist Graham Dyson of Nova engineering. These had all been tried and tested on the old faithful TR.

Only thing is the last 1974 XR05 MK3 were fitted with 6-speed gear boxes, sadly I only have 5-speed, but on the plus side the racing unit is fitted in My Seeley frame. A curved radiator taken from a Suzuki Gamma 250 cc road bike fits neat and completes the conversion together with updates to Seeley forks and rear shocks, made by suspension guru Ron Williams of Maxton engineering.

Fast forward to 1999: 16th September 1999 I started my XR05 water cooled engine for the first time. Note in diary: Sounds terrific! Cats jumping up trees, dogs hiding under bushes... Fantastic!

Preliminary testing proved that all the hard work was worth it, my test rider Steve Tonkin came in delighted with all our efforts. With a little more tweaking it has turned out to be a real rocket ship. The nearest I am ever going to get a full factory racing 500 Suzuki...

Sadly, the downside is there is no classes over here that we can race a 20+ year old water-cooled, we can only race with modern 600 fours turning out 120+ bhp at the back wheel... Track days and several parades by Steve are all we have been too, so at least the bike is being seen and heard.

I hope this has interested all you Suzuki guys out there. It has certainly given me much pleasure and satisfaction having completed my project that started with my first Seeley TR500... this day 31st March 1972 when I took delivery. Thanks to everyone who has helped with advice etc over the last 30 years. If I can help with advice on TR500's please E-mail me at
this e-mail address.

Dave Maskell, March 31, 2002

Dave lives in UK, on the west coast of Lancashire, 3 miles from city of Lancaster.

...and here's an 2006 update

Dave Maskell tells:

Since 2002 we have been out on a couple of parades (sadly because it is water-cooled we can only race against latest 600's). Good news is Steve Tonkin, 1981 TT winner, was invited July 2005 to the Isle of Man Southern 100 50th anniversary celebrations parade — Steve having won the race 30 years ago — three sessions after the days racing, this consisted of three laps; start lap, flying lap and a finishing slowdown lap.

After the first evenings three-lap parade, Steve's first words were 'Bloody Hell, It was not this narrow and bumpy 30 years ago.' He could not keep the front end down.

The following day we had two sessions; 4 pm. after the racing and 6 pm. early evening. Steve suggested we soften the suspension both front & rear to soak-up the bumps. Great! He was all smiles when he came in... He could keep it on line now. Maybe a touch softer on the rear suspension, plug chop showed slight rich on full throttle. EGT readings confirmed this, tailpipes showed dark but dry... Gearing OK... Pulling 10,500 at the fastest straight on the course... Finally adjust rear damping to the softest setting...

Away Steve goes again (I told him to get his finger out). The motor was up to running temp... First lap through start/finish he was mixing it with the big boys. Great stuff; at last we had a yardstick to compare the 500 TR W/C performance on equal terms with racing machines 30yrs younger.

Completing the three laps confirmed that the suspension setting was spot on, engine was now revving to 11,000rpm so we needed to gear up, but best of all; the top Irish road racers came over to see what kind of bike had passed them down the fastest part of the course — both were riding Hondas, 750cc RC30 & last years RS 250cc ps... It made an old man (me) very happy!

More in the pipeline for later in the year...

Dave Maskell, August 28, 2006

Updated: August 28, 2006

The photos courtesy of Dave Maskell

More: All Suzuki models

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