Another HT?


Jim Hunter

Click Here for Pictures of this Beautiful Ariel

At the 1993 Annual Ariel Rally in Norwich, (UK) Lou Walwork offered my son Doug and I a ride on his HT5. Doug rode some of the sections in the trials with it, and I tried it in a few sections with it after the event was finished. We were hooked. We had both wanted an HT, for vintage trials, for many years; mainly because of our long involvement with Ariels. Doug currently rides a TL250 Honda in CVMG Vintage Trials here in Canada, and wanted to stay with a four-stroke machine for a pre-65 mount. An original HT was out of the question, as there were only four imported into Canada and none were for sale. The only solution if we wanted one, was to build one, as I have done with all of my Ariels except the Square Four. Building from scratch would also allow use of the famed Sammy Miller innovations, lightweight parts, etc., available in the UK aftermarket, as opposed to the rather low and heavy production HT of the fifties.

Years passed, until the summer of 1997 when a friend advised of a late Ariel single (1956 it turned out) on a farm in Hemmingford Quebec that might be available. Doug said he would fund the building of the HT, and we would use it jointly and share ownership, if I built the bike. The project was a "go". We arrived at the owner’s farm, and were shown the Ariel, a pathetic looking mutilated, long silent machine with a tractor headlight on it, stored in the back of a derelict van out behind the barn. It was a rusty mess, with no engine or gearbox. They were in the basement of his brother’s house just up the road, we were told. I was apprehensive. If it was in anything like of the condition of the bike, it would be a lost cause. We went to the brother’s house, and were pleasantly surprised at the apparent condition of the engine and gearbox. It was intact, still mounted in the mounting plates and complete with the magdyno, sitting on the basement floor. We started negotiating at $250, which produced a pained look on the owner’s face. Did you ever notice how often owners of "barn fresh" un-restored machines think they have their "pension fund" in a rusty old piece of junk? We pointed out reality to him, and he finally agreed to an increased offer of $275. He produced other parts out of the barn, a gas tank, a good looking speedo and a voltage regulator. We loaded it in the van and took it home. Even if the machine was entirely junk, we could certainly get $275 worth of fun out of it.

Starting the disassembly was easy, as most of the bike went in the garbage. The frame was so butchered it was unrepairable. We got a tool box, oil tank and fork clamps out of it. The engine was another matter. It looked to be in good condition, no broken fins or casings. Then we opened the primary chaincase, which was quarter full of sand. The clutch, sprockets and chain were toast. I thought the magneto was the same, as it was full of sand; but when cleaned up and lubricated, produced a healthy spark. Not so with the dynamo, it will be used for parts. The gearbox came apart with great difficulty and was half full of what looked like gray washwater, (like the laundry tubs had overflowed once upon a time, and the water had sat in the gearbox since) and badly corroded inside. And did it stink! Some of the gears and shafts, surprisingly, were in good shape; some were corroded beyond use. Disassembly of the engine revealed it to be in surprisingly good condition considering the rest of the machine. It probably would have cleaned up a bit and could have been run -- no sand, no washwater, no butchery. Our $275 investment was now secure in the engine alone.

With the unusable bits heading off down the road in the garbage truck, restoration began. Doug ordered a new manufacture frame, an alloy cylinder and an aluminum bash plate from John Bartram in the UK, and the engine work got underway. All bearings were replaced, and the local Ducati guru changed out the big end roller bearings and lightly honed the raceways. We decided to replace the big end rollers, the crankshaft was reassembled and trued, and the crankcase reassembled. There were some anxious moments when we wondered if the Ducati truing jig would handle the 8" diameter of the Ariel flywheels. It did – just! The new alloy cylinder and the Miller-type "oil in frame" frame arrived from John Bartram, and the cylinder was bored to accept a NOS +.020" 7.5 - 1 piston and NOS Wellworthy rings that I have had for years. We chose this CR as we thought we could use the extra power to handle the weight of a big heavy rider. New valves and guides were installed in the head. A Lucas KNR1 Magneto was obtained in a swap for a magdyno, and then overhauled by Warren Wheeler. The gearbox was rebuilt out of my parts stash, serviceable casings, gears and shafts. An outer housing from a Matchless Burman gearbox was modified to fit. While this is an easy modification, I can see no real reason for it, as there are minor gains in decreased dimensions and weight. I believe that an unmodified Ariel box would do the job quite nicely. I think that even the clutch cable routing would be better with the Ariel box. I guess it’s just that "it’s what Sammy does". Anyhow we did just that, even though I now have reservations about the requirement to do so. Gearing, internally; is as per the road models. Incidentally, the scrap washwater filled gearbox housing was given to a friend who "thought he might be able to do something with it", and delivery was arranged for the CVMG Annual Rally at Paris Ontario last June. It was stolen from my campsite overnight before he could collect it. I think the thief will get more than he bargained for when he opens it up. The smell alone is enough to spoil your day.

The engine was installed in the frame, using John’s alloy front mounts and Lou Walwork’s alloy rear mounts, as John wasn’t making them at the time. All fasteners are stainless steel with locknuts. We made some departures from the "its what Sammy does" theme. Instead of usual Norton forks, we used Ceriani forks and new manufacture Volante rims (an Akront knockoff) with new stainless steel spokes, onto Rickman conical polished aluminum hubs. Norton forks were not available at a reasonable price, (the old pension thing again, I guess) and the Ceriani forks were generously given to us by CVMG/AHRMA expert class vintage trials rider Eric Pritchard. The forks required relocation of the brake plate anti-rotation boss, and a couple of internal parts that were missing. Modern Pirelli radial tires are fitted.

The primary drive line uses a 15 tooth Villiers 37A sprocket on the engine, with no compensating device. It uses a 3 spring Norton clutch with a 42 tooth sprocket, running dry; with the chain lubed before every trial. (Norton clutches, you may remember, have rubber damping snubbers in the hub). All this fits very nicely in one of Sammy Miller’s fibreglass primary chaincases, with a flat .070" sheet aluminum inner chaincase. The rear chain and wheel installation required all my fitting knowledge to get it right, because the clearances are so critical. First, the wheel has to run centre to the frame. The chainline has to be straight, and everything else has to fit somewhere in between, yet not interfere with each other. I think I spent more time getting this right than on any other part of the build. The footrest support installation was tough as well, and that must be why almost every HT that I’ve seen has a different footrest installation. (Different solutions by different builders.) The rear sprocket is aluminum, 52 teeth. We are going to change this for a 54 tooth item currently on order. After all, the bike needs a lot of low down grunt to pull two rather large riders (one at a time of course) around trials sections. It would be OK for a normal size rider with the 52, I think. The rear axle was made by a friend, from 15mm stainless steel. This same "artist in metal", Steve Busby, also milled the rear brake lever and the rear brake pedal from 6061 aluminum. Three thread forms are used on the bike, Metric on the forks and rear wheel, CEI on the engine, and UNF on the frame. Not good engineering practice, but something we have to live with. One of Sammy’s fiberglass gas tanks was used. The first one leaked so badly that it had to be replaced, and it finally was; courtesy of Miller. One of his fiberglass-based seats was used, but had to be modified before it would fit. The exhaust system also from Miller, fits very well, and with the aluminum muffler, has a distinctive and authoritative bark to the exhaust note. (You know it’s not Japanese!) Interestingly, Miller supplied the exhaust pipe with a stud welded on to accommodate a brace, thoughtfully including even the nut. Unfortunately, the engine fired about six times, I think; before the nylock facility melted and dripped out on my polished crankcase. Somebody is "unclear on the concept"!

Another Ariel has now been was resurrected. The first "test flight" on the 4 year long aftermarket HT project was held dodging snowflakes up and down the road in front of the house on 2 April. Luckily, I could get a couple of litres of fuel in the defective fuel tank without it leaking, for test purposes; so I was able to at least ride it down the road and check it out. The engine runs very well, and so it should as everything is new in the engine, mains, big end, piston, valves etc. It pulls like a steam engine. The only adjustments I've had to make so far was a small ignition timing adjustment, and the usual ones to the carb. I had to make an adjustment to the rocker feed, and install a ¼" I.D. restrictor in the oil return line to restrict the return to the tank (oil in frame) and force the oil return supply to back up, and feed into the rocker shaft. For this reason, we used clear plastic oil lines to check the oil flow.

It has been a very interesting project, perhaps the most interesting restorations I have ever undertaken. Fitting all these parts that were never designed to work together, and to make them work together, was indeed a challenge. There were some real "headscratcher" problems. New Volante alloy rims and stainless spokes from Central Wheel Company that I had to wait a year for, despite their "largest stock in Britain" advertising. There have been a lot of modifications and fabrications accomplished. We've bought parts from suppliers that are supposed to be for the HT, but are for all intents and purposes unusable.

It won’t be "just another pretty face", either, but an operational trials bike. The bike weighs in at about 225 pounds, not bad for a 500 single. We had to change out the springs on the rear Betor Gas Shocks as they are not strong enough for heavy riders! The bike’s first trial was in the fall of 2002 and after some jetting and other dialing in, the bike performed well. Nice steering, suspension compliance, good ground clearance and very light feeling. Power is incredible, eating up hills encountered with minimal revs and massive torque, effortlessly carrying the front wheel if so desired. Of course, half the weight of the bike must be flywheels! In many ways it felt better then our trusty old TL we also had along. To be fair, the Ariel is much "fresher" then the well used Honda, being essentially a 2002 model! So far so good, and we’re looking forward to a full season in 2003.