Made this a little easier on the eyes.
The great singles of the ‘50s – BSA Gold Stars, Velocettes, Norton Manxes – ruled roadracing for a long time. They were light, they handled beautifully, considering the level of suspension development of the time – and they were fast. With riders like Mike Hailwood and Geoff Duke aboard, the Great Singles owned the terrifying Isle of Man TT, hitting speeds as high as 130 mph on the longer straights. And the exhaust note those beasts would throw off behind them! With an open pipe a good single could move your eardrums back and forth as if some vengeful primordial drummer had worked his way into your very skull.
With legends like these loose, we were a trifle disappointed with the new Honda FT500 Ascot. Yes, it handled very nicely, and its relatively light weight, quick steering, and first-rate brakes made it a natural canyon racer and all-around, in-town giggle bike. We soon discovered, however, that the canyons the FT liked best all pointed downhill. The FT, you see, is a bit slow. We found it very hard to take the 7000-rpm redline seriously in our more spirited test sessions; it was hard to believe the power the motor had put out before 7000 was all we were going to get.
Our course was clear. We’d talk Honda into letting us keep the FT a few extra months – all in the interests of the advancement of vehicular science, you see – and tweak the motorcycle until it went down straights as well as it went through corners. We’d turn it into one of the sweetest little café racers in town. The Honda 500cc single-cylinder engine is perfectly adequate in the XL500, with its dual-purpose tires and drum brakes, and in the XR500R, which is seldom called on to go faster than 50 or 60 miles an hour out on the trails. The motor’s strong lowend torque and substantial flywheel effect make the four-valve thumper a pleasure in the lower speed ranges, but the Ascot’s taller gearing, rat-racer image, and sticky tires conspire to get it out of the lower speed ranges as soon as the rider senses winding asphalt ahead.
The Ascot’s four-valve, counterbalanced motor has been around since 1979, and while its credentials look impressive on paper, it’s never been known for eye-opening horsepower. Dirt-oriented four-stroke tuners like White Brothers, Mugen, and Powroll immediately got into the hop-up act, and even Honda marketed a staged series of parts kits intended to send the dyno curves of the XLs and XRs farther skyward. Of the hop-up specialists available, we picked White Brothers to do the lion’s share of the work on our machine. Dan and Tom White have been building and racing hot four-stroke machines for a long time, and they had in stock, or were willing to build, just about every part we would need to turn our Ascot into an RD-eater. Besides, Dan White, the technical half of the team, had an ulterior motive. He had just bought an Ascot to use as his personal street bike, so we knew the project was going to get his undivided attention.
The first step was to keep things cool inside the Ascot’s crankcases. Big singles are very difficult to cool – a 500cc explosion 3500 times a minute pumps a lot of heat through the combustion chamber. Honda did its part by designing the Ascot with an add-on finned sump underneath the engine, but for front-line combat duty we knew we’d have to take more drastic measures. In our Ascot test we made a few canyon runs that had the poor thing on the verge of meltdown, finned sump or not. White Brothers markets an oil-cooler kit for the XL and XR motor, with a Lockhart cooler and all the fittings necessary for installation. The fittings go on to the FT motor’s clutch cover just as they do on the dirt bikes; the only difference on the FT kit is the location of the weld-on frame bracket. Just so we could keep an eye on the oil temperature, Dan White put a combination oil-temperature gauge and dipstick onto the Honda’s oil filler. Oil volume is critical in Honda singles; the small end of the connecting rod is lubricated by splash, and the oil level can easily drop enough to gall the small-end bearing under hard going.
With cooling problems handled, we were free to look for more horsepower. We decided to keep the power delivery and noise production of the Ascot within rational limits. Screaming, snorting, bloodboiling project bikes look great on paper, and they’re fun for the three or four fast rides they usually survive, but in the end they wind up in the back of the garage, underneath a pile of decomposing roadracing slicks. We set out to make the Ascot a pleasant, day-in-day-out street bike; one that just happened to go fast. The two-into-one stock Honda pipe is a pretty piece of work, and the header pipes seem to be of acceptably large di ameter for heavy breathing – until you pull them off the bike and look inside from the exhaust-port angle. The pipes are a double-wall design, which keeps the outer pipes a bit cooler and acts to reduce the noise level, but the inner pipes are a relatively skinny 23mm in diameter. Also, just after the two pipes converge into a single collector, there’s a nasty kink. The Whites hadn’t yet built a pipe for the FT, so the one on our bike is the prototype unit. Jigs for the production pipe will be built using ours as a model, but the production pipe will be finished more carefully and will have fewer weld joints than the prototype. The head pipe I.D. on the White header pipe is 1.125 in., or a little under 32mm, for increased flow. Bent to conform closely to the underside of the Ascot’s engine and frame, the White pipe is designed to give good ground clearance. The silencer is the ubiquitous SuperTrapp Discojet, packed with fiberglass around the baffle core. The Discojet is easily tunable for achieving an appropriate compromise between noise and power. With four baffle discs bolted into the end of the pipe,the sound (and power) is mellow and unobtrusive. With six or eight discs, noise is still in the acceptable range for hospital zones, but power output is rising fast.
With 12 discs in, the sound with the throttle open can be a little disconcerting, but the bike will turn quarter-mile times within a tenth of a second of those run with an open megaphone, and with only a fraction of the sound. We also did dragstrip testing and some street riding with a Kerker pipe bolted up in place of the White Brothers’ pipe. The Kerker design is closer to the stock Honda pipe in finish and design; it’s a single-wall design, like the White “Brothers’ pipe, and its 32mm head pipe I.D. is the same as the WB pipe.
With the pipe situation more than covered, we turned our attention to carburetion. Honda uses a 35mm CV carb on the emissions-controlled FT. A CV carb tends to flow even less air than its venturi diameter would indicate, because of the floating piston in the carb bore that never quite pulls itself up out of the air-stream. The Whites sell complete carb kits for Honda 500s, using Mikuni slide/needle carbs in both 36mm- and 38mm-venturi sizes; we went for the 38mm-venturi heavy-duty mixmaster. The White Brothers kit comes with a K&N air filter to replace the stock airbox, along with a K&N mini filter and hose to replace the airbox-ducted crankcase breather. The single-cable Mikuni carb is not compatible with the stock Honda push-pull throttle. Dan had two options; he could chop off the throttle tube of the stock setup and substitute a new quick-pull Magura throttle, or come up with a trick cable setup to utilize the stock throttle. Our bike went the Magura route because we liked the quicker throttle action, but the Whites will likely off both choices to their customers.
All the engine externals had done their deep-breathing exercises now; it was time to open up the motor and give it gas-passing capacity to match. White Brothers sells Wiseco, Venolia, and Pro-Tec pistons for the Honda motor; Dan settled on a 10.5:1 compression ratio, forged design made by Wiseco to his specifications. The Honda designers pay a lot of attention to the way piston-crown design and combustion-chamber configuration work together to get higher compression figures to work with low octane gas. Dan feels the dome design on the special-order Wiseco matches the combustion chamber best. The piston uses a chrome-plated top ring, a cast iron second ring, and a threepiece oil ring with chrome-plated rails. The Wiseco design is 40 grams lighter than the stock piston, and Dan has kept an eye on how this might affect the vibration level of an engine counterbalanced for a heavier piston. Ours vibrated no more than the stock setup. Honda made some subtle changes in the FT500 head, and one of them is a slightly lower combustion-chamber height. Our XL/XR piston touched the outer reaches of the chamber lightly the first time we started the motor. We had to machine the piston top down a few thousandths of an inch to clear the chamber; the White Brothers will have special FT pistons with slightly lower deck heights in stock by the time you read this.
With the free-flowing pipe and the big carb installed, Dan couldn’t resist climbing into the ports with his Roto-Rooter and cleaning things up a bit. He confined himself to a relatively mild clean-and-polish job on the intake side, and reshaped the guide bosses for better flow. More metal came out on the exhaust-port side and around the guide bosses; diameter was opened up toward the ends of the ports to make the transition into the bigger pipes a little easier. The valve train of Honda thumpers is not all it could be for a high-horsepower motor. The shape of the slipper on the rocker arms makes cam grinding difficult; it forces a smaller base circle diameter than the grinders like to see for long life. Also, with valve lift higher than .350 inch, the valve keepers come into violent contact with the valve guides; special shorter guides must be installed to accommodate the wilder cams. Lubrication up in the head is not as good as Dan White would like to see – the oil comes up through the head via one of the head hold-down studs, and it’s pretty hot when it gets there. The stock cam rides in the unbushed aluminum of the head, a configuration that works better than it sounds. Megacycle cams, which the White Brothers stock alongside their own designs, have a small-diameter needle bearing fitted inside the stock journal; the cam is ground down to fit inside the needle bearing. Dan doesn’t feel this is necessary as long as there’s good oil coming through the bearing. We planned to use White Brothers’ high-lift WBX-2 cam grind, and we had the Brothers install Precision Machine shortened valve guides and stiff valve springs to match it. When Dan took the Ascot for its first modified ride, he felt the radical cam made the Ascot a little less controllable than he wanted it to be. The thing had power about equal to stock below 4500 rpm, but above that, took off like a turbo. He had trouble keeping the front end on the ground well into third gear, which is no joke on an already wheelie-happy machine like the Ascot. When he tore back into the motor to lower the piston height to clear the new chamber design, he replaced the wild cam with the milder WBX-1S, a slight modification on the grind used in White Brother’s popular WBX-1. Neither the WBX-1 nor WBX-1S need the sophisticated valve train we have in our Ascot to function properly, but it’s nice to know we can just pop in the wilder cam once we’ve got our insurance fully paid. The milder cam is more low-end and mid-range oriented than the wild one – and gives a much smoother powerband from 2000 through 8000 rpm. Its grind is not far from that used in the Honda hop-up kit or the one offered by Mugen as an all-purpose design.
We now had the power we wanted, but we still needed a power train that could handle it. Dan liked the Honda clutch plates fine, but the springs required some beefing up. S&W springs went in, giving a medium-stiff clutch pull, by modern streetbike standards, and a clutch that would stand the abuse we’d give it at the dragstrip.
With the engine choices locked in and the engine buttoned up and ready to roll, we diverted our attention to the Ascot’s chassis. The overall layout of the chassis, as we’ve said before, suited us just fine, but the stock Honda shocks brought back childhood memories of our first solo pogostick attempts. It took us less than 2000 miles to turn the stockers into debris. S&W came to the rescue with a set of Street Stroker SS shocks set up with the stiffer of the two springs S&W recommends for the Ascot. The shocks we used are the same length as the stockers, but the stiffer springs and heavier compression damping gave us a slightly higher ride height for quicker steering and increased ground clearance. The new shocks’ valving and spring rates strike an effective compromise between firmness and harshness in fast going; they locate the rear wheel under the bike much more precisely than the stockers did, without a great increase in harshness over freeway joints or potholes.
We couldn’t leave our Gold Star replica Ascot looking like any old stocker – and we’ve always been impressed with the look of the Kawasaki GPz-style fairings. We called Jerry Greer of Greer and Associates, builders of the first GPz fairings, to give us a hand with the Ascot’s lines. He recommended the slightly larger Greer HP fairing over the GPz-style instrument protector. It would give us some real protection from the wind, he said, and suit the tall, angular look of the Ascot a little better than the smaller fairing. A shot of Lubri-Tech Monza red, a little rub-out of the paint, and it was all over except for the stickers.
After a suitable break-in period for the new piston and internal components, it was time to see how our Ascot looked in the harsh glare of Orange County International Raceway’s timing lights. Our first runs were made with the White Brothers’ street pipe and the Discojet silencer; we’d piled 12 discs into the end of the unit. Jeff, our resident dragstrip tester, had trouble keeping the nose of the Ascot anywhere near the ground during a hard launch. We tried letting all the air out of the fork tubes to get the bike lower at the starts, but Jeff was still not satisfied with the way the little Honda left the lights in a series of leaps and bounds. Even with the takeoff difficulties, our Ascot was building up some serious ground speed. Our stock unit ran no faster than 14.9 seconds at 83.3 mph; that’s why we started this whole project in the first place. With the streetable White Brothers pipe set to medium-loud, we were making consistent 13.6 runs in the high 93s, with a best run of 13.59 at 94.43. This put our little Ascot well ahead of the times run by stock RD400s, and Japanese 450s, and not that far off the 13.20-at-97.5-mph best run of Yamaha’s new XZ550 Vision, which has one more cylinder and 50 more cc’s to play with.
In roll-on performance the FT took the competition and thumped everything but the Vision into submission. The GPz 550 Kawasaki is not exactly a torquer, but it is the fastest 550 in the standing quarter; the hot Ascot roll-ons were consistently 1.5 mph faster. Our Ascot picked up a solid mile per hour in its roll-on performance, which measures horsepower in the 4000- 5000 rpm range, and that’s not where we made the big gains in our power curve.
In the interests of science, we ripped the street baffle off the WB pipe and threw on the racing megaphone Dan had given us. It made the windows of the Orange County Raceway tower move in and out like the ribcage of a winded thoroughbred – the thing was LOUD. For all the discomfort the megaphone cost us, it did little for performance. The best ET was dropped a little, to 13.53, and terminal speed went up about three-quarters of a mile per hour. We took the megaphone off and waited for our eardrums to stop flapping.
Next up was the Kerker pipe with the street muffler. It seemed as loud as the WB pipe with 12 discs in, but its looks are much more refined than the delightfully racer-cobby WB pipe. The Kerker pipe’s performance was bit off the pace set by the White Brothers’ unit, which is understandable; the White Brothers built their pipe knowing exactly how far they were going to go in tuning the motor. The best run with the Kerker was a 13.72 at 92.78, a tenth of a second less quick and a mile and a half less fast. Roll-ons were likewise a bit slower; the average of all the runs was about one mph slower, or about the same as the stock Ascot’s roll-on speed. Kerker had also sent us a noisier competition baffle, and like the WB megaphone, it was more trouble that its damage to our eardrums was worth. With the competition muffler Jeff managed a slightly quicker ET than he had with the street muffler: a 13.64 versus a 13.72. Their terminal speeds were identical at 92.78. This indicates that Jeff made a slightly better launch with the loud pipe – but that horsepower hadn’t gone up enough to notice. It’s possible, in fact, that the loud pipe took a little power away at the lower part of the rev band, and that this helped Jeff keep the front wheel low enough to get nominally better starts. With the WB pipe muffled down a little, it would be hard to tell you’re riding a modified motorcycle at all. The stock jetting offered in the White Brothers’ carb kit suited the FT very nicely; the bike starts easily, idles in a civilized manner, and pulls through the rev range without flat spots. A violent tug on the throttle with the engine at idle will kill the motor in one gulp, but a slightly more restrained roll-on gives you flawless response. We’ve learned to use the fast roll-on as a kill switch – just don’t forget to turn off the ignition afterward.
Our new project bike is still very much an Ascot – only more so. Where the stocker was a mild-mannered but sure-footed leopard in the corners, our faster, cooler, stiffer, and prettier machine might be a bit more of a tiger. You can now imagine yourself flying off Ballaugh Bridge and setting up for the sweeper at Bishop’s Court, hearing that beautiful rhythmic bark as the throttle rolls on out of the apex, the sound echoing off the deserted hillsides like cannon fire. That must be Hailwood just ahead, his own Manx heeled over and sliding, his foot dragging the ground, his pudding-bowl helmet hunched over the black-leatherclad shoulders, the arms and knees held in tight to the tank… M
