Cycle News is a weekly magazine that covers all aspects of motorcycling including Supercross, Motocross and MotoGP as well as new motorcycles
Issue link: https://magazine.cyclenews.com/i/125791
management. "Well, we don' really t.e> iel too hot an engine, 0 Ie 'not operld too much on getting aU the potential out of it. I mean the American public wants a docile trail machine. And we can't make that ligh tweigh t frame and all at a profit. Besides, it might go fast, if we don't do something." So management and the marketeers did their number and, to some extent, they were right because Honda dealers are selling a lot of XL 250s. But, unknown to those japanese enginee,rs, they have secret collaborators in this country. There is a definite conspiracy among dirt bike riders (Probably acting with the aid of a foreign power; in this case, japan.) to make dirt bikes go fast. An increasing number of rider-racers have gotten their hands on the mid-size four-stroke and started developing the potential that was originally built in to it. Somebody really ought to tell those engineers at Honda R&D that it was all worth it. One of the hotter set-ups for the XL (Sounds like we're talking about a Harley.) has come out of the Hi-Performance Cycle Center division of Long Beach Honda. The HPCC· was recently established to focus entirely on off-road competition and recreation. They prepared the 250 Honda that Bob Hosford has ridden to several class wins in the highly competitive CMC night motocross at Ascot. Using that bike as a guideline and applying the lessons learned from motocross and the dyno, HPCC is now building up competition 250s for John Rice and jim MacDonald who will round out their team. A very scien tific approach is used in developing the XLs. There is trial bUL not much error as all mods are checked for efficiency on the dyno, including pipe length and configuration. There is no guesswork or opinion of the "Shore feels stronger".type involved with the set-up described below. IL either proved out on the dyno or it iSD't on the bike. OIl.... CHANGES The sLock carb was removed and replaced with a 32mm Mikuni that is fitted to the barrel with an HPCC manifold adaptor and CB/CL350 rubber manifold. The carb is rejetted and the slide seat modified (among other internals) LO geL the breathing righL throughout the power band. as indicated on the dyno. They also d'l""'loped a sligh t1y iercer €am in cdnjanction with Weber that pla~e the stock item. A piston with a more racerly look is substitu ted for the stock flat unit. To get the full advantage from this change, the head should be cleaned up. No radical metal carving; just smooth ou t the castings in the flame and valve areas and remove the excess around the guides that is left from the manufacturing process. While you're inLo the cleaning up, you also have to remove the step between the new manifold and the stock barrel. Otherwise you have an abrupt deflection of inlet flow. Since you've changed the carb, you'll also have to change the throttle linkage from the Honda two-way action to a universal type of Mikuni cable and spring return. It's no big thing, but it has to be done. A Kawasaki 250 quick throttle fits just right. & .. n 0.. ,.. '" en co ~ ::l .., CJ) ;: w Z W ..J U :> u REMOVALS The stock pipe, which weighs a hefty 14 pounds with muffler, is taken off and replaced with an HPCC pipe designed particularly for a bike via the dyno and detachable sections on model pipes, Both straight pipes and pipes incorporating silencers and spark arresters have ,been successfully designed. The pipe change alone is worth three or so horsepower (3.5 seems LO be a figure every body agreed on.) without any other mods. The stock seat is taken off and Lhat lightens the machille by about seven pounds. The seat on Bob Hosford's bike is plenty comfortable at 11 ounces. 1t's assumed that you already have the lights, instruments, etc. off the machine and have thereby saved the extra seven pounds. While you're unbolting, the stock shocks migh L as well come off aL this time, too. Hi-Performance Cycle Center relies on Lhe stock Honda frame. Bill Bell, who has guided the developmen L of the XL 250 as a racer, claims that it really isn't that heavy and is a good design. They don't cut it or modify it. Even use the stock springloaded footpegs and peg positions. The mounting tabs and brackets (for the seat latch, fork lock, etc.) are cut off to -keep it looking sanitary and Lhat's all. The removal of (Please turn to pg. 4'9) Carry your bikes, and camp meet Have anything you ever wanted in a van Sleep on a round bed or wall-to-wall Portholes· Built-ins· Custom swivel seats IF YOU DON'T LIKE OUR EXCITING STANDARD FLOOR PLANS,_ WE'LL BUILD IT YOUR WAY! Call or write now for information and the name of your nearest dealer H/J1,1IJ.6Y 7296 Murdy Circle, Huntington Beach, California 92647 Telephone: (714) 842-8787. I Bill Bell explains the principle of the motorcycle rear brake to a fascinated John R. You learn something new everyday. THE HONDA HOP-UP T AS Cam (Exchange) ,.' ,.' ..•... _ Piston (Built Up New) ........................•.................. Manifold (To Adapt Mikuni) , 32mm Mikuni " '.' ..•............... Up Pipe w/SiJencer '., , Downswept Pipe w/Silencer , ...•............ _......•.... Seat .. , , ,,, ,, , Head Porting , ', ,,, , , Your Piston Built Up .. , , , .. , ,.' , , , .. Engine Guard (Desert) , .. , , , Engine Guard (TT-Moto) . , .......•......•.........•..•. ' $29.95 $29.95 $14.95 $37.00 $29.95 $34.95 $39.95 $65.00 $22.00 $29.95 $24.95