Custom Yamaha YZF R1 - Semi Serious Business

Motorcyclist's Project YZF-R1 Makes The Big Transition From The Gum-Flapping Stage...

It all seemed so natural and simple in the beginning. The time had clearly come for our local expert roadracer/test-pilot Curtis Adams to upgrade from his slightly used GSX-R1100 if he intended to ever again beat long-time Willow Springs Motorcycle Club nemesis Chuck Graves. And semi-retired technical consultant Kaz Yoshima, of Ontario Moto Tech fame (e-mail, wanted to see what he could do with an R1 and a rider capable of shoving it to the front.

Willow's Toyota Gold Cup Formula One race is the money event every third Sunday of the month, with run-whut-ya-brung rules just like the ones in the AMA's Formula Xtreme class. Heh heh.

Our boy Curtis fell off an Attack Performance bike at the last AMA Xtreme race held at Willow, in 1998, but is game to try again. After that last one, some unkind things were said on the podium by a young Erion Honda rider, to the effect that some of the locals had been riding over their heads. Yes, Curtis said, and I can do it for 25 laps (most of the time anyway). Our Curtis does have an assertive style, all legs and elbows and alpha-male ego. I wanted to call us Curtis Interruptus Racing, but got voted down again.

A plan evolved: to beat the factory teams at the next Xtreme race. Why not? Kaz builds the bike, Curtis brings home the trophy, I show up in time for the champagne and laurel wreaths. So far it's not working out that way.

PACE screwed up everything by starting up its new race series, and offering enough prize money to render Curtis unable to just say no. In PACE's mislabeled "Unlimited Superbike" class, though, you can only have 145 rear-wheel horsepower, have to use the stock fork, stock gas tank, etc.-which means our all-out R1 needs to be two bikes in one, and therefore twice the work.

We chose the R1 because it's the lightest package 130 horsepower comes in. Yamaha gave us the customary industry-guy discount and we paid for the bike. OK, our man Brad Bannister at Yamaha also hooks us up with the occasional wheel bearing and brake pad (OK, spare wheels, some levers, oil filters, 10 head gaskets, two cases of oil, etc.), but there's no factory stuff on this bike. Everything was bought or built by Yoshima or obtained from one of the following sponsors.

At this level it's all about tires, and to do well you need more of them than any magazine should ask for. We're using Dunlops because Curtis has raced on them for years, and because Curtis earned the tire deal his own damn self. Dunlop, in fact, uses C.A. as a regular tester; if a tire lives at Willow in the summer under C.A., it's a pretty good tire. Long-time proprietor of Dunlop's West-Coast-based Sport Tire Services (805/226-9410) Dennis Smith sponsored Curtis to a pair of 16.5-inch Marchesini wheels. The 16.5 rear's been in use for several years; the 16.5-inch front is a recent innovation. It puts down a bigger contact patch.

The Marchesinis are lighter than the stock wheels. You already know that less unsprung and rotating weight aids acceleration, deceleration and suspension action. Did you know lighter wheels make a bike much easier to turn at 150 mph due to less gyroscopic force? Curtis tells us the real advantage comes when muscling the bike into Willow's fastest turns.

Penske (610/375-6180) has been making dampers for race cars for years; its motorcycle shock is now the right motorcycle thing to do as well. For starters, its three-way adjustable shock has separate low- and high-speed compression damping adjustments-which means you can tune the rear to absorb bumps and big G-outs. Also, a check valve means adjusting the rebound circuit doesn't also affect compression, as is the case with other shocks. Apart from that, it's a well-machined piece, carved from 7075-T6 aluminum, and you can revalve it yourself (but you need a nitrogen bottle to recharge it to about 200 psi afterward). Our piggyback-reservoir, three-way unit sells for $1125. (You can get a titanium spring for $600 more, and lose a couple of pounds.)

Our big creepy friend Tom Houseworth at Yamaha Factory Racing was going to loan us an unused hlins fork off one of his many R7s, but never quite did. Just as well, since we wouldn't be able to use it for PACE anyway. A little fettling of the stock R1 fork, a couple of R6 race-kit rebound-damping internals, a little Kaz massage-and the stock fork works pretty well.

Kaz thinks the R1 doesn't get enough, thus the U-boat surplus shnorkel, which picks up air from above the windscreen (Lockhart Phillips) and shoves it into the airbox through a hole in the gas tank. Gas tank? For PACE, we'll have to return to the stock steel one, but for now we have a beautiful and 4.8-pound carbon-Kevlar weave FuelCel from Erospace Technologies Inc. (561/388-0966 or com/fuelcel). Carbon-Kevlar is what they use in military fighter aircraft, it saves seven pounds, it's much more ergo than the stock tank (more like the R6)-and the nice Erospace man put the four-inch hole right where Kaz wanted it, all for $1360 ($1160 for the standard R1).

And the FuelCel was designed to fit over and seal our Sharkskinz airbox. We've looked at-and crashed-all brands and types of bodywork, and like Sharkskinz best. A combination of fiberglass and resin, this stuff arrives primed and ready for paint after just a little sanding-but mostly it survives crashes better than its competition. Our R1 is currently wearing Sharkskinz' R7 kit, designed to fit R1 mounting points. Cool. The one-piece upper sells for $360, the lower for $240, and the tail for $235. For PACE, of course, we'll have to have R1-pattern bodywork, just to make it a little more difficult. Thanks. (Dial 561/388-9621 or check While we're at it, moto-enthusiast Jim Granger at Granger's Classic Auto Body in Reseda, CA, remains a soft touch for Motorcyclist project paint jobs (818/881-4558).

Kaz is liking the Mikuni rearsets we got from Yoyodyne because they move Curtis' big-ass feet 31/48-inch or so rearward compared with the competition and make him think the rear spring is softer than it is. Part of the epic struggle we're involved in here is Curtis' soft-in-back, spin-the-tire-out-of-every-corner philosophy vs. Kaz' firm resolve to get him to hook the back end up and accelerate. Every time that tire spins, Kaz is fond of saying, equals one bike length at the end of the straight.... The Mikunis also contain needle bearings, which help the bike's shifting. They're uncheap, at $595. (Yoyodyne is at 973/401-1954 or

The R1 needs a steering damper. In fact it needs two steering dampers. The one we have is a transverse-mount hlins unit, which is very cool in that it is an entirely bolt-on affair and mounts out of harm's way. The downside of it, for racing, is that it has to be removed every time the fuel tank has to come off, but it comes off easily. It sells for $571.95, from Parts Unlimited (

Yes, there's one in there, and Kaz tells us it's stock except for some head and valve work and a three- to five-degree advanced intake cam. The starter motor's still there, and right now Kaz estimates 160 horsepower or thereabouts, without the snorkel. With it, Curtis reports a top-speed improvement at the end of Willow's front straight of 10 mph, according to the bike's digital speedo.

The hard part so far has been making the bike carburet right with the snorkel, balancing float-bowl pressure against carb-throat pressure. When it's right, it's very good, and C.A. must chop the throttle to keep from wheelying over backward through Willow's humped Turn Six. When it's bad, it's dangerously bad, but the only way to get it right is through repeated, educated trial and error. A nice bank of flat-slides would be easier to tune and would give more immediate throttle response, but that would be too easy, wouldn't it? And Kaz wouldn't have it. Instead, he's heavily modified the stock CV carbs, including tricky, epoxied-up float bowls with removable plugs that make main jet access possible without removing carbs or airbox. We would've avoided it all if PACE hadn't mandated stock carb bodies for its series.

The LeoVinci Ti exhaust is sweet, light, makes good power, not too loud and not too expensive at $781-but it needs to be removed to drain the oil. We don't like that. (Indigo Sports 770/719-3800 or;

It's amazing how quickly this Glorious Racing stuff becomes work. Work for me: I'm a certified tire-changing fool and parts scrounger. Work for Kaz: We're all growing tired of hearing how late he was up last night and how stock the bike is. Mostly though, work for Curtis: He's the poor schmuck who has to ride a bike that I repeatedly take apart and put back together. What a manly man he is, though; Cletus' 100-mph wheelies over Turn Six and flying-squirrel tales of sliding both ends at 150-plus in Turn Eight leave our mouths agape back there in the pits. His daring jabs up the inside of Turn One have the crowd ooohing. and the girls swooning.

And then the big galoot high-sides himself off while pulling out of the garage last week en route to a practice session, on a cold tire-knocked himself out cold and thrashed the right side of our bike. Why do we subject ourselves, after all these years? Why do we keep coming back? It's all right to cry, sometimes'