TBM Racing's Limited-spec SX-R PDF Print E-mail
Written by By Josh Burns / Photos by Blake Conner and Josh Burns /Personal Watercraft Illustrated / May '05   
Saturday, 09 June 2007 16:00

Ask anyone with a modified boat what they hate most, and the majority of them will tell you wrenching on their craft. In the racing world it's commonplace for parts to get added, changed or rebuilt in an effort to constantly keep the craft in prime condition for competition.

For factory teams or racers with mechanics, this constant shuffle of changing major parts is reality. But for the weekend warrior and privateer racer - which constitute almost everyone in the race world - having to tear apart an engine every other race is nearly impossible.
What about the go-fast recreational guys - you know, the guy who never sets foot on a racecourse but wants to have the quickest craft on his local waterway? Having to wrench on a play boat regularly makes riding more of a chore than anything.

TBM Racing is offering a craft that will hopefully alleviate the worries of both parties. TBM Racing owner Tim Bushman is no stranger to stand-up racing, as the Expert Limited World Champion and Superstock National champ has put in quite a bit of "track" time. It's pretty fair to say he's no stranger to wrenching on craft, either. Pretty much since Kawasaki introduced the SX-R, Bushman has been racing it, and he has subsequently been involved with working on different ways to improve upon the already good platform.
Roughly a year and a half ago, Bushman started TBM Racing, a small business that provided a handful of parts for the SX-R. This year, TBM's number of parts has increased significantly - enough so that Bushman has teamed up with Kent Kawasaki to offer a Signature Series Limited race boat. The reasoning behind producing the ski?

"The idea is to build a turnkey performance package to get more novice and junior riders in this sport without having to build it up on their own," Bushman says. "It's designed to be a competitive performance package that comes right off the showroom floor at a discounted price. It is basically a trimmed-off version of a race ski that doesn't have all the parts that a novice racer would not need." Bushman looks back to his experience when he first started racing, and he knows that more wrenching means less riding.

"We were working on them more than riding them," Bushman says. "You've got to be out on the water and not in the shop to get better. Basically, this is a recreational or race ski that you can ride without really sacrificing reliability over the stock package."

TBM Racing has paired up with Ultimate Watercraft in Hayward, California, to build the units, which will be sold through Kent Kawasaki in Washington. Kent Kawasaki, which has been around since 1977, has been promoting racing for roughly 20 years. This partnership between TBM Racing and Kent does offer a few good things to the customers, because Kent Kawasaki can offer financing on craft, and it regularly ships units across the country, which it says can be done in a pretty inexpensive manner.

When Bushman first contacted me about the project, he mentioned that his SX-R package would be similar in scope to the now-defunct Polaris Octane. It would include a number of performance-enhancing parts, but it would be put together in a very reliable package - so that a person wouldn't have to worry about wrenching on it on a regular basis. The package includes a number of parts one might expect in such a package, but overall there's not much that's over-the-top or flashy - just the right combination of components to produce a strong increase in performance.
Although the engine receives some updates, TBM Racing claims the reliability factor of this craft should not be a problem. First thing to get changed in the engine is the stock cylinder head, which is replaced with a TBM Racing Head Kit. The two-piece head's body and cap are machined from 6061 billet aluminum, which is a durable material that TBM Racing says is rarely used because of its cost. TBM Racing says the two-piece head design allows for improved water-flow control that cools the cylinders evenly - something that is not possible with a one-piece head. The head, which comes in both a girdled and non-girdled design, also requires no gaskets or silicone, as it is completely sealed by O-rings. Although TBM Racing offers domes that range in size from 19cc to 29.5cc, it equips the 29.5cc domes on the engine for this kit. Constructed of 7075 aluminum alloy and hard-anodized for even heat distribution and corrosion protection, these domes are said to feature a unique bowl design that offers improved performance over the different spherical configuration used on other domes. The domes also feature a stepped squish-band design that recesses the squish band slightly into the bore to provide the optimum piston clearance for the most efficient burn.

For simplicity, TBM Racing equips the craft with a Factory Pipe SX-R wet pipe, which isn't quite as demanding as the dry pipe and therefore doesn't require a girdled head. The wet pipe also doesn't require any modification to the stock hood for installation, which the dry pipe does. TBM opted not to run water injection with this package. The stock ignition is retained, but the timing is advanced to accommodate the pipe.

The carburetors are left stock on the TBM SX-R, though they are rejetted to fit this application, and the choke plates are removed to increase airflow. A primer kit is installed for easier starting, and Hot Products flame arrestors are installed to improve airflow to the engine.

Also installed on the craft are TBM Racing reed spacers, which position the reed cages in an optimal position for fuel atomization. The spacers feature a full 3 degrees of angle. They also include an integrated pulse line. It is not needed for this kit, but the second pulse line is there should the customer decide to add aftermarket carbs in the future, so there's no need to drill into the crankcase. All in all, the spacer's main benefit is to increase acceleration and midrange power, as well as prolong reed life, since it pulls them further from the crankshaft turbulence.

V-Force reeds are also installed on the SX-R to increase the bottom end and midrange.

A TBM Racing billet flywheel vent plug replaces the plastic flywheel unit. To remove the stock piece, you normally need a wrench, but TBM's billet vent plug can be taken out with your fingers to relieve the air pressure.

While the stock handlepole has been kept, TBM Racing's spring tensioner is installed. TBM Racing offers two different heights, but the standard height is used for the stock handlepole. (The shorter height is ideal for aftermarket aluminum handlepoles.) U.M.I. 4-degree Freestyle handlebars replace the stock bars, and Renthal Grips are installed for grip. For reinforcement, TBM Racing's billet front-hood latches replace the stock pieces, which TBM claims can wear and even break over time.

For handling components, a TBM Racing Super Scoop replaces the stock intake grate. Bushmans explains that the biggest difference between his grate and others lies in the primary scoop, which on his grate covers the entire width of the pump shoe, while its wing design grabs water all the way out to its leading edge. TBM Racing's rear sponsons are also equipped to the signature SX-R. The sponsons, which are constructed of 6061 billet aluminum and use stainless-steel inserts, provide a little extra edge in the corners that really bites into the turn. Bushman explains that he has spent countless hours fine-tuning this design. The stock ride plate is retained on this unit, though TBM does modify it by making a "D" cutout. Bushman says that he hasn't found a plate on the market that works better than a modified stock plate.

An Impros/Solas impeller is used in place of the stock unit, but it is bent and repitched to work specifically for this package. Not much is done to the pump, though the stock nozzle is bored just a bit to match the impeller to optimize the powerband. Though mainly cosmetic, at the stern a TBM Racing billet flange replaces the stock exhaust opening.

One of the most important features of this craft is that it runs on 91-octane pump gas, which is premixed with oil at a 32:1 ratio.

After talking about the craft and what went into it, it was time to take it for a spin. Having ridden the SX-R in quite a few different versions, from Superstock to Limited to full-blown surf skis, it's tough to compare the small nuances between them. Unless you're talking about top speed, which can vary greatly, it can sometimes come down to splitting hairs. But the one way to always bring it back into perspective is to compare any craft to a stock SX-R, so we brought along a stock 2005 800 SX-R for comparison.

We performed radar runs while the waters of Long Beach, California, were still smooth and the air was cool. The TBM Racing SX-R had a pretty impressive top speed, as our Stalker radar gun nailed it at 56.15 mph. This is a gain of 7.64 mph in top speed over the stock craft, which only went 48.51 mph - and the TBM Racing ski got there much quicker, too. (See radar graph >>) The acceleration was notably better as well, with the TBM SX-R jumping off the line and going from 0 to 20 mph in under a second (0.95 seconds). It took the stocker 1.76 seconds to cover the same ground. It showed marked improvement over the midrange as well, as the stock unit took 1.57 seconds to go from 20 to 35 mph, while the TBM Racing SX-R only took 1.32 seconds. We gauged the peak rpm at 7290, which is quite a bit over the stock setting of 6250 rpm but still in a respectable range that won't cause concern for those looking to stay away from the toolbox. All in all, the performance numbers looked pretty good. But how does it ride?

I may have said it once, but I'll say it again: The SX-R is a pretty awesome ski in stock form. It offers enough power and performance to keep even experienced riders entertained. With that said, TBM Racing's package is designed to offer notable performance gain - not just in speed, but also in turning prowess and handling ability. With our makeshift buoy course setup, we learned pretty quickly that this thing carves turns very well. It pulled away from the stock craft on the straightaways with ease, and it can be railed through the turns like a hot knife through butter. The SX-R is a pretty confident turner in stock form, and the added components of this package only enhance this quality. Even when chasing a rider around the buoy course, the TBM Racing SX-R stayed glued to the water and was not easily deflected. In simple terms, the biggest difference is that the TBM Racing SX-R can go through turns faster and harder, and still with a high level of confidence.
Jumping from ski to ski, it was obvious that there is quite a bit more hit on the TBM SX-R compared to stock. It certainly accelerates quickly and felt fast on the straightaways, but the good thing is that its power is very usable and not overwhelming. The TBM Racing SX-R carbureted cleanly and had a very clean, smooth power delivery.

If TBM Racing was looking to produce something comparable to the Polaris Octane - which retailed for $7,999 in 2004, the last year it was readily available - then this fully exceeds expectations. Our last test on the Octane pegged it at close to 54 mph... and TBM's ski is at least 2 mph faster than this. Not to mention that the SX-R has a great natural turning style that is in another league compared to the Octane. So, in that respect, there really is no comparison.

Really, this is a great ski for someone who wants to purchase an SX-R with a little more power. It would be a really great craft for a recreational rider who wants something just fast enough to beat his buddies, but it is even more ideal for beginning or intermediate racers who want something they can ride day in and day out with little or no concern of it breaking down. The package is well put together and well thought out, and its performance speaks for itself. And in case you're wondering... it is Limited-class legal. While TBM Racing is looking to expand its line to cover more than just the SX-R, its focus on this one craft has led to what Bushman feels is the most complete product offering for the SX-R. If this well-rounded package is any indication, we might have to agree.

TBM Racing's Signature SX-R model can be purchased through Kent Kawasaki. Contact Kent directly at 253/852-8670. TBM Racing products can be ordered directly from Hot Products.


Last Updated on Sunday, 28 June 2009 18:50

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