Readers Rides: 1999 Honda VTR1000F Firestorm – Part 1

[Peon Maface]

When you think of a 1000cc Honda V-Twin sportbike from the start of the millennium, what comes to mind? Naturally, it’s the VTR1000F, right? Wait, what’s that? You’re thinking of the RC51? Well, Micky Garneau wasn’t. Granted he was looking for a street bike, but the time, effort, and money he’s put into his VTR1000F Firestorm, otherwise known as the Superhawk in the US, rivals that of many racebike builds we’ve seen. Here’s Part 1 of Micky’s bike build.

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The OCMD Chronicles

It’s referred to as OCMD, an abbreviation of Obsessive-Compulsive Modding Disorder. You won’t find it in any Compendium of the American Psychiatric Association, but that doesn’t mean it doesn’t exist. So, “what is OCMD?”, you ask. Well, to make a long story short, it’s an affliction that compels its victim to embark on a virtually endless process of “modding” to a specific object, in this case, a motorcycle. I bought my VTR used (with 15,000 km) in February of 2001, without a test ride (such was my faith in the unanimity of the various reviews I had read). Being in the throes of winter in Canada, I was counting the days until I could throw a leg over it. When Old Man Winter finally decided to aestivate, the moment of truth had arrived; I had never ridden a V-twin before and was not sure what to expect, to be honest. Off I went and my initial reaction was one of disappointment, for nowhere to be found was the rabid surge of acceleration I had expected from a literbike. It was compact and agile, but it seemed… slow. And so began my quest to make one medium metallic blue Honda VTR1000F the bike I hoped it to be.

Pre-OCMD… Needless to say, it’s evolved quite a bit in 19 years and over 260,000 km (160,000 miles).

Engine

Following my initial mild disappointment at power quantity and delivery, I set about bringing it more in-line with my expectations. The list of mods has been plentiful and the road has been long, and at times bumpy. Of course, lessons were learned along the way, leading me down the path to my current set-up:

– 99 mm (1mm O/S) JE forged pistons (claimed 11.5:1 compression ratio) with moly skirt coating

– custom Carrillo conrods

– balanced crankshaft

– lightened flywheel (-2.6 lb)

– ported cases (to improve internal airflow and reduce parasitic losses); in an attempt to further reduce parasitic drag, the two crankcase breathers have been routed together to a single Krankvent valve, which helps to create a slight partial vacuum in the sump, reducing drag while also improving ring sealing

– ported and decked (0.015″) heads; by my calculations, compression is up to just shy of 12:1, a significant jump from the stock 9.4:1

– Yoshimura Stage 1 intake cam (+5 degrees duration, +0.8mm lift) and OEM exhaust cam; lobe centers are indexed at 104 deg. intake and 107.5 exhaust, producing 36 degrees of overlap (stock is 35)

– DLC-coated valve buckets

– ceramic water pump bearing (for reduced friction)

I am unable to provide an accurate power figure as the bike has not been dynoed in its present tune.  The last dyno run, which dates back a few years, was done with an engine whose calibration was significantly inferior in a few key areas. For the record, the last readings were 123 hp and 77 lb-ft of torque. The current engine tune is noticeably more potent and I can conservatively (but confidently) estimate it’s pushing over 125 hp and 80 lb-ft of twisting force. To give that power slightly more vigor yet, the stock (tall) gearing (16/41) was lowered slightly (to 15/40, a drop of about 4%), adding a bit more zip without raising cruising rpm to excessive levels.

“V-twin inside” indeed! The heavily revised mill spools up with surprising quickness and smoothness, serving up copious amounts of instantaneous torque regardless of engine speed; chronic downshifters need not apply!

Intake

Freed of the obligation to meet stringent EPA sound requirements, to say nothing of production cost-cutting measures, I was able to greatly improve airflow into the twin jugs via extensive airbox modification. Capping off mods to the lower portion of the box, a heat reflection film was applied to the underside (as well as the carburetor fuel bowl exteriors), helping to diminish the intake charge density-reduction effect from the heat radiated by the engine.

The OEM airbox bottom on the left, the modded version on the right. As you can clearly tell, the airbox was emptied of all internal plumbing (ie. crankcase venting tubes and chamber), increasing its effective volume. It was also expanded where possible (via the removal of the venting tube mounts and a re-shaping/expansion of the cavity in the upper right corner). Finally, a 10 mm spacer was added to lift the lid, the end result of the combined efforts being an approximate 1.5 L effective gain.

On the topside, the intake snorkel was dispensed with and the filter element was moved from the inside (ie. a blade filter) of the box directly into the lid, dramatically increasing air entry area. This (and the aforementioned spacer) also helped to dramatically open up space in the critical area above the velocity stack bell mouths, as well as creating a direct path into the stacks. Why is this important? In one of my many Google research sessions, I stumbled across some information that laid out the case for the critical importance of free space in the area immediately above the velocity stack bell mouth. More specifically, a testimonial from a gentleman who did work on Porsche racing engines indicated a gain of over 3% in engine power from freeing up the area 5 cm above and 2 cm beside the bell-mouth openings. The directness of the intake air path is also critical and some may recall that Aprilia engineers paid particular attention to this very element when redesigning the RSV4 airbox for the 2015 model-year.

The stack are billet pieces, to which I adapted a set of custom Boyesen X-Wing replicas fabricated from sections of brass plate, these essentially converting the Keihin 48 mm CV carbs into two-barrel units. The product of a chronic OCMD episode, it turns out these units work extremely well, the engine being noticeably stronger than before at partial-throttle settings. Who doesn’t like a successful experiment? Further downwind, the carb throats were matched to the rubber boot and intake port, ensuring a smooth airflow free of any unwanted turbulence.

Breathe, baby, breathe!

The carbs received some attention too, including needles by HRC (Honda Racing Corp). The slides use the stock two-hole arrangement (numerous other configurations have been tried). Slide springs are by Dynojet, these being shorter and lighter than stock. Fuel screws are custom made longer units that can be easily adjusted by hand. Finally, both the main jet and pilot circuits are fitted with Flo-Commander units, these evening out and controlling airflow into their respective air jets. More importantly, they allow quick and virtually infinite fine-tuning of the jetting, a handy feature to quickly adjust for the temperature variations one encounters in Montreal, Quebec. They were shipped to Factory Pro to have a set of their High Dispersal needle jets pressed in. These are said to greatly improve fuel atomization and a close inspection of the engine running with the airbox lid off reveals the claims to be true. The last pieces of the puzzle are an HRC 1/6-turn throttle tube for quick response and a Vista-Cruise throttle-lock for short-term relief on long rides.

The front cylinder velocity stack is from Moriwaki (rear left in picture) and the rear cylinder gets a longer unit from HPower (rear right in picture). These were selected for their positive contributions to mid-range power.

Exhaust

The first exhaust modification consisted of replacing the stock cans with a set of Micros slip-ons. These were eventually replaced when the urge to put a 2-1 system to the test got the best of me (I still dream of getting my hands on a lovely and lightweight Yamamoto titanium 2-1 full system but have all but given up on the possibility of it ever coming to fruition).

A fellow superhawkforum member (who resides in Europe) alerted me to a pristine Akrapovic full system for sale on the German eBay site. A successful bid was submitted and, after some harrowing days which included a personal intervention from said forum member’s law enforcement officer sibling, the Akra finally showed up. It was equipped with low-mount link pipes but I have since bought high-mount links and the requisite carbon supports. However, these remain in storage as I like to keep the passenger pegs handy to take my daughter for the occasional ride. I ended up getting the system coated with a black heat retention coating, augmented with heat wrapping. This helps to not only isolate the sump from the heat emanating from the front downpipe, but it also keeps heat in the pipes to help improve gas flow and scavenging.

A renowned engine builder tasked with doing development work on the then-new VTR for Moriwaki noted a 4 hp gain (on dyno) from proper heat wrapping of the entire exhaust system.

Transmission

The stock VTR has decent, but not stellar shifting. As the First Law of OCMD clearly states “when there is room for improvement it must be acted upon.” This had to change. So, the transmission was treated to a complete Factory Pro shift kit, consisting of shift star and detent arm. Hyperplate aluminum clutch plates (hard anodized and cryogenically treated) took the place of the OEM steels (for weight savings) and Barnett springs help keep things from slipping. The stock shift lever was replaced with a billet unit from Daugherty Motorsports (DMr). The original pivot bushing was replaced with a needle bearing for both tighter and more fluid action. A Woodcraft folding lever tip was added for added protection in case of a fall-over. The shift linkage heim joints were replaced with high-end versions which are significantly tighter than the stock units. Also, a shifter shaft support (fit with a needle bearing) was recently added to remove any remaining play in the system.

Cooling system

The VTR is borderline thermally-challenged in stock form, a side-effect of Honda’s decision to equip it with side-mounted radiators. While this design helps contribute to the bike’s trademark slim profile, it comes with a significant downside in that it counts on a pressure differential created outside the lateral air scoops to pull air through the rads for cooling. This pressure differential is speed-dependent, so the VTR struggles to stay cool at anything below highway speeds. Its ability to cool is also put to the test when outside temperatures start to climb. This is true with a stock 9.4:1 compression ratio, and so one need not be a specialist in thermodynamics to know that upping the internal squeeze ratio to roughly 12:1 could play to its Achilles Heel. So, in order to provide additional cooling capacity, the stock two-row oil cooler was dispensed in favor of a larger four-row unit from a Honda EX400 quad. The replacement was not a straight bolt-on, however as one of the inlets was angled at 45-degrees and so had to be rotated at a local radiator shop.

Upping the engine’s compression ratio creates heat, so many avenues that could potentially help evacuate it more efficiently were explored. One that was acted upon was the insertion of a finned inline cooler (designed for a Polaris RZR 900 UTV) mid-way into the lower rad hose.

The quest for cooling efficiency also led to the replacement of the stock coolant fan with a high capacity SPAL 5.2″ pusher fan. As an added bonus, fan replacement and removal of the stock shroud netted a weight loss of almost one pound. Not comfortable with seeing the analog temperature gauge creep up on occasion (desperately waiting for the fan to kick on automatically), I installed a manual fan switch, allowing me to proactively turn it on. Finally, the stock rubber hoses were replaced with blue Samco (silicone) hoses, this mostly for aesthetic and durability considerations.

Electronics

With its carbureted engine and absence of any hint of rider aids, the VTR is definitely more analog than digital. There is still room for OCMD play in moving electrons around and an HRC ignition control module (with no rev-limiter… don’t ask!) controls the spark. The stock coil packs and high-tension leads were eventually replaced with OEM stick coils from a CBR600RR. These were eventually led out to pasture as well, replaced with Takai Racing Weapon-X coils, again CBR600RR models.

The OEM “chin fairing” was dispensed with partly for aesthetic reasons, but mostly to provide the engines cases and sump better access to cooling air (as an added bonus, it shed 0.7 lbs of weight too). This, however, left the oil filter exposed (and vulnerable), so a carbon fiber oil filter protector originally designed for a CB1000R was fitted to address the issue. At some point, I’ll get around to having a set of custom, braided oil cooler lines made up.

The stock (and problematic) shunt-style rectifier-regulator was first replaced with a more reliable “mosfet” type before finally giving way to a series-type unit (Shindengen SH847AA) from a late-model Suzuki V-Strom. Why the change? My research indicated the series version was more accurate and reliable, but even more importantly, its design allows the stator to only provide the current necessary. This reduces the load on the stator, reducing its temperature and helping to improve its durability. It also reduces load on the engine, freeing up power to drive the motorcycle forward instead of creating energy that will only be shed as heat by the regulator. Less heat, less drag, what’s not to like? To keep a close eye on the charging system, an LED voltage monitor has been installed in the instrument cluster, helping to easily monitor any changes in the system’s status and operation.

LED lighting also found its way into the headlight (Cyclops 3800 Lumens H4 replacement LED kit), the front turn signals (by Proton), and taillight (with integrated turn flashers). Better visibility, unlimited lifespan, and reduced energy draw, it’s all good.

Lastly, the cherry on the sundae was the addition of a HealTech QuickShifter, the unit’s ignition-cutting design making it adaptable to carbureted engines. Quickly adjustable via a smartphone app, it gives flawless performance when called upon.

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There’s a lot more to Micky’s Superhawk build. A lot more. Stay tuned for Part 2 of this story next week.

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We’re suckers for nice photos and descriptive words and reasonably decent pics of your favorite motorcycle, or maybe just your most memorable one for all the wrong reasons? Send yours to contact@motorcycle.com, title it “Readers’ Rides,” and see yourself in this spot one of these weeks.

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