Sunday, 11 November 2012

Bimota V-Due 500 - The Bike That Killed Bimota

In 1996-97, Bimota was set to introduce a new machine that would revolutionize sport bikes. It would be an unstoppable, razor sharp 500cc two-stroke that would give 1000cc four strokes a run for their money, in a time when it appeared that two-strokes were on their way to the boneyard. There was a lot of excitement brewing around the forthcoming V-Due (literally, V-twin) - not only because of the mouth-watering specs and the fact it was being built by one of motorcycling's most legendary boutique marques, but also because it promised to fix the "problem" that two stroke road bikes were facing.

That "problem" was increasingly strict emissions laws. In the 1990s 'strokers were getting phased out, quickly, due to stricter EU and EPA emissions requirements. They were being relegated to off-road and track use - as either motocross machines or track-only racebikes, with street legal bikes an impossibility in the US and Europe in the face of the new restrictions. Two strokes, by their very design, are nasty polluters. Not only because of the mix of oil and fuel required to lubricate the bottom end, but also by the nature of a two-stroke cycle.

You might want to skip over this next bit if you get bored to death by technical theory.

A two-stroke operates by simplifying the usual four stroke cycle. Four strokes are "suck-squish-bang-blow" - intake charge of air and fuel on downstroke, compression stroke up, ignition and push of piston back down, exhaust stroke up to expel gasses. Valves in the top of the combustion chamber open to let the fuel/air in, close to allow compression and ignition, then open again to let the exhaust gas leave. Repeat. Two strokes have two cycles - suck/blow-squish/bang. The "valves" are open ports in the walls of the cylinder, routed through the crankcase. When the piston goes down, it pulls fuel mix in on one side of the chamber while simultaneously forcing exhaust gas out the other side. When it goes up, the chamber is sealed, compression is made, ignition, piston goes back down. Repeat.

The advantage of 'strokers is far more power per displacement than a four stroke of equivalent displacement. Sometimes double - a 500cc two stroke is roughly equivalent to a 1000cc four stroke. But in a much lighter and simpler package. Hence why the V-Due was so hotly anticipated - here was a lightweight supersport with top shelf components that could eat bigger sportbikes for breakfast. It was hyped up to be the closest thing to a road legal GP bike since the RG500 and NS400R bowed out in 1987. In fact, it was touted as a legitimate GP bike for the road - the original V-Due was a racing project that was later switched to a road bike program. Power was expected to be 110hp in a bike that weighed just over 300lbs - remarkable numbers for the mid 90s, when a typical superbike was easily 450-500 lbs.

The disadvantage of 'strokers is short service life (frequent bottom end rebuilds) and terrible emissions. Up to this point two strokes used carburettors - a carburettor will flow fuel constantly, even when the throttle is closed, because it delivers fuel based on the vaccum of the intake. The most strictly controlled emissions are usually unburned hydrocarbons (unburned gas) making its way into the exhaust. It's a problem on four strokes as well. Two strokes are especially bad because the exhaust and intake ports are open at the same time - so raw fuel mix will always flow across and get into the exhaust no matter how carefully you tune the engine.

Still awake? Good, back to the Bimota.

Why was the V-Due the only game in town, and why was it so anticipated? Because Bimota claimed they had fixed the emissions issue by developing a fuel injected two-stroke with electronic ignition, something that had never been done in a motorcycle before. Direct fuel injection delivers a jet of gas when needed into the cylinder, and shuts off completely when it isn't - unlike a carburettor. You can time fuel delivery precisely so it won't slip through the combustion chamber and into the exhaust, and the electronic ignition can time the spark to ensure a full burn. The V-Due also used forced lubrication for the bottom end, with only minor oil mixing required to lubricate the pistons. It was topped off with a trick cassette gearbox and dry clutch, racy stuff for a road bike. So, some revolutionary technology and clever engineering and the two-stroke lives to fight another day. All eyes were on Bimota, and some early press reviews praised the handling and power the V-Due was going to offer.

With this kind of hype, disappointment was inevitable. And boy, was the V-Due a disappointment when it hit the market.

The first production models arrived in 1997 and right away major problems became apparent. Yes, they passed emissions testing and the bike was 50 state legal - but the fuel injection system was not at all sorted out, and the bikes were almost completely unrideable. Throttle response was terrible, the engine hunted badly at steady speeds, and power delivery was extremely violent and only came on at the top of the rev range. While it was light and quick, power wasn't up to snuff among the crop of high powered superbikes that began to emerge in the late 90s. Aside from being despicable to ride it also had electrical faults, a tendency to foul spark plugs, and had some major mechanical faults that led to piston and crank seizures. Oh, did I mention that this half-baked Italian cost about $30 000 (£14500)? Yeah, that definitely did not help the reputation - especially among UK magazines where writers have a penchant for being brutal in their reviews when something doesn't measure up.

It wasn't all bad. While the in-house engine design (built by Franco Morini Motori) was more or less a turkey, the chassis was brilliant. It looked sexy and had stellar handling, helped by a dry weight right around 320 lbs. Front suspension was courtesy of Paoli, rear by Ohlins. Brembo Goldlines took care of stopping power. Carbon fibre was used liberally. It looked the business and could find its way around a track, even if it didn't run properly. Like many Italian motorcycle fans have said since time immemorial - it's brilliant, when it's working.

It quickly became clear that the V-Due was a liability for Bimota. They began accepting returns and in 1998 they release the Evoluzione upgrade - which ditched the wonky fuel injection for a pair of 39mm Dellorto carburettors. Suddenly the modus operandi of the V-Due (introducing modern FI to two strokes) was ditched in an effort to simply make the thing work. But it was a case of too little, too late. Bimota went bankrupt in 1999, after having produced 340 V-Dues of the proposed 500 example run, 21 of which were the Evoluzione.

But all was not lost. One of the project engineers, Piero Caronni, bought the remaining bikes and spares when the company went into receivership. He subsequently began modifying and fixing the issues, culminating in the Evoluzione 03, Evoluzione 04 and Edizione Finale models - introduced in 2003 and 2004. All used carburettors and modified engines with much improved reliability. Power was up as well, to 120 hp for the 03 and 130hp for the 04 and Finale. These sorted bikes have a strong cult following, with dedicated owners who are quick to dismiss the bad reputation surrounding these machines.
The V-Due Stockpile. More info about the post-Bimota V-Due can be found at

Today you can still encounter the odd "new in crate" V-Due that has escaped modification and retains the original, flawed injection system. There are a few die-hard fans out there who work hard at modifying and tweaking the FI system to make it functional - and with the recent advances in fueling and ignition, as well as dyno tuning, some people are succeeding at making a rideable fuel injected V-Due. I tip my hat to these brave souls.
If nothing else, it was a very pretty failure.

Technology has advanced a lot since 1997, and today fuel injected two strokes are available (if not common). Unfortunately the dream of a high powered, light weight, two stroke, road legal sportbike died with the V-Due. It also killed Bimota, who were fortunately resurrected in 2003 under new management. Today the V-Due has a small, loyal following among die-hard Italophiles and two stroke enthusiasts, a contingent who keep the dream alive and save the V-Due from reviled obscurity.          

Ed. Note December 2013 - Since writing this piece in 2012 I've learned that the main problem with the V-Due is improper crankcase sealing due to flaws in the crankcase castings, not simply a wonky fuel injection setup. You can fix a V-Due! Bob Steinbugler at Bimota Spirit offers newly manufactured crankcases that fix this issue and allow you to rebuild the V-Due into the screaming sport weapon it was meant to be. If only Bimota had known... 

Interesting Links and Image Sources
Bob Steinbugler's Bimota Spirit site - one of the premier North American Bimota specialists and one of the only shops that can sort out a V-Due
Click here for an optimistic period (1997) preview of the Bimota V-Due from 
Click here for a recent article on direct injected two-strokes making a comeback from Cycle World.
A US-based specialist website with shop manuals and details about repairs and spare parts.
The post-Bimota home of the Caronni V-Due, where you can find details about the Evoluzione models as well as reviews and manuals.

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