Suzuki Rgv 120 Engine Diagram

Suzuki RGV 250

Make Model	Suzuki RGV 250
Year	1991
Engine	Liquid cooled, two stroke, 90��V-twin, reed valve.
Capacity	249
Bore x Stroke	56 x 50.6 mm
Compression Ratio	7.3:1
Induction	Mikuni TM34S
Ignition / Starting
Max Power	62 hp 45.2 kW @ 11000 rpm
Max Torque	39 Nm @ 11000 rpm
Transmission / Drive	6 Speed / chain
Front Suspension	Upside down forks adjustable preload.
Rear Suspension	Monoshock adjustable rebound, compression and preload.
Front Brakes	2x 300mm discs 4 piston caliper
Rear Brakes	Single 210mm disc 2 piston calliper
Front Tyre	110/70 R17
Rear Tyre	150/60 R17
Seat Height	766 mm
Dry-Weight	139 kg
Fuel Capacity	16 Litres
Top Speed	130 mp/h
Manual	diff.ru/manual/files/Suzuki_RGV250_Service_Manual.zip

The 1991 RGV250 delivers yet more race track technology to the road/David Lancaster

hen someone, somewhere, comes to look back on the 1980s with some degree of hindsight, they might find themselves looking rather closely at the 250 class. Closer than some would have predicted. The capacity that new legislation threatened to kill off has survived a few lean years, and now makes young men and women drool at the sight of the latest hot kit from Japan. But what is more interesting perhaps is the technological battlefield the class has become. Freed from the public-spirited, legislation-conscious pressures that larger capacities have to live under, the 250s of today can, well, go balls-out for speed and handling without hindrance.

And that's exactly what they're doing. Suzuki's new RGV250M marks another step towards two-stroke perfection. It cocks a snoot, yet again, at the big-bore obsessed among us who ring this and other offices complaining that their ZZ-R1100 'needs more power...' and it shows that for single-purpose riding, a 250 can supply as much fun as any other capacity. Finally, it shows that gull-arm swingarms and inverted forks are more than mere fashion statements. That doesn't stop them from being the latest trendy paddock wear though, which they undoubtedly are.

With fairly major engine revisions dealt with last year, Suzuki have decided to concentrate instead on a few tweaked electronic gizmos and creating a chassis that is nearly up to GP standards. The bike's closest competition, Kawasaki's KR1-S, just won the votes of road and proddie racers last year due to its greater power and more complete chassis. The RGV looked the biz, and behaved near perfectly, but a slight delay and notchiness in the gearchange and equally slight sloppiness at the front prevented it being the outright winner. Everything is slight in this sector; the competition is very close, closer even than in other classes. This may well be a function of the manufacturer's single-minded quest for speed which is, largely, absent in other capacity with trifles such as pillion comfort and luggage capacity to consider.

This year's RGV250, then, gets upside down forks and a so-called gull-wing swing arm. Some debate centres on the correct term for this new species of rear swingarm. Suzuki call theirs a Call-Box swingarm -Crescent Aluminium Box, of course. Honda, it is believed, go for Gull-Arm. But gulls don't have arms. Another term finding some favour - or should it be flavour? - is banana swingarm, but somehow this would seem a too frivolous label for such a neat piece of kit, and anyway, there wasn't a banana in sight at Misano where the RGV was launched. I looked. Personally, I take my cue from two things: first, it does look like a gull's wing. But if that isn't enough for you, the sporting minded under-thirties among you (that's Tom out) may recall a type of skateboard truck popular, and expensive, in the late 70s - the Gull-Wing. This would seem to end the debate as far as we're concerned.

Fashion statements they maybe, but they have undoubtedly wrought more than superficial benefits. Suzuki claim, and who are we to disbelieve them, that the upside downies give 33 per cent greater 'flexural stability' and 30 per cent greater 'torsional' rigidity. The gull-wing swingarm makes way for the twin exhaust pipes which now run up

the same side of the RGV so reasonable ground clearance is thus maintained with better routing. The pressed single unit construction item also allows an enlarged section of swingarm to be deployed, so increasing rigidity. What more excuse could you want for wearing flares?

On the road, well, race track, the improvement is immediately noticeable. This is one solid little bike. Up front the slightly altered size tyre (110/70 compared to last year's 110/60, still a 17 incher) would seem to have helped things, but most of the credit must go to those upside down forks. They boast a full 120mm of travel which the now 300mm disc brakes use to the full. But stability and steering input are maintained even under the heaviest braking input or turning force. The back's improvement is less obvious; but the rod and bell Link-type system absorbs road irregularities and acceleration without a worry. On the standard set-up - characteristically soft -you can feel things working fore and aft, but this is called feedback. The four-piston calipers on those massive floating discs ask a lot of such a small bike. But they give as much in return with heaps of feel and power. The 250 can be braked until the front tyre screams in protest without anything getting unsettled; it can be braked into and in a corner and only in the last instance does the transference of forces have any down-side.

With the powerband as narrow as ever, you have to be sure that the needle is suitably placed on the rev-counter for the drive to be there when it's needed. It won't drop-in on a corner dramatically, nor will it run straight on without the power to keep it on line. All it'll do is lose you some momentum which, however, is crucial to the RGV because there isn't the torque to get you out of trouble if you're in the wrong gear. Nevertheless power comes in a usable form at just over four thousand revs, and starts to get exciting at around seven grand. Peak power, a claimed 61 hp, is at 11 .000 rpm

But what would you expect a from a 249cc crankcase induced V-twin two-stroke? Nothing major has changed in the basic measurements of the RGV with the bore remaining at 56mm and the stroke 50.6mm. Compression ratio is however now lower at 7.3:1. The 180 degree crank is still in place along with the six-speed box but second, fourth, fifth and sixth gears use different ratios. However, the rear of the exhaust pipes is less convoluted in its pattern, so improving gas flow efficacy. The improved mid-range response and wider power band come about mainly from this and work to the ignition and timing mechanisms. Suzuki's Advanced Power Control (SAPC), apart from being one of just three acronyms the RGV sports, endeavours to control the twin cylinder engine running with help from AETC-II and MDIS. These stand - come on, bear with me, someone out there must want to know - for Automatic Exhaust Timing Control and Multiple Digital Ignition System. Engine revolutions and throttle openings are monitored through two branches of the air passage the twin 34mm Mikuni Slingshots:

a main one, utilising a valve with stepless air intake control, and a pilot route, with a new on/off valve control for much closer regulation. At the top end the exhaust timing also watches rpm through a sensor, but with the help of a valve just back of the exhaust port. The new AETC system -hence the II - has three stages of timing control, over last year's two. The AETC has settings for high, medium and low and varies timing accordingly for most efficiency and, it is hoped, better mid-range power.

To cap all this is the MDIS which also monitors rpm and throttle openings and alters the ignition to suit by reference to a memory of the best ignition timing for each set of circumstances. The cunning little thing can even detect whether you're running an opening, closing or trailing throttle - all at the same rpm. What all this adds up to is a plethora of electronic systems which, by any other name, would be called engine management. Nothing is private and it's difficult to imagine outwitting the bike. The rev cut-out, at 12,500rpm, further alerts you to this dividing up of the power stakes. The RGV250 may be an increasingly easier bike to ride, but this owes everything to a development plan of ever baffling sophistication.

But will little Johnny or Janie care when they throw their eager legs over the latest hot 250? I doubt it. What they'll find is a bike which wears all the latest gear, wider tyres than last year, a claimed increase in power to 61 hp and brakes that make stopping as much fun as accelerating. It's also a lot smoother in operation at the gearbox where a coaxial gearshift uses needle roller bearings to smooth things out. The coaxiality comes from the shift lever being located along the line as the footpeg which ensures a cleaner, easier, gear change. This alteration makes the RGV a bike with a beautifully slick gear engagement. The increased mid-range makes this only a slightly less called for performance, but you still have to play the gearbox. Still, when you think of the amount of power that's been extracted from a 250 - top speed reached on the back straight of Misano was an indicated 130mph, with probably a little more to come - it is a drivable bike. All things are relative, and it's better than last year's bike on first impressions.

On a circuit like Misano where lefthanders predominate only a couple of options are open to the peaky RGV rider. First is the easiest, but not the fastest. On the tighter bends, of which there are only really two left handers, a single gear can be used, but the set-up is crucial. Come in on the power, and the chances are it'll be long gone by the time you exit. Shifting up a gear on entrance seems strange, but as the track opens, it really is the best way of keeping bike on line and mind on other things than the impending rev-limiter. The other option is to shift part way round. The coaxial set-up certainly smoothes the way for this, but until it's clear exactly how much space is there on a certain line, there is a risk of running out of ground clearance. Not with the bike, but with your foot. It needs, indeed it repays, a quick, definite flick.

Such minutia may seem far removed from everyday riding, and in one sense it is. Riding the bike at the peak of your abilities is never so sustained on the road. But knowing when you need to shift up, and where it's possible, is part of the fun of riding an RGV. With such a stable chassis liberties can be taken - they frequently were - but the correct gear for a corner is crucial on the RGV250. Get it wrong, and you'll be pulling too high a ratio with the subdued wail of the pipes long gone behind you or swearing at the rev-limiter for cutting in, or at yourself for not watching the tacho.

So, the quarter-litre bike is still challenging to ride. The riding position does nothing to alter this. There's no pretence at being anything other than a racer on the roads; the blurb tells us that the RGV250 has 'proportions derived directly from the RGV Gamma' - the factory race bike. It feels like it too. The bars are low, the pegs are high and the seat minimal. It's not comfortable, even when ridden hard, and even the smooth clutch and brake levers can't save it from being what it is - a backside in the air, short-hop bike. Still, the mirrors are effective as well as being suitably minimalist... the same goes for the new double tailight section. The detailing throughout is damn good, from the remote reservoir at the rear to the intricate mounting of the front brake fluid reservoir on the bars.

The improvements made to the RGV250 tell of Suzuki's continued dedication to both the bike and the class. While the engine management system undoubtedly contains some very trick stuff, and this stuff makes for a smoother, better running unit, it's on the chassis side that things have really moved. With the standard of both the RGV and the KR1-S it's difficult to say it now handles/steers/brakes better - neither bike did those things badly last year. Where the changes might tell is in how far you can adjust your RGV to suit your own tastes. We weren't able to play much with the settings in Misano, but a brief foray with a increased preload setting at the front showed only that there's lots to play with; most of it, I suspect, without any penalty in terms of performance. Only time will tell. The upside down forks are more than mere gimmick, especially on a bike like the RGV.

Why? Because steering and braking are so important to this bike; the power is good, but nowhere near breathtaking, so the little Suzuki makes ground up through brakes which are among the best in the business, and light, sensitive steering. There's a hint of oversteer evident, but otherwise the setup is completely neutral. The range of preload, rebound, and compression adjustment is phenomenal. Not only is the degree and rate of travel adjustable, but with this amount of adjustment, braking and steering behaviour too. The RGV's rake of 25 degrees is a little down on last year's 26, the trail shrunk by 4mm to 94mm.

In the final analysis the RGV250M, available in either black or blue/white this year, can only really be judged against its nearest rival, the Kawasaki. Preferably on a race track. The RGV steals a lot of ground with its trick suspension and wacky swingarm though. The aluminium-alloy double cradle frame has gained rounder edges (for better aerodynamics, it says here) but otherwise is unchanged. Wheels have grown slightly, the radiator has changed shape, and bolt-on seat rails make maintenance easier, but it's the smooth flow of the Gull-Wing and meaty appeal of the inverted forks which'll win friends and influence people. Suzuki have once again shown that what was, only a couple of years ago, the preserve of a select few to thrash around the circuits of the world can now be yours to do what you will with. Suggestions as to what to do with a Gull-Wing on a postcard please.

Source Cycle 1991