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Suzuki X7 – Worlds First 100mph Production 250

The 1978 Suzuki X7 was an all new ground-up design, however the origins of the bike go way back to 1966 with the original T250. 

Following the T250 came the 1971 GT250 and it was then revised again with an updated engine in 1976. 

Fundamentally the aim of the game was to create a 250cc bike that could hit 100mph. That was the end game for the Big Four Japanese marques, to build the fastest road going two-stroke. 

It was the 1978 Suzuki GT250 X7 which was the bike that could break that barrier thanks to its lightweight chassis and 12 year design development. Finally a quarter liter road bike with the performance to join the ton up club. 

The X7 was the final iteration of the GT250 which was the foundation for the new RG250 Gamma that came at the end of 1981. 

The RG250 and RGV250 series of motorcycles are considered classic iconic bikes from Suzuki, but they would not be here without the GT 250 X7 and therefore we shall shine a light on this earlier legend to give it the respect it deserves. 

Let’s get started.

Suzuki X7 Review

Suzuki X7
Suzuki X7″ snapped by grobertson4 and kindly licensed under CC BY 2.0

Engine and Transmission

The original T250 engine was a 180 degree piston ported two-stroke, twin, with an alloy head and alloy barrels which had cast iron liners. 

In 1971 it received the Ram Air cooling system, designed to ensure the engine received as much air as possible for efficient cooling and optimum performance. 

After further design enhancements, for 1978 the engine was again reviewed along with the rest of the bike and the GT 250 X7 was born. 

The new engine retained the same 54 x 54 mm bore x stroke, but it was more compact than earlier GT250 engines and weighed a lot less, more than 7kg less. 

It is thought that the new engine didn’t actually produce any more power but thanks to its re-design and the overall weight savings made on the bike; that is what gave it the advantage to hit the 100mph mark over and above its predecessors. 

The 247 cc X7 engine was equipped with Suzuki’s Power Reed Valve induction system which was intended to increase the breathing of the engine to ensure maximum efficiency throughout the rev range. 

The dual induction system had only been used on Suzuki’s off-road machines prior to being used on the GT 250 X7. Operated by crankcase pressure the engine draws on both the piston port and reed valve. 

It was the new dual induction system that gave the new X7 the edge over the earlier GT250 models and the other 250’s of the day such as the Yamaha RD250 and Kawasaki KH250. The engine now had the oomph that riders had been hoping for from the quarter liter two-stroke. 

Piston porting is designed to provide the fuel induction in the mid-range, but the power reed valve opens, thanks to the crankcase suction pressure at the top end to draw in more fuel which therefore opens up the power through the top of the rev range. 

It was a clever system that would be implemented going forward for years to come. 

The gear ratios were also altered from the previous model, they were designed to give a more even ratio between each gear. 

So, what does all this mean when riding the bike?

As with all two-strokes of the 70’s and 80’s the engine takes a short while to come to life until the top end has fully warmed up. 

However, the GT 250 X7 also requires a smooth and delicate hand on the clutch, there is a definite need to keep the revs up to take off and a smooth release of the clutch and roll of the throttle to get going. 

When in the correct rev range the power is strong and delightful, it feels more powerful than other two-stroke twins of the time simply due to the fact it is such a lightweight engine in a lightweight chassis, it almost feels like overkill from the engine. 

The front wheel is all too quick to rise in first or second gear if you over-rev but the ability to pull away in any gear when in traffic makes for a useful machine. 

Therefore, the GT 250 X7 is a little bit like Jekyll and Hyde with equal measures of positives and negatives when it comes to the power out of the engine. Great care is needed to master the little monster. 

Gear changes are slick and smooth, the only real issue being that neutral can be hard to find and sixth gear is little good for anything except to act as a cruising gear over 70mph.

Chassis, Suspension, Handling, Brakes

The GT 250 X7 gained a newly designed single down tube frame over its predecessor’s duplex cradle frame and as with the engine this meant there was weight saved, around 1.5kg. 

Weight loss wasn’t the only gain, the frame’s rigidity was increased, which given the capabilities of the engine was far from a bad thing. 

Handling can be said to be very easy, steering light and responsive. Cornering would be great fun thanks to the immediate response of the handlebars to the slightest touch. 

However, it is safe to say the lightweight feel of the bike is also its downfall. The slightest bump in the road, change in road surface etc. would make for a quick decision to be made to rectify the bikes direction. 

Concentration is required at all times, and the flighty nature of the bike at speed can be disconcerting, arguably even a little dangerous. 

The Suzuki GT 250 X7 is not for lighthearted riders especially those who want to chase that claimed 100mph top spot. 

Get a nice smooth race track however, and the GT250 X7 will be your best friend, with its short wheelbase, light handling, precise steering you will be in for the best time.

Suspension was adequate but nothing to rave about. It would only be suited for a single rider, 2-up riding is a no go from a comfort point of view.

However solo riding the bike is a fairly comfortable ride at all speeds with noticeable vibrations through the pegs and bars but nothing off-putting. 

The position is reasonably neutral and the seat absorbs a lot of road bumps, is padded well so you could endure many hours riding. 

The only niggle would be as the rider is slightly pushed forward there may be some tension on the wrists if it is not a position they are used to. 

As for the brakes, they make for an interesting experience. The single front disc is very sharp and needs to be used with care, the rear drum brake can easily lock the back wheel so there is a delicate balance the rider needs to maintain when applying pressure on either brake. 

Wet weather riding with the single front disc is quite dicey, so avoiding this would be a good idea unless you do some upgrades to the braking system; which I would recommend if you plan to use an X7 for riding rather than just adding to a collection.

Overall the 250 X7 is a breath-taking, fear-inducing, fun two-stroke for brave riders and collectors. 

It isn’t a bike for novice’s looking to get in on old school two-stroke fun, the lightweight chassis and engine make for an intense focused ride where finesse, care and skill can be applied. 

Suzuki X7 Specifications

Engine and Transmission

  • Engine – Two-Stroke, Air Cooled, Parallel Twin
  • Capacity – 247 cc
  • Bore x Stroke – 54 x 54 mm
  • Compression Ratio – 7.5:1
  • Cooling System – Air-Cooled
  • Induction – 2 x Mikuni Carbs
  • Ignition – PEI
  • Kick-Start
  • Max Power – 30 horsepower at 8,000rpm
  • Max Torque – 27.5Nm at 7,000rpm
  • Transmission – Six speed gearbox
  • Final Drive – Chain

Chassis and Dimensions

  • Frame – Single Downtube 
  • Front Suspension  Telescopic fork
  • Rear Suspension Twin spring shocks
  • Front Brake – Single Disc
  • Rear Brake – Drum
  • Length – 1985mm
  • Width – 870mm
  • Height – 1065mm
  • Seat Height – 787mm
  • Dry Weight – 146kg
  • Wet Weight – 160kg
  • Fuel Capacity – 15 litres

How Fast is a Suzuki X7 ?

The Suzuki GT250 X7 had a top speed of just over 100mph. 

Suzuki X7 250 For Sale

eBay UK
Suzuki X7 For Sale Suzuki X7 For Sale
from £4995

Check out over half a dozen Suzuki X7 classified listings with prices ranging from £4995 to a completely rebuilt example with a £7995 price tag

I may earn a commission if you make a purchase, at no additional cost to you.

In the UK you will be looking to pay between £4,500-£6,500 for an X7 today in ride away condition. Expect to pay up to £8k for a showroom condition example.

This 1979 model has an asking price of £4,495 which is at the lower end of the price range, simply because it needs a little bit of work to get it back to excellent condition. 

It is not a mint example but it is a very good one, that with a little work will increase in value over the years to come.  

In the US you can expect to pay $3,500, however, they do not come up very often and are increasingly difficult to find in the US.


While the Suzuki GT250 X7 gave way to the RG250 Gamma, if it wasn’t for the continued development of the GT250 the Gamma wouldn’t have existed. 

The X7 was the culmination of that 12 year development and what Suzuki had at the end of it was a 250cc bike that could (in favourable conditions) hit the 100mph mark. 

Yes it was a little crazy and temperamental, but with the right rider in the right circumstances it was a highly evolved fast weapon of the era and has become a two-stroke classic.

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