RGV250 K VJ21 1988

In the Beginning

The bike was purchased in June 2003 after seeing it on Ebay - non runner, which is always a mistake, for £550. It was brought back to the Griffydam workshop, and stripped down. The more I looked, the worse it got. The main things were :-

The logbook said it was an import, and as the engine had no stamped engine number (but no damage to cases), and a few things were weird. Looking around for parts, we managed to locate a bloke in Maidstone who had three VJ21s in various state of disarray. These bikes had the front and rear ends transferred to RD350 YPVS (which is something I should have done) so the main body of the bike was still there. These were loaded up into the back of the Corsa, and away we went.

Later, another VJ21 was located that was being stripped in Newark, minus front and rear ends of course. With all these parts available, the RGV was stripped completely, and rebuilt using the best parts from all engines and chassis.

A set of cylinders were obtained from Wolfram Aupperle in Germany, stainless nuts and bolts everywhere, alloy spacers from Jim (Cobra Precision - Arch on the RGV forum). The bike was rebuilt and MOT'd on 15th May 2004.

In the Beginning

The RGV was:

1. Avaiable in Japan as the VJ21 J model in 1988
2. Avaiable as VJ21 K in UK in 1989 - minor updates (suspension bushs etc) 
3. VJ21 L model avaiable 1990 - very similar to VJ21 J/K same but slightly uprated
4. VJ22 model with banana swingram, Upside down forks etc avaiable 1991 onwards

I said above, I am interested in the VJ21 models, but intended to use the improved, revised parts from the VJ22.

Cases.The VJ21 is marked J205 whereas the VJ22 has J206 marked, and the Aprilia RS250 is marked J208. How I laughed pointing out the little Suzuki logo next to the J208 marking to Naive Aprilia RS250 owners who were convinced their engine was made in Italy, not Japan.

Alternator. The VJ21 has a conventional alternator where the pickups/coils are mounted to the engine cases, requiring a longer alternator taper. The later VJ22 uses alternator/pickup coils mounted in the cover, and a smaller alternator rotor for better acceleration. The alternator rotor you need depends on the electrics you want to run. Apparently, the VJ21 has 4 degrees of static advance built into the flywheel. More details on electrics below.

Crank. The VJ22 crank can be fitted to the VJ21 provided the VJ21 crank end is swapped over - a relatively minor job. The problem with the crank stems from the lightweight design of the engine. Only one bearing is used in the crank centre, which means the bearing wears out quickly. As it wears, the inner race picks up up on the centre journal, skidding and wearing the journal out, rendering the centre piece scrap.

If the centre is worn, usually the centre Labyrinth seal also wears out too. Suzuki originally sold the Lab crank seal separately, but this was dropped in 1992 when the crank centre was only available as a whole.
An alternative is to use the Lab Seal from the RG250, part number 09289-32004. This is known to work as it is the right dimensions, but does not have the locating lip so you need to position the crank when you install in the cases. Thanks to Patrick (Thomasnur) for the part number and RGVMax for the pictures, both on the RGV forum.

UPDATE: Patrick says the seal part number 09289-33008 is also the correct dimensions, but has the locating lip - looking at http://www.cmsnl.com this looks correct!  Since it is not a Lab seal, it may cause more comparative wear, but since the inner spacer is replaceable, this should not be a problem. See the Crank Stroking Page for details.

Another problem with the crank is that only one big end pin is truly free - the other is an integral part of the web. This is to prevent one crank web having two pressed together pieces as these are likely to crack. So if your big end picks up on the side which is integral, the crank centre is scrap. In reality, other things can be done, such as building up the crank centre and grinding back, and also honing the Lab seal and using an oversize spacer, but many places do not like the RGV crank.

Gearbox. The VJ21 gearbox output shaft is made of soft cheese, and the gearbox sprocket is held in place with circlips for easy swapping at the track. This means the sprocket chatters away on the output shaft and destroys the splines. The gearbox is mounted to a gear carrier plate, which makes swapping gearbox easy. But, the VJ21 engine has a smaller diameter gear change shaft than the VJ22, so you need to use the VJ21 carrier plate when swapping in VJ22 gears. The VJ21 also use a bush on the kickstart idler gear and the VJ22 a needle roller, so this needs swapping too.

Take care when swapping over to VJ22 gearbox as the dogs on the 2nd gear driven wear out, which requires new forks and gears.

See below for details on Close Ratio and dry clutches.

Cylinders. The VJ21 was available in 2 versions - J/K and L. The J/K cylinders do not have any markings other than 249cc and the date code on a bulge on the L/H side of the cylinder. The J/K cylinders must be used with J/K pistons as the ring peg is in a slightly different spot. The J/K cylinders produce the most midrange, apparently. The L cylinders are marked 12C on the opposite side to the 249cc, make more top end power and can use the latest VJ22 pistons. The VJ22 cylinders are marked 22d0, and Aprilia RS250 cylinders are marked 22d5. You must use the latest pistons (part number 12110-22D61-0F0) with the VJ22 as the early VJ22 pistons (part number 12110-22D01-0F0) cracked.

The latest pistons are from the RG125 Fun and are available from Redcar Suzuki.

Powervalves. The VJ22 is the model which had the problems with the powervalves, not the 21.  A roll pin is used in an alloy sliding piece, which can drop into the engine. 

Having said that, poorly adjusted powervalve cables, seized up powervalve pulleys and coked up powervalve assembly can cause the valves to crack, and then drop into the cylinder, destroying pistons. The powervalve pulley runs on a bush, and a leaf spring transfers the powervalve motor force via the cables to the powervalve pulley shaft. If the powervalve pulley is seized on the shaft, then the valves are subjected to the full force of the motor, and can crack.

Having said that, VJ22 valves can be used in a VJ21 if you ignore the std alignment marks, and run a controller than can handle them - see electrics. I run VJ21 L valves, and set them by taking the pipes off and feeling what is going on. I also fitted a RG125F powervalve cover to the R/H cylinder since this has built in drain, as the 'bottom' cylinder can pool oil which turns to carbon. I also keep meaning to machine up a set of titanium pulleys and bronze bushes which would look great, but this is a lot harder since I sold the lathe. 

Aftermarket power-valves are avaiable from The Tuning Works - these have a different profile and give slightly more exhaust duration - take care when fitting these with a 1.4mm base gasket as you may have too much.
Tekaturo sell revised 3 piece blade centres in case yours have a loose pin - make sure you get teh right one (4 or 5mm pin) or machine your 4mm pin to 5mm to clean it up.

Heads. There is a large choice of heads for the VJ21 and VJ22 RGV. The VJ21 ran higher compression ratio than the VJ22, but the early heads were prone to overheat on the track due to insufficient water volume. VJ21 L heads were better. The VJ22 heads had less CR, but plenty of water and also had a proper squish. The Aprilia 22d5 head are higher CR too. I run the Suzuki RG125 heads on L/H cylinder as this has a straight plug (as done on the Honda NSR250 MC18) and an RS250 head on the R/H cylinder as this has an angled plug to clear the front wheel. These are used with RGV250SP head gaskets (part number 11141-22D10), as they are 0.8mm thick, compared to stock gaskets (part number 11141-22D00) which are about 1.4mm thick, and use Super unleaded where available.

Carbs. The VJ21 J/K has 32mm carbs with no electric magic such as electronic powervalve or electronic air jets. These are sometimes used on RD350YPVS tuning projects. The VJ21 L has 34mm carbs with a single air bleed solonoid, and the VJ22 has different TMX 34mm carbs with two air bleed solonoids. All carbs have integral powerjets.  I do not believe the carbs pose a restriction as there are 70bhp tuned RD350YPVS about which use stock 26mm carbs. So I stuck with 32mm carbs as they are simpler, keep the engien bay tidier and should eb eaiser to jet - less sensitive to atmospheric changes etc.

Electrics. The J/K model runs different electrics to the L, which is also different to the VJ22.

The J/K model run a Suzuki PEI ignition - this has two boxes, one for the sparks (a CDI, marked CB1202), and one to control the powervalve motor (Power valve control box marked CM1107 or CM1108). This must be used with a rotor stamped GP9141 and short pickup. This model has a built in advance and controls the powervalve in a single stage, cycling when the power is turned on.

The L model use a 'Digital' ignition (marked CM7401, CM7402 or CM7403), which is the precursor to the VJ22 SAPC below. This system uses a micro-controller to adjust the advance and control the powervalve, using a Throttle Position Sensor on the cable splitter. A separate high voltage generator (marked CB1203) is used to actually discharge the sparks, superceded by the CB1204 box as used on the VJ22 (this means it works on the VJ21L).

A separate box (marked TV86) controls the single solenoid used on the 34mm VJ21 L carbs. These all require a flywheel with a long pickup; the L flywheel is marked GP9146 but should also work with the VJ22 rotor, but check. The CM7401 retards at 11,000rpm to save the engine, the CM7403 has an extra wire to the gear selector drum to retard in 6th gear (simply disconnect to have a free revving 6th gear) and the CM7402 is the Kit box.

The VJ22 uses a SAPC, which combines the Digital igniter and solenoid control systems into a single unit - see the page on the RGV forum for details. As the VJ22 SAPC requires a long igniter, you should be able to use it on a VJ21 L engine, but double check the extra built in advance does not cause too many problems.

Aftermarket Ignitions
If you are after improving performance, consider an Ignitech or Zeeltronic system as these are programmable - I like the look of the Ignitech as it is self contained. However, be aware that it takes time and effort to get the best from these - they are not bolt on fit and forget upgrades.

If you have a 'stutter' at approx. 8,000rpm that you can't get rid of after fitting thicker base gaskets of Couger Red Valves, then this could be because the powervalve is now opening too early. Consider the standalone Zeeltronic powervalve controller to tune this out, but you will need so tweak.

Front Suspension. The only major letdown of the VJ21 is the 41mm front forks. These are budget items, and while they work, can be improved. The following options are available:-

• RGV250 VJ21 SP - the SP model had cartridge forks as standard with rebound and compression damping. AFAIK these were available as part of the VJ21 F3 race kit (or you had to start with the SP) with springs and things. If you can find them, they are the perfect fit - part numbers below.

• Maxton front fork upgrade- Definitely works, costs around £360 + Tax in 2006. They install Cartridge fork internals with new fork tops to give preload, compression and rebound damping. Advantage is the forks will be setup for you.

• GSXR400R GK73 - These forks are a bolt in fit - right diameter, right stanchions, right caliper mounts. The std GSXR forks are cartridge, so better than the std VJ21 forks, and have firmer springs, which is good for Europeans who weigh 20lbs more than the Japanese. The GSXR400R SP also has rebound damping on the fork lower. Disadvantage is that both these forks are longer than stock, so you have to set the ride height carefully and have some stanchion poking through the top yoke. Part Numbers and rebuilding data below.

• CBR600 F3 (1995)- The last of the steel framed CBR has 41mm cartridge forks which can be swapped into the RGV lowers - they have preload and compression damping adjusters. Again, longer and might not be optimal but a potentially cheap upgrade - I heard about this from WebDev511 RGV forum member.

• Others - A number of other bikes have 41mm right way up forks, such VTR1000, which could fit, but you are on your own. NOTE that the longer stanchions mentioned above could be machined down to the right size, with the cartridge internals also being modified, by someone who knows what they are doing.

Note that the GSXR400 GK73 uses an alloy bottom yoke that is a direct swap compared to the Ugly, Steel VJ21 item.

Brakes. The VJ21 has good brakes, but if you are running standard rubber hoses then throw them away as they should be replaced every 5 years. Stainless braided steel hoses are cheap now swaged fittings are available, so get fit these. If you are stripping the calipers (and you probably should) then the GSXR600 SRAD has alloy pistons and it is cheaper to get used SRAD calipers from Ebay than buy new Suzuki RGV front brake pistons.

The front rotors are prone to wearing, but are the same 296mm dished items used on many Suzuki budget line vehicles, such as SV650, GSXR600, GSXR400 GK73 and a few others. EBC pattern brakes are available too which are lighter, but not cheap.

The rear rotor is problematic as there are no other bike replacements and difficult to find used good . The Rear caliper is horrible (though should be rebuilt), and some people fit a Brembo caliper from a Scooter or Caliper from a Kawasaki KX80/100 or AR50. The alloy torque arms available for the 750 and 1100 range are not long enough to fit - ask me how I know - and I am too scared to weld a long one together.

Wheels. The front 17" wheel has a 3.25" rim which is fine for 110 cross section tyres. If you want to fit 120 cross section, then a 3.5" rim is probably better. Look at a late model GSXR400 GK76 - the disks should line up, but I have not checked it.

The rear VJ21 item is 18" which limits current tyre availability. It is easy enough to fit a VJ22 17" rear. To ensure handling is not affacted, you could also install different suspension linkage plates (dog-bones) to restore the ride Height - ask Jim (nickname Arch) on the RGV forum. You also have the option of slotting the chain adjuster holes 12.7mm towards the swingarm pivot which will reduce wheelbase and make the handling even more sprightly.

Whatever you do, make sure you fit the right tyres for the bike. I believe that ZR rated tyres, designed for a 200kg, 200mph Hayabusa are NOT the right choice for a 130mph, 140kg motorbike. They take a lot of warming up, are heavy and I struggle with feel. The H rated tyres intended for Japanese 400s are the best.

Rear Suspension. The rear suspension bearings will need replacing unless they have been done recently. The J model used some steel bushes, but I replaced mine with caged needle rollers. The suzuki OEM bearing have integral lip oil seals, but I used separate oil seals and needle rollers as the oil seals were dual lip types. The rear shock was replaced with a good used one from a VJ22, and the remote reservoir hose clipped to the steel rear sub-frame. You can always fit an aftermarket Shocker if you wish - see the Tuning Works.

May people fit VJ22 swingarm (mainly the Banana) - this is possible but you need the whole lot - linkages, wheel, brake etc. I think it is a waste as the swingarm is heaver, but people do it for aesthetics. In My opinion, the GSXR240R GJ73 swingram better suits the VJ21 as it is top braced.  However, I do not know if it is a direct bolt in fit.

Frame. Most of the VJ21 K models do not have a steering damper lug - all the VJ21 L models do (some slight overlap). The VJ21 has a steel fairing bracket at the front, an alloy seat subframe, alloy engine cradle, and a steel ancillary subframe bolted to the back of the seat subframe, which supports the two-stroke oil and coolant reservoirs plus rear brake light etc. The steel parts can be rebuilt in alloy if you are talented.

Many Suzuki alloy framed motorcycles suffer from headstock bearing ovaling in the event of a front end prang. If your bearing races drop out easily then this is why. Repairing requires welding and remachining - in the UK, it is cheaper to get a used frame and log book from Ebay. The engine mounts can also break off if the chain is constantly too tight, and the engine cradle can also crack at teh front weld for the engine lug.

Data

You WILL need the genuine Suzuki service manual (part no. 99500-12077-01E for the English version). Other, less easily available useful data, privided under fair use copyright, is below. The GR77 GSXR750 shares some parts like adjusters, so is here for your reference. It is a very good idea to print all the part numbers off to cross compare.:-

• VJ21 SP Parts Book Suppliment (Japanese) PDF
• GSXR400R SP GK73A Front Fork Service Manual (Japanese) PDF
• GSXR400R SP GK73A Front Fork Parts List PDF
• GSXR400R GK73A (Not SP) Front Fork Part Numbers (Japanese) PDF
• GSXR750K GR77 Front Fork Part Numbers PDF
• GSXR400R GK73A (Not SP) Front Fork Service Manual (Japanese) PDF