(from the BSA web site)
250 Superstock...a new way forward? Or the way it should be?
In 2006 we will see the arrival of a new formula "superstock", many of you will
already be aware of the new formula that has evolved for over the year, or you
will have seen the guys at superkart trackdays and Viper racing during the
recent kart show.
The concept seems a great one, everyone on equal terms with the same engine,
same ancillaries and same BHP, the only difference will be your choice of tyres
and chassis.......not such a wallet orientated class. Also the expected
longevity of the engines between rebuilds will appeal to many current and new
competitors looking for a less stressful weekend of motorsport, after all its
supposed to be fun!
The prices seem to be very fair on the engines and rebuild work, unlike most of
the other "stock" classes in karting which seem to really inflate the prices on
"sealed" motors. I also think the decision to enable competitors to still do
their own engine rebuilds if wanted is a good one, and it reduces the chances
for a monopoly, which always increases the costs to us the racers, although @
£65 plus parts for a rebuild why would you want to do it yourself?
I personally think it could be a great way into 250 long circuit for many, and a
breath of fresh air for current competitors on a tighter budget. I believe that
Ian Harrison of Viper racing will run a honest and professional setup, and the
series appears to be very well thought out, so good luck to him and the
superkart track days team who have developed the series! Bring it on!
(from Viper Racing)
CR250 Superstock Technical Regulations
Engine
The aim of the series is to provide competitive racing with good engine
reliability, reasonable service periods and costs. To this end modifications are
limited. The cylinder head modifications allow economical inspection (due to
O-Ring sealing) and easy replacement of the combustion chamber in the event of
damage.
It is anticipated that competitors wishing to compete in this category will wish
to enter into the spirit of "fast, economical and fun motorsport" and that there
will not be any tendency to "bending the rules" or indeed outright cheating.
However, the motor specification is formulated to allow quick and easy
inspection by an eligibility scrutineer.
Engine/Gearbox
The motor is based on Honda CR250 Series Production Crankcase Induction Motor
manufactured between 2002 and 2004 inclusive.
All engine castings must be the originals of O/E manufacture and unmodified
apart from any allowable modifications detailed in the following.
A Viper Racing UK aluminium cylinder barrel spacer plate must be fitted. Part
number: VIP/SS/01. One base gasket of Honda O/E manufacture (nom 0.5mm thick)
must be fitted either side of the spacer plate.
The kick-start mechanism and kick-start idler gear may be removed if desired, in
which case a secure blanking plug must be fitted to the clutch housing to
prevent oil leakage.
A Viper Racing UK supplied 2-piece cylinder head is mandatory. The head insert
regulates the combustion volume and squish band, which is fixed. The part number
of the complete head is: VIP/SS/04
Cylinder Head Nuts can be replaced with Dome Nuts and Brass Washers.
Original Honda Crankshaft must be used. Crankshafts can be rebuilt using either
Honda O/E or Prox (Part No. 03.1322) Con-Rod kits.
O/E or Pattern Clutch friction and plain plates can be used.
Piston must be 2-ring type of either O/E or Prox (Part No. 01.1322) manufacture.
No other changes are allowed to the internal components of the engine/gearbox
and clutch.
Positioning of the pulse take-off is free.
The standard cylinder barrel must have no modifications whatsoever. Any
machining, polishing or removal of material from the cylinder barrel, its
ports, etc. is prohibited.
Standard power-valve flaps must be fitted and locked open by means of
bolts/locknuts through the original cable channels in the side of the
power-valve pulley housing or through the back of the powervalve pulley housing.
It is also permissible in addition to bond the flaps open with epoxy adhesive,
silicone RTV or similar between the tops/sides of the flaps and the cylinder
casting. The epoxy/silicone can be used to fill any small voids between the
powervalve flaps and barrel, but not to reshape ports, etc in any way. No
machining is allowed. It should be noted that if powervalve flaps are bonded
with Devcon Epoxy or similar it may be difficult or impossible to remove the
flaps again and this may preclude cylinder barrel replating.
Max bore size permitted is 66.36mm (Grade C).
Total swept volume cannot exceed 250cc
A CIK approved airbox must be used, as per F250 National. A foam filter may be
added to the airbox and is recommended
Carburation and Induction
A Viper Racing UK supplied hand finished, polished and jetted Dellorto 39VHSB
carburetor is mandatory.
Jetting is as follows:
Fuel cut-off valve: 170
Tube: DQ269
Needle: K44
Needle Clip Position: Free
Pilot Jet: 55
Pilot Jet Emulsion Tube: 38
Main Jet: Free
The Honda O/E reed block must be used.
A Viper Racing supplied adapter plate and inlet rubber is mandatory, this allows
the engine to be installed on either the right-hand or left-hand side of the
kart.
Ignition
The ignition system must be PVL analogue. The part number for the complete
system is VIP/SS/05. Individual Parts Numbers allowed are:
Viper modified PVL Stator VIP/SS/51
Special PVL Rotor with keyway VIP/SS/52
Standard PVL Coil 458 100
Viper PVL Mounting Plate VIP/SS/06
No other parts are allowed in the ignition circuit
It is permissible to remove material from the ignition housing to accommodate
the ignition system.
Exhaust
Exhaust mounting stub must be Viper Racing Supplied. Part number is VIP/SS/08
Expansion chamber must be Viper Racing Supplied Superstock Item. Part Number is
VIP/SS/09
Connecting Pipe and silencer are free (Noise levels must not exceed limits set
for F250)
Sealing
Engines will have the ignition, one cylinder barrel stud and one exhaust stub
bolt sealed using stainless steel lashed wire and lead seals with a series
imprint. This will prevent tampering yet still allow competitors the freedom to
remove the cylinder head to check for jetting etc. It will also allow a full
eligibility check to be carried out very quickly with removal of only the
cylinder head and reed block.
All engines built and supplied by Viper Racing UK will be sealed Free-of-Charge.
Competitors building their own engines will need to have them checked and sealed
by Viper Racing UK prior to the first championship round that they wish to
compete in.
Viper Racing will attend all meetings and will be available to check and seal
engines at the track. An initial sealing charge of £30 will be made. Any
subsequent sealing due to eligibility scrutineer wishing to break seals or
through maintenance will be Free-of-Charge.
