Post by Roger on Oct 22, 2011 13:37:31 GMT -8
2013_2014 AKRA Rules.pdf (235.43 KB)AKRA Builder Prepared Clone (note: mufflers required on all engines 92 max db)
These rules allow a builder into the engine, but are written with the intent of making it possible for the average guy to build his own engine.
Age: 16+..or with Race Directors Approval
BP (Builder Prepared) 6.5 OHV –– Approved Engine: 6.5 OHV 196cc clone engine modified only according to BP OHV Engine Spec. Single cylinder, 2-valve overhead 4-cycle engine. No aftermarket coatings of any type are permitted on any part of the engine (exception Blower Housing and Shrouds).
Tires: are Burris only. Any size or compound allowed. No Chemical Tire Treatments allowed.
Fuel: Gas ONLY
Cylinder Head Requirements: Stock cylinder head only.
• Machining of gasket surface is allowed.
• No addition of material in ports or to cylinder head allowed. Porting and / or grinding are permitted.
• Valve seats may have two angles, 45° valve face and 30° top relief. Inside diameter of valve seats must be stock(Into .897” max ID and Ex .862” max ID). Valve seats must appear stock and must be in stock position and depth. Stock head bolts are required and all four are required.
• Head gasket/s maybe after market, must be of stock configuration, and gasket thickness non-tech.
• Depth check between the valves, front to back and side to side may not vary by more than .005” max.
• Cylinder head guide plate for pushrods must remain stock.
• No other alterations to the stock head are permitted.
Bore and Stroke:
Stock bore is 2.685” and may be over bored to 2.718” Stroke is 2.123” +.010”-.005”.
Connecting Rod: Stock or Billet aluminum rods, with or without bearing inserts allowed. No titanium rods allowed. Rod length is a non tech item.
Carburetor/Intake Requirements:
• Stock Huayi or RUI*ING carb. Venturi .625” NO-GO. Rear carb bore .751” NO-GO. Carb bore finish, non tech.
• Throttle shaft - .115” minimum. Butterfly - .037” minimum. Throttle shaft, washer, and butterfly must be stock and must be present, butterfly screw non tech.
• Air Filter adapter of 1.375” max length allowed. No air rams.
• Pulse-type fuel pump is mandatory. Fuel pump must be pulsed from either the crankcase or the valve cover.
• Black phenolic carb insulator must be used.
• Choke assembly may be removed.
• Jets, air bleeds jets, and emulsion tubes are non-tech. Stock intake runner gasket configuration only.
• No other alterations are permitted.
Ignition system: Ignition timing is non tech. Stock ignition module only. No modifications of any type allowed. Sparkplug connector must be stock as from factory.
Piston Requirements: Must be stock dished piston with no modifications. Oversize Clone or Honda ZOT dished piston is allowed up to .035" oversize. Rings must appear stock and all rings must be installed. Piston may not pop out above cylinder deck.
Valve Train: Stock valve-train only in stock configuration except:
• Any single valve springs and valve spring shims are allowed;
• Any 5.5mm stem steel valve (including stainless) After market valve retainers allowed.
• Intake valve head Max OD .982” +/- .005” and Exhaust valve head Max OD .945” +/- .005”.
• Valves must be one angle only, 45°.
• No knife edging of valves (1mm min. margin).
• Valve length is non-tech.
• No additional support for rocker studs permitted.
• Outside face of valve head may not be below the combustion chamber floor. (i.e. don’t sink the valves) Valve cover may be drilled for fuel pump pulse fitting, otherwise, it must remain unaltered. Valve cover gasket is non-tech.
Camshaft Requirements:
• Stock camshaft cores only, ez-spin assy must remain as stock.
• Duration check for Intake and Exhaust lobes (taken off pushrod) .
o Intake duration of 248 degrees at .050 lift/107 degrees at .200 lift.
o Exhaust duration of 247 degrees at .050 lift/116 degrees at .200 lift.
• Max lift at the valve retainers, Intake .238” and exhaust .242” taken on valve spring retainer with zero lash. (To achieve zero valve lash for checking running lift, preload dial indicator by .001”.)
Crankshaft Requirements:
• Stock, factory crankshaft only with stock, factory timing gear in factory location.
• No modifications to crankshaft allowed.
• Aftermarket steel main bearings of non self-aligning type, with or without seal are allowed.
• No ceramic bearings. Crankshaft Journal diameter is 1.180”, 1.168” minimum.
Block Requirements:
• Stock Block, as cast and produced with no alterations or modifications other than those specifically permitted.
• Block head matting surface may be machined, however, no piston pop out is allowed.
• Blocks may NOT be welded for repairs. No addition of material to block (i.e. welding, jb weld, etc).
• All bolt bosses in block may be drilled and tapped for repairs or other uses. Fastener type and size for sidecover is a non-tech issue
• Additional side cover gaskets as required for crankshaft thrust are permitted. Gasket sealer allowed
• All parts associated with the governor and the low oil sensor may be removed, plugging any associated holes.
Flywheel:
• Approved SFI certified billet aluminum flywheel only.
• No machining or alteration of any kind allowed.
• Minimum weight for flywheel is 3.3 lbs. Any timing key or no key at all may be used.
• A flat washer or spacer may be used, and is recommended, between the flywheel and the nut.
• Handheld electric starter may be used, but compression release mechanism must remain on camshaft.
• Current Approved flywheels: ARC 6619, ARC 6618, Raceseng Flywheels RSP-13-075 Rewheel NF- S1 & RSP-13-077 Rewheel F-S1.
Header and Muffler Requirements:
• Header Pipe Length: Minimum 18”- Maximum 22”.
• Silencer must be a RLV 91_L type with .1285 no-go hole. Header must be securely wrapped from flange to muffler prior to the race.
• Exhaust Pipe must be double nutted or safety wired. Use of studs or bolts permitted.
• Silencer must be supported by clamped on brace to secure it in place.
These rules allow a builder into the engine, but are written with the intent of making it possible for the average guy to build his own engine.
Age: 16+..or with Race Directors Approval
BP (Builder Prepared) 6.5 OHV –– Approved Engine: 6.5 OHV 196cc clone engine modified only according to BP OHV Engine Spec. Single cylinder, 2-valve overhead 4-cycle engine. No aftermarket coatings of any type are permitted on any part of the engine (exception Blower Housing and Shrouds).
Tires: are Burris only. Any size or compound allowed. No Chemical Tire Treatments allowed.
Fuel: Gas ONLY
Cylinder Head Requirements: Stock cylinder head only.
• Machining of gasket surface is allowed.
• No addition of material in ports or to cylinder head allowed. Porting and / or grinding are permitted.
• Valve seats may have two angles, 45° valve face and 30° top relief. Inside diameter of valve seats must be stock(Into .897” max ID and Ex .862” max ID). Valve seats must appear stock and must be in stock position and depth. Stock head bolts are required and all four are required.
• Head gasket/s maybe after market, must be of stock configuration, and gasket thickness non-tech.
• Depth check between the valves, front to back and side to side may not vary by more than .005” max.
• Cylinder head guide plate for pushrods must remain stock.
• No other alterations to the stock head are permitted.
Bore and Stroke:
Stock bore is 2.685” and may be over bored to 2.718” Stroke is 2.123” +.010”-.005”.
Connecting Rod: Stock or Billet aluminum rods, with or without bearing inserts allowed. No titanium rods allowed. Rod length is a non tech item.
Carburetor/Intake Requirements:
• Stock Huayi or RUI*ING carb. Venturi .625” NO-GO. Rear carb bore .751” NO-GO. Carb bore finish, non tech.
• Throttle shaft - .115” minimum. Butterfly - .037” minimum. Throttle shaft, washer, and butterfly must be stock and must be present, butterfly screw non tech.
• Air Filter adapter of 1.375” max length allowed. No air rams.
• Pulse-type fuel pump is mandatory. Fuel pump must be pulsed from either the crankcase or the valve cover.
• Black phenolic carb insulator must be used.
• Choke assembly may be removed.
• Jets, air bleeds jets, and emulsion tubes are non-tech. Stock intake runner gasket configuration only.
• No other alterations are permitted.
Ignition system: Ignition timing is non tech. Stock ignition module only. No modifications of any type allowed. Sparkplug connector must be stock as from factory.
Piston Requirements: Must be stock dished piston with no modifications. Oversize Clone or Honda ZOT dished piston is allowed up to .035" oversize. Rings must appear stock and all rings must be installed. Piston may not pop out above cylinder deck.
Valve Train: Stock valve-train only in stock configuration except:
• Any single valve springs and valve spring shims are allowed;
• Any 5.5mm stem steel valve (including stainless) After market valve retainers allowed.
• Intake valve head Max OD .982” +/- .005” and Exhaust valve head Max OD .945” +/- .005”.
• Valves must be one angle only, 45°.
• No knife edging of valves (1mm min. margin).
• Valve length is non-tech.
• No additional support for rocker studs permitted.
• Outside face of valve head may not be below the combustion chamber floor. (i.e. don’t sink the valves) Valve cover may be drilled for fuel pump pulse fitting, otherwise, it must remain unaltered. Valve cover gasket is non-tech.
Camshaft Requirements:
• Stock camshaft cores only, ez-spin assy must remain as stock.
• Duration check for Intake and Exhaust lobes (taken off pushrod) .
o Intake duration of 248 degrees at .050 lift/107 degrees at .200 lift.
o Exhaust duration of 247 degrees at .050 lift/116 degrees at .200 lift.
• Max lift at the valve retainers, Intake .238” and exhaust .242” taken on valve spring retainer with zero lash. (To achieve zero valve lash for checking running lift, preload dial indicator by .001”.)
Crankshaft Requirements:
• Stock, factory crankshaft only with stock, factory timing gear in factory location.
• No modifications to crankshaft allowed.
• Aftermarket steel main bearings of non self-aligning type, with or without seal are allowed.
• No ceramic bearings. Crankshaft Journal diameter is 1.180”, 1.168” minimum.
Block Requirements:
• Stock Block, as cast and produced with no alterations or modifications other than those specifically permitted.
• Block head matting surface may be machined, however, no piston pop out is allowed.
• Blocks may NOT be welded for repairs. No addition of material to block (i.e. welding, jb weld, etc).
• All bolt bosses in block may be drilled and tapped for repairs or other uses. Fastener type and size for sidecover is a non-tech issue
• Additional side cover gaskets as required for crankshaft thrust are permitted. Gasket sealer allowed
• All parts associated with the governor and the low oil sensor may be removed, plugging any associated holes.
Flywheel:
• Approved SFI certified billet aluminum flywheel only.
• No machining or alteration of any kind allowed.
• Minimum weight for flywheel is 3.3 lbs. Any timing key or no key at all may be used.
• A flat washer or spacer may be used, and is recommended, between the flywheel and the nut.
• Handheld electric starter may be used, but compression release mechanism must remain on camshaft.
• Current Approved flywheels: ARC 6619, ARC 6618, Raceseng Flywheels RSP-13-075 Rewheel NF- S1 & RSP-13-077 Rewheel F-S1.
Header and Muffler Requirements:
• Header Pipe Length: Minimum 18”- Maximum 22”.
• Silencer must be a RLV 91_L type with .1285 no-go hole. Header must be securely wrapped from flange to muffler prior to the race.
• Exhaust Pipe must be double nutted or safety wired. Use of studs or bolts permitted.
• Silencer must be supported by clamped on brace to secure it in place.