4 Cycle Karting Forums - 2012 AKRA Stock Appearing Engine Specs

12-09-11,, 07:51 AM

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2012 AKRA Stock Appearing Engine Specs

Use of these Rules and Regulations require Tracks, Clubs, Promoters or Series be sanctioned by the American Kart Racing Association. Any other use is strictly prohibited without the express written consent of the American Kart Racing Association (AKRA).
The information posted here on 4cycle.com consists only of the engine specific technical data for the specific classes listed. There is considerable important information concerning general requirements, measurement procedures, class structures and tolerances that are only supplied in the printed rule book. A failure to comply with the rule book in its entirety may result in a disqualification. It is strongly suggested that racers obtain a copy of the complete book by contacting AKRA. No ruling appeal on any disqualification will be heard by AKRA unless the Track, Club, Promoter or Series involved is sanctioned by AKRA and the individual racer involved is a member of AKRA. www.akrainc.com

These rules take effect 1/1/2012

This class will take the place of the Superbox Class

Quote:

ENGINE SPECIFIC TECH SHEET FOR: STOCK APPEARING 6.5 OVH

Description: Single cylinder, 2-valve overhead 4-cycle engine. Fuel Methanol Only The engine, unless otherwise noted, must appear like a BSP, or Harbor Freight 6.5 HP engine. Parts may be interchanged between engines. Internally, you can change whatever you want as long as it meets the restrictions below. The restrictions are only for cost control by restricting some expensive machining options, expensive billet parts, and containing performance to levels with reasonable durability expectations.

Cylinder Head Requirements: Stock cylinder head only. Machining of gasket surface allowed. Porting allowed, and no addition of material in ports or to cylinder head allowed. Stock Head Bolts are required and all four are required. Must use stock configuration head gasket, thickness non tech. Cylinder head guide plate for pushrods must appear stock.

Bore and Stroke: Stock bore is 2.685 and may be over bored to 2.745 (approximately .060 overbore). Stroke is 2.133 max taken from top piston

Combustion Chamber Volume: Non Tech.

Carburetor Requirements: Stock Appearing Huayi or RUI*ING carb. Air Filter adapter of 1.375 max length allowed, Air filter may be up to 8 long. Floor pan mounted fuel tank required (stock tank to be removed) and pulse-type fuel pump allowed. Fuel pump must be pulsed from either the crankcase or the valve cover. Black phenolic carb insulator must be used. No epoxy on carb exterior. Choke assembly may be removed, if removed, choke shaft hole must be plugged. Jets, tubes and orifices are non-tech. Any throttle mechanism allowed that works with the stock throttle shafts bell crank. Remaining stock throttle mechanism parts may be removed. A plate may be bolted to the top of the engine to mount fuel pumps and/or throttle mechanisms.

Valve Train: Rockers, ball adjusters, rocker arm studs, lock nuts, pushrods, and lifters must appear stock. No additional support for rocker studs permitted. Any single valve springs allowed. Valves and retainers may be used in any combination on either side. (Example: Exhaust valve, retainer and lash cap may be used on intake side). Valve head diameters must be between .940 and .990.

Camshaft Requirements: Max lift of .285 taken with zero valve lash directly off valve retainer.

Ignition system: Box Stock ignition module only. No modifications of any type allowed. Sparkplug connector must be stock as from factory.

Piston Requirements: Oversized Piston must be flat top or dished. Honda OEM dished (ZOT) pistons or Box Stock Project pistons may be used. Piston CAN NOT ALLOW FOR ANY POP OUT!

Connecting Rod: Billet aluminum rods, with or without bearing inserts allowed. No Titanium rods allowed. Rod length is a non tech item.

Crankshaft Requirements: Stock, factory crankshaft only with stock, factory timing gear in factory location. Timing gear may be tack-welded to crankshaft in 2 places to avoid slippage. No modifications to crankshaft allowed. Aftermarket main bearings of non self-aligning type, with or without seal, allowed. (No ceramic bearings). Crankshaft Journal diameter is 1.180, 1.175 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 be welded for repairs as long as the repair does not constitute a functional modification to the block. No welding to block from cooling fins upward to deck surface. Governor stub hole may be tapped and plugged. All bolt bosses in block may be drilled and tapped for repairs or other uses. Additional side cover gaskets as required for crankshaft thrust are permitted. No welding or addition of material (such as epoxy) of any kind to the head, side cover, or block.

Flywheel: SFI certified flywheel with cooling fins only (mandatory) with 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 may be used, and is recommended, between the flywheel and the nut. Pull starter may be replaced with a flywheel cover and any electric starter nut may be employed.

Header and Muffler Requirements: Any header is allowed. No muffler unless required by track. If required use RLV-4106. Header may be bent in any configuration to keep it away from the driver and so the muffler will not extend past the rear bumper. Header must be securely wrapped from flange to swedge prior to the race. Exhaust Pipe must be double nutted or safety wired and silencer must be supported by clamped on brace to secure it in place.

ANY corrections, additions, or changes to these rules are submitted to the rules committee and approved PRIOR to being posted here. Each edit will be documented below.