This was a major rebuild I did for a customer and friend on Moped Army. His case seals were shot on a motor I rebuilt and ported the top end on last year. Now it’s getting a reed block and a fresh bottom end.
The rebuild went predictably: They were some unpleasant surprises, some parts that needed persuasion, and of course some Dremel Action to get everything right. Even so, the engine apparently developed some air leaks resulting from the use of gaskets made from material that was Bone Dry, and a Gen1 reed block on a 1977 cylinder kit. Gen2 reed blocks (Retail Version) have a reduced port window to ensure compatibility with all cylinders. Even so, make sure you do a leakdown test, something I Verymuch failed to do.
In my Defense, I was 60 miles from home on a housecall, in his Basement. Lugging an air compressor to Cambridge was not an option.
Steps for installation:
You will need: Gen2 Reed Block, Athena AV10 Reed assembly, Bendy SHA or PHBG intake, AV7 intake gasket, AV7 Base Gasket, AV10 intake and reed gasket, 2X 25mm M6 Socket head cap screw, 4X 20mm Socket head cap screw. Loctite is suggested for Screws.
I am going to assume (Perhaps wrongly) that anyone purchasing this product has proficiency in moped engine performance tuning and possesses the tools and skills required for basic cylinder porting.
1: Disassemble AV7 engine top end, and isolate Cylinder and piston. Remove rings, circlips and wrist pin from Piston. Remove old intake from cylinder, and remove Studs.
2: Remove old gasket material from all sealing surfaces and check sealing surfaces for flatness. Commercially available intake and reed gaskets may be used with Gen2 Reed blocks.
3: Cutting cylinder/piston for longer intake duration and/or boost porting is entirely optional. Greater power gains will be realized with a piston window cut to allow mix to flow from the intake to the cases even at bottom dead center.
Note: A 15* boost port cut into the rear wall of the cylinder is also suggested, either as a supplement to the piston window, or to be used without a window, on high suction pipes. This falls into the realm of end user design intent. Only you know what you’re tuning for. Port matching reed block to cylinder is suggested.
4: Once porting has been done, assemble reed block to cylinder using AV7 intake gasket and 25mm M6 screws. Loctite is suggested to prevent screws from backing out. See Photo # 7. (Note, reed block was not port matched to cylinder)
5: Assemble Athena reed to reed block as shown in photo #8. Attach intake and intake gasket as shown in photo #9 with 4X 20mm M6 screws. Again, loctite is suggested.
6: Re-assemble engine and Check For Air Leaks. Reed blocks have been flycut flat, but due to manufacturing variances in cylinder intake surfaces, I cannot assure they will seal in every situation.
AV7s were never designed to have reeds, and humans were never designed to exceed 20MPH in a straight line. Nevertheless, this reed block will help you exceed both limitations with relative ease. It won’t magically transform an American Bike into a European model, but if you already have an AV7 you’ve sunk some money into, or just a stock cylinder you want some more bang out of, they do their job of adding more torque, allowing for Boost ports and preventing blowback.
You can -Always- Contact me at Motodrachen@Gmail.com with any questions regarding this, or any of my products.