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Old 06-11-2016, 07:12 PM
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salorr33cc salorr33cc is offline
Motorized Bicycle Member
Join Date: Apr 2016
Location: pennsylvania
Posts: 44
Default Help a Veteran with New engine crackiling and 4-stroking

I purchased a Silver Flying Horse Kit from Gas Bikes .. I believe it is a GT5 38mm stroke motor. I know there are a lot of different kits out there,, like PK80, 40mm stroke, 2 different pistons and 5-6 connecting rods out there,,, I seem to have the 38mm smaller piston and no marking copper color rod,, I would like to say that my cylinder was in good quality,, barely any casting flaws.

I have the slant head with spark plug towards rear of engine.
stock NT carb with needle clip in 2nd down from top out of 5 positions, the first carb they sent had all chinese markings on it and a 4 position needle, they sent me a new one cause plastic float leaked, new one has slight differences like 5 postion needle and different looking main jet.. I know that these carbs have a way to big.079 main jets and that can cause 4-stroking
I have a banana type expansion pipe,
stock cdi and magneto in 1 oclock postion and ohms out at 320
spark plug boot real crappy and has like this loose spring clip inside it,,, dont like it but get spark
tried all types of different spark plugs ,, no difference
running 32 to 1 synthetic mineral 2 stroke Bel Ray oil..
tried adjusting needle clip posistions,,, a little better a low throttle and rpms
i port matched the exhaust pipe flange to be more oval then small round
trimmed base gasket where there was overlapping but have not case matched to jug or done anything with intake except add o-ring to prevent leaking
bike has real good compression and lots of power,,, i never have to pedal,,, and starts right up even with out choke,,, never used choke yet
i live in Stroudsburg PA, and probably a little high here in elevation
**** Like I said,, when starting off under load and throttle it purrs good and smooth, as soon as it starts to rev up like when the pipe should be kicking in some powerband it just starts to break up and crackle and loose power and at 15-20mph half throttle no load cruising it does the same crackiling and popping.

and also what should i do with my dremel and light porting,, like i can see a good bit of piston in exhaust port a BDC which also means my transfer ports arent getting un covered all the way either,, and the intake is all overlapping and can see piston skirt at TDC.. and bottom case to cylinder jug transfers is also all overlapping not matched metal... please help as i read and hear all types of things to do and everyone says he or he is wrong ... confusing... just want it to run smooth from low to high and feel a powerband kick at like 5000 rpms... I think if i port matched everything and smooth the flow out thru engine should run better,,, dont know what to do about piston skirt on intake side and raise exhaust port a little,,, or use thick base gasket and sand down head ???? also should i just adapt a Walboro 15mm carb and adjust hi and low speed settings like on my 50cc scooter... please help
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