my 66/80 cc i had some fun with and you really helped get it running as best it could with your advice which i followed you obviously really know what you on about but i got a clone 4 stroke engine gx200 weighs 8 lbs more ( aftere you have taken off the bits you dont need ) ive had bigger steaks lol its 6.5 out the box and the karting idiots can get 30-35 hp out of it it doesnt vibrate its quieter and i dont have to fix it every 4 yards its a lot more expensive to buy in first place but the savings on 2 stroke oil soon claw that back i use mine about 200 miles a week i commute on it
I'm calling BS on a lot of the points here. I had my Grubee Skyhawk engine installed in the frame in a couple hours, including filing open the front mount for my mountain bike's massive front tube and no need to widen the pedals. The bare weight of the Grubee motor is less than 20 lbs (24 lbs for mounts, tank, chain, sprockets, controls and all)
http://www.gasbike.net/products/grubee-skyhawk-gt2b-48cc-bike-motor-kit-black-finish#tabs-1 whereas the GX200 weighs 35 lbs without oil
http://engines.honda.com/models/model-detail/gx200 . The mount plate and hardware (bits you really need) for the GX200 weigh more than 8 lbs! An entire 2 stroke bike can be built (40 lbs
http://grubeeinc.com/Skyhawk Instructions.html ) for less weight than the GX200 engine and mounting kit.
It is going to cost you a huge amount of money to get 30-35hp out of a 5.5hp(see
http://engines.honda.com/models/model-detail/gx200 ) base engine. Cams, bigger valves and seats, valve springs, carb and custom exhaust all cost money. When I do the math it is not possible unless you take that 3600rpm GX200 motor and spin it 10,000rpm, and then where are reliability and vibration free? I can triple the 2hp the Grubee makes (exceed the stock GX200 hp!) for the cost of common tools, epoxy and gaskets. I come with some experience, but anyone that follows the "good" advice on this site can make 6hp by removing metal and filling other places in with epoxy, while running the stock pipe, carb, head and ignition. Put a good pipe ($100?) on a Grubee and you have double the hp of the GX200, for 1/2 the weight. Investment? Less than $300.
"Fix it every 4 yards"? You clearly don't know what you are doing. I drive my Grubee 45 kms to work and back daily, and go out for 50-100 kms evening rides without worry. I've had 2 failures. A circlip failed from continuous 9000 rpm operation (my modifications and hard riding) and I just had a meltdown from overlean (again my fault). If I had driven this motor as supplied, neither of these would have happened. Each cost me $36 to repair. My motor had over 1000 miles on it at the time of the first failure and likely (no hour meter, just weekly calculation) over 2000 miles now. Still running.
Cost of 2 stroke oil? Are you kidding me? I use very good synthetic at $20 bottle. I mix rich at 32:1 and drive full throttle most of the time getting 160+ kms out of the 3 L tank. 200 miles is 2 tanks of fuel. Cost of the fuel even up here where it is expensive is $6 and cost of oil is $3.75. Slow down, lean out and use a cheaper oil you will have that down to a buck a week in the US, and less than $4 in fuel. Cheap riding.
The 2 stroke motors weigh much less, make ample hp in the legal 49cc requirement and have huge modification and hp gain potential over the 4 stroke engines, but I'll admit they are tricky. You have to know what you are doing. You are rewarded with a 40mph bike that you can throw over a fence. I will admit also that the 4 strokes, while being heavier, slower and more expensive, are more idiot proof. Perfectly suited to those that need that quality.
Steve (you can see where my bias lays)