Am I too fat for a 35cc 4-stroke engine on my bicycle? I weigh 240 lbs, and I'm afraid to admit the unthinkable. Could I actually need a 2-stroke instead of a 4-stroke? I'm considering the purchase of a new Staton-inc axle mounted kit with a new Tanaka PF4000 (40cc 2-stroke) on it, and I seek enlightened guidance on the issue. Background: in 2011 I bought a new Staton-inc axle mounted kit with a new 35cc Robin-Subaru 4-stroke engine on it (with a 60 tooth large sprocket on the rear wheel and a 12 tooth small sprocket on the gear reduction box,... later switching to an 11 tooth small sprocket for more torque going up hills). I installed it on my 26" wheel hard-tail mountain bike, and rode it with glee all 4 seasons in NH, changing the oil and filters regularly, and putting approximately 2000 miles on it. Then one day the engine started losing power. I figured I had probably lugged it to death by going up one too many long, steep hills, especially given my weight, and given that the engine only had 1.6 horsepower. But instead of troubleshooting and fixing the Robin-Surbaru, I decided to just replace it with a new Honda GX35 (35cc 4-stroke), which I also ordered from Staton. However, after only 4 months of use, the Honda started losing power, too. :veryangry: Oil started seeping out and dripping from the cooling fins, and gas started getting into the oil reservoir (which I noticed whenever I changed the oil -- the used oil emitted a strong gas odor, and it also had an unnatural color to it, like coffee with cream). Some people later guessed that this was likely a mechanical problem called "blow by" (a bad valve or whatnot--I'm not an engine mechanic), but that was just a guess on their part, as I never actually got it diagnosed and fixed. So I'm wondering -- can "blow by" (if it was, in fact, blow by) be caused by a 240 pounder riding a kit with 35cc 4-stoke on it? And/or can it be caused by using E10 gas (10% ethanol--sold everywhere in my neck of the woods) without adding ethanol fuel treatment? I never used ethanol treatment in the E10 gas. For whatever it's worth, Honda's official small engine website says that their engines can take E10 (but maybe it gradually destroys the engine over a long enough period of time that Honda considers it no big deal?) In any event, last summer I just got fed up :icon_cry: and sold my motorized bike: kit, frame, wheels, tires and all. With the money from that sale I bought a used touring/hybrid bike with 700c sized wheels, upgraded it a bit, bought some camping gear, and did some long distance touring & stealth-camping. I even lost some weight (but, alas, I regained it). Now, after several long months without any engine whatsoever on my bicycle, I find that I've lost enthusiasm for pedaling to get everywhere, and I really miss my motorized ride. So, to make a very long story short, I'm wondering if I'd be better served by a Tanaka PF4000 (40cc 2-stroke) instead of a 4-stroke. Whether or not I choose a 2-stroke or a 4-stoke, I plan to put my new kit on another 26" wheel mountain bike. Could it be that, given my weight, I lugged these poor lil' 4-strokes to their early deaths? God I hope I didn't do that them, those poor fellow creatures,... I don't like the idea of the added noise pollution from a 2-stroke, nor do I like the idea of added air pollution from burning 2-stroke oil, nor do I like the added cost of 2-stroke oil, nor do I like the inconvenience of having to mix oil with gas, but maybe it's the best I can do. Any ideas :idea: , suggestions, comments? Thanks.