Hey guys, so I'm making a Go kart, (vertical shaft) and I'm wondering, before I weld the frame I want to make sure that this isn't unhealthy for it. So I planning on using this (in video) to rev it up and go faster. Will it blow if I possibly open it constantly? (skip to 25)
Yeah I have no Idea, My guess is if it's warmed up, it should be fine. Because why would they let the mower do that unless it could?
Not sure about that either. It is better to rev it when it's warmed up, it would hurt it easier if it's cold.
WIll it kill it? Without knowing alot more about the engine than likely comes in the mowers handbook, its hard to say whether or not it will kill the engine. Bare minimum, you will wear the engine out faster. That goes for any engine though be it a V12 car, i6 truck, 26cc RC car or whatever. The pistons moving in the cylinder alot faster can cause issues. The piston rings and the contact point with the cylinder. The rings will wear out alot faster, like I said before, happens in a car and can make the difference between a car lasting 100000 miles and 200000 miles, the cylinder bore will also be worn faster. When it does go, engine wont run so well, possibly not at all. It will run hotter. Its air cooled, so this might actually be a problem as it probably wasnt designed to cool the increased temperature. Stick an electric fan over it perhaps. Overheating can certainly kill an engine. Higher speeds put more stress on crank shaft and connecting rods. Either the shaft and rods themselves can snap or their retaining bolts can snap under the increased load. This is almost always catastrophic, tends to put the engine well beyond repair. Connecting rods snapping in a consumer car can rip entire chunks out the side of the engine block, the oil on the road from a blown engine? Thats from the massive hole the connecting rod tore out the side. You aren't fixing that if it happens. The engine in my car is actually known for some of the bolts on the lower end snapping at just over 7000rpm, there are aftermarket replacements available good for 8000 at which point the rod itself becomes the issue and you have to start getting custom forged rods ($$$, even the bolts = $$$). On a 4 stroke (most mowers are 4 stroke at least) you can get issues with the valve springs not returning the valve to the closed position properly, the piston then hits it, damage ranges from bent valve to destroyed engine, usually tending towards latter. Those are just some of the risks laid out. As for whether any will occur? No idea. I'd imagine that engine can probably cope with its own open throttle revving, probably isnt going to explode or tear holes in the side of the block. I've seen a few mower engine go karts. I dont think it will have any major issues mechanically. I think you're more likely to run into overheating issues. - - - Updated - - - Oh. The whole thing about a warm engine. That is because pistons expand as they heat up. They are designed to run at a set temperature and are a loose fit in the cylinder prior to that (the rings alleviate this somewhat, but model car/plane engines often have real issues running cold due to lack of rings and the pistons loose fit, although some larger models do have rings). Then something unique to engines with a true dedicated oil system as opposed to lubricant added to the fuel (like cheap 2 strokes and again some model grade 4 strokes). You have to wait to get the oil up to temperature for it to do its job properly, hammering the engine before that will wear it out faster as its basically running with no oil, the colder oil doesnt pump properly.
(deleted derpage). An idea i have, which i should have done for my own (this is what caused it to die) is a gearbox or transmission or whatever. Nothing very large or complex, but at least a couple gears, so on the second gear, you can go just as fast, but at lower rpm, which somewhat reduces risk of engine damage edit:6677 is right about engine parts malfunctioning edit 2: the spring connected between the pull "wire" and the carb is used to control the rpm (mostly for tuning and whatnot). And yes, newish mowers do have governors. I googled "lawnmower rpm governor" and it came up sooo...
Dude, that's a throttle, on a carburetor. A device to actually set rpm, that's a governer, they are too complicated to justify sticking on a mower.
Everything 6677 has said is right so far; Hi, I'm Wolf and I'm a semi- qualifyed diesel mechanic.. The thing you would worry about most is cooling issues, Attaching a cooler onto a sump helps alot, You can setup a dry sump if you have some mechanical knowledge. Valves can be a issue; Is it Overhead Valve or Over head cam, It should say ''OHC'' or ''OHV'' on the front of the engine valve cover. By the looks of the carburettor set up it is a Briggs & Stratton motor Also You need to be more specific when using google for situations like this. 70 dodge modder Most Briggs & Stratton Motors don't have Governers, However most honda motors do, Best example would have to be.. Arrr let me think... HRU 216 Buffalo classic motor. Mostly found on self propelled mowers... Also be careful with those little springs, They are known to break really easy on a Briggs & Stratton whilst messing with the throttle assembelly...
