Roelf, last head button pic. Did ya get a little tight on the clearance Clarence or did she lean out on you?
No, that was an old NovaMega EVO5 engine with a broken conrod, I have to polish it a bit for new use. The new USE is a cheap p/s set from the Basic collection: http://www.bb-hardware.com/modules/n...12562&forum=22
I modified the sleeve to the old EVO5 specs to see if it will become a good spare/trainings engine but because the flat piston I think I have to modify the buttonhead as well.
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Speed is only fiction but a 130+km/h MRS4 is for real.
what would happen if i increased the height of one of the ports above the exhaust port so i could make use of a supercharger/turbocharger? i can't see anything against it, but it might just make the engine explode in a ball of fire....
i think he means he wants to make a port above the exhaust so that the exhaust port can be closed and and a intake port still open so more air/fuel can be rammed in by a supercharger or turbo. there may be a possibility of this working if you had a low enough exhaust port and a high enough intake port so part of the time when the exhaust is closed an intake port is still open but the intake port cant be too high. because all the ports need to be sealed before tdc
If you have an inlet port higher than the exhaust, think about what happens when the mixture is ignited and the piston starts moving down... what's the first port that opens? Where do the exhaust gases flow? It might not be the brightest idea to have exhaust gasses going back to the inlet port
There's a good reason why the exhaust port is the highest one of them.
sorry, what i mean is to extend one of the intake ports slightly above the exhaust (maybe a millimeter), so you could have one port open when the exhaust is covered. as 2 stroke engines are from the factory, the exhaust is open when the intake ports are closed.
I do not think it will work, as example you can rotate the sleeve 180 degrees so the exhaust will become the inlet but from experience I can tell you the engine will not run perfect.
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Speed is only fiction but a 130+km/h MRS4 is for real.
I do not think it will work, as example you can rotate the sleeve 180 degrees so the exhaust will become the inlet but from experience I can tell you the engine will not run perfect.
ok, the engines useless anyway, so i might as well try. i wish i hadn't sold that glowplug in it now...
Roelof thank you for sharing your knowledge, very cool of you.
I am an amature modder, I have ported and polished four mills and had sucess with them. so, now I am trying to learn more about timing and how it effects power, mileage , etc.
funny you shouls mention that book, I just started reading it. It is from the 1970`s but very informative.
I am finished with break in on an Axial .32 spec 1
It runs buitifully, 230 degrees all day pulling real nice but, as you know we can never leave good enough alone.
I want to do some port work and polish but, this time I would like to mess with the timing.
I know you cant tell me exactly what to do but, any pointers>?
thanks again for the great thread.
Dan
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Hello, my name is Dan. I am addicted to rc
A big win can be found in the timing of the crankshaft. Take away about 0.2mm of the side that is closing the intake from the carburator so it closes a bit later, it will give a better responding and more powerfull engine.
And so far I know the Axial has just 1 exhaust port, you can grind the upper coners 1 mm wider. a wider exhaust will give a same result as making it higher but without affecting the combustion stroke. In other words, it will give a tiny bit more rpm without loosing bottom power.
When grinding the ports be sure smooth the grinded edges
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Speed is only fiction but a 130+km/h MRS4 is for real.
Engine tuning knowledge, can be an expensive problem to people who are new at it. You have to decide what it is you want your engine to do that your are currently unhappy with. Please remember that some gains are possible in modding engines, but be realistic in your expectations. Making huge HP gains and torque gains on high end motors is not realistic. The other thing is to go slow....small cuts and changes only(tenths of mm's) ... really small cuts on exhaust ports and crankshaft timings make big changes in timing numbers. You will need a steady hand with dremel cutting tools in order to not to ruin an engine.
"GREAT THREAD"
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