ORIGINAL: aussiesteve
ORIGINAL: Oupagryse
Hi Does someone have a complete manual for the 15cc engine? I'm glad i read this forum, would have never thought to check the timing of the engine.
I was looking for the performance curves of these engines but could not find them. Sent a mail to the manufacturers but they replied with a statement saying they don't have any... How is that possible? They state the kw rating of the engine but they don't know at what rpm they achieved it or anything... Stated bore and stroke is also wrong. It's 31mm and 24mm stroke. If you take into consideration the exhaust port ect it does come out at 15cc, so atleast they wern't lying about that.. Anyway, if anybody could help I would appreciate it.
Fuel consumption vs load and power vs rpm and fuel vs rpm
The Old Grey Grandpa AKA Oupagryse in Afrikaans
@ ACERC P.s a Nylock nut is only suppose to be used once... The plastic bit should be threaded, you can use them about 3 time before they stop the nut from vibrating loose..
31mm bore and 24mm stroke comes out at 18cc.
Oupagryse is correct, on a two stroke engine, you measure the compression chamber from the top of the exhaust port. I work with two stroke engines in my line of business and thats the way to do it correctly.
You can also ..tinker...with the exhaust port timing some to get more rpms if you are racing
Just shave some off the TOP of the exhaust port to increase rpm. BUT, as with all engines, to gain one is to loose one. By doing the port timing change, you gain rpm but you loose idle stability and torque. So if you have a light plane that you want to make go fast, change away
. I used to do about .oo2 inches at a time till I got what I wanted. If you go to far, you kill the engine by going over the power curve and then your on the back side of the curve. No way to fix that but replace the cyl assy. LOL
Just experience over the years.
An easy way to find the point to meassure from on the exhaust port, that Ive used, is in a darkened room, shine a light into the exhaust port from muffler side
, with piston at tdc, looking down into the cyl, rotate (either way) till you just see light enter the cyl through the port. Stop and mark location somewhere on the crank and block. This is your start point to measure the actual stroke of the motor.
Hope this helps
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