Suzuki 2 Strokes

Hi,
I have been looking into fitting the reed valve block and carb from an Aprilia RS125 to the GT550.

At this time work has only been done on scrap cylinders so nothing has been lost.

Please follow this link and download the PDF document.

https://www.dropbox.com/s/liz6v1n6q81e6 ... 0.pdf?dl=0" onclick="window.open(this.href);return false;

Any comments please.

Dave
Southampton UK

Dave,
I have but one question: why are you wasting time here when you could be welding up those reed blocks?

OK, so I lied, I have couple of others. What advantage do you expect to gain from just the reed block or do you anticipate porting the cylinders at the same time? 33HP from an RS125 at whatever revs requires a pipe that works with those ports and an ignition timing curve that works too. In addition, the heads are probably a little different in shape and effectiveness.

On a 181cc long stroke motor you will be looking at very different port areas and timing to achieve the correct port-time area. There are two primary advantages of reed valves. The first is what Yamaha exploited on the RD twins, namely that wild inlet timing required to make good top end, no longer hurt low RPM torque. That implies using longer inlet port duration to take advantage of the reeds.

The second advantage is the extra transfer port area. In the RS125 that boost port can work either way - to flow into the crankcase or into the cylinder from the reeds or from the crankcase up to the cylinder through that small boost port. So that means adding a boost port into each cylinder.

Access from the reed cage to the transfers is a neat touch on the Rotax cylinder. Those are generally known as Boysen ports and generally seem to work well if a cylinder can't access enough flow from the crankcase straight up to the transfers and work well with a great pipe design. GT550's don't have much crankcase volume and I suspect that the extra (Boysen) ports will help.

Of course the transfer ports and exhaust port dimensions need to match the power target but calculations we have done suggest that you new motor with the right ports and pipes could be incredibly powerful, to the point that engine cooling and other mechanical issues may be the limiting factor.

Good luck and keep us posted.

Go for it! I have been doing reed conversions on the triple Kawi's since 1995. Makes a world of difference!

Dave , any updates ?

Very interesting ideas there.

I don't think adding reed valves will make any more peak hp as desired?

If goal is more HP a change of port timimg and or area is needed.

Now if you change intake timing reeds should give you back bottom end which is very nice.

Work is impressive .

Hi,

I have not been around for some time due to work projects.
It must be noted that this work is intended for the Euro Nykasil cylinders with the extra boost ports as standard (7 ports).
This cylinder (Jug) was never available in the USA.
Further work so far is to start to enlarge the inlet port for the reed valve as per:

https://www.dropbox.com/s/r3biba0rco6jm ... 8.jpg?dl=0" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;

I am still within my scribed lines (just about visible) and now I need a finer burr.
Inlet port size has not been changed so far.
As you can see the inlet will be much improved.

I also state again that this work so far is on a scrap cylinder that I have that was part of a GT550 engine that I purchased some years ago.
Engine advertised as fully working but with only 2.5 con rods and 2 pistons.

Dave

Dave , did you get any further on your 550 reed intake idea ?

bump