Do a search for Gordon Jennings two stroke tuning . It can be found in .pdf on several well known torrent sites . The short version is you will gain more from addition of a well designed exhaust than you will from any other single modification but as Jennings says that is just the tip of the 'berg . This all has to looked at and done as a system . Although compression is part of it squish area and angle , distance between the piston and head , percentage or ratio of oil to fuel and carb tuning , gearing for expected use all impact the performance of a 2 smoker . Do take the time to read Jennings and don't take any hurried short cuts . You'll find it a great and easy to understand read from one of the masters .
Thank you for the help. I found and read the book online. You were right. It is a nice informative file. I think that I have decided to leave the compression alone. I still want a reliable bike when I get done. The cylinder and piston were trashed when my son not keep an eye on the 2-stroke oil. I discovered today that the cylinder will need a sleeve instead of boring. It's too expensive. I am now in the market for a used one.
Nice thing about sleeving a chrome bore is having up to 4 bores after that and if you ever have to replace the sleeve the bore for the sleeve is already done . Also the Iron liner is much more tolerant of user indiscretions like lack of oil and other seizures . In minor cases all you have to do is clean the aluminum off the cylinder and replace the piston . Phosphoric acid is your friend here .
Another thing to consider is using either two or a single thicker base gasket, and a thin aluminum head gasket rather than the stock brass head gasket.
This has the advantage of slightly increasing the port timing without raising the compression ratio. This, along with the afore mentioned exhaust (which I agree is the #1 by far, BUT impossible to find a off the shelf item for the KE100) tends to wake these bikes up a bit.
If you look towards the factory hot rod rotary disc engines, you can see how Kawi modified the inlets discs along with fitting bigger carbs on some of there early 70's racers. Much can be done, but at this late stage it is just plain expensive to recreate something which passed from favor 35+ years ago. Still fun to think about though.
I currently have two KE100's - a 89 and a 94, and for my uses, I keep the engine stock, but I do change the gearing to suit the needs - I use the stock gearing for the street, and drop one tooth on the front sproket for the dirt (no need to change the chain) I have tried two teeth less on the front sproket, it would only be good for the really tight trails as it tends to really limit the top end.
These bikes could have really used the six speed from the KE125, but I do understand why, at the price point they sold at that they only have 5 gears.
Still, it is fun to hunked down on the fuel tank and with my feet on the rear pegs I can get about 57 or so tucked in as tight as possible, on the freeway... fast enough to be legal in the 60 mph roads in my part of the country...
$268 is the cheapest I've found for the sleeve and all of the machining work. That does not include piston, rings, and gaskets. That is a little bit more than what I wanted to spend. I think I will sit back and try to find a good used one. Thanks for all of the replies.
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