Hi guys.
I'm Eros and I'm Italian, I own a little dirtbike workshop and a race team near Milan and I am a two stroke addict since I'm 8 years old.
Back in the day, It was 1999, I fall in love with Torrontera's and Procircuit Kawy, so, i promise to myself to build a bike like that when i was grow up.
(Sorry for my horrible english skill, but I've learned to write by myself).
Three years ago i spot a relatively well used Kawy to my project, paid 1400 bucks, loocks pretty and works relatively well.
Unfortunately I've discovered that the bike looks amazing but has some critical engineering issue:
-the engine has a weird powerband, dead slow on low rpm, good hit on mid so I think "oh yes dude, it goes!", and no top, flat overrev that make useless to go on and need continuos shifting to keep the engine in the meat.
-clutch lever is relatively hard.
-front fork is weird, starts hard, then fall down for a little and after became really hard, smashing on the arms at every single bump.
-brakes were mushy and has no power.
-shock was decent when compared to the rest of the bike.
-rims are prone to crack on nipples hole.
-general bike quality is near to crap, footpegs have a terrible play, screws from tank pops out with the nut, triple clamps with no possibility to set the handlebar position (but on the same year 250 it is possible Whatta**ck???).
So i decided to rebuild entirely the bike to made it perfect in every aspect.
KX 98 to 02 engine are difficult to made fast, YZ or SX can have big improvement only with a couple of tweaks, kawy engine seems to refuse any kind of conventional tuning improvement such as porting, reeds exhaust or head machining.
I've modified my KX this way:
First I've create a mold of the transfer port (don't look to the piston, it isn't from kawy) to study where i can work, then i decided to leave it stock, except for the front scavenge port.
I have grinded it on crankcase side of about two mm on the perimeter to achieve more precision in reed control by the exhaust.
I've not grinded the other ports to prevent a lack of primary pressure, kawy transfers aren't perfect, but grinding material can cause the engine loss the bad low and the decent mid pull from stock configuration.
For build up more pressure I've put two plugs into the crankpin (made from a 7076 AL bar) and i switched the stock rod with a forged wossner rod.
I've tried to use many different piston on this bike, honda, KTM and even the old Husqvarna piston.
The only configuratio that was interesting is the KTM one but I've removed it before the ring being catch from a tranfer port, due of the different pin position.
So i bought a wossner piston for kawy and i made it flat by turning about 0,5 mm form dome.
I also machined the exhaust port, removing 1,5 mm on each side.
Because of the KIPS design i cannot made the exhaust port any higher so I've put 2 gasket instead of one under the cylinder, then i have turned the head down to match the right (0,9 mm) squish measure.
I've bolt on a KX 125 1993 reed valve with aktive reeds, a KX 250 PWK 38,5 (with powerjet and KTRICK) and a Messico Exhaust with a Bud silencer to let the engine breath properly.
Clutch, bearings, shift shaft and all the engine ruined parts was put on brand new from Partzilla.
