Bill you just "wouldn't" want to know what i did a lifetime ago--ok i'll admit it, just don't tell Lozza!!. Used to ride my Yamy CT1 [piston port] to work & used a KDX175 piston in it. Had a boost port hole high up on the skirt side & was say 10 or 12mm in size [guessing now]. In desperation i threaded the hole [about two turns of thread] & screwed a bolt in & cut it off then dressed it up. Made the thread tight plus loctited it. Worked well, just can't remember for how long. Think the skirt had a 'slight' cut away on the lower edge just advancing the inlet a bit [on my Yam anyway]. Thing used to fly with a [nz yamaha redundant stock--cheap] MX175 chamber adapted to fit. Sold it to a female neighbor who thrashed it for ages & used to carry her dog [called hedgehog] at [an indicated flat out] 70mph with hedgehog dribbling furiously into the wind. God i'll have nightmares over that now. Thanks for reminding me. Bottom line is--don't do it [piston]. Probably run but have gaspy low speed running & go like hell up top. One more thing. Yamaha & Kawy [i think] might have the same 70mm bore [std] i know on my 175 the gudgeon height was the same, 250 might be the same too but you'd have to check out piston port DT1MX wiseco pistons if available or something modern with 'case reed' where the piston has no reed holes or cutaway. Anyway--me getting silly. Night. ps, jeez we used to get right into the annual redundant stock list at work. Bought [amongst other things] TWO RT2MX new cylinders. Scrapped one when i bored it to 85mm YZ400 piston in the hope that the "fins wouldn't fall off" [nearly did & was unusable bugger it], before i realised "79 YZ400 was 82mm. Think other cylinder is on Macka's Cooper Yam thingy' nowdays--depressed again now. Cheers . tears.
