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One for RT325
Ok, found the video, Bit of a hard watch. Clutch slipping like crazy & think it jumps out of 3rd or 4th. Cylinder has horse & car clearance which you hear rattling. Done properly ie spend money rebore & stiff plus high compression, she'd go well. A closer ratio trans would help too. Plus i see at the end ov the video that i have my heavy weighted flywheel on so a small rotor YZ/MX stator would be good. Plus a pipe to suit--where does it end. Bugger its private, i'll alter it if i can remember how. Was 4 years ago looking at the date but actualy seems longer.
When i finish what i've got on here now, i'm going to look at experimenting with that. I ask this after reading what Turbo dan did with his DT360 motor.
When you look at the piston position in relation to the exhaust port at BDC, the RT is exactly as described by him on his DT 360.
As you have said, you can cut away the piston crown as long as you leave 0.8 mm over the top ring untouched. I couldn't swear to this but after reading the Clymer manual, its stated in with the GYTR mods on the porting map section for the CT1. So don't see that the 360 would be any different.
I do wonder what could be done with the head. I also think an 06 KX 125 reed cage would go in. It's pretty close as it is.
The other thing is rather than doing the head, the gasket area of the cylinder could be dropped and thus the liner. I did that on my LC 350 by .08mm and cleaned the gasket area of the head up. Big difference with it after that.
So ill gather some info as time goes by and see what happens.
The clip is good and despite the bike sounding like a cross between a YZ, Woody Woodpecker and a Daimler auto, it just demonstrates what's possible.
Thanks for the response RT.
Found the video of that but its almost unwatchable haha.
I probably mentioned i went the other way on another motor running a 360 crank in a 250. That worked good too. Might have a video of that, in the same twin frame. Getting away from your question sorry.
Found the video. Bit hard to watch & dodgy sound. Has a DT1MX top end & 360 crank. Makes a lazy but long legged fast motor with good power from zero to infinity & revs out of sight. Carburation is dodgy as had been parked for a long time & the usual blocked up varnishy fuel mess inside.
The 360 earlier video has a flat slide EI carb that i've had for years & never used. Carburation is a bit hit & miss but close. Only adjustment is via needle height & different flat taper needles if which i have none damn it. Well, have one someone had filed down probably for using methanol fuel. Just a bit of a novelty carb i thought i'd better try incase i want to sell it--carb that is. Only a 32mm. Talking bigger carb on an RT1, i used to ride to work on an RT1 with a 38 bing stretched into the biggest manifold i could find to fit the studs. Then mate took his 38 bing back after many years & left me with a his 36 bing with one float missing. So that worked just the same & never flooded with one float. Sorry lost track of where we are. Things to do--till later.
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Replied by MarkT on topic One for RT325
Gordon Jennings had a good discussion on it in his "two stroke tuners handbook" which you can find in the tech library.
I know those methods are archaic and modern two stroke design has come a long way... but I won a lot of races in the 80's and 90's with my home-brew porting and modifications that followed Jennings' recommendations... I was also a member of the SAE and had access to the published Yamaha time-area engineering studies Jennings presents in his book. I spent many hours carefully mapping the porting on fine grid graph paper, identifying the existing time-area, and modifying the ports on the graph paper to achieve the time-area I wanted. Then I simply transferred the port dimensions to the cylinder using a manila folder template. No computers back then!
My budget home-built engines were fast enough to compete with the high dollar teams in the Mickey Thompson Stadium Off Road Stadium series and in many desert races with several wins. So I believe the Jennings info is valid... that's not to say the new computer porting and pipe software isn't better... but I also believe that what allowed the big advancements in two stroke power (modern YZ85 has more power than a DT400!) are the advancements in engine cooling. I doubt an air cooled engine would survive long with modern high-power porting... at the very least the heat problem would limit the output. So Jennings info is still pretty valid for the old bikes.