Project DTZr.....a DT125R love story
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Hello,after a long time,it's a slow project due to some personal matters from time to time.
"Last minute" tuning to crankcases for matching,widening,angles retaining and "little" tuning to Athena cylinder/head (trasnfer port shape and sizes,exhaust port shape,size and timing,combustion chamber volume,compression)
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Hello after a long time.
I had to open the crankcases because of a faulty gearbox part (even checked I've missed it).
Did some further tweaking to the cases,matched them 99+% I believe,and gave a texture to help flow and "grab" more mixture,widened a little the reed valve space and removed some metal from the low right corner for the RZ350 reed valve to be installed.
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The finished DTZr,it's on the road,I am doing some runnin km's and will go to a friends dyno.
Passed technical inspection with "flying colors".
I didn't put the 3ET headlight because it's no good for night,if you want to see and not just others to see you.
PS.I will shorten a little the front fender.
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Bike looks great and similar (not wheels) to my old DTR that I built years back (profile picture).
I've just bought a 3ET light unit for my 200WR as I believe that they are the same so I'm gutted to hear that they are poor output but I want to go back to stock as the 125X unit I've got does come in white and therefore looks odd.
Interesting that you've also gone down the 3ET swingarm route as I've got one ready to go on my 3SH build - great minds think alike!
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Finishing my modification of 80's YZ/RD/DT125 reedcage,to fit the DTZr.
It is used because it has less pedals,it's shorter and doesn't block the C boost port of the cylinder the.Widened to fit the carb rubber joint,bolt holes relocated and smoothed the angles.[
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Time for a little update.I've finished the reed cage modification and will explain why did it.
I had 2 failures in fiber reed pedals,and you know how difficult is to take out the reed valve.My first set of boyesen dual stage where used but in very good condition,they bent in various places probably because of age but after doing 1000km,the second set was simple fiber pedals and even the adjustment's I did because of bad finish quality,they couldn't handle the tune of the engine at high rpm's.So i went back to basics,searched the yamaha 2 stroke engines with similar specs as my tuned and saw what reed valve they used. RZ350,RD125LC,YZ125(80's models),TZ750 had the same reed valve.
Purchased everything genuine,made the mod's to fit the DT rubber joint and already had done the widening to the engine cases as future plan.I preferred the above setup because of the shorter and wider steel pedals.Shorter pedals handle higher rpm better,wider are more robust,genuine yamaha made in japan quality steel.
For the long run,I asked a good friend and old timer mechanic in 2 strokes that helped me with his knowledge,if he has ever see failed steel reed pedals especially in Yamaha's.He said the the worst he saw was bent pedals to touch the stoppers from racing engine,never broken,but where genuine.
PS. Added bonus,this reed cage does not block the c-port in the back of the cylinder and you don't need spacers that are used in the DT reed cage for that reason.
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@MadGyver I believe the reason for changing reed petals from stainless steel to carbon/ GRP was not for fear of them breaking, though it would be catastrophic I think it's very rare. But more due to them suffering from metal fatigue and flutter.
