Vintage Dirt Bike Q & A

hi
i started to sort out the boxes of parts for my cr250 and the engine has a alloy reed valve block bolted to where the std inlet rubber goes.has any one seen these and can you get parts for them.my cr needs a total restoration no rubber part has passed the 20years in the weather in texas
jim garvey
sydney
australia

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Jim Garvey
1x honda cr250m 1973 in bits
1x honda cr250 champion dirttracker
1x yamaha tt500 dirttracker 1976
1x yetman triumph dirttracker
1x tt500 longtack speedway bike
1 x 1940 350 ariel speedway bike
1 x bultaco astro grasstrack bike antig

There were and are several different types and manufacturers of the reed blocks for them. Does it look like a cast or billet reed assembly? Does it say GEM on it? If it's a billet one it could be the Klemm Research one and takes a Banshee reed, it has to be altered though. There was also one by Don Jones, it is cast also and has ribs running the length of the sides if I remember right, not sure which reed it takes, but it is probably a Yamaha one from that period. I prefer the good ole piston port myself, much faster!

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Sam Alexander

1974 Honda CR250M
1976 Honda CR250
1974 Maico MC440
1974 Maico MC250
1977 Maico AW400

the outer plate of the reed valve has ribs running accross the top and bottom.i checked it against my 1979 yz400 f reed cage and the one on the cr is bigger.also the barrel is ported to great extent even a window on the piston
cheers
jimg

_________________
Jim Garvey
1x honda cr250m 1973 in bits
1x honda cr250 champion dirttracker
1x yamaha tt500 dirttracker 1976
1x yetman triumph dirttracker
1x tt500 longtack speedway bike
1 x 1940 350 ariel speedway bike
1 x bultaco astro grasstrack bike antig

It sounds like it may be a Don Jones reed, or a replica, there were some made recently, I have no idea what reed they used. If it is a reed it will have holes drilled or windows cut in the skirt of the piston on the intake side. It could also have Boyensen ports cut down through the bottom floor of the intake into the case area. The GEM setup drilled boost ports down through the cylinder walls into the intake port. There are all sorts of things that could be done, it's just a matter of who did it. Where did it come from? You can email me pictures and I can probably tell you what it is. It could be one of those Halpen cylinders, but it doesn't sound like it.

_________________
Sam Alexander

1974 Honda CR250M
1976 Honda CR250
1974 Maico MC440
1974 Maico MC250
1977 Maico AW400