Vintage Dirt Bike Q & A

Race season is over and its time for a rebuild. I searched a bit and i had trouble finding a rod kit for the red rocket. Although one company in england was selling the same rod for 78-01 cr250. None of the other companies sell the same rod for the same years?? ANy help would be appreciated.

Thanks

you can use all rodkits you can get for cr250 till 01.
they all have a crankpin that´s 60mm long but for 78-80 models you need a 58mm pin.
your rebuilder has to shorten it about these 2mm.

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80 CR250Ra
80 CR250Ra
78 CR250R
80 CR80
82 Bultaco Sherpa 340
78 Bultaco Pursang 250 MK12
76 Bultaco Frontera 370 MK10
76 Bultaco Alpina 250
73 Bultaco Lobito 125 MK6
76 Suzuki RM125A
90 Kawasaki KX250

that pin is very hard i think, i have access to a full machine shop but i wonder if it could be shortened in a lathe?

this pin is hardned to 58-62 HRC.
it can be machined with a CBN tool.

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80 CR250Ra
80 CR250Ra
78 CR250R
80 CR80
82 Bultaco Sherpa 340
78 Bultaco Pursang 250 MK12
76 Bultaco Frontera 370 MK10
76 Bultaco Alpina 250
73 Bultaco Lobito 125 MK6
76 Suzuki RM125A
90 Kawasaki KX250

http://www.racerstoystore.com/. Did two of my engines and dropped in an IMS Hot Rod kit from a later Honda.

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Michael Stiles
1979 Honda CR250R Elsinore | 2006 Husqvarna SM510R | 2007 Service Honda CR500R-AF

Well i ordered a newer rod kit, and a guy i race with is an expert machinist for a production shop. We were talking about how to shorten a pin that hard without marking the pin. He says he can put in on a magnetic table, and precision surface grind the 2mm off it no sweat. I am going to press apart one of my spare cranks and measure first then match it with the new pin. SHould be good to go!! Thanks for all the help guys.

Just to clarify, they didnt modify the pin at all? As in all that i just mentioned is a waste of time most likely?

Must have been a don't ask, don't tell thing.

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Michael Stiles
1979 Honda CR250R Elsinore | 2006 Husqvarna SM510R | 2007 Service Honda CR500R-AF