Vintage Dirt Bike Q & A

Does anyone know which rod kit I need to use with the spacer plate kit? I bought one kit complete with spacer and crank kit, but now want to rebuild and replace rod. I can get the Hot Rod kits cheaper at my local dealer, but don't know which one to buy. I know it is from a later model, but which one?

I am going to have to rebuild my crank/rod also and would like to buy one of the kits you have purchased. Do you remember where you got it and do they still have them? I dont know a lot about these bikes but the 76 used a different piston than the 73-75 at least from what ive read. I assume the kit you used just had a slightly longer connecting rod shouldnt be to hard to figure out cant you just ask the people you bought it from? Was the tourque increase from the kit noticeable?

The piston changed between 73-74 M models and the 75-76 M1 models, but it was only because they moved the ring pins to avoid an extra port, not because of any rod changes.

The longer rods are 4mm longer, from what I've read. And I might be wrong here, but I think that's what the 75-76 rods are.

There is a thread that talks in depth about this. It had been over 30 years since I really rode one of these bikes, so when I bought and rebuilt this one I really didn't have anything but a memory to compare to. Badbrush racing has them for sale on Ebay.

Get in touch with the guy at Badbrush.com. Good guy has the parts. Its where I get mine

I know I can buy it from Badbrush, but if I knew which rod kit I could get it locally. I think it is from a TRX250R 87-89, but I am not sure.

i got a kit from vintage elsinores it was a hot rods kit he scraped the modle no of the packet.i pick up my crank tomorrow all finished
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

On one site it has the part number HD8103. I looked on Hot Rods website and this is a later model CR250 and a TRX250R model. It gives all the measurements on that site so as soon as I press my crank apart I will measure it and let everyone know. The reason I want to buy from my dealer is that retail is around $90 (and I get a discount from that) and they are charging $129.95 at elsinores.com. Badbrush is not a bad deal at $142 when they supply the rod kit and custom machined spacer and gasket, but I have that.

Allright guys here is the info on the rods. I measured both a stock and kit rod. I also looked at the spec sheet on the Wiseco site to make sure of my measurements. The stock rod is 121mm center to center, 31mm big end bore, 22mm small end bore, 16.75 bottom width, and a 20mm top width. The Wiseco rod kit WPR124 which fits 84 to 2001 CR250 along with some ATVs has the exact same measurements except for length. It is 125.3mm in length. SO it is 4.3mm longer and needs the spacer plate to make it work. Hope this helps someone. As I said before, $142 from Badbrush is not a bad deal when you figure the custom made spacer plate, but if you have it like I did and only need a rod it is nice to order from my local dealer who gets overnight service from a couple of his suppliers.

Just wondering what would you gain by fitting the longer rod kit thanks Simon

It's mostly because we can't get the regular rod anymore and are making these long rods work by using the spacer. Some say you get more midrange with a little less top with the long rod, but it's mainly because they are available.

mx317 thanks for the info and follow up.. It will save some of us $$