Vintage Dirt Bike Q & A

i'm just getting ready to paint my 79 cr125 frame. i have it blasted but i would like to do the frame mod that was done to these. does any body know what needs to be done. seems like i saw something on here before but i can't find it. i have the stock forks and a 21 in. wheel and an 80 swing arm and shocks for right now. allso dose anybody have an oversize wisco piston they would like to trade for a std bore new wisco

There is an article on this site that tells you how to do the 79 cr125r frame modification. It's the one where you cut out a few mm from the frame backbone and re-weld. It changes the rake to work with the 21" wheel.

i can't find any info i have searched for hours here but no nuthin

I have the article somewhere. I will look and post if I find it. I thought I got it here.

I'm leaving mine with the stock rake and the 23" wheel. Not ideal but it sure looks cool. The 1979 CR125R is pretty unique. I would rather buy a 1980 model before I messed with my sweet 79. The 80 is basically the same with the 21" front wheel and a little better back shock placement.

I just love my 79. I got a brand new 78 xr75 back in the day and after a year on that, I wanted this 125. Took me 29 years to get one, but it was worth the wait! Just happened to see it on craigslist and came home with it from work that day. It had been sitting up for 20+ years but was still running. The air boot was all cracked up and was leaking air like crazy. Once I got the boot and carb issue cleared it ran great. Now with a new top end job (replate and piston), it's like brand new. It even looks great.

I just put in a fresh tank of gas with blenzall castor bean oil. Smells like sweet heaven. Can't wait to go ride!!!!!!

thanks that would be great, i still think its on here some place. i think it was on a post that trailed off onto this frame mod it might be imposible to find

I found this, but it is not complete.

this is great keep the info comming. a least it shows were to cut the 8 mm out it should be easy. i work with a guy that use to race with some guys that raced these semi pro and pro. and he remembers cutting the frames and welding them but he couldn't remember how much. thanks nola_fiddy for taking the time to find this

No problem, I put out a request for the rest of the article. Hopfully someone will have it. At least we know it's in the nov 79 issue of Motocross Action.

Would love to see pics of a modified frame if anybody has them.

i think i will try the 8 mm the story said that they were going to cut more than 8mm out? but i'm going to look a 8mm and see what i will do. i remember reading an artical in a dirt bike mag about setting your rake and trail. and what each one did for your handling and how to adjust it that would be interresting about now

Cutting the 8mm out will move the rake out a little further forward of the bike. So with the smaller wheel, the tire should still hit the ground a relatively the same spot. If you get 16.5" - 16" rear shocks at the same time, you should get better handling, lower profile bike.

I'm looking at my stock 79 cr125 now and it certainly has a very unique (bizzare) stance. But that is what makes this bike special in a way. That said, I would rather ride the modified bike.

Can't wait to see your work!

nola_fiddy

ps -> got a project bike running today!!!! 1979 Yamaha DT100F for my brother. Sweet little two stroke. Had to redo the carb, air filter oil pump etc. Replaced with all new parts - had a hard time fitting everything correctly because of the yami's frame design. But I got it now! (Went with the OKO carb - keihin copy cat - very nice).