1987 yz125 roller?

[Grasshopper]

Well i am new here and mostly new to mx. I have mechanical experience with small two stroke (rc cars) and i take auto mechanics classes at school.

Here is my senairo (spelling?) I am looking to rebuild a 1987 yz 125 and wanted to know things about this bike. I can get a roller right now for 50 bucks of craigslist and just wanted to know what the engine costs are and the specs of frame. (i.e. mounting measurements). I am sure I am going to have to ask more question in the future so thanks in advance.

[mx_563]

If you're getting a 1987 rolling chassis, you may have trouble finding a motor for it. No modern YZ125 motor is going to fit that frame so you'd need to find a motor from probably a 1985-1988 chassis (just a guess).

Go to bikepics.com to get an idea of what these bikes look like so you can get a rough idea regarding frame geometry. It should be obvious when they made major changes...the 1989 YZ125 is going to look way different than this 87' you're considering buying.

To get a better idea of part interchangeability, go to bikebandit.com and find the engine case part number for the 87'. Then look at the 85', 86' and 88' bikes and see if the part number is the same. That's a starting point but not a guarentee that the other motors will fit.

Even if you find the motor on ebay or someplace, you'll probably still need a carbureter, radiator hoses, etc. You are probably better off looking for a ~$300 basket case that you can work with (rebuild) instead of getting the roller and *hoping* to eventually find matching parts.

Another option is to get the roller, sell the pieces on ebay, and hope you make enough to buy a complete bike.

EDIT:
Looks like this thing needs a fuel tank, levers, grips and some plastic too. 1987 was a long time ago, you'll have a tough time finding all those parts cheap. Take a look on EBAY and you'll get an idea of what to expect.
[Only registered and activated users can see links. ]

[bitshifter]

I agree with mx_563. I have an 88 and 89 yz250 and to try and find all the parts that the roller needs would take a while. Remember that you don't have what you are missing so it is harder to find what you need. It's not quite the same as having a broken part and looking for a new one. I think that you will end up paying more with the roller than you would holding out for a complete bike that needs work. Just the little stuff like hardware and spacers will drive you nuts. I got my 88 for $100 complete but in a box and the 89 for $800. I don't think the 89 was ever ridden, it is still a standard bore, but I was lucky. The early yz's may be old but they are still fast, reliable and a whole lot of fun. Keep looking, they are out there.

[Grasshopper]

Would it be possible to fabricate mounts to a modern 125 motor?

[Grasshopper]

Well i got it. Turns out that guy is really chill. It had a gas tank, radiators, original seat, electrical, and most of the plastics. the only real thing i might need would be a motor..and little stuff like clutch and hand brake levers etc. Best part is that it all was 50 bucks. I am pretty sure he said something like to the effect that motors from that era 86-90ish fit in that frame but i do not know for sure. I would like to fit a 250 in there considering that i am 5'8'' and on a good day 165 lbs. (Bad days i get up to 173 lol ) Is it possible to do this transformation?

[CRF731]

With a little bit of determination and some $$$ anything is possible.

[brucem]

i just looked on bikebandit at part numbers for the crankcases and 86 and 87 had the same part number

[bitshifter]

As far as I know the frames for the 125 and the 250 were the same. I think that a 250 would bolt right in but I don't know what other years. You might check the motor mount part numbers and see what years they fit.