How hard is it to put a honda engine in a yamaha dirtbike?

i have an older 250 2-stroke honda engine and ive found an 80's yz125 dirtbike with a bad engine, so what i was wondering is how hard would it be to put the engine in that bike and what modifications, parts, ect. i will need to do the engine/frame to swap the honda engine into the yamaha frame... anything you can tell me will be a big help, thanx in adv.|||Ok look, I hate to bust your bubble but if your asking it is a job that is over your head. The above people are right, it can be done but it takes alot of work, tools, you need to be a good wrench spinner and welder, and it has to be done right.|||forget it unless you are a welder and a machinist and have all the tools including a frame jig everything needs to be modified and without a jig you will never be able to everything lined up you are more likely to kill yourself than get it right|||with time a patience it can be done,you will have to do lots of measuring some cutting and welding but it can be done.hardest thing is making sure the chain runs straight.


i recently put a 2001 cr500 2stroke engine in a 2006 crf450 rolling chassis,it took me 3 weekends some cutting and welding but now have a wicked fun beast.|||first thing is to see which side off the engine the sprocket is on,if it does not match the side with the rear sprocket you may as well quit now,from my own opion i would not try it because i am afrad you will spent money on it and it still will nit work when you are through,go to a bike show and ask them there opion,then you will have the facts