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View Full Version : What are the differances between 85-86 250 big reds, need to swap some engines around



pipeline triker
09-12-2013, 08:45 PM
I have an 86 that runs and works great engine is very low hour and maintained great, trike looks like total trash, most cables are broke or not working, forks are bent front rack is gone back rack is bent up and damaged, rear fenders mia, an old farmer had this and tied calves to the racks, he also would park it in the barn yard while he worked. Cows rubbed on it and chewed on stuff. This is the engine I want to use. I run this and use it as it is, starts one kick all the time if run daily, 3-5 kicks otherwise but there is no choke so that is pretty good.

Then I have a very nice 85 that has a trans issue, This machine lived an easy life of lawn sweeping and yard work, racks do not even have the paint rubbed all the way off on the tops. this machine starts right up with a push of the button. Runs good with a slight top end tick. The problem is the trans is messed up, it is in 2nd or third gear and wont go below or above, when you go down it is like neutral but inbetween gears. There is no metal in the bottom end oil. The problem was it had the factory oil and filter in it and the guy brought it in to get it tuned up and when they changed the oil or what used to be oil. They had to poke up into the drain plug to get it to flow out. They put new oil and filter in it and ran it a little then drained it out. before the oil change it shifted fine I was told. I have changed the oil and filter also, I have 15x40 high detergent oil in it to loosen up some of the gunk. it worked as the top end is alot quieter but the trans is not getting better.

What I want to do is put the 86 engine in the 85, what are the things I will run into if any. I plan on using all 85 wiring I can and cables on the 85 as they are all super nice and work smoothly. I have a good 85 250 SX bottom end to use if I decied to put the 86 together as a beater again, if there is somthing major wrong in the 86 bottom end. Any insight would be great. Thanks

pipeline triker
09-12-2013, 08:47 PM
This is the 86.
http://i656.photobucket.com/albums/uu287/mbsdirtbike/1986atc250esrockload5-21-13001_zps320c738c.jpg (http://s656.photobucket.com/user/mbsdirtbike/media/1986atc250esrockload5-21-13001_zps320c738c.jpg.html)
http://i656.photobucket.com/albums/uu287/mbsdirtbike/1986atc250esrockload5-21-13002_zpsc04973e0.jpg (http://s656.photobucket.com/user/mbsdirtbike/media/1986atc250esrockload5-21-13002_zpsc04973e0.jpg.html)
http://i656.photobucket.com/albums/uu287/mbsdirtbike/1986atc250esrockload5-21-13003_zps4570ed94.jpg (http://s656.photobucket.com/user/mbsdirtbike/media/1986atc250esrockload5-21-13003_zps4570ed94.jpg.html)

pipeline triker
09-12-2013, 08:49 PM
This is the 85
http://i656.photobucket.com/albums/uu287/mbsdirtbike/1985%20atc%20250%20Big%20Red/1985BigRed1100CubCadet7-24-13001_zps3c9bd0e4.jpg (http://s656.photobucket.com/user/mbsdirtbike/media/1985%20atc%20250%20Big%20Red/1985BigRed1100CubCadet7-24-13001_zps3c9bd0e4.jpg.html)
http://i656.photobucket.com/albums/uu287/mbsdirtbike/1985%20atc%20250%20Big%20Red/1985BigRed1100CubCadet7-24-13002_zps63373998.jpg (http://s656.photobucket.com/user/mbsdirtbike/media/1985%20atc%20250%20Big%20Red/1985BigRed1100CubCadet7-24-13002_zps63373998.jpg.html)
http://i656.photobucket.com/albums/uu287/mbsdirtbike/1985%20atc%20250%20Big%20Red/1985BigRed1100CubCadet7-24-13004_zpsdb702704.jpg (http://s656.photobucket.com/user/mbsdirtbike/media/1985%20atc%20250%20Big%20Red/1985BigRed1100CubCadet7-24-13004_zpsdb702704.jpg.html)

honda4h
09-12-2013, 10:25 PM
you will have no issues using the 86 engine in your 85 its a direct bolt in and hook up

just ben
09-12-2013, 10:26 PM
I'm no expert but as far as I know from my experience is the cdi is different as well as the wiring to it. Also the carb had a slight modification for 86-87. If you are just swapping the engine you wil have no issues that I can tell. The engine is a tight fit and does take a lil finesse to remove or install. I found it easiest to "rock" it in or out from the left side,I believe the manual says to do it from the right but I think that is with the shaft removed.

redsox
09-12-2013, 10:44 PM
i've done multiple engine year swaps in 250sx's. 85, 86, 87. everything hooks up and works fine. BR's will also swap without an issue. as justben said, it's tight in there, and that puppy is heavy. i forget which side i went in/out from, but i do remember that it was opposite of whatever the manuel said.

dougspcs
09-12-2013, 10:58 PM
In/out the left side..only way!!

It's tight and will likely be a PITA the 1st you do it.

pipeline triker
09-13-2013, 12:00 AM
Thanks for the info and the tips. There tight to get in and out of the sx I know.

newfiebullet
09-13-2013, 05:14 AM
85 has no rev limiter, but the crank tends to break off right by the centrifigual clutch. wire harness has will plug in fine.86 is better all around motor imo , i changed my wire harness to a 85 on an 86 motor gained a very slight bit more top speed.