need info on longrod motor

[frocashmoney24]

Allright, buddy of mine brought me his 250r to rebuild. He's got the longrod in it now, with the shortrod piston and spacer plate. He wants to take it out and go back to stock. so my question is, Ill have to get the longrod piston to go back to stock which i know, but he needs a new cylinder to since his is on the last bore. so does it matter what year cylinder i use? Or is it a specific year since it has the longrod in it? Thanks in advance.

[MossboysRacing]

you should need an 87-89 cylinder. those were the years of the long-rod crank. Or, you could keep your spacer plate, get another 85-86 piston, and buy my 85 cylinder i have for sale. Its on its second bore (.020 over) and has plenty of bores left :D

[kookennay]

I DONT THINK IT MATTERS ON THE CYLINDER BUT YOU WILL HAVE TO USE THE LONG ROD PISTON AND NOT USE THE SPACER PLATE. THE LATER YEAR MODELS HAD THE LONG ROD I THINK 88 89, BUT I NOT 100% SURE ON THAT.

[woodsracer144]

Wrong-O it does!

[rustyATV]

The '87-'89 cylinders have the bridged intakes which are made for the late style piston skirt. You can still buy new '89 cylinders from servicehonda.com for about $270, I think, but don't quote me.

What bore is his cylinder on? If he were to keep the current setup with the base plate, then he could get stock piston sizes up to 0.140 over with the early style piston. I think the late only goes up to 0.080 over.

[machwon]

Any year cylinder trx/atc 85-89 will work with the following atc and trx combinations:

85/86 crank with 85/86 pistons

87-89 cranks with 87-89 pistons

87-89 cranks with 85/86 pistons

pistons and cranks must match or use the space plate combo. The cylinder used does not matter.

[rustyATV]

Keep in mind you'll want to avoid late model pistons in early model cylinders; the skirts have the potential of lodging in the intakes as they get time on them. Early pistons in late cylinders don't have anything to worry about.

[Rich250RRacer]

Originally posted by rustyATV
Keep in mind you'll want to avoid late model pistons in early model cylinders; the skirts have the potential of lodging in the intakes as they get time on them. Early pistons in late cylinders don't have anything to worry about.

This is correct, and the proper way to avoid serious engine damage.

[woodsracer144]

com on rusty! post your base plate vids and all your other useful 250r stuff! come one man you know you want to!

[atv fan 28]

yeah i love rustys vids on youtube! very informative!

[frocashmoney24]

thanks for the info guys, i thought it didnt matter, but i was aware of the bridged intake, so ill want to go with the later year cylinder, ie 87-89. His cylinder is on bore .80, but the cylinder is balooned .30 from getting hot, so the cylinder is junk. Well i guess the hunt is on for the later year cylinder with a bridged intake to go with the longrod piston. Thanks once again.