250r cylinder??

will a 88-89 cylinder fit on a 86 bottom end? i think the stroke is different but you could just change the rod....right?

[NJ250Rrider]

All 250r cylinders are the same. You wont have to change anything. Only the crank and pistons change from year to year.

[Taco]

You are correct sir hahahahaha

[thorspapa]

Let me see if I can get this right, I too get confused sometimes:

'86 bottom with '86 crank and short rod: '86 jug with '86 piston. '87-'89 jug with '86 piston.

'86 bottom with '87-'89 crank and longer rod: '86 jug with '86 piston PLUS spacer plate, '87-'89 jug with '87-'89 piston and NO spacer plate.

This is based on the +5mm of the '87-'89 rod and the corresponding 5mm higher rod connecting hole of the post '86 pistons.

Feel free to jump in if I've stated this incorrectly.;)

[dune250r]

'86 bottom with '87-'89 crank and longer rod: '86 jug with '86 piston PLUS spacer plate, '87-'89 jug with '87-'89 piston and NO spacer plate.

This is correct. 86-87 motors are the same. Honda went to the long rod on the 88-89 250R's. I have an 86 250R with a Hotrod longrod kit, 4MM spacer plate, 86 cylinder, 86 piston. 86-87 motors are the same. If you have the longrod installed you can use an 88-89 cylinder with an 88-89 piston with no spacer plate.

[beerock]

I want to correct you dune 250r

the 86 is the only short rod crank.

87-89 are long rods.

the connecting rod was extended 5mm and the wrist pin height was raised 5mm in 87. This adjustment gives the engine more longevity from the forces that be.

if you use any year cylinder you can use any year piston depending on your connecting rod length.

if you are using a 86 piston with a 87-89 connecting rod you have to use the spacer plate.

if you are using a 87-89 crank/ piston you can just swap the cylinders, no spacer plate.

same goes for using a 86 piston with 86 rod, no spacer.

you see people like to use the 86 piston with a 87-89 long rod so they can increase there crankcase volume. which in turns smooths out the power delivery and gives a more useable powerband.

Although, I am starting to believe that this setup may be great, I think maybe a short rod will make more power by revving out faster(due to the 5mm of extra weight on the 87-89 rod).

Alot of people use the trick 86 piston/87-89 rod/spacer plate set up.

I hope I cleared things up?:D :D

[dune250r]

Thanks for the correction Beerock. I always thought the 86-87 had the short rod.

I do know I noticed that after going to the longrod I had a lot more torque. I have also heard that the long rod is easier on the rod bearings because it throws at less of an angle thus giving longer rod bearing life.

[beerock]

ya thats why they changed it, for longevity. ;)

so...this set up will work......89 cylinder...86 bottom end....89 long rod....89 style piston

what kind of piston would you guys recommend?

[dune250r]

I like to use Pro X pistons. They are cast pistons which are more like stock. Supposedly they last longer. Weisco would be my second choise. Its all a matter of preference to me. You may want to ask someone who races. They would be more apt to know which pistons work better since they are around a lot of people who build engines.