Going from 80 ci to 88 ci

[mom2kids01]

I am going from an 80 ci to an 88 ci cylinder will it fit in my current crankcase?

[60195]

Yes. Your cases will need to be bored to fit the larger cylinders. Stock Evo bore is 3 1/2" the 88" Evo has 3 5/8" bore. This used to be a very common modification.

Depending on which pistons are run, the engine height may decrease some.

Stock Evo cylinders have a length of 5.550". Cylinders and pistons from S&S for an 88 Evo are like 3.350". Not much but certainly not taller.

Will fit just fine in your frame.

[mom2kids01]

That sounds great.. So what do you think money wise it would take to bore it

[60195]

You will have to split the cases and press the crankshaft out. Once the cases are emptied they can be bored. I think I paid $100 to have a set of cases bored.

Send them to a shop that specializes in Harleys. If you do not know of a local shop, you can do no better than to send them to Axtell in Des Moines, IA.

If you do not already have cylinders and pistons you should talk to Ron or Chaz about them as well. Axtell manufactures cylinders, and builds record holding engines. They have will do you a good job.

[davesnider]

Fyi. I have a 88"and am real happy with it.Just had my superstock heads ported and a new cam put in. It is an animal. Love it!!

[johnr733]

Originally Posted by econnor

Yes. Your cases will need to be bored to fit the larger cylinders. Stock Evo bore is 3 1/2" the 88" Evo has 3 5/8" bore. This used to be a very common modification.

Depending on which pistons are run, the engine height may decrease some.

Stock Evo cylinders have a length of 5.550". Cylinders and pistons from S&S for an 88 Evo are like 3.350". Not much but certainly not taller.

Will fit just fine in your frame.

econnor, maybe you can help me out then. I had this mod done three years ago and the bike (97 RK), has not run since. My cases were bored and I was given an S&S Sidewinder kit to reassemble the engine with. You are already aware the cylinders are -.175 shorter than stock.

The problem is the top motor mount will no longer reach the heads. I cannot locate any aftermarket mounts. Additionally the exhaust doesn't line up as well, especially under the transmission. Pushrod clips don't fit anymore either. Any help to get back on the road would be greatly appreciated.

--john

P.S. MOM2KIDS01, I have had many conversations with Axtell, and was thinking of buying their kit because it is stock length. However the cylinders are made of cast iron and therefore the fins cannot be polished as they will rust almost instantly. If you have polished fins on your heads like I have you might want to consider this before purchase.

[60195]

John, the easy issue to address is the push rod clips. Shorten the ones you have or buy new ones the correct length from S&S. Look in the S&S catalog (online), find the pushrod section and the clips for an 88" evo, S&S will show the length.

Next is the top motor mount. Your RK has adjustable mounts on the top and the front. They are both the same and are used to align the drive train. The top motor mount has a couple of nuts that must be loosened and then the center threaded section can be adjusted. It should reach without an issue.

The exhaust is what is. Short of cutting and rewelding, which you should not have to do. Tell me more about what the issue is with the exhaust and the lower transmission area. -Ed

[60195]

Originally Posted by johnr733

P.S. MOM2KIDS01, I have had many conversations with Axtell, and was thinking of buying their kit because it is stock length. However the cylinders are made of cast iron and therefore the fins cannot be polished as they will rust almost instantly. If you have polished fins on your heads like I have you might want to consider this before purchase.

Axtell also makes 88" evo cylinders from Aluminum. One of the many great things about Axtell is they actually manufacture in house and the guy you talk to on the phone might be the same guy that makes your cylinders. -Ed

[sixshooter44]

Forget the 88 and go straight to the Axtell 97 kit