There is a lot of information on this subject and I have searched the site and yes I own a manual. Here is the question. I have leaky base gaskets and need to replace at some time. I want to do myself and would like to look at replacing the pistons. Do I or should I have the jugs bored out or can I simply replace the pistons and rings with stock HD stuff. I am also interested in the screaming eagle heads. By the time I am done having the stock heads ported and value job completed I am close to the cost of new SE heads. Also If I have bored out what what spec is recommended, I want reliability above all. My bike is a 98 Fatboy with 35k miles and a Dave Mackie DM 500 cam, Mikuni Carb and Vance 2 into 1 exhaust. Thanks for the feedback
Evo engine rebuild
- Thread starter 98fat
- Start date
J
Jack Klarich
Guest
If you bore the cylinders it will Require extra costs I E new pistons and rings and the boring costs and honing, IMO I would stick with stock and have a good machine shop hone the cylinders with torque plates and check them for taper, if your pistons are OK, just re ring them and you can re do the wrist pins at home yourself, How much is your budget?
maine-e-axe
Junior Member
The best thing to do is to take the jugs to a machine shop to have them checked for "out of round" and the machine shop will tell you if they need to be bored out and new piston and rings.
Well not much, but am willing to spend some money to keep r running for many years to come. My concern is most machine shops may not know how to handle motorcycle jugs (need torque plates etc...) So need to find someone local or use someone via mail. But I figure I will have em off so should replace rings gaskets etc....
J
Jack Klarich
Guest
They need to be checked properly with Torque plates, and as Smitty says take the pistons with too
Breeze3at
Experienced Member
Specs for my '92 Evo are taper not to exceed .002", out of round not to exceed .003". I believe a later model like yours would be the same. And if anyone says torque plates are not needed for measuring, honing etc., go elsewhere. Evo's are tall alum. cylinders and deform under pressure.
J
Jack Klarich
Guest
NUFF SAID Breeze is 100 here:s
With only 35K on an EVO all you need to do is replace the base gaskets with Harley's fly paper ones. I had my 1988 base gaskets repaced and teh mechanic just put the pistons back into the same cylinders. When you take the heads off you will see the cross hatching from the factory. The piston rings never 'seat'. Cold the cylinders are barrel shaped and this is why you need torque plates to do any measuring or boring. The cyclinders go straight when the engine is warmed up. Who doing your heads and do they have a good reputation for this? The SE heads are good but they are mass produced and not ground and polished like a shop would do them. Polishing is some thing that isn't that productive on an EVO heads. Look at the SE heads and see if they are polished or just ground smooth. If cylinder base gasket leaks are your only concern then you may find the pistons and rings are good. Just make sure you read your manual real close and do this job once. You didn't mention a cam or carburetor. Horsepower costs money.
I don't plan on ever getting rid of my Fatboy. If I have the heads off, it just seemed like a good idea to replace rings and have the cylinders looked at. Can anyone recommend someone I could mail to have this done? I know of no one locally that does this kind of work especially on evo jugs. I want to do all of this myself and have never done this, so..... Would like to put on the Hayden fix and re-ring and put on SE heads. Thanks for any input. 