'89 evo heads

Discussion in 'Engine, Fuel and Exhaust' started by W.Bacon, Jan 1, 2014.

  1. W.Bacon

    W.Bacon Member

    In the couple of months since I joined this forum I have made regular use of the self help pages and forum searches.I feel the need to thank everyone who participates in putting all this information together. I'm really glad I found this place.
    I picked up this '89 fxr as a fixer project for the winter. Among other things, I noticed that the head gaskets were leaking. When I removed the heads, I found that the bolts on the carburetor side of the cylinders were loose, both cylinders, and the left side bolts were tight. So my question, is there anything specific to these early evo's that would cause this?
    I'm thinking that if I just carry on and do the repairs properly, all will be well, but if there is some other issue that I should address?
    Thanks, Bill.
  2. HDDon

    HDDon Experienced Member Contributor Retired Moderators

    I don't think there is anything specific to the EVO heads that would cause this, probably lack of attention to detail during the last assembly. Since one side was loose I would check the cylinders to make sure they are still round and all surfaces to make sure they are all flat. Do the piston skirts have any skuff marks? Did you do a compression or leak down test before you started disassembly?
  3. fin_676

    fin_676 Experienced Member Staff Member Moderator Contributor

    It is not unusual for lower rocker box and cylinder base gaskets to leak on these evo engines however I am not aware of there being a head gasket issue although head gaskets can blow if the engine is not warmed up correctly prior to using full throttle
    There have been changes to the design of the head gasket the earlier ones required the fitment of an o ring on the dowel pins and some replacement gaskets require the o rings to be removed if o rings are fitted when they ought not to be then that may cause an issue
    There are very specific procedures for the head bolt torque if it has not been done correctly then things could come loose

  4. Jack Klarich

    Jack Klarich Guest

    Check and or replace the cylinder case studs if you find them to be loose:s
  5. Breeze3at

    Breeze3at Well-Known Member

    Also be aware that Harley made several changes with cylinder studs in the late 80's & early 90's. Some were installed shoulder up, some shoulder down. Some had more threads than others. A google search will turn up lots of info.
  6. W.Bacon

    W.Bacon Member

    I didn't do a compression check, and I won't bore you with my excuses.
    Pistons are wisco and have no visible damage, look fairly new as do all the gaskets. Cylinder walls still have good cross hatched pattern on them, so I assumed OK, But will measure before reinstall.The mating surfaces of the heads and cylinders are good. I have all new gaskets and will not reuse.
    The bike was in a pretty sad state of neglect when I got it ( not licensed for 5yrs not started? Not prepped for long term storage.) Complete fuel system refurb was where I started. Noticed evidence of head leak while trying to scrub years of grime from engine. I believe that I may have gotten lucky with the condition of the engine.I will double check everything before I put it back together, just want to make sure there isn't some other thing I should look at.

    Cylinder case studs stayed tight in case. I was going to clean the threads and leave them in. Also thought I might put some blue locktight on to prevent bolts from vibrating loose.
    Last edited by a moderator: Jan 1, 2014
  7. TQuentin1

    TQuentin1 Well-Known Member Staff Member Moderator

    I did a partial rebuild of my '91 in '99. It was the result of a blown head gasket that was the result of leaking base gasket on the cylinder that blew. Once the paper gets too saturated with oil, it mushes out and finally allows the jug to move up and down. Not long until the head gasket blew after that!!

    Since you don't know exactly what happened to the engine before it got laided up, I suggest replacing all the studs and head nuts. The torqueing procedure will stretch the studs, and the ones in the engine now may be shot. I think the manual will suggest replacing them anyway.

    I also believe that if you are disassembling the engine, you should redo the stuff you can. So I would suggest a valve job and getting the cylinders honed. You need torque plates to do the cylinders, so I just take them to an good indy or HD to have that done. Any good machine shop should be able to do the valve job if you don't want to invest in all that rig up (I didn't).

    Rebuild the oil pump with new stuff, or get an after-market pump.

    Decide on whether you want to upgrade the cam shaft. New lifters and adjustable PRs.

    Then the big decisions: do you split the case and redo all that stuff in there, or assume the lower end of the engine is OK? And, do you pull the gear set out of the tranny and redo all that stuff (upgrade to one of the six speed builder's kits?)?

    I have my Dyna back on the project list too. I am facing all the same issues as you, except that I know the condition of things since I have owned the bike since '95, and redone it once already. But the tranny is shot, so I know I need to do that. I think I am gonna split the case and do all that too. Top end all the way of course.

    Good luck on your project. Take lots of pix and make a pictorial history of the project so we can see it. I use Photobucket for this, but there are lots of alternatives these days.


  8. W.Bacon

    W.Bacon Member

    I guess it's better to provide as much detail as possible, so here we go.
    I got this bike from a friend. I'm 47yrs, he's79. Poor health caused him to stop riding a few years ago. I suppose he went through a little bit of denial, thinking he'd fire it up and go for a rip, next thing you know the bikes been siting too long.
    Approximately 5000 miles ago he had someone do this
    Fisher harmonic balancer?
    Crane adjustable push rods
    Crane single fire ignition
    175lb valve springs
    Wiseco piston
    High performance clutch
    Mikuni HSR42 carb
    These are the things he remembers. Unfortunately there's a grey area there in his memories. At this point my interest is to spend as little as possible to get the bike up and running and ride around next summer. I've been riding since I was a kid playing in the dirt, but I've always been on sport and sport touring bikes. This is my first HD and I'll just need to boot around on it and see what direction I end up going.

    Cheers, Bill.
  9. Jack Klarich

    Jack Klarich Guest

    Good luck with your project, clean ALL surfaces good try not to nick the heads or deck of the engine, follow ALL torque values and sequences Harley Davidson Forums here is a good link for you:s
  10. HDDon

    HDDon Experienced Member Contributor Retired Moderators

    Seems like we have given you all the things that should be done and some things that would be good to do and a few things that would give you more HP and torque. Since the cylinder bores look good and the top end was redone just a few miles ago (long time though) and you already have some of the upgrades that should be done. I think you should at the very least replace the studs and nuts. With everything else your friend did to the motor I would almost bet he had an aftermarket cam installed with a new timkin bearing. Next summer you can see if there is anything else you want to upgrade. Have a good time with the rebuild and let us know (pix please) if you need any advice. There are some great motor people here.