So, I took my cylinders to a place nearby that services Harleys to get the cylinder bases machined, but the mechanic there said that it wouldn't be worth the money, because the head studs of old, high mileage EVOs (1993, 48K miles) like mine tend to pull out of the crankcase. Are you guys aware of this problem? Was that bad advice? I've never heard anyone here mention it, but he seemed pretty sure of himself. He said that the new gasket set will help for awhile, but eventually the studs pull a little further out and leaks start again.

It was interesting that he brought it up, however, because when I removed the cylinders, I noticed that there was a gap between the "flange" on the head studs and the crankcase. Below is a typical picture. The gap is roughly 0.015" and it varies slightly between the studs. Is that normal, or should that be flush to the mating surface?

 

Hello,
I ask out of curiosity...
When you removed the 8 cylinder studs, were the threads in the crankcase in good order?
Or were they striped/damaged?
Cheers.

 

I know in your other post, there was a pic of your head/stud bolt looked pretty corroded. It is not uncommon for a stud to unscrew from the block while removing that top head bolt/stud. I wonder if that stud "unscrewed" a little during removal? Is the stud loose at all? Any play if you try to rock the stud a little? Basically, does the stud act like a loose bolt? Factory instructions are clean dry threads in the block, red loctite, collar down and torque to 10 ft lbs

Kind of odd, this is a 1993 engine? I know on my virgin 94, the collars (flange on stud) were up in the head area from the factory (different issue, different topic), but my point is, I wonder if someone else has been in there because the studs used to be installed buy the factory collar up till around March of 1994, then they switched to collar down (the way they should have been all along). So that is the only reason I am asking. See attached TSB. I suppose at this point it don't matter.

Yes, there are some threads here and on other websites about the studs pulling, and the the fixes are anywhere from helicoil to timeserts. Not gonna say which one is better, not sure if you even have a problem yet. But at least worth checking into. YD

 

I did not remove the 8 studs. They're still in the crankcase as shown.

 

Although the heads of the cylinder nuts (I guess that's what they really are...really long nuts that go over the studs) where rusty, they came off without much fuss. I loosened each one 1/8" of a turn (in the torque sequence pattern) until I could remove them by hand. Like you, I wondered if the studs had backed out a bit during the process, but shouldn't they be left-hand threads going into the crankcase to avoid that problem? In any event, all the studs seem to be firmly installed without any signs of rocking.

I got the bike in 2012 after my brother-in-law had it in storage since about 2002. I don't know how long he had after buying it from the original owner. Having said all that, I doubt that anyone did any significant engine work.

 

Studs pulling has happened but believe it was on the older Evo case which was also prone to cracking at the lifter bore area traveling to the head stud holes and it was a no-no to bore the spigots for a larger bore. The 92-98 cases were made stronger in the spigot bore area that also houses the cylinder stud holes, they could take a overbore in the spigot area showing the stride made to the good plus the cracks from lifter bore to head stud hole disappeared.

If your asking for Evo experience, many of us on the forum has successfully ran compression ratios 10-1 to 10.8-1 running the dog chit out of them without pulling head studs. Was a fella on here a few years ago running 11.8-1 on a stock case on the street knowing it was a time bomb but didn't pull the studs, since your cases are 93's I wouldn't be scared to go ahead with your plan.

If you machine the bases back to perfect, use modern Cometic gaskets, it will not leak, the base gaskets leaked from the paper gasket getting harder than a wedding dick and couldn't seal any longer was the original problem. You also need to read the dealer Harley mechanic your talking to, most of the older dealer mechanics are gone that had first hand knowledge of the Evo, The incoming mechanics might have dabbled in some Evo's on the side but only hear their problems while most of us know different from real world experience.

Need to look at the mechanical side, if your head studs backed out, hardened base gaskets and a cold start without cylinder expansion present yet, those base gaskets would be pouring out oil from the slight positive crankcase pressure a Evo keeps. Just put it back together by the book, put new head studs in if you want for peace of mind and don't look back.

 

Thanks!

Regarding the mechanic, to start he was about my age (I'll be 60 in March), and he spoke of having first hand experience with the problem, because he said attempts were made in the past to use helicoils and Keenserts to address the problem, but since the issue was with the hardness of the case, nothing really worked. It could be, however, that he was talking about bikes older than my '93. Oh, and not that it matters, he's not a Harley dealer...it's an independent shop.

So, I have my Cometic gasket kit already to go. I just need to decide whether to find someone else to machine my cylinders (or, I'm sure that mechanic would take my money if I insisted), or just use them as is.

 

Understand, sounds like he has worked on a Evo. Studs pull out but the percentages are really really low unlike the mechanic saying it happens every time you put cylinders on, just hasn't been a problem on this forum and about every member on here has done the base gaskets, piston replacement or have ran at the edge. I'm just not buying into the theory, Hillside would never touch a Evo then, they have done more Evo builds than able to keep track of over the years

 

Posted a article on base gaskets

http://www.bigboyzcycles.com/showthread.php?t=76

The Trock plate is almost obsolete, machine shops with a lathe can do it and the easiest if you want some material taken away but if your an pioneer a Trock plate can be made.

 

drm, I was hasty on my last post to this thread and also mis-read your measurement of the rear and wanted to clarify. The dirty little secret is, std OEM pistons are small, generally 3.4965 (+) or (-) .0002 so the rear is already borderline but possibly usable as it stands. I may have missed some posts but I assume you are at least planning on using a ball flex hone and new rings? (please say yes) and don't re-use any removed wrist pin locks, period.

Your measurements for the front are typical of a virgin cylinder but especially after seeing the replacement studs, someone has been in there before. Maybe warranty work when the bike was young considering the older rocker lower gaskets or who knows... they likely pulled the front with piston remaining and since you have to push the piston back into the bore to get the rear out of the frame (do -able but tedious going back together), they probably pulled it and had to hone it for rings. My point at the moment was, if the cylinders, especially your rear, are chucked in a lathe there's a better than even chance they'll be marred to a point that honing it out will get you to a size that won't seal well. Maybe some guys have done it, but everyone I ever knew who trued or milled bases on a lathe went to an oversize piston.

A lapping plate works great cleaning up the bases with a little patience. I use a bottom torque plate with 220 grit, 6" d/a sand paper (hole cut out of the middle) and WD40. They turn out just like the last photo on the link that bagger posted.
Have a general machine shop cut a piece of 1" thick x 6" (round or square) plate with a 3 - 11/16" hole in the middle, milled smooth on one side, and use the sandpaper trick if you want the cheap way out for lapping the bases true.

You've gotten some excellent info and advice from others on here and if I may add one general thing - don't EVER try to get a machinist (or mechanic) to do it "your" way if they offer any resistance. You'll most often end up with a very bad result. The guy saying the "studs pull" was actually telling you, in his own way, he doesn't want to do it!