I'm tearing my 75 ironhead down for rebuild and there isn't enough room on the rear to get the rocker box bolt on the front of the rocker box out.The middle one.Any help would be appreciated

 

pitbull1........
On a Sporty rear cylinder/head you must remove the head and rocker box as a unit because there is not enough to get the R/Box off with the engine in the frame. Take out the rear head bolts, then remove the rocker and head as a unit. Take off the rocker box when you have it on the workbench. You will have to re-install it back in the same fashion of course.........pg

 

thanks..that's kinda what I done..first I had to loosen the rocker bolts enough to raise the rocker box enough to get the pushrods and tubes out of the way of the head bolts on that side..Man those head bolts were tight.Broke 2 jap wrenches with a cheater pipe before I got the snap-on out..No prob for it....What kind of pistons and rings would you go back with and do you think I am making a mistake just doing the top end without cracking the cases.I dont want it to put to much strain down there.thanks again piniongear.You are indeed a righteous man for sharing your abundance of knowledge with us ole bikers...Ironheads rule...I'd rather have mine that a new one..And rest assured that it will suck the headlight off most of them...lol..I uploaded a pic that is a couple years old..It sports a new s&s super e shorty in place of that old bendix.

 

pitbull...
OK, glad you got it off.
Yes, the headbolts should have been tight. Use your Snap-On (or Craftsman at a minimum) tools to work on the bike.
When you put it back together you will want to bolt on the rocker box to the head tightly. Instead of removing the rocker box to get the push rods back in....do this instead: Loosen the locknuts on the lifters. You have probably already done this. Screw both adjusters down into the lifters as far as possible. This should leave you plenty of room to get the pushrods back into place without having to lift that rocker. Be sure the lifters are at the lowest position when you install each push rod. Remember, front intake at it's highest position= rear intake at it's lowest position. Same for the exhaust side of things.

For the top end you will have a choice of pistons. You could choose to put forged pistons in or use cast. Forged are stronger and much more expensive. If it were a racing engine I would use forged. I suspect this is not the case, so I recommend cast pistons as the choice for pistons. I have used cast on my engine for both rebuilds and have had no problems at all.
Don't just go out and order pistons. Take the jugs to the shop that will do the rebore and let them measure the wear. Then bore it out the minimum required and get the piston size needed after that determination is made.

If it were me, I would let the shop that bores the jugs sell me the piston and rings. It just makes an easier package. The shop will bore each cylinder with the required clearance to fit each piston as they come out of a box. The pistons, being massed produced may well be slightly different in size, so this is important in getting a correct fit. Use a shop that is known for it's competent boring work. You may want to assemble all of it yourself, but I know you are not going to do the cylinder bore job in your garage, so a shop will be involved.

I would face the valves and face the valveseats in the heads as well and install springs if they fail a test for wear. This will depend on the miles you have on the bike. The free spring length of brand new springs are: 1 1/2 inches for outer. 1 23/64 inches for inner spring. If either spring is 1/16 inch or more shorter then replace that spring set.
That will give you a complete top end job. A Sportster has a pretty stout bottom end because it uses roller bearings on the male/female rod journals. There is no way to check these except to split the cases and open the rod journal. Even at this point the condition cannot 'be checked'. The only thing you can do is to lap out the bearing race and install new .003 oversize rollers. A very expensive choice if you do not need a new big end bearing job.
You will not 'blow out' the lower end because you have renewed the top end. This just will not happen unless you engine now has a very bad knock in the lower end. I recommend that you not be concerned with the lower end unless you have 60,000 miles or more on it. If that is the case then perhaps you should do the lower end.

The rocker bolts get torqued down to 20 ft lbs each. Tighten each bolt 1/8 to 1/4 turn until they are at 20 f/lbs. Same with the headbolts except the torque on these is 65 ft lbs. Be sure to install new cork washers in the PR tubes and new rubber sleeves on the rocker oil lines. Hope this helps and I agree with you on preference of having an ironhead to an EVO. No choice for me to make there.....................pg

 

thanks pg.One last question.Should I use new head bolts.Thanks

 

No, the original bolts are fine and do not need replacement. Just make sure the threads are clean so that you get a true torque reading when you tighten them down......pg

 

Wow PG, something I knew the answer to and you beat me too it [:@] Oh well you explained it better than I could of.

 

Does anybody know if it is possible to remove the cylinders while the engine is still mounted to the bike? It is alluded to in this article, but never really talked about. Trying to figure out how far I can break it down without taking the engine off the frame. any input would be much appreciated.

 

Yes, it is the usual way to proceed. You do not remove the engine from the frame to do the top end.

You need to let us know the year of the bike.

You must have the factory service manual 99484-?? and the factory parts catalog 99451-?? to do this work. These are widely available thru a local indie bike shop, HD dealer, J&P Cycles, eBay, internet sellers, etc. Just Google the part numbers.

The last two digits depend on the year of your bike. They are one of 69, 78 or 85.

 

thanks for the reply. i took the heads off to see how the clearance might shape up. lots of space with the heads off. the cylinder walls and piston looked to be in such great shape i decided to put it back together with new gaskets (my original intent along with an inspection). my bike doesn't have a speedo or odometer and looks to be surprisingly low mileage. nice to catch a break. it's halfway back together already. hopefully i'll be on the road next week.