I've got my 1981 shovelhead torn down for new rings and valve job. It is the season here in Michigan for such things.Anyway, with the top end all off is there a way to really tell if I should do the bottom end too? I've always kept the engine well maintained with oil changes and such and have had no problems.Rebuilding the bottomend is a little more than I feel comfortable doing myself the first time. So are there any good ways without completely tearing the case apart to judge the condition of things?I'm pretty mechanical but I'd hate to make a good engine my first one to practice on.Let me hear what advice there is out there.Like most people I'm not made of $$ and do all my own work.Thanks.

 

Didnt see any mileage mentioned or if lower end was ever gone thru.Alot depends like you stated on how bike was maintained,how its ridden and so on. A 1981 model exceeding say 50000 miles should be at least looked into in my opinion,knowing bikes history may help with decision.Cheap insurance if you plan on keeping.Usually when pushed too far,you end up with busted cases or alot of uncalled for machine work.Ask around in your areafor a good rebuilder.All are not equal.

 

Jugs are off, grab each rod and jiggle them side to side. Is there a fair bit of movement?
Get a dial gauge and measure just how much play there is. IIRC, i rebuilt the bottom end on my '81 at around 35,000 miles (could have been 40,000 - it's a while ago so don't remember exactly). It had around 160 thou play in the front rod. Good ol' AMF...

 

Holy Crap! 160 Thou!

That is a lot of play.

I had .004" on my Sporty and it clacked like a son-of-a-bee.

I have NO shovel experience, but I would find out what the front rod play tolerance is and use a quality dial indicator and check it out.

I was told by my tech that there used to be specs to measure the rod play at the TOP from SIDE to SIDE (vs pulling up on it).

I personally would pull up on it and indicate it that way.

 

Yeah, it was bagged. I know a couple of guys with '81 AMF bikes with over 80,000 miles on them that have never had the heads off. Mine was more the type that cemented AMF's reputation [:@]
It runs great now that just about every major (and most minor) components have been repaired/rebuilt/replaced.

 

Sorry to hear you had a bad one.

My Sporty (sold) was bad too. '93 - I ATE 2 sets of rods in 30,000 miles.

Tech said the first time "Sportsters are bulletproof, I have never replaced rods in them".

HA!

 

Hey, it was a great, 18 year learning experience! And I think I appreciate my gas-and-go twinkie FLHT 10 times more than I would've without having had the shovel first...

 

It's pretty hard to judge how many miles are on the engine.The speedometer rattled to pieces about 15 years ago with 30,000 miles on it then. I'd have to say it's probably got 60,000 on it now.I've never ridden it hard but as far as I know it's never been apart before.I'll stick a dial indicator on the rods and see what the side to side is and on the crank end to see if there is any end play.Anybody got any recommendations for books on how to rebuild a shovel? Gotta be something out there.The service manual isn't to detailed about stuff and this being my first time I'd like details. I'm gonna take it into a bike shop and see what they charge to do a rebuild.Should just be a matter of replacing old parts and re-assembling.How much can that be?Thanks for the input out there.Gottastart looking for a good rebuild manual.

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You'll need access toa couple of special tools to do your ownlower end.

press
flywheel support jig
Flywheel truing stand w/ dial indicators
race lapping tools
tool to pull cam cover bushings
Reamers and pilots for your newbushings in the cam cover
reamer for your wrist pin bushings
special tool for reinstalling the left side timken bearings

Might be a good time to consider a new flywheel assembly, or even go the stroker route.

Good luck.

 

Also, be carefull when moving the rods from side to side - if you put any pressure on the bearings, they may deform or otherwise scar the crankpin or rod bushing.

I would suggest the up and down (put the rod between your thumbs and push up at tdc) to find your play.

You can tear down to the point of having the crank assembly in one half of the cases without too much in the way of special tools, then send out that partfor pro work.

IF the rods are cooked, you will have to have the wheels re-trued - which requires a pro shop anyway.

lplugw makes a good point - stroke em if you got em!

If you are going that far, for a few extra bucks, do everything you can, send out the balance and have piece of mind.