Tech1

One day you walk into you father's ( grandfather, uncle ) shed and what's that under that blanket there...?

Holy s#!t it's a Harley Davidson never seen one like this tho !!! You put your foot on the kick and put some weight on it..

mmhh it turns over, lets have a closer look....key still in the ignition ....where's the petcock .... aha...while shaking the bike ....

you hear there's some gas .... you turn the key and start kicking it and you manage to get it going....amazing this sound isn't it.

Then you start to think, a fresh paint job a new seat, maybe it needs new tires and I' am good to go.

Unfortunately it doesn't come out of your bike like that, but as a assembly like the picture below.

By now you got the gunk out of the crankpin, but there's still more in the oil passages.

So please do read on, as I got more info on it from some guys who know what they are talking about !

A very thorough explanation of the problems associated with the crankpin in the Sprint engines. Also, Thanks for the credit for the plug dimensions. One word of caution on that however, I've noticed that there are slight differences in the hole diameter of the crankpin. It would be advisable to take the crankpin to the machine shop that will be making the new plugs for you. The plug should have at least 0.003" press fit. Any less than that would worry me. Due to "machining tolerances", you could wind up with a fit that is not tight enough. You mentioned that you didn't have a 10 ton press, why do you need a press? Are you going to "split" the crank? If you plan on doing that, you'll need a press closer to 20 tons capacity. I've found that "breaking" the pin loose requires quite a bit of pressure. Once the press fit has been "broken", the pin moves rather easily. When reassembling the crank, make sure you start the end of the crankpin with the oil passage hole into the correct side of the crank. You should mark the crank and the crankpin in such a manner as to insure the correct alignment of the holes in the crank half and the pin. If these holes aren't lined up correctly, no oil to the crankpin bearing. I always check for good oil flow using a "squirt can" to pump oil into the crankpin from the end of the pinion shaft. When pressing the pin into the crank halves, use a good "press fit lubricant". This will make the pressing procedure go more smoothly and aid later in the truing process. The next problem is the "truing" of the crankshaft. The book says that the crank must be "trued" to 0.001". This requires some kind of device to hold the crank so that indicators can be used to check for run out on the pinion and alternator (generator) shafts. I use one of the Rowe truing stands but one could do this using a lathe. Having the truing stand isn't all there is to it. You need to have an understanding of what you're trying to accomplish and how you go about doing it. I took days, literally, to get the first one I did correct. The trick is understanding just what the dial gauges are telling you. If the crank needs to "slipped" or "spread" is pretty straight-forward. Where it gets tricky is when both procedures need to done. I'll be glad to explain it but it is quite complicated to explain, not so complicated to do once you understand how to do it. I can true a crank in less than an hour now and get it within specs. There is no "trick" to do it. Rather a good understanding of what you're trying to do and a bit of experience.

Jack, if the crank isn't "true", it ain't gonna turn very well in the case bearings. If you plan on using the crank, it has to be trued. I think once you get the crank pressed apart that you'll understand why you have to go through the truing process. The same holds true for the crank in a Big Harley. It is especially important on a generator model Sprint. If the generator drive end of the crank has more than a few thousandths run out, it will cause the generator brushes to bounce at high RPM. That why you hear so many generator-equipped Sprint owners complaining about dead batteries. The generator won't charge enough to recharge the battery at idle RPM and when the engine is revved up, the brushes start to bounce and it won't charge there either. Wear on the commutator ring of the armature will cause the same problem. To understand why the crank has to be trued, read the service manual. It gives a pretty good picture describing why the crank has to trued. Take care Jack.

Just my 2-cents.Jack has explained it well. The only thing I would like to add. Make sure you flush it out through the oil feed holes. As you might expect all of the graphite, or whatever you want to call it, must wash out through the bearings. you don't want any of that in there. It will cause premature wearing. I still prefer to split the crank, then I can check sizes etc. And go with oversize bearings if needed. Ron L note : see below for pictures

Your message on Jacks masterpiece is spot on. I would never even consider going that far with out splitting the wheels as you say but at least it shows the "newbies" graphically what you have been preaching for a couple of years. The mystery of the closed aluminum box is now over. Lets hope that a lot of people who in the past would say Oh what the heck mine is different will take heed and save a lot of money and parts. Have fun. Eddie

Well this complete assembly is spinning around as fast as you see the revs on your tachometer.

The oil or better the heavier small parts in the oil are swung ( centrifugal power ) to the " wall " of the crankpin center

At the end there won't go any oil through the tiny holes and the rod bearing runs dry,

Thanks to Steve Bentley, Ron Lancaster and Ed Boomhower for providing the additional info.

Put it somehow that you can work on it without it falling off your work bench ! ( I put it on a Black & Decker "Workmate" )	Now drill out the plugs ( they are not shown in the exploded view drawing above)	The plugs are 0.3" / 8mm thick, no need to drill too deep.

Both plugs out ? Ok, then look inside, what you might find in there may vary from thick oil to "concrete" hard stuff. This is what came out of this crankpin, I used a wood drill bit to open it up.	Looked and felt like crushed charcoal. Well now the crankpin is open like it should be !	Here's a close up ... I tried to get the inside as smooth as possible so it's harder for the hot oil to stick on it and build a new "crust" note the 3 holes inside.

by now (Feb. 2004) the crank has bin taken apart , in the previous picture you can see that I spend some time to clean up the crank pin on the inside, well that was a waist of time ! It's all gone and no good to use anymore.	here a close up from the bearing and rollers.	and that middle section should look smooth as a baby's butt.