I think the primary chain on my 2004 sportster 1200c needs tightening.I've looked to both my owners manual and shop manual for clarity, but was left with more questions than answers....
First, It says to "rotate sprockets to find the tightest point on the primary chain". This implies that at some point in the rotation the chain is tighter, which I find hard to believe! I'm guessing that this actually means to create as much slack in the chainbetween the gears at the top. It also doesn't explain how to rotate the gears.... I assumed that I'd want to roll the trans gear forward against the non-running engine gear to move the slack to the top run of the chain. I put the bike in gear and kinda bumped the trans forward. Is this a suitable method?

Next, It shows a diagram that implies that the slack measurement is from the top of the chain while pushed up (which can't even be seen!) to the bottom of the chain while pushed down. Since the chain is almost a half an inch (vertically) by itself, the loosest parameter on the chartimplies "no slack". I'm thinking the measurement is bottom-of-chain-while-pushed-up to bottom-of-chain-while-pushed-down.... Is this correct?

Third, the chart shows more slack for a cold engine with cold parts. Maybe the metals that HD uses have special properties where they expand as they cool, but every other metal I've ever worked with expands when heated, which would create more slack when hot, NOT cold.... Am I missing something here?

I've been an auto mechanic/rodder/fabricator my whole life, but never had the reason or opportunity to work on motorcycles until recently. I'm finding some of the mechanical concepts to be different and a little intimidating in their details, which are often confusing or lacking completeness or proper illustration.
I'd like to have confidence in the HD manual, but I'm not sure that's going to be possible!

 

There are a lot of posts about adjusting the primary chain over in xlforum.net. Use the search feature. Check out the posts by 'Hero". I haven't tried it yet, but several people claim to have used his method successfully.

Ron

 

Maybe the sprockets get bigger and tighten the chain when it gets hot?

 

Even Harley mechanics hate the Harley service manual! I was told to get the Climer manual so I probably will.

Getting ready to check My primary as well. Hear is what I uncovered.

Tip: When you check the primary chain for the proper adjustment ..take aold 3/4" tape measure and cut it at the 4" line.

Now you have a 4"inch ruler with a hook on one end to hang over the Primary chain.

Hang the ruler over the chain and eye ball the ruler with the top of the inspection cover hole---- move the chain up and down and you'll see how much play you have in the chain.I'm sure just one way of many

To check Primary(Engine off) roll the bike up a few feet at a time. When you begin to feel resistance, this will be the tightest point on your chain. You can mark the position of your back tire on the pavement to see how far it rolled to get to that spot. In the future you can use this measurement to check how your primary is maintaining its spec.

Still trying to sort this out in my head as well.

Cheers

 

I think you're reading way more into it than is there...

I thought it pretty simple...

It is obvious that you can accomplish this at the inspection hole... if as you say the chain is 1/2 inch wide, using the top of the inspection hole as a guide and knowing the thickness of the chain you should be able to determine how much the chain is moving... adjust it until you come to the 3/8ths of slack required...

Yes it is true that metal expands when heated... you are not considering that the chain has pins and holes,these pins fit into these holes creating a "link"... wouldn't it be reasonable that when the chain gets hot these pins would expand inside the holes and cause the chain to get stiffer/tighter...

All the warnings and notes seem to make it more intimidating than it really is... though important to heed... go through the adjustment process and then see if it falls into the parameters of the warnings and notes...

The first time is always the hardest... after you get through with it... the second time will take you all of five minutes or less...

Hope this helps...

Charlie D.