Saturday, 1 December 2012

An Easy Method to Fine-tune a Primary Chain

By Darnell Austria


The design of a Big Twin's Powertrain is non-unitized. And that is, the gearbox is attached apart from the engine, meaning the two should work side by side so that it can send power. That's where the primary drive, found in that huge metal case near the rider's left foot, takes into action.

As the primary drive passes power from your engine to the back wheel, the alternating power that's provided from the engine's crankshaft is transformed into revolving energy through the moving major chain and sprockets that spin the transmission's input shaft. After the power recollects inside the transmission it's distributed through the gears and inside the second drive, which is the belt or chain drive that turns the bike's rear tire. This is usually a short explanation of a Harley Davidson powertrain, and, basically, each section performs part in running you and the bike along the highway.

Given the fact that powertrain is made up of a series of moving parts, you're going to have to render periodic adjustments to them to make sure they will work properly. In time, movable parts, such as the main drive's sprockets and chain, break. As it degrades, they require adjustment to help maintain correct tolerance. And it's the main driver's multi-row roller chain that must be checked and tweaked once in a while. It's a fairly clear-cut procedure, at the same time, a method that can be done within your garage area or shop.

Most of the action comes about around the inspection window that's accessed by detaching the plate secured on by four screws. You'll need a ruler to make the sizing and a couple of basic hand tools to perform the adjustments. To adjust, loosen the adjusting shoe's 9/16" bolt just a few turns and rotate the shoe upwards to tighten the chain or downwards to loosen up.

An excellent time to inspect and adjust the main chain is when you ought to drain and change the primary case oil. Harley highly suggests its multipurpose manufactured oil, however, if you do have a desired brand that's been designed for the main drive, at all cost, use it. Just make sure no matter what lubricant you decide is designed for this purpose.

Once the inspection plate is off, you've got a decent look at the chain's rollers and the adjuster shoe, so utilize the time to check them for wear. Take a look at the chain's rollers to find out if they're getting full lubrication, and look the adjuster shoe for cracks and such. Examining and adjusting the primary chain doesn't take long, and when you're finished you'll have one thing of the checklist of things to do on the next long drive. Just be sure to change the inspection plate gasket.

Things You'll Need:

Pipe sealant Pan for Draining T27 Torx T40 Torx 9/16" deep socket Ratchet Ratchet extension Measuring Stick or Ruler

1. Basic routine service like adjusting the primary chain can be performed within your own garage or shop when changing the primary oil. Make sure the motorcycle is secured in an upright position when you start.

2. The first thing to do is to drain the main case of the used fluid. After placing a drain pan underneath the primary, have a T40 Torx to get rid of the drain plug that's positioned just underneath the derby cover.

3. Leave the used primary fluid to drain into the drain pan. While it empties, you'll be able to check the primary chain to see if it requires tuning.

4. Use a T27 Torx socket to get rid of a few bolts that keep the primary inspection plate in place. It's recommended that you change the inspection plate gasket just before you mount the plate.

5. With the inspection plate removed, you may check out the chain's rollers for signs of wear. Also, check them for signs of damage. With the transmission in neutral, check the rest of the chain by spinning the engine a few turns.

6. Measure the chain in several places and try to take two readings each time. One is with the chain's top run at slack. For the other, the ruler is raised against the top run to take off the slack and to measure once again. The main difference in the 2 on the chain's tightest point is definitely the chain's slack.

7. Utilize a 9/16" deep socket to adjust the chain's free play. With the chain cold, set the free play from " and 7/8". Right after you have retightened the nut, again, make measurements of the slack to ensure that you have set the proper amount.

8. While the inspection plate is exposed, check the adjuster shoe that's pushing against the chain's under run. You can see the adjustment nut in the upper right corner.

9. Not like the engine and transmission drain plugs, the O-rings are missing. To make sure it is sealed, apply a little pipe sealant around the bottom edge of the bolt.

10. After cleaning all the lube out of the primary cover, re-install the primary case drain plug. When already set, gently torque the four inspection plate bolts and the derby cover bolts to 108 in-lbs.

11. You may now stock up the main case with fresh new fluid. Many mechanics use lube from the big barrel rather than retailed cans.

12. Fill in 32 ounces of fluid. Put in the proper amount for your bike's model and year.




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