Motorcycle Engine Rebuild the Tear Down



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We are preparing to do a Motorcycle Engine Rebuild. This is the engine tear down. We speed up the entire process, so you can see the complete engine tear down.

We use our DIY Motorcycle Engine Stand to hold our motorcycle engine during the motorcycle engine rebuilding process.

Hi, Gordon the Tool Guy here. Today we’re preparing to do a Motorcycle Engine Rebuild and we’re starting off with an Impact Driver by Vessel to remove the Engine Case screws. We’ll use the Impact driver to loosen all of the crankcase screws.

This is the left side cover and holds the Stator Coil. The Rotor and Stator generate AC – alternating current (3 Yellow Wires) for our charging and operating current. The Alternating Current runs through the Rectifier which converts it to DC – Direct Current.

Most motorcycles have a separate lighting coil, but on this particular off-road model, lights and the lighting coil are not installed. The Green Wire and small screw are the Neutral Sensor Wire.

Here is another look at the Stator Coil and Rotor.

A Compressor and Air Impact make quick work of removing the Rotor Bolt We need to start the threads of the puller by hand to be sure there is no cross-threading that would permanently damage both the Rotor and the Puller

Again, the Compressor and Air Impact wrench make quick work of removing the Rotor.

With the Rotor removed, we can see that the back side is also a Starter Clutch. The small electric, 12 Volt starter motor turns the small gear, the small gear then turns the larger Starter Gear. When the Starter Gear is driving the Rotor, the Rollers are clamped onto the Crankshaft Gear and Hub.

As soon as the Engine starts, the rotational speed and load releases the Rollers and centrifugal force keeps them pulled out and away from the crankshaft gear.

We remove the Woodruff Key and gears, the starter pinion shaft. Now we’re ready to turn this assembly over and disassemble the other side.

Working now on the Right Side, we’ll remove the Crankcase cover and expose the Clutch and Oil Pump Using the same Impact screwdriver, we loosen and remove the crankcase screws. We remove the Oil Filter Cover and Filter We remove the Electric Starter

Light tapping around the cover with a plastic mallet and the cover is easily removed

This is the Clutch Assembly – we’re looking at the Clutch Pressure Plate, Basket, Friction Disc, and Clutch Plates. We’ll start by removing the Springs that are held in-place by these 6mm screws/bolts. I like to remove the tension on the screws/bolts evenly

The Clutch Pressure Plate comes off first, then the friction plates and disc. We’ll cover these parts and how they work in a separate video. The locking tabs are opened so that we can remove the large Basket Nut.

Using the Clutch Holding Tool, we can use our Air Impact Wrench to remove our Basket Nut. We can then remove the Inner Clutch Hub and the Clutch Basket itself. The locking tabs are opened and the correct socket chosen

We pull the sparkplug from the cylinder head so that we can rotate the crankshaft and gain access to the Oil Pump screws Using the Air Impact Wrench, the crankshaft and engine balancer shaft nuts are removed The Woodruff Key is removed from the Crankshaft

We pull the Shifter Shaft and the attached Detent, the Centering Spring Guide, and Ratchet Assembly Removing the Oil Pump screws is easier now and we work through the holes in the drive gear We lift the Oil Pump away and remove the displacement rotor

The crankshaft gear is removed.

We position our engine in the Engine Stand so that access to the cylinder head and cylinders easily. This repositioning demonstrates why we like this economical DIY Engine Stand a lot. We remove the Camshaft Sprocket nut then sprocket

The cam chain is pulled down through the cylinder The cam chain tensioner is removed we reposition the engine in our stand to access the head bolts

The head bolts are loosened evenly and carefully so as not to warp the head. Bolts are removed along with their special Copper washers – Copper being a softer metal that provides sealing.

Two 8mm bolts along the side removed The head just lifts off and exposes the head gasket, locating dowels, and the special sealing dowels that carry oil to the top end.

The small 6mm bolts are loosened and removed from the base of the cylinder With the small bolts removed, we can lift the cylinder off the case and piston The rubber cam chain guides pull up too

A quick look at the cylinder bore shows wear and vertical scratches which usually means dirty/contaminated oil and improper lubrication

We reposition the engine in our engine stand so we can access the Center crankcase screws. This is the next step before splitting the case. We remove the cam chain guide

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