z900 A4 Engine Assembly
I was at an event somewhere and a friend I hadn’t seen for a while came up and asked me if I had the time spare to come up to his place and help assemble his z900 engine, he didn’t feel confident that he could do it right. So it got me thinking that a simple guide to putting the engine together correctly was in order. It’s not a difficult process if the engine parts are good and you have all the bits on hand ready to go. So here is a first draft at engine assembly. You need to refer to the service manual for torque settings and the visual pictures of what goes where.
Note: Somewhere I have photos of the process, so this is going to be updated.
Bill of Material
To assemble the engine you first need to ensure you have a few items on hand:
- Complete Gasket Set.
- Three Bond (also sold as Kawasaki Bond) Supplied by 3M.
- Oil Seal Kit.
- case Half oil Seal.
- Screw Kit.
- Metric tool set.
- Torque Wrench.
- Cylinder Head “D” rubbers – Half Moon Shape.
- Oil Filter.
- Piston pin circlips (8)
Additional Items you may need to purchase:
- Lock washer – front sprocket. – Usually stuffed after many removal attempts.
- Cam Chain – Your old one is most likely worn so replace it!
- Cam chain adjuster guide and wheel. – Often worn with chunks missing.
- Lower cam guide (sits at base of cylinder block).
Points of Interest
- When installing the two case halves, ensure you use a new oil seal. it does not come in the gasket set and is a separate part listed in the parts manual.
- Always use new circlips on the piston pins (wrist pins). They are cheap and in stock at almost all dealers.
- Many of the internal engine bearings have guide pins to align the assemblies together. Ensure they are aligned as you install parts in.
- Assemble the head prior to any engine work. It need to be ready to install once the head gasket is put onto the barrels.
Assembly Process – Bottom End
- Place top case upside down on bench and next to it place the bottom engine case upside down.
- Position crank shaft into case while feeding over a new cam chain (don’t be tempted to reuse the old one, it will have stretched over time). and bolt the main bearing cap – 4 bolts 11 ft-lb in the correct sequence and then do it again at 16.5 to 19.5 ft-lb in the same sequence.
- Install shift drum into bottom case but do not install dog shaft yet (installed when bottom case is installed).
- Install gear cluster and output shaft into top case.
- Install clutch hub and shaft as a complete assembly.
- Install kick starter assembly, return spring cannot be installed until bottom case is bolted down.
- Install neutral guide bolt. Align shift drum to neutral position. Refer to book to see what the correct position is. I might get a copy of the diagram and put it here also.
- Use 3M on the case half faces and place “O” ring onto main oil gallery opening.
- Install bottom engine case onto top engine case. Install all bottom engine case bolts.
- Using long nose plies manipulate kick start spring into place and push in the spacer assembly. Test mechanism. Fit gasket and screw cover into place.
- Install shift drum pins and gear selector mechanism.
- Install neutral switch.Install oil seals into transmission cover.
- Partially push the dog shaft rod into place and slip the shift dogs onto the shaft through the opening at the bottom of the engine. Ensure the selectors are aligned into output shaft and contact the appropriate grove in the shift drum. No part of the mechanism should be tight or require force to assemble. Push dog shaft right through until circlip contact outside engine case.
- Install transmission cover gasket and assemble cover. (The cover holds the shift dog shaft in place).
- Fit the front sprocket and lock washer.
- Install oil seal on points cover end of crankshaft.
- Install gasket and points cover. Fit mechanical advance assembly. apply lubrication to mechanism and ensure weights move out as required.
- Install points assembly, note orientation.
- Install clutch cover.
- Install oil pump assembly.
- Fit new oil filter.
- Place sump gasket into place and bolt down sump.
- Bolt down oil filter cover and sump bolt.
- Flip engine over and chock base of engine so it is held in place. it should be level.
- Install starter motor and route starter power cable.
- Install starter gear and pin from inside of alternator space.
- Install alternator into cover (3 cap screws) and fit gasket.
- Smear a large amount of 3M to cable exit point, push the rubber seal down into it, smear some 3M onto the alternator cover and install gasket and alternator into place. Route cables to rear of engine.
Assembly Process -Barrels
- Tip barrels upside down on your work bench and install new cam chain guide rubber if the old one shows signs of wear and tear.
- There are 4 o-rings that sit at the base of the barrels, fit these now.
- Smear some 3M to top engine case where the barrels will sit.
- Position chain guide roller, if its worn, buy a new one first.
- Fit base gasket, feeding cam chain through centre hole of barrels and slide down barrels over the engine studs.
- Install cam chain guides at front and rear. If the rear one has a worn rubber wheel then get a new one.
- Push the cam chain tensioner plunger right into the body of the tensions and do up the holding screw, fit a gasket and fit the tensioner to the block.
- Place the odd shaped rubber O-Ring that goes around the cam chain tunnel and smear in some 3M into the channel first.
- Rotate the pistons so 1 and 4 are at TDC (Top Dead Centre)
- Fit the head gasket, it should be in two parts.
- Install the cylinder head, feed cam chain into place and torque down the head.
- Feed the cam camshafts under the cam chain and align the camshafts so the arrows point horizontal to the head when the shafts are seated correctly.
- Screw the cam bearing caps into place, they are numbered, don’t mix them up! Apply downward pressure on each shaft to force open any valves as you screw the caps down to avoid stripping the threads of the cam cap set screws.
- Align the cam chain onto the inlet cam sprocket and count 28 links starting at the arrow stamped on the sprocket, then align the exhaust cam using the “28” mark stamped on the camshaft sprocket.
Once aligned and double checked, screw down the top tensioner, you need to make sure the mounting rubbers do not drop into the cam tunnel. (The sump can be easily removed to retrieve the rubber).