Yamaha YZF600R Thundercat (all models)
Engine removal and installation guide
Theo, Dec 2004
Introduction
This guide explains how to remove and reinstall the engine of the great Yamaha Thundercat.
Certain repairs cannot be done with the engine in the frame, notably major bottom-end and gearbox work. Even if you don't want to attempt the repairs yourself, you can save a big chunk of the garage bill by removing the engine for them.
Note that all of the following can be removed with the engine still in the frame, but you may still need to do most of the stripping down described below:
- Cylinder head
- Camshaft & valve shims
- Camchain
- Cylinder block & pistons
- Gearchange mech
- Oil sump, strainer, level switch and relief valve
- Gear selector drum and forks
Of course you might simply be fitting a replacement engine, which is often cheaper than a major repair if your gearbox has eaten itself as mine did.
The job is not very difficult — three "Haynes spanners" — but it is quite long. The removal and refit took me about six hours each, but I'm sure it would be much quicker next time. While a Haynes manual or service manual is useful it's not essential as I have including everything you need to know including torque settings.
Other bikes
This guide will be largely valid for any inline-four sports bike, but please don't use my torque settings on a different bike, and seek help if the design of your bike differs significantly from this description.
Tools and equipment needed
- Good socket set including 24mm socket for rear axle nut
- Set of hex bits to fit the socket set
- Set of decent screwdrivers
- Torque wrench (to at least 50Nm)
- Rear paddock stand
- A jack, preferably a trolley jack
- 2 litres of ready-mixed aluminium-friendly coolant
- 4 litres of good semi-synthetic motorcycle oil
- Oil drain tray (if draining oil)
- Some penetrating oil or WD40
- Some ordinary (LM) grease
- Some Coppaslip / copper assembly grease
- Notebook and camera
- An assistant to help you lift the engine in and out
Getting started
Clear yourself a big space to work in and make sure it is well lit. Spannering is potentially dangerous so ensure someone knows where you are and what you are up to, and can check on you from time to time with a cup of tea. Keep a first aid kit handy for cuts and scratches, and protect your hands at least with barrier cream, preferably with latex gloves.
You will need lots of room to place the parts as you remove them. Keep them well organised and labelled, and bag or gaffa tape all bolts and fixings to their parts as you remove them. Keep your notebook up to date as you go so you don't forget anything on reassembly. It's a good idea to take photos as you go along to remind you what goes where.
Read through this whole guide before you start.
Here we go...
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Remove the side fairings
I'm sure you know how to do this, but if not here's a quick guide:
- Remove the three black screws securing the black plastic cockpit panel to the top of the left fairing (below the left bar) and remove it.
- Remove the screw holding the two fairings together at the back, under the shock.
- Remove the two large screws holding the fairing onto brackets towards the rear
- Remove the three screws holding the left fairing to the v-piece behind the front wheel, and the two above this holding it to the fairing inner.
- Remove the three allen-head bolts securing the fairing along the top edge.
- Finally, remove the 10mm bolt holding the fairing at the top, and carefully wiggle it down and back to free it from the front fairing.
- Rest it on your toes and undo the indicator connector.
- Remove the right fairing in the same way, but you can leave the v-piece attached to it.
Give the bike and engine a thorough wash; this makes the job a lot less unpleasant!
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Draining the oil
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Drain the oil. This is only necessary if you will want to work on the bottom-end or gearbox, not if you're just switching engines over. Always change the oil in a new engine unless you know for sure it was done recently.
- Run the bike until it's reasonably warm if safe to do so (not indoors!!).
- Shut off the engine.
- Position an oil drain tray below the oil drain bolt, which is on the left side of the sump in front of the gear change linkage.
- Remove the drain bolt and let as much oil drain as possible. This will take some time. It drains best on the sidestand.
- Clean the drain bolt, replace it and torque up to 43 Nm / 33 ft-lbs.
Meanwhile, put plenty of penetrating oil or WD40 on all the nuts you will need to remove. Pay particular attention to the exhaust downpipe studs as these often get corroded.
Remove the seat.
Disconnect and remove the battery. Remember to undo the negative lead first. If you have an alarm fitted, put it into service mode first or it will go off when you disconnect the battery. The beeping noise will stop eventually.
Remove earth lead. Disconnect the earth lead from the engine (near the oil filler cap) and from the wiring loom and withdraw it.
Remove the right seat fairing. You will have to remove the grab handle first.
Detach the gear lever linkage from its shaft on the engine. First ensure the bike is in neutral. Scratch a line across the end of the shaft and the linkage so you can get it back on in the right place, then remove the pinch bolt and slide the gear lever linkage off the shaft.
Remove the allen bolts securing the sprocket cover and remove it. There will be a hideous amount of foul black stuff inside. Unclip the clutch cable from its lever arm inside the cover and secure the cable out of the way.
Loosen the front sprocket nut. This can be very tough nut to crack. First bend the tabs on the lockwasher away from the nut. Get an assistant to apply the rear brake hard and slide a metal pipe over your wrench to get more leverage. If it's stubborn, or if it looks like this, don't worry. The sprocket can be left on its shaft and the chain removed instead (see below).
Get the bike into position in your "workshop" and deploy the paddock stand.
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Have you ever seen your bike take a leak before?
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Drain the coolant. There is a coolant drain plug on the waterpump, which is just below and forwards of the sprocket cover. Beware it comes out pretty fast! There are two more drain bolts on the front of the engine (click for pic), drain these too. Replace all the plugs; 10 Nm / 7 ft-lbs for all three.
Remove the tank. Remove the rear bolt first, loosen the front bolt and swing up the tank just enough to get underneath, and prop it up. Disconnect the fuel light wire and breather hose. Turn off the fuel tap, and detach the fuel hose where it meets the fuel pump — be prepared to catch any spilled fuel with a rag. Remove the front bolt and lift the tank clear (it's heavy.) Don't lose the rubber frame pads. Support the tank on wooden blocks to keep the fuel tap off the floor and the tank the right way up.
Detach the fat coolant hose from the water pump.
Detach the coolant hose leading to the right side of the oil cooler (the bit behind the oil filter).
Remove the crankcase breather hose (the one connecting the crankcase to the airbox) and plug the hole in the crankcase with a bit of clean rag.
Remove the airbox:
- Loosen the huge jubilee clips securing the front of the airbox to the ram air feeds, and the bolt holding it onto the frame.
- Loosen the jubilee clips that secure the collars onto the carburettor inlets underneath.
- Detach the drain hose and withdraw it, noting where it runs.
- Lift off the airbox
You might want to take the opportunity to clean and reoil the air filter while it's accessible.
Remove the radiator:
- Disconnect the fan wiring at the connector block in front of the carbs, then feed the wiring down through the hole to free it.
- Detach the three coolant hoses leading to the top right of the rad.
- Remove the three fixing bolts, and carefully wiggle the rad and fan down and free of the bike.
While the rad is off the bike, it's a good idea to clean it. Soak it in warm water, then try to get all the mud and flies out of the fins by spraying pressurised water or air through it from the back. Take care, as the fins are fragile. If you can be bothered, straighten all the bent fins with a small screwdriver.
Remove the exhaust:
- Loosen the clamp between the downpipes and the silencer.
- Remove the bolt securing the silencer to the right pillion peg hanger.
- Wiggle the silencer backwards off the bike
- Remove the eight nuts securing the downpipes to the engine. These can be tricky, use lots of penetrating oil and tap gently with a mallet if they are stubborn. Even so, don't be surprised if you break a few.
- Remove the bolt holding the downpipes to their bracket, wiggle them forwards and free of the bike.
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Tank, airbox and carbs removed
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Remove the carbs:
- Detach the idle adjuster knob from its mounting bracket on the frame.
- Detach the fuel hose at the fuel pump end. Be ready to catch any fuel that may come out.
- Detach the choke cable
- Detach the two throttle cables, noting which goes where and the position of the two lock nuts (access is tricky).
- Detach the wiring connector to the TPS (black unit on right end of carbs).
- Detach the carb heater hoses.
- Detach the air vent hose from the front
- Loosen the small allen bolts securing the four collars onto the inlet manifolds. Number 3 cylinder is a right bitch.
- Unclip the four vacuum take-off hoses from their clips on the inside of the frame rails and secure them out of the way.
- Lift the carbs carefully off the bike and store them the right way up in a clean bag. Note the carbs are still full of fuel so don't tip them up. You can drain them before removal if you wish.
- Plug the inlet manifolds on the engine with clean rags.
Remove the thermostat assembly:
- Detach the temperature sensor wiring connector.
- Detach the coolant hose leading to the main coolant gallery on the engine.
- Free the large coolant hose from between the engine mounting bolts, noting how it fits.
- Lift out the thermostat assembly.
Detach the four wiring connector blocks on the top of the engine, and withdraw the side stand switch cable. Detach the starter motor wiring. Secure the wiring out of the way.
Label the four HT leads (ie. spark plug leads) with their cylinder number (1 to 4 counting from left), detach them and secure them out of the way.
Remove the front sprocket nut, slide the sprocket off the shaft and free it from the chain. If you couldn't loosen the nut, you will need to remove the rear axle nut and slide the rear wheel forward. This should give you enough slack in the chain to wiggle the chain off the sprocket, which stays on the engine. If not you will have to remove the wheel completey and try again.
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Aw, poor litte puddy tat...
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Loosen the pinch bolts on the upper engine mounting brackets, then loosen the engine mounting bolts (and any crash bungs that may be fitted.) Take care not to lose the collars in the bolt holes.
Remove the exhaust downpipe mounting bracket and the rear engine mounting nuts.
Position your jack under the centre of the engine with piece of wood between the two. Take the weight of the engine on the jack. You may have to fiddle about a bit to find the balance point (click for pic).
Remove the engine:
- Have a quick check that there is nothing else still attached to the engine.
- At this point you should recruit the services of a willing assistant.
- Remove the engine bolts one by one, ensuring that the engine is balanced on the jack, and have your assistant hold it steady.
- Carefully lower the engine. If you have a trolley jack you can slide the engine forwards as it drops to clear the sidestand. If not, it's probably easier to shuffle the rest of the bike backwards.
- Lower the jack as much as you can, then slide the engine out to the side and free of the bike. It's heavy — don't drop it or let it rest on the oil filter.
Reinstalling the engine
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Fitting the engine is, more or less, just a case of following the same procedure in reverse. Take great care to do it in strict order and to "tick off" all the steps on this page and in your instructions as you go along to avoid missing anything.
Probably the hardest bits are manoevering the new engine into the frame (you will need at least one assistant to do this) and doing up the rubber carb collar on number 3 cylinder. It is important that these are tight, and access to the bolt is very restricted. I suggest attaching your hex bit to the bolt before you fit the carbs.
If the engine has not been run for some time, or if you have a new one, whip out the spark plugs and put half a teaspoon of engine oil into each cylinder, as they may be quite dry. This is also a good time to check / change the sparkplugs while access is easy. Take care not to let any crud drop into the cylinders. Tighten sparkplugs to 12.5 Nm / 9.2 ft-lbs.
As you replace the screws, nuts and bolts, grease them lightly with coppaslip to prevent them from siezing in the future.
All the required torque settings are below, but try to develop a feel for torque and possible overtightening yourself as well as trusting the torque wrench. The front engine mounting bolts and downpipe mounting studs are both prone to faliure, so if you feel any 'stretch' or 'creep' as you tighten them STOP tightening. Leave the bolt alone until you have a replacement ready as it may break on removal.
Torque settings:
- Front engine mounting bolts: 54Nm / 42 ft-lbs (see note above)
- Front engine mounting pinch bolts: 64Nm / 49 ft-lbs
- Rear engine mounting bolts: 48 Nm / 37 ft-lbs
- Sprocket cover bolts: 10 Nm / 7 ft-lbs
- Rear axle 117 Nm / 90 ft-lbs (about as hard as you can with four fingers)
- Front sprocket nut: 70 Nm / 54 ft-lbs
- Downpipe nuts: 10 Nm / 7 ft-lbs
- Downpipe-to-silencer clamp: 20 Nm / 13 ft-lbs
- Silencer mounting bolt: 20 Nm / 13 ft-lbs
- Fuel tank mounting bolts, front: 10 Mn / 7 ft-lbs, rear: 16 Nm / 10 ft-lbs
Yamaha specify new gaskets on the exhaust downpipes and between the downpipes and the sliencer, but you only really need these if the existing ones leak once you have the engine running again.
Get everything connected and installed, but don't put on the fairings yet. Run through your list and double check everything.
Don't forget to refill the oil and coolant! The radiator should be filled right up to the neck, then the expansion tank filled to the appropriate level.
When you are satisfied everything is ready, fire her up with as little throttle as possible (the cylinders may be quite dry). As the bike warms up, check round for oil or coolant leaks, or anything else unusual.
Stop the engine and let it cool for 10 mins, then check and top up the oil and coolant again. If all is well, refit the fairings and off you go!
Take care the first time you ride, as the clutch and throttle may well feel different and might need adjustment. If you have had major engine work done, remember that the engine will need running in as if it were new.
That's all folks
Questions and corrections very welcome. Email: cat@jeremythomson.co.uk.
All text and pictures © Jeremy Thomson 2004. No commercial reproduction allowed. You are welcome to reproduce the text and pictures for any non-for profit purpose provided you include a credit and link back to this page.