TC88 teardown and rebuild.
#1
05-18-2011, 07:41 AM
TC88 teardown and rebuild.
Here are a few pictures of a TC88A teardown and rebuild. This really isn’t a how-to post, but more of a general idea of the steps involved. The motor is a 2000 model, and has more than a few miles on it. It had apparently never been opened up until these pictures were taken.
The entire teardown and reassembly sequence took place over 3 consecutive (and unhurried) Saturdays. I work Saturday evenings, so we’d generally be wrapped up by about 2:30 or so in the afternoon. I’m working on this with one of my closest friends and riding partners. A clean work area and a service manual are the first two things you need.
This motor was already out of the bike, so we just mounted it up in an engine stand. If I was going to rebuild the motor that is in my bike, I’d most likely take the top end apart while the engine was still in the frame, and then remove the bottom end from the bike to make that part a little more manageable.
Remove the Rocker covers and gasket, and set them aside. Pay attention to the torque sequences when you are disassembling the same way you do when reassembling.
If the motor is in a stand, like we have here, you use a wrench to turn the motor over to put the cams on the base circle. (spark plugs out).
Pop the pushrod tube top clips out and collapse the pushrod tube. This will allow you to spin the pushrods with your fingers to determine that there is no tension on them. Turn the motor over and watch the rockers. You’re wanting the put the piston on TDC on the compression stroke. There will be a sequence when the exhaust valve opens and closes, followed by the intake valve. If there is an overlap period, the exhaust valve will open, then the intake valve, followed by the exhaust closing, and finally the intake closing. If you put a long straw in the spark plug opening, you can watch it rise. Stop the piston at TDC and verify by spinning the pushrods.
Take out the breather assembly, then loosen the rocker arm supports in the torque pattern prescribed in the manual. Take your time and do this right.
With the rocker assembly off, you can pull up the pushrods through the top of the motor. I’ll wait until later in the sequence to pull the lifters out of the motor.
The entire teardown and reassembly sequence took place over 3 consecutive (and unhurried) Saturdays. I work Saturday evenings, so we’d generally be wrapped up by about 2:30 or so in the afternoon. I’m working on this with one of my closest friends and riding partners. A clean work area and a service manual are the first two things you need.
This motor was already out of the bike, so we just mounted it up in an engine stand. If I was going to rebuild the motor that is in my bike, I’d most likely take the top end apart while the engine was still in the frame, and then remove the bottom end from the bike to make that part a little more manageable.
Remove the Rocker covers and gasket, and set them aside. Pay attention to the torque sequences when you are disassembling the same way you do when reassembling.
If the motor is in a stand, like we have here, you use a wrench to turn the motor over to put the cams on the base circle. (spark plugs out).
Pop the pushrod tube top clips out and collapse the pushrod tube. This will allow you to spin the pushrods with your fingers to determine that there is no tension on them. Turn the motor over and watch the rockers. You’re wanting the put the piston on TDC on the compression stroke. There will be a sequence when the exhaust valve opens and closes, followed by the intake valve. If there is an overlap period, the exhaust valve will open, then the intake valve, followed by the exhaust closing, and finally the intake closing. If you put a long straw in the spark plug opening, you can watch it rise. Stop the piston at TDC and verify by spinning the pushrods.
Take out the breather assembly, then loosen the rocker arm supports in the torque pattern prescribed in the manual. Take your time and do this right.
With the rocker assembly off, you can pull up the pushrods through the top of the motor. I’ll wait until later in the sequence to pull the lifters out of the motor.
#2
05-18-2011, 07:42 AM
As parts come off the motor, I lay them out on a bench that I’ve covered with heavy paper towels. I can make notes on the paper towels. I will keep the front cylinder parts together, and lay out the rear cylinder out separately, with the top of the motor farthest back on the bench. By the time I’m done, I will have the entire motor laid out in roughly the sequence it will go back together in, and will simply begin working my way back up the bench. I keep all the fasteners and gaskets with the components as they come out. When it’s time to reassemble, I’ll take the old gasket off and compare it with the new one, then throw the old one away.
If you need to take the rockers out of the assembly, you just remove the pivot shaft. It’s held in place by a notch that one of the bolts goes through
Take the lower rocker boxes and gaskets off, exposing the heads
If you haven’t already done so, the intake manifold needs to come off
Again, paying close attention to the torque sequences, gradually loosen the head bolts. These come out ¼ turn at a time, in a prescribed pattern. Pay attention to your manual. Remove the cylinder head and head gasket.
With the heads off, there is nothing holding the cylinders on the motor. You can secure them with special bolts made just for this purpose. Keep the jugs secured until you’re ready to remove them.
Here’s a look at the underside of the early TC head.
With both heads off, carefully lift the jugs up off the pistons enough to place some clean shop towels under the pistons and covering up the opening into the bottom cases.
As you lift the jugs up off the pistons, it helps to have a helper to reach underneath and hold the piston up off the cylinder studs. You will place protective sleeves over the lower cylinder studs and on the connecting rods.
Set the jugs along with the bottom O-rings aside. Again, I keep all gaskets, O-rings etc together with the components they belong to until I begin reassembly. Then I will take my package of gaskets and pull out the new one, compare it with the old one, to make sure it’s the right one.
Here’s the cases with the jugs removed
If you need to take the rockers out of the assembly, you just remove the pivot shaft. It’s held in place by a notch that one of the bolts goes through
Take the lower rocker boxes and gaskets off, exposing the heads
If you haven’t already done so, the intake manifold needs to come off
Again, paying close attention to the torque sequences, gradually loosen the head bolts. These come out ¼ turn at a time, in a prescribed pattern. Pay attention to your manual. Remove the cylinder head and head gasket.
With the heads off, there is nothing holding the cylinders on the motor. You can secure them with special bolts made just for this purpose. Keep the jugs secured until you’re ready to remove them.
Here’s a look at the underside of the early TC head.
With both heads off, carefully lift the jugs up off the pistons enough to place some clean shop towels under the pistons and covering up the opening into the bottom cases.
As you lift the jugs up off the pistons, it helps to have a helper to reach underneath and hold the piston up off the cylinder studs. You will place protective sleeves over the lower cylinder studs and on the connecting rods.
Set the jugs along with the bottom O-rings aside. Again, I keep all gaskets, O-rings etc together with the components they belong to until I begin reassembly. Then I will take my package of gaskets and pull out the new one, compare it with the old one, to make sure it’s the right one.
Here’s the cases with the jugs removed
#3
05-18-2011, 07:43 AM
To get the pistons off the connecting rods, you need to remove one of the circlips holding the piston to the wrist pin. There is a tool for this, but really, just a very small screwdriver works much better. Slip your screwdriver into the notch and pop the circlip out. MAKE SURE YOU HAVE CAREFULLY COVERED THE OPENING INTO THE BOTTOM OF THE ENGINE. Or you might be doing an unscheduled bottom overhaul if you lose a circlip into the crankcase. You only have to remove one circlip. Leave the other one in place if you’re re-using the same pistons on reassembly. You can generally gently persuade the wrist pin out with a brass drift, or use the piston pin puller designed for the job.
Here’s a look at the pin end of the connecting rod on a TC88
Compared to the tapered wrist pin end used on the TC96, which reduces reciprocating mass. There’s lots of running changes to the TC motor, both big and small.
Like I said earlier, I would come back to the lifters. With the jugs out of the way, it’s a lot easier to access the lifter cover. Remove the covers and pull anti-rotation pins and the lifters out of the motor, paying careful attention to their orientation. Look for the oil holes. They generally face outward, but regardless, you want to reinstall them in exactly the same orientation they came out.
I will make notes on my bench as I lay parts out. The lifters are left with the covers, in the orientation I want them to go back in the motor. These were all oil hole out, so I didn’t need to make any additional notes, but if one had been different, I would have noted that on the paper towels.
Now, we’ll pull the cam cover off. Do not mix up your cam cover screws with your cam plate screws. The longer cam cover screws will ruin your day in a big way if you try to use them to secure the cam plate. Again, here’s where I like to keep all my parts together with their gaskets and fasteners.
The older TC88s had a cam position sensor on the inside of the cam cover. The new motors don’t need it. More refinement.
To get the cam drive off, you need to lock down the pinion and cam sprockets. The silver colored tool between the two sprockets mesh with the teeth on the sprockets, preventing them from moving. Retract the tensioner and hold it in place with a pin locking device. Remove the flange bolts and washers from both sprockets and pull them off the assembly. On the older cam plates, there is another chain tensioner inside the cam plate. You can retract it with a screwdriver through the gap at the top of the cam plate. Note here how the dots on the two sprockets are aligned.
If the dots are misaligned on reassembly, you’ll never get the motor properly timed.
My pile of parts is getting bigger
Remove the cam support plate, followed by the oil pump. The cam support plate and the oil pump have specific torque sequences for removal and installation. Sometimes when you pull off the cam support plate, parts of the oil pump will come with it.
The oil pump is a remarkably simple design. There are two gerotor sets separated by a pair of thrust washers and a wave washer.
The wider gerotor set is the scavenge side, and goes inside, followed by a separator plate, a wave washer, the second separator plate and then the thinner (pickup) gerotor.
Assemble with the punch marks facing outward
With the cam chest out of the way, we can rotate the bottom of the motor on its side and remove the crankcase flange bolts. Again, pay close attention to the torque sequences, and loosen the bolts in steps.
Here’s a look at the pin end of the connecting rod on a TC88
Compared to the tapered wrist pin end used on the TC96, which reduces reciprocating mass. There’s lots of running changes to the TC motor, both big and small.
Like I said earlier, I would come back to the lifters. With the jugs out of the way, it’s a lot easier to access the lifter cover. Remove the covers and pull anti-rotation pins and the lifters out of the motor, paying careful attention to their orientation. Look for the oil holes. They generally face outward, but regardless, you want to reinstall them in exactly the same orientation they came out.
I will make notes on my bench as I lay parts out. The lifters are left with the covers, in the orientation I want them to go back in the motor. These were all oil hole out, so I didn’t need to make any additional notes, but if one had been different, I would have noted that on the paper towels.
Now, we’ll pull the cam cover off. Do not mix up your cam cover screws with your cam plate screws. The longer cam cover screws will ruin your day in a big way if you try to use them to secure the cam plate. Again, here’s where I like to keep all my parts together with their gaskets and fasteners.
The older TC88s had a cam position sensor on the inside of the cam cover. The new motors don’t need it. More refinement.
To get the cam drive off, you need to lock down the pinion and cam sprockets. The silver colored tool between the two sprockets mesh with the teeth on the sprockets, preventing them from moving. Retract the tensioner and hold it in place with a pin locking device. Remove the flange bolts and washers from both sprockets and pull them off the assembly. On the older cam plates, there is another chain tensioner inside the cam plate. You can retract it with a screwdriver through the gap at the top of the cam plate. Note here how the dots on the two sprockets are aligned.
If the dots are misaligned on reassembly, you’ll never get the motor properly timed.
My pile of parts is getting bigger
Remove the cam support plate, followed by the oil pump. The cam support plate and the oil pump have specific torque sequences for removal and installation. Sometimes when you pull off the cam support plate, parts of the oil pump will come with it.
The oil pump is a remarkably simple design. There are two gerotor sets separated by a pair of thrust washers and a wave washer.
The wider gerotor set is the scavenge side, and goes inside, followed by a separator plate, a wave washer, the second separator plate and then the thinner (pickup) gerotor.
Assemble with the punch marks facing outward
With the cam chest out of the way, we can rotate the bottom of the motor on its side and remove the crankcase flange bolts. Again, pay close attention to the torque sequences, and loosen the bolts in steps.
#4
05-18-2011, 07:43 AM
This motor has a Timken bottom end, and we will have to press out the flywheel. On the newer motors, the flywheel simply lifts out. You can see in this picture, the inner cam bearings are still in the case. They'll be replaced later, when the cam chest starts going back together.
The flywheel on the Timken bottom ends needs to be pressed out with a hydraulic press. I don’t have any pictures of that, unfortunately. I attempted to get it out with an arbor press, but that was a completely futile exercise. I finally gave up and give the left side case and flywheel to a friend to press out for me.
At this point, the motor is completely apart, the flywheel and cases are set aside, and the components are laid out on my bench.
The flywheel on the Timken bottom ends needs to be pressed out with a hydraulic press. I don’t have any pictures of that, unfortunately. I attempted to get it out with an arbor press, but that was a completely futile exercise. I finally gave up and give the left side case and flywheel to a friend to press out for me.
At this point, the motor is completely apart, the flywheel and cases are set aside, and the components are laid out on my bench.
Last edited by Mike; 06-22-2011 at 05:58 AM.
#5
05-18-2011, 07:44 AM
Going back together
Set the flywheel up in a vice to press the case back onto it
Remove the old oil seal
Press the flywheel back into the case, and press a new oil seal back into the bore.
Apply a thin bead of sealant to the split line face, and replace the ring dowel O-rings, and using a crankshaft guide, slip the right crankcase half over the crankshaft
Replace the crankcase bolts, following the torque sequence prescribed in the service manual. Torque to about half the torque value, then to the final value.
Replace your cam bearings if you haven’t already done so. You can get pullers from George’s garage or other sources. The old bearings are half-complement bearings, with no inner race, and a crappy bearing puller could possibly lose a needle down into the case, which would require a teardown. We could have replaced the bearings while the cases were split, but where’s the fun in that?
This puller has a collet that ensures no chance of losing a bearing needle. After using it, I’ve decided never to use the cheap Autozone blind spot puller ever again.
Install the oil pump, with new O-rings. Here’s where you start pulling out your new gaskets and O-rings and compare them with the old ones that are with your components. I use the same grade of oil I use in my crankcase for assembly lube. Slide the oil pump housing onto the scavenge port stub in the back of the cam compartment. Assemble the gerotor gears, (punch marks facing out), with the wider gears first, followed by a separator plate, the wave washer, and the second separator plate. Then fit the narrow set of gerotor gears into the pump housing. It takes much longer to type it than it does to do it.
Check the alignment of your cams with a straight edge across the punch marks. Lube up the inner bearings and slide the cam plate into place. Torque the cam plate using the sequence prescribed in the manual.
Start the screws that secure the cam plate to the oil pump but don’t snug them down. You want them to just contact the cam plate, then back them out ¼ turn. Turn the motor over to center the oil pump. Make sure your connecting rods aren’t banging into anything while you’re doing this. Torque down the oil pump.
Install the cam drive sprockets. Make sure the long flange bolt with the thicker washer is on the camshaft sprocket.
Replace the lifters and anti-rotation pin, making sure to orient the lifters exactly as they came out. Replace the gasket with a new one and replace the lifter covers.
Set the flywheel up in a vice to press the case back onto it
Remove the old oil seal
Press the flywheel back into the case, and press a new oil seal back into the bore.
Apply a thin bead of sealant to the split line face, and replace the ring dowel O-rings, and using a crankshaft guide, slip the right crankcase half over the crankshaft
Replace the crankcase bolts, following the torque sequence prescribed in the service manual. Torque to about half the torque value, then to the final value.
Replace your cam bearings if you haven’t already done so. You can get pullers from George’s garage or other sources. The old bearings are half-complement bearings, with no inner race, and a crappy bearing puller could possibly lose a needle down into the case, which would require a teardown. We could have replaced the bearings while the cases were split, but where’s the fun in that?
This puller has a collet that ensures no chance of losing a bearing needle. After using it, I’ve decided never to use the cheap Autozone blind spot puller ever again.
Install the oil pump, with new O-rings. Here’s where you start pulling out your new gaskets and O-rings and compare them with the old ones that are with your components. I use the same grade of oil I use in my crankcase for assembly lube. Slide the oil pump housing onto the scavenge port stub in the back of the cam compartment. Assemble the gerotor gears, (punch marks facing out), with the wider gears first, followed by a separator plate, the wave washer, and the second separator plate. Then fit the narrow set of gerotor gears into the pump housing. It takes much longer to type it than it does to do it.
Check the alignment of your cams with a straight edge across the punch marks. Lube up the inner bearings and slide the cam plate into place. Torque the cam plate using the sequence prescribed in the manual.
Start the screws that secure the cam plate to the oil pump but don’t snug them down. You want them to just contact the cam plate, then back them out ¼ turn. Turn the motor over to center the oil pump. Make sure your connecting rods aren’t banging into anything while you’re doing this. Torque down the oil pump.
Install the cam drive sprockets. Make sure the long flange bolt with the thicker washer is on the camshaft sprocket.
Replace the lifters and anti-rotation pin, making sure to orient the lifters exactly as they came out. Replace the gasket with a new one and replace the lifter covers.
Last edited by Mike; 06-22-2011 at 05:53 AM.
#6
05-18-2011, 07:44 AM
To check your piston ring end gaps, slip them into a cylinder and square them up with a piston. Don’t take any shortcuts here, make sure your rings are gapped properly.
Follow the manufacturers’ specifications for end gaps, and install the rings on the pistons. There is a chart in your manual that identifies the ring gap orientation. In a nutshell, the end gaps should be off the thrust surfaces, and spaced every 90*.
There is basically two ways to install your pistons and jugs. The book way is to install the piston on the connecting rod, position the cylinder over the piston, and rotate the engine slightly to raise the piston up into the cylinder. If you install your jugs this way, you pretty much need a ring compressor. Use a piston support plate under the piston, slide the wrist pin into the piston, and install the circlip. It’s a bit of a balancing act bringing the cylinder down onto the piston, simultaneously raising the piston into the cylinder. Then you’ve got to work the ring compressor off around the cylinder studs. It’s a very good idea to make sure to cover the spigot area with clean shop towels in case your circlip pops out of your hands. Some guys can install the circlips with a little screwdriver and their fingers. I use a circlip installer, it’s a tool that I consider indispensible. Use assembly lube, of course, and install a new base O-ring. Your pistons have arrows stamped into the tops to make sure you’ve got them aligned properly.
With the first cylinder in place, secure it with the threaded cylinder (HD-95952-1).
The second way to install your pistons and jugs is to slide the piston into the cylinder from the bottom first, then, with the very bottom of the piston exposed at the bottom of the cylinder, install the wrist pin and slide the whole assembly over the cylinder studs. This is how Jims recommends you install their kits, and the method I prefer by far. It’s much simpler, you don’t even need a ring compressor, although it helps.
Secure the second cylinder. Your motor should look like this.
If you’ve sent your heads out for porting or a valve job, hopefully they’re back by now. The heads are marked (F) and (R). Make sure the valley in the cooling fins is facing the right side of the motor to accommodate the pushrods. Set a new head gasket in place over the ring dowels and ease the cylinder heads down onto the cylinders. Clean and lube the cylinder head bolts before you install them.
There is a specific torque sequence for the cylinder head bolts in your manual. This is one of those areas where you want to be very careful to follow the book, or risk head gasket leaks or worse.
With the heads in place, place a new Rocker housing gasket in place. This one is easy to install backwards, and there is a breather channel that needs to be completely covered, so pay attention to the orientation.
Install the lower rocker housing
Set the pushrod tubes in place and slide the pushrods into their original positions. Silver is intake, black is exhaust. Intakes go to the inside of the lifter cover, exhaust to the outside. One cylinder at a time, make sure the lifters are on the cam base circle. Both lifters must be on the base circle. You want to be on TDC on the compression stroke.
Reinstall the rocker assembly,
Followed by the breathers
Almost done
Follow the manufacturers’ specifications for end gaps, and install the rings on the pistons. There is a chart in your manual that identifies the ring gap orientation. In a nutshell, the end gaps should be off the thrust surfaces, and spaced every 90*.
There is basically two ways to install your pistons and jugs. The book way is to install the piston on the connecting rod, position the cylinder over the piston, and rotate the engine slightly to raise the piston up into the cylinder. If you install your jugs this way, you pretty much need a ring compressor. Use a piston support plate under the piston, slide the wrist pin into the piston, and install the circlip. It’s a bit of a balancing act bringing the cylinder down onto the piston, simultaneously raising the piston into the cylinder. Then you’ve got to work the ring compressor off around the cylinder studs. It’s a very good idea to make sure to cover the spigot area with clean shop towels in case your circlip pops out of your hands. Some guys can install the circlips with a little screwdriver and their fingers. I use a circlip installer, it’s a tool that I consider indispensible. Use assembly lube, of course, and install a new base O-ring. Your pistons have arrows stamped into the tops to make sure you’ve got them aligned properly.
With the first cylinder in place, secure it with the threaded cylinder (HD-95952-1).
The second way to install your pistons and jugs is to slide the piston into the cylinder from the bottom first, then, with the very bottom of the piston exposed at the bottom of the cylinder, install the wrist pin and slide the whole assembly over the cylinder studs. This is how Jims recommends you install their kits, and the method I prefer by far. It’s much simpler, you don’t even need a ring compressor, although it helps.
Secure the second cylinder. Your motor should look like this.
If you’ve sent your heads out for porting or a valve job, hopefully they’re back by now. The heads are marked (F) and (R). Make sure the valley in the cooling fins is facing the right side of the motor to accommodate the pushrods. Set a new head gasket in place over the ring dowels and ease the cylinder heads down onto the cylinders. Clean and lube the cylinder head bolts before you install them.
There is a specific torque sequence for the cylinder head bolts in your manual. This is one of those areas where you want to be very careful to follow the book, or risk head gasket leaks or worse.
With the heads in place, place a new Rocker housing gasket in place. This one is easy to install backwards, and there is a breather channel that needs to be completely covered, so pay attention to the orientation.
Install the lower rocker housing
Set the pushrod tubes in place and slide the pushrods into their original positions. Silver is intake, black is exhaust. Intakes go to the inside of the lifter cover, exhaust to the outside. One cylinder at a time, make sure the lifters are on the cam base circle. Both lifters must be on the base circle. You want to be on TDC on the compression stroke.
Reinstall the rocker assembly,
Followed by the breathers
Almost done
#7
05-18-2011, 07:45 AM
Rotate the motor a few times to make sure nothing is binding
And close up the pushrod tubes and reinstall the clips. There is a tool for this, although it’s not one I have in my toolbox (yet). I use a screwdriver, but I think I’m gonna pop for the pushrod tool next time I think about it.
Slide the screwdriver under the bottom of the clip, and rotate the screwdriver upward, while simultaneously pushing in on the clip
When you reinstall the rocker cover, it helps to torque it down a bit at a time, holding it in place as much as possible to keep it from sliding towards the right side of the bike. The cover is designed with an angled base, and it gets cocked out of place as it gets torqued down. I try to minimize that as much as possible, but there’s always going to be a little bit of a shift.
That’s pretty much it in a nutshell.
And close up the pushrod tubes and reinstall the clips. There is a tool for this, although it’s not one I have in my toolbox (yet). I use a screwdriver, but I think I’m gonna pop for the pushrod tool next time I think about it.
Slide the screwdriver under the bottom of the clip, and rotate the screwdriver upward, while simultaneously pushing in on the clip
When you reinstall the rocker cover, it helps to torque it down a bit at a time, holding it in place as much as possible to keep it from sliding towards the right side of the bike. The cover is designed with an angled base, and it gets cocked out of place as it gets torqued down. I try to minimize that as much as possible, but there’s always going to be a little bit of a shift.
That’s pretty much it in a nutshell.
Last edited by Mike; 05-18-2011 at 08:03 AM.
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#8
05-18-2011, 08:29 AM
Wonderful job on the write up!!!
I've just completed my first top end, and referred to pictures in other threads. I believe your post is perfect!!!! Gives visual reference for everything your going to see, but leaves out specifics so all can refer to their specific manual.
Instant sticky material!!!!!
Congratulations sir, it's a job very well done!! Very well done indeed!!!
Many thanks from the countless folks who will use this visual aid in the future!!
Beav
I've just completed my first top end, and referred to pictures in other threads. I believe your post is perfect!!!! Gives visual reference for everything your going to see, but leaves out specifics so all can refer to their specific manual.
Instant sticky material!!!!!
Congratulations sir, it's a job very well done!! Very well done indeed!!!
Many thanks from the countless folks who will use this visual aid in the future!!
Beav
#10
05-18-2011, 09:46 AM
