This is the third part (check out part two here) in our extremely popular video series in which Todd Muller, Head Motorcycle Tech here at Lowbrow Customs, disassembles a unit 650 c.c. Triumph motorcycle engine and rebuilds it.
With helpful tips and tricks, Todd takes you step-by-step on the disassembly of the primary side of a 1968 Triumph 650cc motor. He shows you what to look for and how to know when certain motorbike parts and hardware need replaced or refinished.
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You can read a full transcription of this video below:
Hey, guys. Todd from Lowbrow Customs here again. Part three of Triumph 650 motor disassembly today. Last time, we did the top end. Today, we're going to attack the primary. Let's go ahead and get started. Make sure you drain your primary before you take your cover off or it will make a big mess on your workbench. This plug here is basically a level plug. You can take the chain adjuster nut out of this right here and that will essentially drain the primary.
I'm going to go ahead and take these two caps off using Lowbrow tool that we make. Handy little tool fits very nicely in these. I'll just use my handy-dandy adjustable wrench. We'll take these two plugs out because they're going to have to come out sooner or later, so I might as well do it now. This hole is for adjusting your clutch center push rod right here. This one is for checking your chain tension.
Okay, now we'll go ahead and take fasteners off the outer cover here. Got two dome nuts at the front here and those should have a sealing washer underneath them if it is correct. Well, this one is. Then you've got three screws here, three here, two here. There are different size. The two on the back are going to be -- let's see we got a 730 seconds. These are a little bit larger socket head than the other six.
The other one's going to be a 3/16 unless of course your motors never been apart and then you may find some with a cheesehead screw that looks like a Philips head. This motor must have -- someone must have put the upgraded socket head screws on there, which does make life a little easier especially if they've been in there a long time. These are much easier to remove.
There you go. That one washers on there. I couldn't really get it off with my fingers, so pay attention. There it goes. Here's your primary cover removed and I already had drained the oil on this one, so we don't have to worry about that. Now, we have the pressure plate, three screws to remove, and three screws to remove on the stator. We have a lock tab on the rotor, so we'll go ahead and get those removed.
It does take a long socket on these because you have these two studs that stick out of the cover and that's the purpose for the sealing washers here. You don't want oil to leak out of there in between the threads on that. These are coming off very easy. These are generally a lock type of nut. Sometimes it may be a little harder to get these off. These are going very easy.
Let's see. The wrench on it, it goes -- socket goes very easy. When I try to do it by hand, they're still -- got some of their lock property going on there. Okay, next thing you want to do before you remove the stator, obviously, the wire is disconnected on the inside, you're going to just pull that wire out of there and then you should have some washers on here. You want to try to bring this stator off as evenly as possible because it is attracted to the magnet.
Also, if one of these two studs is maybe just a tad bit bent, it does come off pretty hard. You want to try to remove this as evenly as you possibly can. There you go. There's your stator. Okay, then you should have a lock tab on here for this nut that is attached to the crankshaft. I'm just going to use a screwdriver and bend the lock tab back. If it looks pretty mangled like this one, you'll put a new one on when it comes time for reassembly.
All right, I have this Harley Davidson primary locking tool here that comes in handy for keeping this from spinning around while you loosen this nut. Just here, just going to stick it on top of the chain there and what happens when you go to turn this, it will get stuck in between the -- this one wasn't very tight. Probably wasn't correctly torqued. Then you've got this long-shouldered nut here that goes down inside of the rotor.
Okay. Well, that's loose. We can go ahead and remove these now in preparation for removing the rest of the primary. One thing I've noticed very often on these studs on the long ones, sometimes they get bent. Like I said previously, it makes it difficult to pull the stator off if one of these is bent. The other thing I noticed very frequently is if you're running with a loose chain, it will try to dig a hole on this.
If you see a bunch of chain groove marks on there, if it's only worn a little bit, it's okay to reuse these. If it's worn down pretty hard, you might want to get another set of these, too long, one short stator. Okay, now we just started making this new tool here. This is your pressure plate spring tool. This tool is designed to use a socket. We'll grab a socket the correct size here. Looks like it's going to be 5/8.
Now, the important thing about using this type of tool on this is if you may notice, the studs for the pressure plates adjusting nuts, there are springs underneath here are proud of this slot. Obviously, you can't just take a large screwdriver on there because it will hit the center. If you notice on the tool, there's two slots and a hole in the center. That's so when you put it on there, it has some place to go. We'll go ahead and loosen these three which are your clutch pressure plate adjusting with our tool here.
You can feel the spring underneath there. It's kind of fighting me to get this off. Once it gets looser, it becomes easier. Each time I try to turn it, the tang on the spring is catching on, so you could see it real good right there. Just be patient, a little bit of pressure. All right, so once you've gotten those past where that stud is sticking out the center, then you can proceed with a normal screwdriver if you so desire.
Go ahead and remove all three of your adjusting screws and springs. Then you can just take the pressure plate off. That's what that looks like. These cups for those springs. Also, it's always a good idea -- I do usually inspect my parts once I've gotten everything disassembled but very quickly will show you. Generally, if you take these three springs and just set them on the workbench and if you see one that's longer or shorter than the other, then that probably means that they're worn out and it's time to put some new ones in there.
These actually look pretty even. You could probably reuse them if you so desire. Now, you can see the first plate is a steel plate and then it's alternating every other plate. It's going to be steel friction, steel friction, steel friction, probably because this motor has been sitting for a long time and hasn't been in service. I would guess that these are probably going to be stuck together.
We'll find out here. Yes, I can feel it already. Look at that. They're definitely stuck together. It won't normally come apart like that if this was a running motor, it would have been take one out, take one out, take one out. Sometimes a pick, if you get a pick with a bent end, you can get underneath this to pull on the plate. You'll have one on each side and slide it out evenly. You can also use a magnet, which will go a little side to side.
The other plate's coming out there and we have a bunch more that are stuck together. There we go. There's all of the clutch plates. Okay. All right, so we've already removed the nut off of the rotor. We have the nut on the main shaft here that we need to remove. We can also take the clutch pushrod out now. This actually is your clutch pushrod. It goes all the way through the main shaft to the clutch release on the other side, which we'll get to later on.
This is the adjuster I was speaking of earlier where you take the cap off of the cover and you can get to this lock nut and this and that basically coincides with that. When you pull your lever on the handlebar, it pushes this and moves this out to release the clutch for shifting. In order to lock this together, we can't just put a socket on there and remove this, because the whole darn thing's spinning around.
Well, you can use one of these handy tools that we have available on the website. Locking tool, basically, it's like a steel and a friction all-in-one so you have the inside-outside tangs. You're just going to slide that in there. You're going to line this up. Now, it's locked together but it still wants to turn the engine over. We grab our Barbie stairs again, I mean primary locking tool.
Okay, on our earlier motor, you're going to find a lock tab underneath this nut and you're going to need to bend that lock tab up. This is the later motor, so it has a lock nut. We don't need to bend that over. We've got everything locked. See, how when I started to loosen it, this jammed against that. These two are locked together. Then we can proceed to take the nut off.
There's also a very thick washer here. That magnet is not going to do it. There you go. Okay, we'll get our lock plate out of here. Usually, these aren't this tight. I don't know if maybe something's a little worn and that's why it's sticking in there. Voila. Okay, now we have both nuts off. We're ready to remove the entire assembly. The first we have to take the rotor off of the crankshaft. There is a keyway there, which coincides the way you'll see when I pull this off, there's a key. Sometimes these will pop right off by just simply pulling on it and sometimes they will not, like this one.
What you can do for this is you can use a two jaw puller and we'll just get that behind there like so. It's a good idea to use something soft like a piece of aluminum or for this instance, I have a penny here that I'm going to put against the end of the crank where the threads are, because I don't want to booger this up with the puller. All right, I was having a hard time getting that to center and stay on, so I just temporarily put the nut back on there.
All right, I'm going to go ahead and crunch my penny down in the hole there probably but once she starts coming off, it should be okay. Basically, see, as I'm tightening this, it's moving away. We'll start over here because it wants to center itself there. Okay. Now, you can see the keyway and that is associated with the key on the rotor. You can just use a pair of side cutters. Pop our key off there and then we have a washer, spaces off the rotor.
We've got everything removed here. This will all get pulled off in one big lump sum. You'll notice there are some threaded holes on this front sprocket. Sometimes, they'll pull right off like this one will. We got lucky. That looks like it's going to slide right off of there with no problem. If you have one that's super tight and it won't slide on there, you can use another puller that looks like this one.
The threaded holes on here, I discovered quite some time ago are the same size as the cylinder head bolt, so you can simply -- if you do need to pull this sprocket off, you can thread these in and you want to thread it in and use all of the threads that are available. Then you're going to simply install the puller, start the other bolt. Since I don't have to pull it, I'm not going to show you. I'm just going to show you how the tool would be attached here.
Then you want to run those down into the hole so they're even. Then once again, you could put your penny on there and just tighten this up and see this rocket moving. Okay, the other thing I just noticed when I rolled the crank around a little bit here is it looks like ham-fisted Harry was in here with a pair of channel locks on this threaded -- this basically has threads on both ends. That will need to be replaced. That will not be reusable.
I would not want to count on those threads to secure my rotor even though there is a lock nut. It will probably be easier to remove that now rather than later. Since it's already buggered up, we'll go ahead and use a pair of vise-grips on there and see if it will come off. The proper way to take that off would be to double nut it. It is very loose. I didn't really even need the channel locks. I don't know why someone would do it like that. Since this is going to be replaced with a new one or a good used one, we'll go ahead and remove that now.
As you can see, it has threads on both ends. That is the end of the crankshaft. This will thread in. Once again, also, if you're pulling it might be a better idea to pull against this than this. Had I noticed it was loose, I would have removed it. Sometimes you'll find this suckers in there. It's tight. If the threads are good, you don't need to remove it. You can just leave it in there.
Now, we're going to use another special tool that we offer on the website. This is a clutch center puller. You'll see it is a very simple tool. It has threads here, not here, and a flat here for tightening. If you could see down in there, you would see that there are some threads on there. The only reason those threads are on there is to use this puller. There really is no other way to remove this other than using this.
You'll see when we get this apart. The main shaft is tapered with a key. When this nut is torqued, when you're assembling, it pushes that center onto the taper and holds it on there. You want to make sure you have this bolt screwed out inside there. Then you're simply going to thread this in. Use your wrench to tighten this on. Catch as many threads as you can there in the center, where those threads are for this tool.
I think a little 86, the extension now. Use this to hold it. Then you're going to tighten this. See that? Boom. Popped it off the taper. You can go ahead and remove this now. Now, you're just going to slide the entire thing off all in one big lump sum. There we go, primaries disassembled. Here's the taper in the keyway. Again, side cutters work very good for removing these keys. Just grab the sides of it. That one was kind of loose. That may be something I want to look at.
Make sure the keyway in here is in good shape. Then the only other thing we have left in here is the primary shoe. To gain access to the screw for that, you're going to need to remove this of which I did tell you earlier you can drain your oil here. We're going to take that out. Should be a sealing washer on there like that. Then there's -- this has threads on it and you can take the new Lowbrow tool and stick it up in there.
Okay, so you're going to put the tool in there. You could see that turning now. The other thing I'm noticing on this shoe, if you notice before I continue to loosen it, see how high of an arc this shoe has on it? That's probably a good indication that this chain's worn out. If you noticed that your shoe is adjusted way up, it may be time for a new primary chain. Also, replace the shoe at the same time.
You may also notice how the end of this that adjusts this is shaped like this. Each time you turn it, it goes easy and hard, easy, hard. This tool makes an easy job of removing this part. If you're using a screwdriver, you're in there futzing around trying to get the flat on it, yadda - yadda. We're just going to go ahead and completely remove this off of the threads so we can take the shoe off in preparation for completely disassembling everything. It is a long-winded one there. Still not done.
There's your threaded adjuster. Now, that it's out, you can see the way the end of this is shaped. Why if you're adjusting your chain and you're not taking stuff apart, you can see why it has that feeling to it because it's curved. It's not flat. The shoe just simply slides off this piece in the front here. Look, down there's this piece of it with the threads and then you'll see there's a slot there. This needs to be in there and then it'll just slide on and that will line up with the slot. That keeps this in place.
There's our shoe. Everything looks pretty good inside here. It looks like someone kept up on their primary chain adjustment. Sometimes you'll see where the chain is hit. The case, it digs into it a little bit there just like I was talking about. You can see where this other alternator stud would be. You can actually see a couple of chain marks on this one. I'll show you here. You can see just a spot there where the chain touched it.
This is what I was talking about earlier. You can see where the chain has just touched that. It's not a problem as long as it's not very grooved, then you want to replace that. All right, the next thing we need to remove is this cover, these screws, and behind here is going to be the main drive sprocket. These can be a bear to get out sometimes because they are a flathead screw. They're very short and they may have been in there for a very long time.
What you want to do is you want to find your very best, highest quality screwdriver that fits that slot perfectly. You don't want to use some junky old Harbor Freight freaking screwdriver on there. Let's try this one. Now, I can see now this is going to be a job. None of these want to come off. The next thing we'll do is we'll go get a chisel. Okay, so I have this chisel that I ground it down. Basically, you're just going to get it in the flat and you're going to shock the hell out of it and then using a good quality screwdriver.
There we go. Look at that. Just shocking it with the chisel got it to come loose. I've got those three loose. I got three more to go. There always seems to be the last one or the last two just don't want to come out. You just have to persevere. See, like I said. It's a very tiny screw. It is imperative that we get them all out and we will. Don't worry about buggering them up with the chisel.
A 100% of the time, I usually replace these because they never seem to want to come out. It always makes you feel better if you get the ones out that are loose and then move on to the stubborn ones. Makes you seem like you're getting somewhere. Okay, so it looks like we have two stubborn ones left. We'll go ahead and beat on them some more with the chisel.
There she goes. One more to go. Okay, danger averted. We got her. I'm just going to take a punch and I'm going to give it a whack. Obviously, use a little common sense there. You don't want to beat the hell out of it. You will see that there is no way to pry on this cover because it has oil fuzz all over it. See, how it has this lip and that goes into the case to seal it. You really don't want to try to pry from this side. I didn't hurt anything by just using my punch in between the sprocket.
You may also notice there's a seal in here, that seal rides on this and keeps the primary fluid from leaking out through here.
This should have had a gasket on it. It does not. Not a bad idea to use a gasket on this. We got them on the website. Also, maybe a little bit of sealer. Reassembly time. Okay, next thing. Here's our main drive sprocket. This will also come in handy for you guys that maybe just replacing your sprocket. You'll be doing everything I've done so far today, primary off.
Obviously, you won't have to remove every single piece to just change the sprocket. Now, you're going to see another lock tab here. Look at that, guys. Does that look like it's correctly torqued? Absolutely, not. It's a good thing the lock tabs on there or this could have been a disastrous effect with the sprocket trying to work itself off of fourth gear. Always make sure you have a lock tab on here.
This is pretty common. I found this on multiple times I've take engines apart, where the nut is loose like this. Other times it's tight. What you could do if it's super tight, obviously, this is all going to spin around when you're trying to loosen the nut. What you can do is put a piece of chain around this and clamp it in your vise. Then you can break the nut free or you can use an impact, a half-inch impact with a large socket and give it a. [makes sound].
This is standard right-hand thread as was this one, as was this one. That's for you Harley guys out there that may be rebuilding your Triumph. This stuff's not like a Harley where it's got the left-hand threads on the nut. We'll, go ahead and bend the lock tab over. Hey, we can use my favorite punch to. Once again on reassembly, this lock tab looks pretty gnarled. We'll just be using a new one.
Okay, since we don't have to use either an impact or if you don't have an impact, like I said you can wrap a chain. There's your nut. There's your lock tab. We'll see if this sprocket wants to come off or not. Once again, this is going to be similar to this one. It's either there are splines here, there are splines there. Sometimes the sprocket will just slide right off, sometimes you got to pull it. That's why it has holes in it.
This one doesn't act like it wants to come off. Well, would you look at that? Our head bolts that we reviewed earlier fit those too. Isn't that great? Look at her. She's coming off now with just by putting the bolts in it. Once again, it pulls off or it doesn't, puller, no puller, whatever it takes to get her apart. There goes our main drive sprocket. Basically as I was threading this in, it was hitting this seal and that's what pulled it off.
I just couldn't pull on it. It just wasn't coming. That is in need of replacement. Teeth are starting to hook. They're all starting to go one direction. That means it's on its way to be worn out, not going to reuse that on my rebuilt motor. Okay, that's it for this side, for the primary. We're done over here, gang. We're going to go ahead and move to the other side of the motor now and take some more stuff apart. Whoo.
You can check out the Triumph 650 Motorcycle Engine Disassembly & Rebuild - Part 4 to continue following along!
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