Tear-down in progress..

Hey guys. So I'm tearing down the engine to replace a chain guide. I'm sure I'll run into plenty of questions along the line, so I'll update this thread accordingly.

I've determined that the chain guide that's disintegrated guides the starter chain. Just so happens this is nearly dead center in the engine guts. Do I need to split the case to remove this one?

Also, I can't remove the block. I've been using a rubber mallet to knock around the perimeter, trying to jar it loose. Should I just keep at it? Manual says absolutely no prying, and the fragility of the fins makes me a bit wary. Do I even need to remove the block to split the case? I'm assuming yes..

 

There is a way to fix the starter clutch without splitting the cases, it's posted on here somewhere, someone will flag it. Yes you have to remove the block to split the cases.

 

Couldn't find a way to change the guard without splitting the cases, so that's what I'm doing. Just about everything's stripped out now. The pistons are nice and dirty, so I'll probably give them a carb cleaner bath.

I've read that you never reuse old piston rings. I wasn't planning on removing them, so should I still change them? Keeping in mind that $150 is a good amount of $$ on top of the new chain guide, gasket set, and other non-engine items I'd like to replace/refresh. Would it be a bad idea not to replace them?

 

I know it's money, but with the motor stripped right down, I think I would be fitting new rings. Take the rings off the piston, put them in the bore & measure the gap between the ends, that tells you how worn they are.

 

Piston rings it is. Couple questions on the issue:

-Do all 1982 xj650 models (maxim, seca, turbo) use the same rings?
-I had no idea my bike had a dynojet kit on it, I don't want to be surprised by bored cylinders. Any way to confirm it's stock size?
-Would an AutoZone cylinder hone tool be a good/bad idea here?

Thanks.

 

as long as your bore is straight the hone from auto zone will work fine

 

Ok, finally split the case tonight. Found I need to remove the bearing from the alternator housing.



Then I do this.



Is this thing too stripped to remove? Will a screw extractor work? I've had mixed luck with screw extractors.. Last item I need to remove before I get to the chain guide... :sad faces:

 

your using a hand impact driver, right?

 

A bit of valve lapping compound on the screwdriver tip will help grip the screw. Just a tip.

 

No, wasn't using an impact wrench.. Hindsight's a bitch..

 

Try using a left handed bit and a very slow speed on a battery powered drill. works for me when I resort to it.

HTH

Greg

 

Just tried the drill. Didn't work, but the bit's got a good bit of bite to it; not slipping around. If I get my hands on an impact wrench, I think I'll be able to coax it out.

 

Might be the perfect time for a good shot of Kroil. If the drill bit has a good bite and you still can't turn it out it sounds like you are likely to snap the shaft. Then you'll be in a real schnizzle. Can you wait long enough to get Kroil? What about the propane torch repeated heat and cool cycle method. Best of luck to you!

 

No, I can stop off for some Kroil. How long does that stuff need to soak in?

 

Doesn't need very long, Crew. Give it about ten minutes and try it. If nothing yet, another ten minutes aught to do it.

 

Waiting on the impact wrench, here's another issue.

With the case split, there are at least a couple bearings with HALF a metal ring keeping it in position.



I'm fairly certain I haven't misplaced/lost any halves of these rings, so either this is how it's supposed to be (to allow oil to pass?), or they were lost before I got the bike (unlikely).

Ideas?

 

Could they be broken what's the technical term "Jesus Clips", you know Split ring "C" clips?

 

hahahaha, I just had a 25 minute discussion about these half-rings with my friend who's helping me on my seca. Theres 2 or 3 of them in my engine too (81 750), each place only has one half of the channel for it filled with a ring. We looked and looked and looked. You most likely didn't lose any, it's just how they were built for some reason.

 

Yeah, they don't look broken at all. Not sure why they'd only be half a ring, but I'll assume that's how it's supposed to be.

 

half ring is normal. Ive rebuilt a few yamaha atvs engine and there like that too.

 

Am I right in assuming that during re-assembly you should put the ring across more than one piece if possible? Like, as an example, my seca's motor output is a shaft, driven by a helical gear inside the gearbox. (Is that the mysterious "middle gear"? I can't find it labeled clearly in any of my paperwork). There is one of those half rings that goes where the gear shaft seats properly. Channel on both the top and bottom case halves. We reinstalled it vertically, so that the clip is in the groove on the top and bottom case halves.

 

Salvation! Managed to remove the three screws retaining the starter clutch asssembly. The chain guide is now exposed.. or what little of it is left, anyway.. Good gawd...

So while I'm in here, I seem to recall that these bikes' starter clutches are a problem area. Anything I should look at before I order the parts I need? Or do I not even need to look, just go ahead and replace something?

 

Crewwolfy,

Can you please post pics of the chain guide assembly, and also your opinion on whether or not it would be accessible through the oil sump (if the bike were flipped onto it's handlebars)? Chacal was theorizing that this might be possible, with the use of extensions and swivel sockets. Your assistance would be invaluable in researching this.

Thanks.

 

Sure thing.


Here's a picture of the top half of the engine, where all the goodies are. The starter chain is lifted over to the left side. As you can see, only half of the chain guide remains. (No, I will not be using that toothbrush on my teeth ever again..)


The red circles indicate the connection points for the guide. I do know that it'd be impossible to replace the guide with the starter chain in place. If you can do it without splitting the cases, the starter clutch would have to be displaced. I don't know if I'd want to try that with the cases intact.

I'll have a better idea on whether or not you can replace the guide without splitting the cases when I reassemble, now that I know what to look for.

 

Dude, that is awesome. I finally have an image of what's going on. Yeah...I don't really see how this can be done through the oil sump but do look into it for us.

 

Crewwolfy, I had to remove the crank to replace mine. Good opportunity to check the condition of the crank bearings.
Hint: DON'T misplace the bearings upon removal (small bit of experience, cost me two weeks). Be sure to use assembly grease upon re-installation.

 

IF.. you ever get the cases split you MUST replace the Primary Chain.
IF .. you want to ride the bike for a bit after reassembly.
Replacement requires the Crank out of the Case, with Rods removed. Pretty well as far as one can dissasemble the engine unit
You realise the Primary chain stretching took out it's chain guide??
Instant "test' for a primary chain condition is to put it on a table where the chain's to row ..must not.. sag enough to touch the bottom. row
Not cheap either as it's a "captive' part just to add insult to injury (means it's only from the dealer) It's a V stupid design.. period, mercifully a long obsolete one.
Rings are not as often needing replacement as the primary chain., if that helps you.

 

This is the first I'm hearing about having to replace the primary chain. Why would splitting the cases require you to replace the chain? I understand the idea that the chain stretching broke the guide, but not the case-splitting part.

 

Crew.......it actually still migh be possible to remove the chain guide even with the chain in place. The replacement GUIDE only has two (2) bolt tabs, one on each end; the center one is no longer there.

The rear mounting bolt is pretty much a straight shot down with the oil pan removed (engine together), all you'd need is a long extension on a ratchet. It's the front bolt that's questionable.......

If you haven't already torn down your bottom case, it would be an invaluable experiment if you could set the bottom case----with all the pieces still in place-----back onto the top case, and with the oil sump pan removed, let's see if there is any way that the front bolt could be reached? If necessary, the alternator rotor/starter drive clutch shaft could be removed; that's actually pretty simple to do.

I'm pretty sure that once the front and rear (and, in the case of an original chain guide, the center mounting bolt, too) are removed, the guide can be snaked out towards the rear.....it's a pretty flexible piece.

Again, all I'm trying to establish is that if it is at all possible to do this replacement with the engine still in the bike. As the years (and miles) go by, this is the most common "wear item" inside the engine case that needs perodic replacement, and if it is at all possible to acoomplish this without having to do an engine teardown, then that would be very helpful to many owners who just don't want to or feel confident to remove th engine and split cases.

I know that someone figured out how to change the starter clutch pins without taking th engine apart, as well as changing the shift fork dogs from the bottom of the engine.


BTW, the starter clutch pins, caps, and springs should be replaced, and the condition of the housing should be inspected carefully for any cracks. I believe that Pollock has posted a great picture of what to look for on it:

http://www.xjbikes.com/Forums/viewtopic ... lutch.html

 

Since it's not a true primary chain (doesn't drive the transmission only the alternator) does it need replacement? Doesn't the guide just fail from rubber deterioration?

 

Yeah..what Len said.

I didn't know that middle bolt tab wasn't there anymore.

 

Ok, so here's the dealio. Keep in mind this is an 82 XJ650 Seca (non-YICS). No idea if it pertains to other models..

Here's an image of the chain guide.

The guide does have three bolt tabs. So removing/replacing all three is necessary.

Overall shot, with the cases together, through the oil pan.

I actually just realized that this doesn't include the middle gear assembly, which is sitting on a pizza box (not pictured). However, looking at where it goes, it shouldn't interfere.

Rear location.

Out of the range of the camera, but reachable. I actually went through the starter clutch hole, as I didn't have an adequate extender for the wrench.

Center location.

Without splitting the cases, you'll need a long extender for this bolt, but you can reach it through the oil pan. All these bolts are coated with Loctite, however, so be forewarned. Not difficult if you have plenty of room.

Front location.

And now for the bad news. I have no picture of this bolt through the oil pan because, well, you can't see it. In theory, I suppose it is possible to remove, but you would need a very flexible extender. Or maybe that thing Tom Cruise uses in Mission Impossible. If you do remove it, it's likely to fall into the head along the chain. And I have no idea how you'd manage to screw it back into place.

So there you have it. While I am no expert, I don't see how one could replace the chain guide on this engine without splitting the cases. I personally don't think it's [realistically] possible.

That being said, I really didn't find splitting the cases to be all that difficult. Seems like a very daunting task, but it was actually quite simple. As far as putting it all back together... Well, hopefully I can answer that in a couple weeks.

Organization is key.

(Insert MasterCard commercial with cardboard box and ziplok bags..)

I'll be ordering parts from Chacal, so she'll be gutted for at least another week. Let me know if anyone needs any shots in particular.

 

I was thinking that with two 90-degree swivels on an extension, and with the crank throw rotated out of the way (over by where the front bolt is), that maybe you could get to it through the large opening on the right side?

I think if you used a magnetic adapter on the socket your risk of losing the bolt (and of re-installing it) might be minimal. Yes, they are lock-tited in place but they do not use a lock of torque during installation. Perhaps one of those really funky-offset wrenches like they use on cars to loosen the distributor lock-down bolt (to loosen the distributor so you can adjust the timing)?

 

I tried rotating the crank for a better angle, to no avail. I'll try some more in the near future. Don't want to get too dirty tonight.

 

Okay, thanks!

 

Since it's not a true primary chain (doesn't drive the transmission only the alternator) does it need replacement? Doesn't the guide just fail from rubber deterioration?

 

David3aces, Yup. I've not seen a failure involving the HyVo chain yet. It lives in the oil bath and unless you run the bike out of oil, should last as long as the engine.

 

Great pics and info. I saw (I think earlier in this thread) a mention that the chain stretches and wipes out the guide. Comments?

 

I believe that's the HyVo chain Robert's talking about.

 

oops missed that sorry. I'm easily confused :wink:

 

I dont see how the chain could be worn out as stated it runs in a oil bath and it is only under strain for a few seconds upon start up.
I come from the world of snowmobiles and they run this chain in the chain case and it is under load constantly when the sled is in motion not only from forward motion but also from braking or slowing the machine down.The chain must transmitt in some cases 180hp to the ground.The only time I see a failure is if the chain was run without oil or if the clutch does not engage untill like 8000rpm and even then the chain will last for a lot of high rpm starts.
So while the chain may get a little stretched, I doubt that I will break under these conditions.I also believe that it is just old age/repeat heat cycles and rubber soakedin oil that causes the chain giude to fail and not the chain it shelf.

 

Dunno about that one.. When I was trying to Locate a Non Yama Source for the DID HyVo chain. I talked with the Canadian DID Distributor at length on this. He claimed he sold literally.. Hundreds ... of DID Hyvo chains every single Snow season. His view was that the average sno machine ate their hyvo's ..at least.. every other season. Dependant on the rider one would suppose.
His problem was with Yamaha forcing Yama Sno machine owners to pay their Usurious pricings. While he was prohibited from selling them his DID chains, despite being the national DID Agent.
It's been a while but... if.... memory serves, the HyVo chain IS the primary drive. Ergo the Name?
It ttransmitts the power, at least on my 2 old engines. There is no gear on the Crank shaft end. The Only other way to transmitt power... besides magic.
That's why it stretches out easily and generally causes enough grief so one dare not ignore it.
It ain't just there for the starter.. or it would only be a teeny chain... like the Cam drive.

 

Yes there can be some faliures but I bet most of those chains sold were either longer or shorter to acommadate gear changes(bigger or smaller sprockets)or alot of guys just like to put a stronger (wider) chain so they can bragg about it to thier buddies.
From what I can see the primary chain in the xj series engines is only for the starter motor.

 

Crank wheel for number 3 cylinder is a gear that drives the clutch and transmission on XJ650/750/900. Check pictures on page two of this thread.
This is another reason I love my bike; No sloppy primary chain drive!
XJ/XS 1100s have a primary chain.

 

Danilo, the HyVo doesn't endure high tension strain except at start-up. It shouldn't ever fail unless neglected, much less stretch. The dynamics to stretch it out just aren't in evidence often nor long enough to warrant concern. That is unless the nitwit runs the starter for minutes at a time. On a well tuned bike, startup is a swift affair and I just don't see where it could lead to a stretched out HyVo. Can you suggest anything else that would be a concern that I might have overlooked? I've only dealt with the HyVo in our XJ's so I don't have loads of experience with them beyond that scope.

Danno, you got that one right. The plastic/rubber/whatever-it-is material used dries out after a few decades and just crumbles. New units are not hard to come by but replacement is usually enough to send the uninitiated scurrying for momma's apron. I was not thrilled at the prospects when I had this issue. The process was actually very easy and I now marvel at the simplicity of the design of our beloved XJ engines.

 

The HyVo chain IS the primary drive on my Fz600 AND Radian engines.
NO if's and or buts.
Darn thing transmitts power from the centre of the Crank (ideal location actually) to an intermediate shaft (which the starter Mech uses only incidentally) with a drive gear on it's end which turns the clutch basket... Period .
The Hyvo primary v commonly wears out... it was a poor choice for an 11,000 rpm motor. Go! yamaha.
Local shops claim these are an Often replaced item as they normally stretch excessively subsequently destroying their guides. Which is a symptom of a knackered primary and THE v last warning before total engine meltdown! No small matter that, as the primary chain is the most expensive replacement excercise in the motor. (labour alone is astounding)

Ummm ...Been wrenching on these Long??
Clearly, someone is lacking even the most Rudimentary understanding of exactly ..what.. drives the transmission and makes the wheels go around

 

"Ummm ...Been wrenching on these Long??
Clearly, someone is lacking even the most Rudimentary understanding of exactly ..what.. drives the transmission and makes the wheels go around"

Yes, it would seem so.

XJ motors are gear primary drive.

FZ600 and Radians are not XJ motors.



As David3Aces has said, if you look closely, and not so closely actually,you will see the gear on the crankshaft just in front of the clutch enclosure. This gear provides the drive to the transmission through the clutch assembly. The Yamaha manual states in the specifications that primary drive is by spur gear, 97/58 ratio.

Many XJ's will run just fine without the starter chain guide in place at all. This chain primarily provides the drive to the alternator, which is why it is so beefy (it is under tension all the while the engine is running). You have to pay for the narrowness of the XJ motor with this bit of added complexity. As most other bikes drove the alternator off the end of the crank, you will not see such an arrangement in many other bikes of the era, if any.

There's nothing wrong with chain primary drive, it was used by Saab on the 900 series to drive the tranny off the front (I believe) of the crankshaft.

Yes, Robert, the XJ motor is a wonderfully simple design, but I am constantly amazed how well most all of these old Japanese motors are built, even if they don't have the latest whiz-bang technology. GM bought up a bunch of bikes back in the early 80's to see how they were put together and concluded that the Japanese were basically "building racing engines for the street". Of course, when your product line consists mostly of emissions-choked cast iron pushrod wheezers, your definition of a race engine may be a little broad!

 

XJ550s/FZ600/YX600s also have Primary chains. Sorry.
I forgot the chain set up in the 550. Last time I replaced a set of broken 550 crankcases at our dealership was in 1982.

 

So, been waiting on parts to arrive, so not a lot to do. Also got laid-off, so the bike's been on hold a bit. But no more. Parts are coming in, and I have other stuff to do as well.

Namely, I'd like do some valve grinding. Problem is, I believe AutoZone's valve sprint compressor is a bit too big. And having to guard my finances, purchasing a motorcycle-specific valve compressor is not an option at the moment.

Suggestions? Can I rig something using a C-clamp?

 

Put a block of wood to hold the valve closed & use a clamp with a ring spanner to depress the spring.