Splitting Crankcase

I have had a look around this site for topics in relation to splitting the crankcase and there is a lot of useful information. But...don't think I was able to find information specifically for the following:

1. Is it necessary to remove the gear selector mechanism immediately behind the left side cover plate. All moving parts seem to be below the crankcase half splitting line.

2. Is it necessary to remove the clutch basket. All the clutch plates are out but again the clutch basket shaft runs on a bearing. Unless the chain for the oil pump(?) behind the basket needs to be accessed before the split can occur?

The Haynes manual is not entirely clear as it seems to focus on a complete engine breakdown regardless of the extent of work being performed.

I am splitting the cases to replace the starter clutch mechanism housing as a unit. No other work is planned unless I find some horror inside like the HyVo chain guide on the point of disintegration.

Thanks if anyone can advise on this. Cheers.

 

Hi,
Removing everything from both sides will simplify your experience.
I couldn't imagine not completely stripping it to split.

Take a picture before you pull it off... Just bag all parts after you do and mark the bags.

Removing the clutch basket is easier if the motor is still in the bike mind you or if you use a air rattle gun i suspect.

If you're going to split for that reason only I would check the oil spray nozzle also which will give you a definitive answer as to how stretched the primary drive chain is... If we are talking about xj650-900 that is (your bike isn't mentioned anywhere)

Here are some pics I took last time I split.
http://www.xjbikes.com/Forums/viewtopic/t=38545.html

 

after you take off the left cover the mechanisms and springs can just fall out, so yes and no.

one nut takes the basket off, one bump on the bench breaks the ears off

 

It's not a true "primary drive chain" all it does is run the alternator and give the starter something to grab onto. They really shouldn't call it that. It's the jackshaft chain.

Primary drive in the shaft-driven bikes is by gear. The "primary" (jackshaft) chain carries almost no load, which I assume is why it was only fitted with the infamous crumbling plastic fixed guide.

(Primary drive in the 550/600 is by an hydraulically tensioned Hi-Vo chain.)

Anyone splitting the cases of a shaftie would be well advised to replace the chain guide while it's apart as well as the aforementioned oil spray nozzle.

 

Thanks for the feedback. Bike is an XJ900 1985 model (Australia).

Most helpful. By checking the oil spray nozzle I presume you're referring to it being flattened on one side. I've seen your pic of the nozzle and mine is pretty much worn on one side.

I don't know how many kms/miles my bike actually has on it but there have been no untoward sounds coming from the lower part of the engine nor any metal or plastic bits at the bottom of the crankcase.

I know the expert advice is change everything but bike used to be an every day ride to work but when together will be my Sunny Sunday cafe racer around the local boulevards.

I think I might chance leaving the "primary" chain as is as the plastic chain guide looks ok and there are no apparent cracks.

I guess by the time it might break up I'll be retired and I'll have all the time in the world to do it again!?

 

Hi,
Yeah the oil spray nozzle gets rubbed off by the chain eventually... bit of an odd way to realise that the chain is stretched and like Bigfitz points out it's only to start the bike and run the alternator so you would have thought a bit of an adjustable tensioner would have been tossed in at some point... oh well!

The real problem I see is that the oil spray nozzle isn't spraying oil in the right place once it gets mashed... the right place being around the starter clutch and the stuff that sits above the splash area at the bottom of the motor and so... the problem of 'just' being a bit stretched becomes a bigger problem *sigh* damn you Yamaha!

Maybe we could poke a tensioner in somewhere... a bolt and a nut maybe with a bit of something stuck on it. I digress. but I ran through the whole gamut of ways to get around it and then eventually couldn't bring myself not to do the chain and the nozzle and the guide while I was inside.

But in saying that... I wonder if you could redesign the oil spray nozzle to go higher and not get hit by the chain! I LIKE IT!
Good luck.

 

I can't believe anybody would go through the trauma of splitting the cases without replacing the chain guide. If it's 30 years old, it's GONNA break up at some point; why would you want to do this twice?

 

The more you write the more I'm being talked around to changing the chain guide.

I'll go and see if that can be done with all the top end in place, to get underneath the chain and to the mounting point.

 

Because it's fun?

dave

 

The chain guide is a lottery ticket "time bomb" awaiting inside your engine. We spent quite a bit of time and a lesser bit of money TRYING (in vain) to figure a way to develop a method (special tools, etc.) needed to allow people a simple way (i.e. thru the oil pan and jugs) to change out the guide on their engines....so it could actually become a "maintenance task" rather than a effort akin to a full engine rebuild.

If you're going deep, do yourself a huge favor and replace the guide, perhaps the chain, too (maybe the cam chain, too). And the starter clutch pins, rollers, and springs (assuming the starter clutch hub isn't cracked, in which case you need to replace the hub).

These pieces are typically (99.9%) the only items that will prevent these motors from being 100K mile engines, and should have been designed to be serviceable without a full tear-down.

 

Thanks. So many wise words it's almost hypnotising:

I will change the chain guide. I will change the chain guide...

Cam chain will be changed. Have a complete new starter clutch assembly...case and springs etc waiting to be installed.

No half measures with that. Too many false grinding starts in the mornings to take any chances in sealing the engine up and have more grinding far too soon.

 

Hey everyone----Look! Somebody who's actually LISTENING!!!!!

 

I notice in the pics of the split crankcase where the primary chain guide was extracted that the head of a retaining bolt was broken off. Is this a typical problem when trying to extract the guide and should I patiently apply WD40 and heat at various times to unseize those bolts?

Thanks again.

 

I hit that bolt with gusto and snapped it off... a very depressing moment to be sure.
So the heat and the careful extraction is a damn good idea im thinking.
Carefully, carefully...

 

Thanks for the feedback. Every little bit of information helps to foresee the speed humps.

I'll be uploading pics soon so the progression from a jumble of parts through the build to finished product might be of interest to others.

Cheers.

 

Two things: WD40 belongs in the kitchen, not the garage. WD = water displacement; its only real application in our world. Save it for squeaky hinges. In the garage, you need a real penetrating oil; although a lot of the products we have here in the States aren't available there, a trip to the local auto parts store should get you better than WD40. Another point: DO NOT use it as a cable lubricant on your bike. It gums up when exposed to heat and can cause a sticky cable (and soiled grunties if the timing turns out bad wrong.)

BE VERY CAREFUL (consult the factory book) in regard to exactly where and where not to apply the Yamabond #4 (or specific equivalent) sealer when reassembling the cases. This is uber important and if not carefully followed can cause an oil-related bottom end failure.

 

Thanks for the comments. Will be very very careful during the rebuild re Yamabond placement. Me and the XJ have been down too many tree lined country roads together to lose her on the operating table.

It's taking time but I am moving forward with caution...no impatience here.

Thanks again.

 

those bolts have been living in oil their whole life, do you really think a few days of penetrating oil will matter.
if their going to snap, their going to snap

 

What about the application of heat from a butane torch or similar. That should looses any Loctite in the threads and expand the aluminium case a little faster than it would the bolt. And then apply some torque gently to the bolt with a breaker bar rather than an impact driver?

 

I wish I would have done that! It would have solved it for sure.
+1 on the heat!

 

Status Update:

Oil Pump - When taking the sump off the filter at the "top" of the oil pump had remnants of silicone sealant, what looked like broken bits of gasket, and when I scraped beneath the cover...more bits of silicone sealant. Sort of like little strands all bunched up. I would say that about half the oil pump mesh must have been covered in the stuff.

There's not much room between the cap and the mesh to clean things out but I used an emery board (the cardboard type for filing fingernails) and patiently scraped through the mess all the way through to the closed end of the cap. The only concern was that there were 2 small pieces of metal back there, one of which looked like it had a thread on it. Not sure if I'm yet to find the origin of that or...when I first got the bike and I took the valve cover off and one of the cam caps (not really a cam cap but one of the central ones that simply provide an anchor for bolting the valve cover down) had broken where the thread was.

The fact that these metal bits were way back in the filter means it must have happened a long time ago pre my ownership (6 years).

Anyhow, mesh all cleaned up now. I reckon the oil pump must have been wheezing for oil flow as there was only a small amount of the exposed mesh where the oil could freely flow in.

Tomorrow...the bolts come off and I'm going in deeper into the abyss.

 

Status Update:

Firstly...new site is great. Loved the old one but this is clearer and easier on the phone.

Well...I split the crankcases and it was pretty straightforward. Just follow the bouncing ball on all the top and bottom crankcase bolts and a tap with a rubber mallet and off came the bottom half of the crankcase.

I can see why the starter chain guide can disintigrate. The starter chain after years of use does get a bit sloppy and with age and punishment one day that little beggar will self destruct inside the engine.

Interestingly though...despite the horror stories of broken bolts etc. in trying to unbolt and remove the old guide this operation went very smoothly for me. The front retaining bolt was an allen head bolt. It came loose without too much effort. The bottom rear bolt...a simple twist and it loosened very easily. Not sure if it's the same on all XJ's but it actually feeds through the alternator housing and is retained by a nut at the top of the housing. Is this common? For a curious amateur mechanic who might get a little overenthusiastic with a spanner it seems the nut can be easily undone leaving that bolt unsecured!?

Anyway...got the chain guide out with a little effort. The pic shows the state of decline in its integrity. Wouldn't have been long before that would have cracked completely up.

So far so good...more to come.

 

Hi again. Working through various crankcase parts and now onto the left side cover where the gearshift lever/assembly are connected. The XJ900F has this dowel/pin forward of the splined on which part of the gearshift assembly is mounted. Photos attached for front and back. Can anyone assist in how to remove it from the cover. It has a cir clip at the rear. Not sure whether this is a press fit or threaded. in any case I can't figure out how to remove it. Thanks. I hope

 

On a 750 it's a press fit with a oring. Why take it out ?

 

The shaft/spindle is worn and this makes the gearshift assembly a little sloppy with the sideways movement on the spindle. I thought of shimming it but couldn't figure a way to make it a solid interface with the assembly. Also where the circlip on the end sits in its grove that is also worn creating a further small amount of movement. Extracting this unit and replacing it with a new or less worn one was seen as an option if the original can be removed. Is it pressed in from the outside or from the inside of the side cover?

 

Hi Again,

Working through the open crankcase making sure all worn parts are replaced. New starter chain guide received for Chacal and fitted in place without much effort (cylinders and head were left in place so it was a bit of a squeeze and twist behind the starter chain sprocket on the crankshaft). The old chain guide was worn a bit (and cracking in parts) and the new one does actually take up a little of the slack that was previously there.

I bought a new starter clutch assembly including springs and rollers some time ago and just got around to fitting it this morning. I really couldn't see where the old one was failing as the springs seemed in good order and the rollers seemed round (roll test on the stone bench top!). I can only assume that where the rollers get pressed against the starter clutch housing the landing was shinier and presumably slightly worn down and this may have contributed to the starting problem. Anyway....all parts in place and o rings and oil seals renewed.

Question is this: I've checked the Haynes manual and cannot find the torque setting for the 3 torx screws that retain the plate inside the alternator housing. Any suggestions..?

Many thanks!

 

No takers on this question?

Don't blame you. I've looked everywhere and couldn't find anything so in the end I settled on 10 ft/lbs of torque.

It's a low enough setting so as not to get to the point of stripping threads plus with some Loctite on the threads I guess that they will be there to stay until some future time if ever they need to come out again.

 

about that pin for the shifter. take a look at the part that rotates on it, it's worn too.
so even with a new pin there's going to be slop. the most economical thing is to take the clip off and tap the pin out from the inside, spin it 90 deg and put it back. then the wear areas don't line up.

 

Thanks. It's damned hard to budge but I'll give it another try.