Project "walrus" Yam XS 750

Hi Ryan
Following up on your question about splitting the cases, there are many bolts to remove. From memory you also have to remove the right angle drive unit! I have picked up a photo from your post and marked up the bolts I could see. I will try to take a photo tonight of the 896 engine and show all the bolts that need to be removed before splitting.
Cheers
Tim

Hey tim thanks for the headsup!
I removed already all the bolts,I think one is missing...here are a few pics that show which screw I mean...is this also a screw holding the case?
The screw is besides the neutral switch on the left ignition side.
cheers!

Hi Ryan
The large bolt head in your photo is the gear shift index, it does not hold the cases together.
You must remove the right angle drive unit which is held on with M8 allen head bolts (first photo)
Then you have to remove the oil cleaner and sump to get to all the journal bolts - big M10 bolts. Plus when you are looking at the bottom there is a row of M8 bolts along the very front edge. (second photo)
Finally from the top, per the photo there are a lot of bolts spread around the top basically holding the gearbox shafts. I think there are one or two under the starter that I did not show. (third photo)
I always group the bolts together into plastic bags with generic label from where they were removed, ie right angle drive, engine top, engine bottom!!
Then some not too aggressive work with a rubber mallet. If it does not separate after a few blows then check again for any bolts you may have missed.
Cheers
Tim

Re: Project "walrus" Yam XS 750

Thank you!

This is exactly why I asked more knowledgeable people ...

Sump and filter are removed I think I forgot all the screws that are inside the sump and filter housing as you nicely pictured thanks!
Is it probably that when I remove the upper case that the journala will fall out?

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The journals do not fall out as they are cast into the casings. The shell bearings usually stick in the journals. Make sure you keep the shell bearings together in individually labeled bags. The early XS750 had a history of the middle cylinder big end letting go as it naturally gets hotter than the outer cylinders. Plus when that was combined with leaking petcocks that diluted the oil they let go.
Good luck
Tim

Re: Project "walrus" Yam XS 750

Thanks tim!
Just checked it out...found the two screws inside the oil pan.

Are you sure that there are 3 screws inside the oil filter housing?just could find 2 of them...
What is the screw with the bent tab for on my last pic,guess something for the gearbox...

Hi Ryan
Sorry my dots were a little misleading :-[. There are only 2 large journal bolts in the oil filter. The third dot I was trying to show the line of M8 bolts that go across the front of the cases!!!
Cannot remember if that bolt in the gearbox goes through to the top case???? It might be best if you can rotate the motor up so you can have a better look than trying to look up under the motor. I cannot see from your photo.

Re: Project "walrus" Yam XS 750

I think that screw with tab is the detent plunger.

Hey guys!

I made it!I ' ve successfully split the cases.
The only screws that were holding on were the 2 in the oil pan and the other 2 behind the oil filter housing.
The case popped easily off.

This is what I found.
The upper case has 4444 stamped onto it and the crank web has 11111 on it...does that mean that mean that there should be brown crank shell bearings inside (4-1=3= brown)?
One of the shells seems to be damaged.

The crank surface looks normal with no deeper scratches.



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Case-to-Crank-bearing-shell-calculations

Click to expand...

If that's what the manual says... Basically what we'll be doing is to check, whether crank is actually within spec and not reground. Even though the place I used in the past used to "X" out the old markings, if they reground the crankshaft journals, so you're very likely lucky.

Cheers,
Greg

der_nanno said:

If that's what the manual says... Basically what we'll be doing is to check, whether crank is actually within spec and not reground. Even though the place I used in the past used to "X" out the old markings, if they reground the crankshaft journals, so you're very likely lucky.

Cheers,
Greg

Click to expand...

Looking forward to that!

With some more luck the color marking is still intact on the back of the bearing shells. Your crank will have to be verified with a micrometer first of course.
I have some bearing shells left in a set i found on ebay, not sure which colors are left, plus one thrust bearing was missing when i bought it.
Edit: what further complicates this is that yamaha changed oil film tolerances in the middle of production, so later bikes have tighter spec clearance on the crank, and a higher capacity oil pump.

Re: Project "walrus" Yam XS 750

Shamelessly quoting senlisian on the yam triples forum. Lots of meat regarding crank bearing sizes in this thread:
http://yamaha-triples.org/forums/thread-view.asp?tid=14331&mid=122807#M122807
 Posted 2013-05-21 9:45 PM (#122807 - in reply to #98881)
Subject: RE: Conrod & main bearings  Offline

Regular

Posts: 144

Location: FranceHi guys, I have found the answer to your questions & frustrations...

It's very simple in the end - the XS750s have 2 types of crankshafts with different tolerances.
The first type has a set of 5 possible bearing colours going from blue (thickest) to yellow(thinnest). On this crankshaft there are no markings on the face of the primary gear.
The second type has a set of 5 possible bearing colours going from RED (thickest), then to blue, then on to green (thinnest) - yellow doesn't apply to these cranks. All the other colours in between are the same for both cranks. On this crankshaft there is an 'X' stamped on the face of the primary gear.

The calculation used for the first type of crank is case number - crank number = bearing code.
The calculation used for the second type of crank is case number - crank number - 1 = bearing code (0=RED). This calc is used ONLY for the main bearings, not for big-ends.

The plastigage clearances quoted in previous postings on this thread for 'early' & 'later' cranks are correct.

The reason for this change is that there are mods to the oil passages between the main & big-end bearings to provide more reliable lubrication to the big end bearings at higher revs.
The internal passages for the main bearings aren't drilled through both sides (1 hole instead of 2 - see picture below) as they were for the early cranks. This was done to reduce oil loss due to higher centrifugal forces that could induce aeration of the oil. Hence the revised tolerances for the later cranks.

If anyone is interested in the actual tolerances that the stamped figures on the case, crank, and con rods represent then I can post these as well.

Concerning the 850s I have no definitive info other than the main bearing size changed to be the same as the XS1100 so an educated guess would be to go with XS1100 values (if you can find them ).

PS. Credit where it's due; it all came from the 'revue technique'.

Edited by Senlisian 2013-05-21 9:47 PM

Re: Project "walrus" Yam XS 750

datadavid said:

The plastigage clearances quoted in previous postings on this thread for 'early' & 'later' cranks are correct.

Click to expand...

AND

datadavid said:

If anyone is interested in the actual tolerances that the stamped figures on the case, crank, and con rods represent then I can post these as well.

Click to expand...

Both would be really interesting.

Re: Project "walrus" Yam XS 750

der_nanno said:

AND

Both would be really interesting.

Click to expand...

Yea i am pretty sure i read them somewhere on the yamtriples forum. Or maybe i was satisfied with being on the close side of the old style crank spec sometimes these things make my head spin but plastigage never lies

So guys I have good news...Der_Nanno investigated on my crank and we were able to combine my 2 cranks together with some connecting rods to a crank that will be usable for my XS cafe racer!
Several rods were trash but we were able to put it together.
Plastigauge was used and showed good clearances on the rods...

Here are some pics.

But theres a issue however:
-i cant find a place that sells the screws that hold th connecting rods together (1J7-11654-00)+(90170-09192)
-i´m looking for seals for the Crank on the left 93102-24154
and gears with the number 93103-50103
-clips for the 825cc pistons

Where can I get these parts?

Thanks in advance!

Hi Ryan
The Yamaha seal is not available but you should be able to get a standard seal from a bearing shop. Per the attached description you need a 40mmOD X 24MM ID X 7.4mm thick seal. Most likely you could go down to a 7mm thick but may be a problem if you go above 7.4mm.
The other seal 93103-50103 there are a few on Ebay - Item number 152418000685.
Conrod bolts??? You obviously have the bolts from the engines you have? Are they damaged or stripped? Think you are going to have to use what you have, as they are not a standard bolt. Otherwise you are going to have to trawl Ebay until you find some 2nd hand conrods.
Good luck!

Re: Project "walrus" Yam XS 750

If the workshop manual says they are reusable, i would reuse the old bolts. I reused mine, so i think the manual said they can be reused

Re: Project "walrus" Yam XS 750

datadavid said:

If the workshop manual says they are reusable, i would reuse the old bolts. I reused mine, so i think the manual said they can be reused

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I think I have no choice anyways.No chance getting these...my yamaha dealer in germany who has bought pretty much all rare yamaha part stocks has 2 on stock

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Re: Project "walrus" Yam XS 750

http://www.partssweden.se/xs850sg-1980/crankshaft--piston i found piston clips on a swedish parts page