Splitting Crankcase Halves and Bolt Identification

[DaveBrit]

I am just about to split the crankcase on a 1985 FJ1100n, all crankcase bolts have been removed, including the one under the oil pump, and I am still having a problem in separating the two halves as they appear to be stuck together (really good sealant possibly).  What is the most appropriate method to persuade the two halves to let go of each other as I am very reluctant to 'pry' given various warnings in both the manual as well as this forum?  Also, and possibly related, there is a bolt that sits directly over the middle of the timing chain gallery (situated just to the left of bolt #19 on this diagram http://www.bikebandit.com/houseofmotorcycles/1985-yamaha-fj1100-fj1100n/o/m146986#sch218728 ), can someone tell me what it's for? 

Reason for splitting case is bike drops out of gear on hard acceleration in multiple gears which I suspect is worn dogs.  It also instantly drops out of first gear when selected which I will investigate as soon as I have the crankcase split. Thanks!

[FJ111200]

I think your mystery bolt is the one that holds the rear cam chain blade in place.
And as for splitting the cases, i tap around the sealing faces with a rubber mallet. You could try a hammer hitting on a piece of wood.
Sometimes they are soild and require a bit of persuasion.

[DaveBrit]

Thanks FJ111200, I thought the mystery bolt was for the chain guide as well but needed a second opinion.  Unfortunately I am still struggling to get the two crankcase halves apart.  I have tried a lot of persuasion with a rubber mallet as well as heating it up to about 30 degrees C for three hours and using the solid lugs on the front of the two crankcase halves as pry points still to no avail.  I would put the whole engine in the oven and bake it at a low temperature but my oven is designed to hold a large turkey at most, not an FJ's engine and transmission! (this would also disappoint the other half significantly and I might find gravy poured into my oil)

It would appear the previous person who worked on the engine had a mighty fine RTV product to seal the two halves together.  Does anyone have any further ideas on how to split it?  Other than building an oven around the unit, the only other method I could find was on Dan's Motorcycle website (http://www.dansmc.com/split_crankcase.htm) which had the following:

OK, what if the crankcases are really glued and rusted together ? Well, they have to come apart if you are going to repair what's inside. We need to move to a higher level of case splitting. Everyone says "Don't pry the crankcases apart." They are right and they are wrong. If you pry too hard, you will ruin the crankcases. However, if they don't come apart, they are no good to you. The techniques I going to cover now must be used VERY CAREFULLY. If you are sloppy or ham handed here, you will RUIN the crankcases.

First put some penetrating oil along the seam of the crankcase. Now I take the blade from a wood plainer and picking a strong area of the crankcase, I place the sharp end against a seam. The sharp end is beveled to a sharp edge. I place it parallel with the crankcase seam and ever so gently tap it with a hammer. I don't tap very hard. Many times the case will start to separate and come apart. Other times I have to do this at several spots around the crankcase. Because the edge is sharp and flat on one side, angled on the other and quite wide, very little or no damage is done to the crankcase. It is important NOT to damage the edge of the crankcase. If you do damage it, it will not seal right and you will have an oil leak. The crankcase is made of aluminum and it can be damaged very easily. If the case starts to spread and then pops back together when you remove the tool, you missed a crankcase bolt or screw. Go back and double check for more bolts or screws.

Lot of times the locating dowel pins will be rusted in and, using the wedge tool, you can only get the crankcases to separate the thickness of the wedge tool. If this happens, take a fairly large screwdriver and use it to gently spread the cases further. I can't emphasize enough the words gentle and go slow. The tools you are using are made of steel and the crankcases are made of aluminum. If you get carried away with this prying thing you will RUIN your crankcases. You may have to spread the cases a little, put on some penetrating oil and tap them back together and start all over again. Worry them. Back and forth, back and forth. Do not get mad at them if they are a bit difficult. I can always get my crankcases apart without damaging them. If I can do it, so can you.

[racerrad8]

On the early 1100 and 1200 cases there is a long bolt that is next to the rear chain guide position rod. The tensioner nut is that, a nut with a copper washer below. You can take it loose to confirm that is the chain guide nut and nothing will happen.

The other is a long bolt that usually has the "10" on the head of the bolt and when looking at the engine from the back or seated position it will be to the right of the chain guide nut and offset to the center line of the chain.

You should have removed a total of 22 bolts form the bottom halve of the case and 15 or 16 from the top side of the cases.

After that, you confirm you have all of the bolts out, you can pry on the front motor mount lugs and the are tabs sticking out of the opposite case.

Make sure you do an bolt count first before you start prying.

Randy - RPM

[DaveBrit]

Thanks Randy.  I went back and double checked my bolts from the crankcase and got the 16 count from the top of the crankcase but only 21 from the bottom.  I double checked the Haynes manual's diagram plus the parts diagram at BikeBandit and can only get a total count of 21 bolts for the lower crankcase (which is also the amount cast into the lower case, #22 is cast into the upper half of the case).  Am I missing something fundamental here, perhaps the central bolt in the oil pan takes the total count to 22 (however you have to remove the pan to get at the crankcase bolts inside the sump anyway)?  In any case, the two halves are totally reluctant to separate.

[racerrad8]

Okay, 10 on the crank, 7 at the front of the block all of which are 8mm. Then 4 6mm in the oil pan area.

Are you sure you got the one out from under the oil pump...?

Randy - RPM

[DaveBrit]

Hi Randy.  Yep, got the one from under the oil pump (somebody had replaced it with an Allen head bolt).  So the bolt count in your post is 10 + 7 + 4 which makes 21 bolts in total, not 22?

[racerrad8]

Well, there ya go...

I can count but not add...

I am away from the shop now, so I can't refer to a case now to make sure I counted correctly.

Randy - RPM

[DaveBrit]

Thanks Randy.  I have that problem too, I blame mine on early senility!

[racerrad8]

Well, It looks like you got it apart...Was there a bolt missed or just  really well glued together.

Looks like someone missed a lot of the details by the photos you posted.

The only thing I see that is correct, is the heat shield bracket is not used on that position.

Did you find anything specific with the trans?

I see the first gear issue by looking at this picture.



Maybe this should be a test...

Randy - RPM

[DaveBrit]

Crikey Randy, you really are good; already beginning to answer questions that I haven't got round to asking yet!  There were no bolts missed, just really well glued together which my neighbour (arcraft powerplant mechanic) had a great suggestion which I will recreate on assembly for a photo to be posted to tidy up that part of this thread. 

As for the transmission, the installed shift forks were noted to be the later, more beefed up, spec for FJ shift forks (labelled R - 3XW 6, C - 4KG 4 and L - 3XW 6).  One of these newer spec shift forks (the one that selects first gear) had a trace of evidence that the fork was beginning to bend but nowhere near the classical 'smiley face' of the typical bent shift fork.  The shift cam which drives all three shift forks looked satisfactory with little sign of excessive wear.

Both shafts were carefully checked to ensure the gearwheels, thrust washers, circlips and bearings were installed in the right sequence and were facing in the correct direction and this all looked fine (at least to my limited knowledge of transmissions and the Haynes manual).  I have no prior experience of gear dogs and therefore little understanding if I am looking at a good, slightly worn or badly worn dog other than some common sense.  The gear dogs for first gear looked pretty well worn to me on the installed transmission.  Undercutting on the other gear dogs was evident (this is a good thing isn't it) however I was not able to assess the condition of the corresponding dog accepting windows due to inexperience.

During disassembly, some crankcase bolts were missing or not tightened as per this diagram:



Which may have caused the crankcase to flex and/or fail to correctly position the gear shafts and gear sets.  However to Randy's last point, I think I may have failed the test as I cannot figure out the first gear issue from the photo of the transmission.  Anyone able to give me a clue? 

[racerrad8]

I see the first gear issue by looking at this picture.


Maybe this should be a test...

Randy - RPM

Actually, I am going to sweeten the pot and we can have a little fun at the same time.

The first person to correctly tell me what is wrong with the transmission as  shown in the picture above by 5pm PST on 4/7/13 will receive a 10% discount to my website.

While you might be guessing what the issue is, I will only accept the true, explainable reason why 1st gear is jumping out of gear.

Pass it on to all of your friends, who know they might be the winner.

Randy - RPM

[DaveBrit]

Oh Randy, this is actually beginning to get like fun!  My guess is the wrong gear wheel.

[fj11.5]

im guessing the selector teeth are worn, at least thats how it looks

[racerman_27410]

I can see scoring on the windows of the 2/5 gearset..... scoring means wear..... cant really see what the dogs look like but i bet the shift fork was bent more than a little bit.

it also looks like first gear may be on the shaft backwards.....in the picture it appears to be touching the ouput shaft bearing and i happen to know its real easy to screw that up 


thats about all ive got.  


KOokaloo!  


Frank