Splitting the cases

[Old Rider]

You definitely get the award for persistence. And the writeup with pics is first class. Mods please archive!

Good to see there is some interest about the topic.Im hoping this tread will help others when doing a rebuild and to avoid doing things i done wrong.It is also great guidance for me so i dont
do to many mistakes  
Today i have been at the local yamaha dealer and bought bolt 21 they could not get it before friday,but i can start doing other things.
Right now im scratching my head if i can reuse the new  piston wristpin circlips .They are new and i only used them once in the old pistons  they have only been mounted in the pistons.
today i also bought new wristpincirclips but i have to wait  to friday for them to. If i can reuse the one i got i can start with the cylinders today

[Old Rider]

Yesterday i got a little more done installed the bearing retainer and the rear camchain guide.
I used green loctite on the 3 bolts and 12 NM torque .
On the bolt with the spring that give tension to the rear chainguide i torqued to 10 Nm no loctite here.

[Old Rider]

Today i started mounting the cylinder and connect  the pistons wich  is already installed in the bores with the rings on.I reused 4 wristpinclips that only has been mounted on the old pistons and not used i hope that is okay =)
First i was planning to insert the rods and pistons into cylinders and then put on the endcap rodbolts but im not sure if the rodbolts can be installed upside down..so i used another method instead.
I started with piston 3 and 4 and pushed them out so the wristpin gio in and connects with the rod.
There was a little fiddley because the oilring easy popps out if giong to far out with the piston then have
to push it back in again .
On the last pistons this method was even more fiddley , but i think it is easier than pushing the hole barell
over 4 pistons .
The best method will be to use 4 small pistonring compressors .
I hope i did not miss anything when installing the cylinders  i mean i installed 2 dowelpins and the basegasket
and cylinder o-rings  
Im thinking there should be a o ring at right side of the engine at the rear stud ??

[RPM - Robert]

I would throw that base gasket in the garbage. Those paper ones were junk to begin with. The new ones that Yamaha use are metal with a gasket coating on each side. They don't pooch out and leak over time.

Noel, and several others have had this problem with the paper style gaskets
http://www.fjowners.com/index.php?topic=9889.0    
http://www.fjowners.com/index.php?topic=12091.0

[ZOA NOM]

Mods, this is a treasure trove of images. Will they remain on the server over time? I know that there are some older threads that linked images to external sources like photobucket, etc., that have been lost as the user's subscription expired, or they moved to another service, etc. I wonder if the space on the FJowners server is limited?

[Pat Conlon]

Good point Rick. The only pictures we can control are the pictures in our Gallery.
If Rolf would like to save these images in our FJ Gallery I'm sure we could find the room. If we need the room there are dozens of less important or redundant pictures we could delete. (IMHO)

We have had several great threads lose their third party hosted pictures over the years.

[ZOA NOM]

Yeah, threads like this with so much info including pics are so valuable to this aging marque and it's enthusiasts. We might want to explore adding bandwidth if necessary.

[Old Rider]

after reading about the problems with the basegasket im not sure what to do. I have already bought the steelgasket from RPM but it is very thin and i dont trust its sealing performance. I think that the gasketsurface has to be 100% smooth and perfect with absolutely no imperfections .I dont think the surface on my crankcase and cylinder underside is that.
The gasket that was installed when i teardown the engine is of a hard darkbrown almost like plastic material i dont know where i can get that.
Since the metalgasket is so thin i mayby get problems when trying to align the camchaft timingmarks .Is there any type of sealer that can be used with the metalgasket? or with the papergasket?
Is it so that the problem with the papergasket mayby only happens on bikes that have removed the airbox and use a external crankcase ventilation filter  and have unipods creating higher crankcase pressure?

[Paul.1478]

this is from Randy from another liked thread.

"That gasket failed for no other reason than substandard gasket material combined with expansion & contraction of the case & barrel.

This was a problem addressed by Yamaha a long time ago when they went to the current steel coated base gasket.

Crankcase pressure, not in a normal operating FJ, unless the rings are worn out. If crankcase pressure was an issue, Yamaha would have done somethin different.

Randy - RPM"

[RPM - Robert]

after reading about the problems with the basegasket im not sure what to do. I have already bought the steelgasket from RPM but it is very thin and i dont trust its sealing performance. I think that the gasketsurface has to be 100% smooth and perfect with absolutely no imperfections .I dont think the surface on my crankcase and cylinder underside is that.
The gasket that was installed when i teardown the engine is of a hard darkbrown almost like plastic material i dont know where i can get that.
Since the metalgasket is so thin i mayby get problems when trying to align the camchaft timingmarks .Is there any type of sealer that can be used with the metalgasket? or with the papergasket?
Is it so that the problem with the papergasket mayby only happens on bikes that have removed the airbox and use a external crankcase ventilation filter  and have unipods creating higher crankcase pressure?

No No No No No NO NONONONONONO


Thousands, if not tens of thousands, of motors have been built using the metal base gasket. The metal gasket you have IS the current metal gasket that was used on all new motors built from Yamaha. the mating surfaces between the barrels and case is a machined surface if it damaged or not flat then you have a problem there already.

Every single Legends Car, Thunder Roadster, Kenyon midget, and any other race car that used the FJ powerplant, not to mention the countless FJ/XJ/XJR bikes, do not run the airbox. Crankcase pressure is not the problem. Crap gaskets, which Yamaha HAS addressed by using only metal gaskets now, is the problem.

[Old Rider]

I have not come any further in the assembly because i have got confused about the basegasket.
i have 3 different gaskets first i got a old asbestos gasket with partnumber starting at  1TX which i think is the same type that was mounted in the bike
Second i got a paper gasket with partnumber starting on 4CR  which i think is the one yamaha started to make when asbestos was forbidden.
and the third one is the latest metalgasket
The metal gasket is only 0.25mm thick and the asbestos is 0.60mm thick.I'm thinking that if i use the thin metalgasket there will bee some problems. First mayby i cant get the timingmarks right without buying new slotted camsprockets second i might get to high compression with all the trouble that brings overheating detonation and more.
And will the red cylinder orings fall out when using the metalgasket because of the larger diameter .
the cylinder is also decked 0.07mm so that makes the squish even more .mayby the piston will hit the valves?
I'm thinking of using the old asbestos gasket since the one that was installed in bike have not leaked in 30 years
or use the metal but then i mayby will have order one more and use double  to get thicker ?
also the bolt nr21 that snapped have not arrived and had to be ordered from japan....

[ZOA NOM]

I'm not sure why you are fixated on the thickness of the gasket. Put the new metal gasket in that motor and torque it down properly. Do it, and don't give it another thought.

[Pat Conlon]

If you are worried about the possibility of the timing marks not lining up on your cam chain, you can always get the adjustable cam sprockets.
RPM, HSR and Curt Andrews all strongly recommend the metal base gasket.

If you are worried about valve/piston clearances, use modeling clay.

[Old Rider]

It is because off what i wrote in my last post about mayby it will be  problems with setting the timing marks and/ or to much compression and mayby piston hitting valves .
If anyone have used only the metalgasket without any trouble chime out.
If i use the metalgasket i drop the cylinders about 0.40mm. I can use double metalgaskets and get almost the same hight as it was vhen teardown.
And the old production gasket i have with asbestos made before 1994  i think is more solid than the other papergasket without asbestos.

[racerrad8]

Rolf,

Robert has already said which gasket to use and the reasons behind it. The metal gasket is .010" thick compare to the fiber gaskets at .020". So, if you are concerned you can stack them. We use the gasket as a means of building our engines to the highest possible performance with only the gasket I have supplied you.

You have not taken into account another modification that you have done and created even more of an issue in conjunction with the base gasket. The top of the cylinder was machined after the sleeves were installed.
     Did you find out how much they cut off?
     Did you measure the cylinder bank thickness before and after having the machine work done?

You have also been sanding on the head and removing material from that head gasket surface.
     Did you measure the thickness of the head from when you started and after you sanded the surface?

All of these things will "shorten" the engine stack and cause the timing chain to be "longer". If you are worried about the alignment of the timing marks, then slotted cam gears are the resolution.

There are two thing you need to be concerned with when building the engine.
1) Piston to head clearance at TDC
2) Cam timing.

If the pistons are too close to the head then the gaskets will need to be stacked. We do this regularly, especially on the 3rd, 4th and more rebuilds since the sleeves get changed and the barrel gets cut every time.

If you have good piston the head clearance and the cams will not align the marks because of all of the material removed from the barrels and head surfaces, then slotted timing gears are the answer to the issue.

My recommendation, pull the piston rings. Put it together without any base gasket in place. Measure the distance the piston is recessed into the cylinder at TDC. Once you have that measurement, you can determine if you need a single or a stack of gaskets. If it is not recessed (highly unlikely) then the amount it is protruding from the cylinder will determine how many base gaskets will be needed.

Once you have that sorted and the timing marks don't line up, slotted cam gears are the answer.

Do not worry about too much compression. The valves will not hit the top of the piston unless the cam timing is off more that 2-3 teeth. The amount of material you might have removed will likely be less than a half a tooth.

You have been provided a ton of information and what I, a professional builder of these engines,  uses for all of my builds. We have guided you along the way and you have been very thorough, but you seem to be hung up right here. I have read your concerns, but all of them are fairly easy to rectify if they are indeed and issue.

And finally, take those orange o-rings off the bottom of the cylinders and throw them away. They only swell up and break apart and get into the engine. Throw them away.

Randy - RPM