Winter teardown of the FJ

[indyblue]

Well, it started as simply to remove the head to check for burnt valves since letting it idle a bit too long one day and it overheated.  It started missing and going "POOF" sometimes and 1 & 3 were not firing.  I checked the valves visually and they seemed fine and I did a check by squirting carb cleaner into the exhaust ports and no leakage at all, so it turns out it may just have been fouled plugs (crankcase was 1.5 qt overfilled with oil somehow).

What other things can happen to the FJ if it's overheated?

Anyhow, while reassembling the head and attaching the cam chain sprockets, I thought I dropped a bolt down the cam chain cavity and no luck hunting with a magnet so I took the jugs off to look closer.  I found the bolt, but removing the jugs let a bunch of sand/grit into the crankcase and that's no good so I will proceed with a complete tear-down, cleaning and rebuild.  Since I will have it apart I might as well address the usual trouble spots like 2nd gear/shift forks, etc.

This is my first motorcycle engine rebuild (have done several V8's) so I have some questions.  The motor has 39K miles on it and it was meticulously kept with oil changes, etc.  There is almost no detectable wear on any component I can see so far.

1)  How do I get the pistons back into the bores, the manual does not describe how?  It seems like it will be difficult to get all 4 lined up correctly (I do it one at a time on a v8),  I have a ring compressor, but does it require all pistons to be compressed at once requiring 4 compressors?

2)  What parts MUST be replaced after cracking the case?  I assume any gaskets like the base gasket/o-rings.  Can I re-use the head gasket, they are rather pricey?

3)  What do I need for the 2nd gear fix?  Do I need all the shift forks or can I just replace the critical 2nd gear one?  I may purchase an undercut 2nd gear or send mine in for cutting if the cost isn't too high.

4)  Any other reasonably priced upgrades I should consider?  I don't abuse the FJ at all other than winding it out now & then and I don't race it.

It has been running very well for the past two seasons I've owned it.  I know Randy will probably chime in to tell me to go ahead an get new starter and cam chains though I really don't have any reason for the expense since there is no evidence of noise, stretch or wear.

[andyb]

Overheating can cause the cylinders to go out of round, in addition to whatever else.

1) Ring compressor is the right answer.  You may find it easiest to put the pistons in the cylinders and then attach them to the rods afterwards.  You can put them in two at a time (actually, if you leave them on the rod, you have to), start on the middle two (#1 at BDC) when putting the block back on.  Some people say it's doable with popcicle sticks or strong fingernails, but I didn't have good luck going that route.

2) Base gasket, head gasket, anything else that you're afraid might leak.  Good ideas?  Cam chain, starter chain, cam chain guides, starter chain guide all come to mind.  Main and rod bearings are usually done also.  There's a couple of orings that you should do also, just because they're very cheap and require splitting the cases.  The other stuff I can think of can be done without splitting cases, like the clutch pushrod seal and such.  Not the time to cheap out really, do it right the first time and you'll trust the bike, y`know?  Valve stem seals are probably another good place to prevent oil consumption later on.  And the standard advice, measure everything while you're in there, check for slightly bent valves, the usual suspects.  Don't put broken parts back in.  Some parts you can get by without replacing (the seal at the oil pickup, for example) that honestly you probably should replace because if they leak, you lose oil pressure.

3) You'll need to send the trans gears out for cutting, I just sent the entire trans out to FBG and had them do it.  I'd suggest doing first gear as well while you're there, probably talking $200 per gear you have done.  Replace the three shift forks with the updated parts, and you will be less likely to have troubles later.  In theory, the second gear problem can happen to any gear, but second is just most likely.  My 4th gear, for example, has more wear on it than it should have, in the same way that second usually does.  Up to you, but do you really want to run into trouble in the next year and having to redo things?  Yick.

4)  Setting the quench down to .040 rather than the stock settings (50 thou or more!) will help give you some power (increased compression, a thinner base gasket and some measuring will tell you what you need, stock is .020 thick for reference).  I'd personally get a valve job done and rering it while I was at it also.  That, coupled with new gaskets and bearings means you've got functionally a new engine, how nice would that be!  Depending on what you consider reasonably priced for upgrades also, but it's the best time to consider overbore pistons, aftermarket cams, etc.  Slotting your stock cam sprockets (or spending $50-100 or so for a slotted set) will help you set the cam timing precisely, and you can gain some control over your powerband that way (note:  I had HUGE gains when I took my cams and put them to stock OE specs, they had moved out of optimal timing for one reason or another).  Instead of trying for massive power gains, just try to get as good of a seal on the combustion chamber as possible (rings, valve job), and getting things to work as well as it can work for what it is.  You can adjust your ignition timing without splitting the cases by just slotting the trigger rotor (very easy job).  If you really wanted, you could sit with a drill press and lighten the shift drum to clean the shifting up like on old WSB bikes which would only cost time. 

Sit down and give yourself a good plan to start, and asking this sort of question is probably the right first step in that direction.  There's a truckload of upgrades available to the FJ obviously, but a limited list that requires pulling the motor and splitting the cases.  My personal way of looking at things is figuring out what it costs to do a specific portion, and then deciding if that's money well spent or not.  For example, I've got a head gasket that has almost no miles on it (less than 20min of runtime on it at low pressures and light use), which is a moderately pricy part (for a gasket, anyhow!).  I can of course reuse it, but my odds of failure increase, and I'm planning on putting quite a lot of stress on it (more compression and hard use).  To replace it requires probably a solid afternoon's work.  But I don't own a truck, so it could theoretically also strand me someplace and put me out for the cost of getting the bike home.  So I'm probably not going to reuse it, and be angry at having to spend the money to replace it.  By comparison, the starter motor I've got is probably on the weak side, but it's very very easy to replace, so I don't see any reason not to save the money now and swap it later if it turns out to be necessary.  If it fails, I'd be stranded, but more likely my rebuilt engine will show it having problems right from day one, after doing some breakin riding locally (within pushing range to get home), I'll try a hot start and see how things go.

My biggest thought as I personally work through my rebuild is a simple one, and it comes down to trust.  I want to absolutely trust my motor when I'm done, and if I take a minor shortcut on something, I'm afraid that I'll forever be second guessing it, and not trusting your bike makes riding a whole lot less fun than it should be.  Take your time, pay attention to the details, and get help when you feel over your head, and you'll muddle through just fine, hopefully ending up with an even better engine than you started out with!  Of course, if you do pick up some power, that's going to mean the clutch will need upgraded, and then different sprockets to give it some legs on the newfound grunt, and then modern rubber to keep that power on the ground, and uprated suspension components to keep the power going to the ground, and then you'll of course need upgraded brakes with all the newfound speed and.....

[indyblue]

Thanks for all the info andyb.

I am not looking for more power or other upgrades, I'd like to keep it fairly stock other than the weak points like shift forks.

Does anyone sell a complete kit of engine gaskets or must I buy by the piece?  I plan to buy genuine Yamaha gaskets (pricey) as my FJ has never had any leaks at all and never smokes, but are there any other vendors I should be checking that folks have had good experiences with?

Also I am having a hell of a time breaking loose the upper rear engine mount allen head bolts (that go through the mid-rear frame).  Any tips to loosen and remove?

[racerrad8]

I can tell you the "gasket kits" are not OEM quality, plus they include a bunch of parts you will not need and/or use. I have only bought one since I started all of this 16 years ago, and that one was too expensive and the quality was lacking.

I have all of the gaskets you need excluding the head gasket. It is going to be much cheaper for you to buy them individually.

I have all of the external seals as as well and they are Yamaha parts.

I have the updated shift forks, upgraded valve stem seals, oil pump screen, bearings and the list goes on & on.

If you don't want to replace things like the timing or starter chain that is your call. You might change your mind when you see the start chain guide...

I will be able to supply all of the parts you require, with the exclusion of the 1100 head gasket, unless you are okay using an aftermarket Cometic gasket, which I can supply as well.

I am putting the undercut transmissions into the inventory today as I have them in stock now as well. I also had them undercut the other two cogs & gears on that shaft as well, not just 2nd gear.

And finally, I install the pistons like Andy mentioned, with a plastic tool I made to depress the rings, I do the inner two first, then the outer two. I have not had any luck trying to install the wrist pin & circlip after the pistons are in the cylinders, I always managed to pop out the pistons and/or drop the circlip into the motor. You will need two ring compressors if you decide to use them.

You really do not need to check any further, but there are others out there you can buy parts from, but will you get any support when you need it...that is the question you will have to ask.

I am here providing parts & service to people all over the world. I do not work on any other make or model of bike/engine, so I have a vast amount of experience to assist you when you need it on the bike you own and are working on.

Randy - RPM