FJ1346 from ashes to... Well, we'll see...

[fintip]

entropy can be heat, but it just means 'energy', in terms that include things like 'complexity'. Adds complexity to the system? Yes. I think he understood what you meant and was taking it and spinning it to fit his point.

Interesting theory, sky! Too bad you didn't just dive into the carbs, though. I'm no where near your competence in engineering, but carbs are like my home base. Just take them apart, clean them, put them back together, turn some screws. It can be done in a day or two from start to finish once you know what you're doing.

Hard for me to imagine the vibration being introduced being that much of a factor... I mean, balancing a crankshaft removes built-in vibration. You think the vibration from one poorly firing cylinder combined with the effects of a lighter crank was enough to outweigh the built in vibration of an off-balance crank? I don't even know how to play with ballparks of what those numbers would be, but it's a little hard for me to believe. Of course, if the frequency was just right, maybe it wasn't the fact that it was *more* vibration, but *different* vibration? And on top of this, how things act spinning up to/more than 100 times per second as far as vibration is concerned is probably one of those things that my intuition will not predict well.

It is a compelling idea, though. Was the #3 cylinder the completely white spark plug?

[Flynt]

entropy can be heat, but it just means 'energy'

Not really...  sorry for this in advance, but this conversation's driving me nuts now.

Entropy is a measure of disorder in many ways, but the actual definition is really simple.  When you have an isentropic process, your energy balance will be zero loss...  everything you put in will come out.  There are no processes that actually accomplish this, so the lost energy is called entropy.  It is not energy any more since you cannot power anything with entropy.

FYI - near isentropic processes are slow, very gradual changes that are fairly reversible...  nothing in an FJ engine is isentropic.  If you complete an energy balance on the engine (draw a box around it, take energy in minus energy out at equilibrium/steady state running conditions), the delta you get will be the loss to entropy...  barring any nuclear reactions taking place that might convert some of that energy to mass of course.

If you insist on entropy being somehow a measure of disorder, consider this...  a perfectly distributed gas cloud (ultimate disorder in many ways) is lower entropy than the universe it developed into with stars, planets, galaxies, etc.  The entropy arrow only goes one way (higher), so this is positively true but completely counter intuitive.

Frank

[JMR]

I agree with Dans' approach and am pretty intimidated about taking on a motor job.  I find it interesting how technology has improved power output on modern engines, and am really curious to see how fuel injection and programmable ignition could boost power in an FJ engine.  For example, could an R1 system work on an FJ motor?  I think I saw Randy mentioned that the XJR FI is not so great though.  Musing and dreaming...all part of the moditis condition I am afflicted with.

Yep, sequential fuel injection would be a significant improvement in power, durability and fuel economy.

Cost is another matter... So you gotta ask....How many FJ'ers would put a $1,200-$1,800 FI system on their $2,000 bike?

I suspect....Not many, and certainly not enough to justify the time and cost of developing and supporting such a system.

I just fitted a complete R6 charging system to my 1975 CB750F....on paper that bike is worth about 300.00 and the mod alone was 600.00. That engine is 1000cc and has at least 6,000.00 in it with labor and parts. And than there is the JMC swingarm, Sun rims, Hyperpro shocks etc etc. And the thousands of hours into it after the multiple engine combinations etc. It depends on how much sentimental value exists and I've owned that bike 37 years.
I do a lot of work with vintage Japanese engines and have seen both philosophies (physical worth vs sentimental worth). I do not deal with the physical worth folks  much as they tend to think I can make old shit new. Christ....I have seen people try to reuse 35 year old guide seals after soaking them in Wintergreen and Xylene. It's true!
The FCR's on my 87 FJ were 1,000.00 worth of equipment right there. Than there's the Hayabusa and RC51.  

[andyb]

FI isn't going to improve the crappy chamber design of an FJ.  When it comes to absolute peak power, there's a reason why the FI is occasionally removed from serious dragbikes and replaced with carbs (Lectrons), nevermind the weight savings to boot.

As for cost, it's all relative.  What the machine is worth to you vs what it'll be worth to someone else.  If you don't ever intend to sell it, and you can afford the mods, go for it!  If you're riding it until your grail bike appears, then you need to consider that as a rule, every dollar you put into mods will be wasted.  It's a little like doing work on your house, you'll get back a percentage of what you spent on upgrades, but it's pretty unusual to get it all back.

[rktmanfj]

I just fitted a complete R6 charging system to my 1975 CB750F....on paper that bike is worth about 300.00 and the mod alone was 600.00. That engine is 1000cc and has at least 6,000.00 in it with labor and parts. And than there is the JMC swingarm, Sun rims, Hyperpro shocks etc etc. And the thousands of hours into it after the multiple engine combinations etc. It depends on how much sentimental value exists and I've owned that bike 37 years.

[squidley63]

I've been following this thread as most others have and I feel really bad about what happened with the build. That being said there were a few questions that I've had about the build of the motor that I didn't see addressed. I see where you had the rotating assembly lightened and balanced but didn't see where they checked the bearing surfaces for size and or out of round. I also missed if the hardware for the bearings had been changed.

I haven't been inside my fj's engine yet but the one thing I've learned building engines for cars is that the engine is only as good as the bolts that hold it together. I always change every bolt that I can to eliminate the issues that come with heat cycled and stressed bolts. I also mic every bearing so that I know what the clearances are going to be and then double check with plastigage just to be sure.

I'm not an engineer though I have gone to college for it and I know that improvements can be made in just about any mass produced engine by applying new technology and meticulous assembly practices. That is the true art of engine building maintaining clearances and clamping forces that minimize frictional losses so more power is available to the wheels.

I would really appreciate it if you could share the autopsy of the engine as well as you did on the build of the motor. After all almost all the technology we enjoy today comes from the failures of yesterday.  I hope that many of the parts from the first build can be salvaged for the next one.

[JMR]

I just fitted a complete R6 charging system to my 1975 CB750F....on paper that bike is worth about 300.00 and the mod alone was 600.00. That engine is 1000cc and has at least 6,000.00 in it with labor and parts. And than there is the JMC swingarm, Sun rims, Hyperpro shocks etc etc. And the thousands of hours into it after the multiple engine combinations etc. It depends on how much sentimental value exists and I've owned that bike 37 years.

I'll see what I can do (or more appropriately what my son can do).

[fj11.5]

Sure would be good to see your bike pics mate, , as for spending money and time on something you like/ , go for it, why not , who cares if someone else dousnt understand, improve the bike/car/wheel barrow till your hearts content, then take it out and get it dirty 

[fintip]

Flynt, i still hold that our definitions are not contradictory, just that yours is more in depth. Your example of the universe is a great one; while we think of this as complexity, it's like the 'game of life'; seemingly complex processes come into existence, but they are just temporary relics that fade. They just sparkle before they do.

Can someone explain the crappy chamber design of the FJ? What am I missing here? I hadn't heard about this until recently, and everyone is acting like it's common knowledge.

And yeah, I'm all about putting money into an old machine. Who buys a $15k or $20k machine and then takes it apart and puts more money into it? Boring anyways. Much rather start with an old machine as my canvas.

[andyb]

Can someone explain the crappy chamber design of the FJ? What am I missing here? I hadn't heard about this until recently, and everyone is acting like it's common knowledge.

If my memory serves, back when the FJ was a top shelf sportbike, they were used by Byron Hines (of V&H fame) as the powerplant for a dragbike.  His heads ended up running as many as three spark plugs per cylinder in an attempt to bring the total timing down to something more realistic.  The inefficent flame travel in the chamber meant that the motor was unable to burn enough fuel/air at the right time to make the power they needed.

Or something along those lines.

[JMR]

Flynt, i still hold that our definitions are not contradictory, just that yours is more in depth. Your example of the universe is a great one; while we think of this as complexity, it's like the 'game of life'; seemingly complex processes come into existence, but they are just temporary relics that fade. They just sparkle before they do.

Can someone explain the crappy chamber design of the FJ? What am I missing here? I hadn't heard about this until recently, and everyone is acting like it's common knowledge.

And yeah, I'm all about putting money into an old machine. Who buys a $15k or $20k machine and then takes it apart and puts more money into it? Boring anyways. Much rather start with an old machine as my canvas.

The large crappy chamber is secondary to the the large valve angle. If Yamaha had reduced the angle they could have made a more compact and efficient chamber. The GS1100/1150 chambers were always better.

  I know guys that have done the same thing with their wives through the liberal use of cosmetic surgery.

[The General]

Flynt, i still hold that our definitions are not contradictory, just that yours is more in depth. Your example of the universe is a great one; while we think of this as complexity, it's like the 'game of life'; seemingly complex processes come into existence, but they are just temporary relics that fade. They just sparkle before they do.

  I know guys that have done the same thing with their wives through the liberal use of cosmetic surgery.

Ummm...so what ya sayin is that Fj`s are organic in the modern day use of the word. Surround them with bulls..t and they are right at home, yet we can shape them to our artistic desire...as long as the genetic pool isn`t tinkered with...Pity that surgery doesn`t include an "on" and "off" button for turning...that`s why God made tha FJ me thinks...

[ribbert]

Other than stabbing in the dark, there is really too little info know what happened here, but I will say I have NEVER seen big end nuts "back off" and I always re-use them.

I would suggest taking the engine to a mechanic that can "read" the remains of the motor and perhaps give a qualified opinion.
Not just a mechanic that knows how everything fits together but one that has experience looking inside failed motors. This will not be as easy as it sounds. Most mechanics these days don't see enough failures to build up a good knowledge and the ones that have no longer work on the bench. A well trained eye should be able to examine the parts and tell you what happened, not speculate.

On the one hand you say all you wanted to do was build a good, reliable motor that would last the next 100,000Km's (Yamaha had already done that) then on the other hand you want to experiment and try out ideas.

If you want a rolling test bed to muck around with coatings, combustion chamber design, crankshafts etc and try out some of your ideas, fine, get one, it's great fun if that's your thing.
If you want a bike that is reliable for the next 100,000Km's, get one.
Trying to roll the two into one won't work.
You need a project bike, or at least an engine, AND a daily rider.

All the technical information you have posted and the end result you were looking for have already been addressed by the engineers when they designed the engine. They in fact did such a good job, along with the oil guys, that the bottom end is probably the LAST thing that will wear out. What's to improve on?
We are not talking about a marine crankshaft here that needs to be physically jacked off the bearings before they can start it so it doesn't rip the bearings out on the first revolution.

Is 300,000Km's and still going strong (Leon's recent acquisition) not enough.?

As I have said, if you want a motor to play with, fine. But don't confuse this with adding reliability and longevity. I saw a one owner 1100 with 200,000 on it recently. Other than using a bit of oil it ran like a Swiss watch, never been touched, never seen anything but cheap oil, but changed regularly without fail.

I always reckoned there are guys with no knowledge who do nothing to their vehicles except enjoy them, then the  guys who know a bit and can chuck in a set of rings and bearings. Then the ones who know a bit more that can modify/hot them up, then the guys who know a lot more, have the skills and experience to modify and hot them up BUT are smart enough not to.

Look in any car/bike workshop staff car park, the modified machine ALWAYS belong to the apprentice!

Any departure from standard will come at some cost. You can improve a modern engine in all sorts of areas but not longevity and reliability. The very act of just disassembling it compromises that.
When Saab 900's came out in the late 70's they were available in both turbo and non turbo versions. After they had been around for some years, it became obvious that the turbo engines were shagged at anything up half the mileage of the non turbo engines.

You increase the power of a motor by 40%, it's reliable and it's a lot of fun, but no way are you ever going to see the sort miles on the clock you'd get from a standard motor. Which is a trade off some are happy to make.

What I've done all my life over a very long list of cars and bikes is, If I want more power, I just go out and buy it (with the exception of one bike). It was insanely powerful but needed a new crankshaft every 1000 miles or less, depending  how I rode it. I hadn't thought of that!
IMO modified engines for road use are a waste of money. I've built plenty, but not for myself. This is just my preference. I know everyone enjoys their bikes for different reasons.

When was the last time you were between 6000-9000rpm at WOT, in any gear, cursing the lack of power from your FJ? When was the last time you were pissed off because it ran out of puff at a mere 150mph?
Sure, more power is always fun, but the FJ has enough to do anything we could sensibly demand of a road bike.
If I wanted more power that badly, I go and buy a Hayabusa and change the ergo's to suit me.

If you had a graph, plotting longevity, power and reliability, the gap between longevity and power would increase exponentially until you got towards the bottom where it spikes as reliability starts to creep in (eg racing engines) and finishes off the page with full blown drag engines, with an engine life of maybe a minute and huge power,

Plenty of people would settle for something around the middle for road use and be happy. Good luck to them. But they are under no delusion that the extra power comes at a price.

The effects of minor changes may be very subtle and may not manifest themselves for very long time, but they're still there.

Noel

[fintip]

While I respect you immensely Noel, I gotta say--you sound like a crotchety old guy.

I've already laid out how we clearly have a different philosophy when it comes to bike preference, which is why I own an ambulance and you own a late model FJ (which to its credit, is impressively able to accommodate both ideals with relatively minor changes when all is said and done).

However, yeah, frankly, there are times where I have wanted even MORE power from my FJ.

I can totally understand that. I don't curse it because it isn't powerful enough, but at least I'm not one of those building a drag bike. THAT'S what I just don't get. 

Well, sort of. I kind of get it.

And as far as 'the pros don't build fancy machines for themselves'/'the modified always belongs to the apprentice', that probably is because they got tired of working on engines all the time and the last thing they want to do is work on their own after decades of doing it. 

Anyways, I support the experimentation, and I disagree with Noel to an extent--I know there is room for experimentation that likely increases performance AND reliability, and I know you (sky) know this as well.

But my people *do* have a saying... 'if it ain't broke, don't fix it'. 

And there's something to be said about that.

[Flynt]

If you had a graph, plotting longevity, power and reliability, the gap between longevity and power would increase exponentially...

Really?  This is such a black and white viewpoint on such a complex issue that I have trouble understanding why you are compelled to assert the viewpoint in the first place.  There is a practical reality that is being overlooked here...

Take apart, blueprint (make all parts exactly as designed), and reassemble almost any production power plant and you will increase power (usually by increasing redline) and longevity (by putting tolerances at design instead of within spec).  You might think all machines are designed to be their ultimate rendition and then cranked out one after another as designed.  The reality is scope, schedule, and budget constrain the time put into design and mass production puts tolerance stack into the mass produced product.  Evidence of the latter is the phenomenon of "infant mortality" in machines...  if their particular tolerance stack produces a substantial enough problem that reliability is severely compromised, it usually shows up when the machine is early in its expected service life.  There is a well know "bathtub curve" that predicts any manufactured product will likely either fail early or, if it survives, fail near design lifetime.  So I'd suggest ALL engines are under-designed to begin with, given relatively large safety margins (engineering factors), then pushed out to the manufacturing process with some expected ppm level failure (scrap).

I also have personal experience modifying many engines from their original design, sometimes making 2-3X the original power, with improved reliability.  For example, a 2000 Audi S4 has a twin turbo 2.7l V6.  The same engine with better turbos, different cams, and other support modifications was fielded in the Europe only RS4.  I had a motor built from my S4 incorporating the RS4 components and many other bits to compliment.  AWHP went from about 175Hp to 400Hp and the car was actually much more reliable (as measured by service costs to keep the car on the street/track).  Another example is the 3 liter engine in my 240z...  It is better balanced, has lower compression, and an FI system that runs circles around the original carbys for keeping the fueling on target.  Impossible to prove it is more reliable, but it would be hard to argue that it is more reliable based on precision of assembly and care/feeding delivered by better cooling/fueling/etc.  It is also about 1.7x original power output.

Modders take heart...  you can have your cake and eat it too.  

And BTW - adding a second spring to the clutch works just fine too.  

Frank

PS - I think the key to making improvements instead of just making changes is the advice of an expert builder.  For my Z engine it is Dave Rebello...  Dave has built hundreds of z engines modified in many ways and has the feedback of seeing them broken (most of his engines are for racers).  This wealth of experience allows him the empirically gained knowledge of what works and what doesn't.  For the FJ engine it is Randy.  The key thing is to listen to the builder, align on common goals, then solicit their advice and follow it as best you can.  The alternative is to painfully build your own experience base by experimenting and breaking things...  which is what happened here.