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Can a stock CB 750 bottom end handle an increase i power of 25%

Last set of pics is still wrong. You are not grasping that the spur or planet idlers MUST turn equally on both sides or you have two gear ratios driving at same time. Switching idler planets for spur gears changes nothing, I already know about the bearings, that changes nothing as well. Spurs rotating freely means nothing when they MUST be locked in two gears, THAT is what locks the 1:1 ratio there in place.
 
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Go back to pic A in post #4................I see you have slight center marks for the side axles at the planet facing you in pic end-on. Take those center marks inboard on the planet as if you were creating timing marks to match the two side gears together at that point. You now have a planet with dead center marks on both sides and rotate that planet in your mind by one tooth and see what BOTH marks do, they both move the exact same amount. The SAME AMOUNT.

When you ask the two engines to be in different gears you are telling that planet it must turn only an arbitrary partial amount on one side and different from the other side, it is physically impossible, gear teeth have to break off to do it. You are in two gears at once. Planet ratio is always 1:1, the engine to engine ratio is NOT, unless they are both in the exact same gear.

The problem is that you are trying to apply complete planetary principles but you cut into half of it to render it no longer a planetary. With power into both sides at same time you have done what some ATX do, lock the planets up to hold the assembly for something else to spin around the whole thing. They do it by putting power into both ends of it. Instant lockup. Two gears at once.

I'm getting slower, but I still get there.
 
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I was wrong! "B" will only move WHEN "A" and "C" are different, and it will move the difference between them. "A" = 1,200 RPM, "C" = 1,000 RPM, "B" = 200 RPM. When a load is on "B", and "A" and"C" turn at the same rate, "B" will not move, but the spurs will rotate as "A" and"C" spin. I can make it work by using different sprockets on the two motors so that they never match up. (or, I can go back to bevel gears.)
 
You may likely be better served just ignition killing the engines at shift, simpler than servos on clutch packs.
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Sounds simple. Would the engines start after the shift, or would letting the clutch out drag/start the engines? I was just planning to use the servos to pull and release the clutch cables, and other servos to take the place of my foot on the shift levers.
 
After going through it all again I have just realized the A and C gears must be 1:1 ratio as well. I'm questioning myself again, I do it a lot and how I don't mess things up by building before thinking. I do not have enough pure planetary experience, and it shows even though I have assembled plenty of them. A person has to recognize his own limitations.

It may work, I can find reasons why it will and why it apparently won't. I'd have to put a planetary together to roll and study it to tell for sure. I give up for now and need to let you find your own way. You for sure will still have driveability problems with the two engines fighting each other as one has to drag down while the other takes over in rpm, and I think your seeming to need many more speeds is a mistake as well, you will be shifting all the time, there is simply no need or use for that many trans gears.

Myself, I would be using an 1100 DOHC (OEM HP 110) there in 900 cases to use the 10 speed trans if you still feel you need it and do away with 90% of the unnecessary complication there. One of the best design ideas is to use high tech when you need it and not to when not needed, that lends greatly to reliability and your design is far from that even if it works. A planetary must be 100% lubed, it will not last at all out in the open, you need it fully enclosed to even have a prayer of life from it.

On the ignition cut thing, you have no need to restart at all, you are killing them for so short a period the inertia instantly restarts the engines as soon as you have ignition power again. A simple momentary kill switch does it. What drag racers do on dragbikes so that they do not need to even clutch engines at shifting at all. You'll want that period as short as possible as the freed engine will race up several thousand rpm even in a few milliseconds.

Luck and come back, maybe I can mess you (and me) up some more lol.
 
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After going through it all again I have just realized the A and C gears must be 1:1 ratio as well. .

Are you talking about my first design, or my most recent? he Spur gear design won't work unless there is a difference in inputs. I''m going back to the bevel style. The planetaries must push opposite on each side, or it will not push the center in First/First. The spur gear setup will just stall the center in First/First, and spin, instead of crawling around the hubs rotating the center (The spider will not progress.) I need to order some model bevel gears and experiment.

I do have some logic on the conjoined fours, but not tonight.
 
I think your seeming to need many more speeds is a mistake as well, you will be shifting all the time, there is simply no need or use for that many trans gears.

I COULD use just 1/1, 2/2, 3/3, 4/4, and 5/5. I would still like to have the flat plane V8 sound. 134 HP and matched five speed trannys should be enough, but I think I need the diff as a safety against a mis-shift. A combining cross shaft won't stand a mismatch in gears. With the diff only rotating in a mis-shift, lubing shouldn't be as critical. Let me know how your study comes out.
 
Please forgive me for confusing you even more. I am so full of crap.

The planetary idea in and of itself WILL WORK, I went back and rethought everything I posted that could be wrong and it all is except for the fact that the planets must turn one tooth for one tooth or same side to side but they SLIP one of the gears forward or backwards doing so. I have no idea where my head was at on that one, certainly not where it should have been.

You are wrong about first/first, it would do the same as 2/2 and 3/3. Equal input on the planets locks the center and the whole thing turns as one unit, all 3 sprockets.

I was severely overthinking things and it is only too easy to do. Especially with as much crap floating around in a brain as I have. I considered going back and changing all my posts to reflect corrections but then that would leave yours hanging and not making sense. I need to leave mine in place as it can be helpful (to me anyway) to be shown to be a silly thinker sometimes.

Was lying in bed and it came to my head, I loathe explanation that may be wrong, it drives me crazy. Presently trying to figure out how I got off the beaten path so far, not normal for me at all.

AGAIN, the idea WILL work, the planets simply drop back or go forward in equal amounts on both sides but the action of one or the other outside gears can mask that and what I was not thinking about. Well, I was, but not at the proper time. I was wrong.

FYI, if one used the early 1100 DOHC like I proposed, there is a shifter mod that virtually guarantees no missed shifts at all as long as any shift linkage is solid and reliable. Again, you get a flat plane sound by using a 1-4 and 2-3 paired dual exhaust, BTDT. Pick up a copy of the original Mad Max movie, that's it you hear on most of the bad boy Kawasakis, they used that type of exhaust to make the engines sound wilder and slightly pre-armageddon futuristic
 
Please forgive me for confusing you even more. I am so full of crap.

The planetary idea in and of itself WILL WORK, I went back and rethought everything I posted that could be wrong and it all is except for the fact that the planets must turn one tooth for one tooth or same side to side but they SLIP one of the gears forward or backwards doing so. I have no idea where my head was at on that one, certainly not where it should have been.

You are wrong about first/first, it would do the same as 2/2 and 3/3. Equal input on the planets locks the center and the whole thing turns as one unit, all 3 sprockets.

I was severely overthinking things and it is only too easy to do. Especially with as much crap floating around in a brain as I have. I considered going back and changing all my posts to reflect corrections but then that would leave yours hanging and not making sense. I decided to leave mine in place as it can be helpful (to me anyway) to be shown to be a silly thinker sometimes.

Was lying in bed and it came to me, I loathe explanation that may be wrong, it drives me crazy. Presently trying to figure out how I got off the beaten path so far, not normal for me at all. Funny what can happen with a sudden dose of mental clarity.

AGAIN, the idea WILL work, the planets simply drop back or go forward in equal amounts on both sides but the action of one or the other outside gears can mask that and what I was not thinking about. Well, I was, but not at the proper time. I was wrong.

FYI, if one used the early 1100 DOHC like I proposed, there is a shifter mod that virtually guarantees no missed shifts at all as long as any shift linkage is solid and reliable. Again, you get a flat plane sound by using a 1-4 and 2-3 paired dual exhaust, BTDT. Pick up a copy of the original Mad Max movie, that's it you hear on most of the bad boy Kawasakis, they used that type of exhaust to make the engines sound wilder and dystopian futuristic.

Think I'm where I need to be now and will not be changing (again). Famous last words. Thank you for messing my world up, I need it ever so often.
 
OK, About the 1/1, in post#4, yes, the bevels will lock, and will spin in 1/2 etc.giving a center RPM half way between the left and right input RPMs. (4,000 RPM on the left + 2,800 RPM on the Right = 6,800 RPM /2 = 3,400 RPM on the planet carrier (center sprocket.) Probably don't need 9 gears, but the in between gears (1/2, 2/3, 3/4, 4/5) might be useful as passing gears, and of course, the diff is a mismatch safety that a solid shaft with two in one out doesn't provide

In post #18, holding "B", or putting a load on "B" will simply cause the spur planets to spin as "A" and "C" are fed at an equal RPM, but different RPMs on "A" and"C" will cause "B" to turn at the DIFFERENCE between "A" and "C" (4,000 RPM on "A" - 2,800 RPM on "C" = 1,200 RPM on "B",) but again, inputs must be different. Only five useful gears, but a different spread pattern.

These things I was pretty sure of, but my original question had to do with the added power going through one side. I will address this next.
 
I think I meant "Cross Plain V8". I want the burble
Bang Bang ---- ---- Bang Bang ---- ---- Bang Bang ---- ---- Bang Bang ---- ---- .
Not
Bang ---- Bang ---- Bang ---- Bang ---- Bang ---- Bang ---- Bang ---- Bang ----

The sound I want can be had by phasing the Right engine 45 degrees off from the left engine.
Each Bang Bang pair is a cylinder in the left engine followed 45 degrees later by that cylinder in the right engine, then 90% of no firing, then the next pair
 
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OK, to the engines:
First let's consider a straight eight.
I've put two power take offs on this eight, between CB 750 vs Straight 8 Eight.JPG cylinder 2 and 3, and between cylinder 6 and 7, to simulate the two CB 750s.
The two PTOs pull on dynos with 500 lbs of resistance each. PTO 1 is lower geared, and when both PTOs are engaged, power is split 40%/60% between the two PTOs, but the whole engine feels the 1000 lbs because all the cylinders are connected by one crankshaft.
 
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Now, the two 750s: 2 4s.JPG
First, they are joined by the transfer shaft in front of the engines, and thus act from the top to the crankshafts as a single eight.
A dyno is connected to each output sprocket, one tranny in first, the other in second. The engines feel the thousand lbs across both crankshafts, but the primary chains feel a split of 34%/66%, but because the two engines produce twice what one produces, the strain on the primary chains is 68%/132% of what they are designed for. This is my original question "Can a CB750 lower end and transmission handle an increase in power of (32%) over factory?" That was why I asked about detuning the engines (to 50 HP each) so that under the 34/66 stress, the more stressed primary chain would not exceed design limits.
Ignore the lower image. I can't delete it.
 

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You are going to pay trying to get that 'burble'; the engines and everything else mounted like that will shake more (think Harley, why does everyone admire that???). Closely spaced big hits always do that as compared to more evenly spaced ones. You will be creating more drivetrain misery. With all the engine length you will likely be creating a long rocking couple too. Think of the outboard two cylinders of your eight and when they each hit.

Think you are confusing engine noises in your head as well, the 'sounds like 18000 rpm' thing you mention earlier and a close spaced 45 degree double hit argue with each other, they do NOT sound the same at the opposite ends of the sound spectrum. A spaced 45 sounds like a single cylinder at high rpm , you get no roar like a flat crank.
 
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OK, if I phase them 90 degrees from each other, I would get twice the evenly spaced hits per revolution.THAT will sound like one 750 at 18,000RPM.
Bang ---- Bang ---- Bang ---- Bang ---- Bang ---- Bang ---- Bang ---- Bang ----
I guess the Ferrari sound is just as satisfying. Might have to go four into two into one, on each engine, then those two into one, for that.

https://www.youtube.com/watch?v=FJ8R4tYbX5w
 
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Does the kick starter big gear stay engaged when the motor is running? I'm thinking that might be the place to join the two motors together.Bypasses the Primary chain, and the transfer shaft can stay tucked into the engine package, rather than sticking out in front.
 
The kickstart gear turns the oil pump. It is not a high load gear as it is very narrow and only rides on a bushing. No it could not withstand the force.
 
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