Topic: Did anyone see this? -- Honda CB750 16 Valve Twin Cam Head. Piper

[scunny]

The straight line speed being important as well, but getting to your straight line speed faster is going to make a large difference.


David

Formula 1 cars can be tapped out before the end of the straight, braking, corner speed and power on as soon as you can are the key to good lap times.

[kmb69]

But, the question really starts with, at what power level do you start seeing issues with the chain drive causing a failure? 
.....

I think Brent's racer is making nearly 200 rear wheel HP. The HyVo chain used in the DOHC has both power and RPM limitations not to mention issues with the tensioners. This issue is exacerbated because most of the DOHC racers use the 1" wide HyVo on the 900 and 1000 crankshafts. The 1-1/4" wide HyVo crankshafts, the CB1100F, will break at the rod journal next to the HyVo sprocket at high RPM's and high power. This is caused by heat treatment issues of the sprocket and it's proximity to that journal. Pretty sure the DOHC racers were having to change chains and tensioners nearly every outing due to stretch of the chains and tensioner wear.

[Captain]

But, the question really starts with, at what power level do you start seeing issues with the chain drive causing a failure? 
.....

I think Brent's racer is making nearly 200 rear wheel HP. The HyVo chain used in the DOHC has both power and RPM limitations not to mention issues with the tensioners. This issue is exacerbated because most of the DOHC racers use the 1" wide HyVo on the 900 and 1000 crankshafts. The 1-1/4" wide HyVo crankshafts, the CB1100F, will break at the rod journal next to the HyVo sprocket at high RPM's and high power. This is caused by heat treatment issues of the sprocket and it's proximity to that journal. Pretty sure the DOHC racers were having to change chains and tensioners nearly every outing due to stretch of the chains and tensioner wear.

  110% correct on all of it.

 Captain

[MessnerMoto]

To recapitulate because previous post are gone.

On DOHC crank gear is modulus 2.75, pressure angle 20 and profile shift coefficient -0.35
Gl1000 primary drive it is modulus 2.75 pressure angle 17.5 and profile shift coefficient  1.0

There is a difference in pressure angles and thats no good. It will work but not that good. Potentially fail like Brent described

I made idler with 29 teeth.... will need to make primary also for the best result

[Captain]

 I have already made these gears for Keith  (and a further option) so in a way you are running a parallel project.  He also has my Primary hubs that allows this to all work successfully.

Brent

[MessnerMoto]

Hope I am on good direction Brent I will have primary ready next week I hope. Mean while I am researching and thinking where to place holder for idler. It would be great if I could avoid welding, but it seams almost impossible. I was even exploring crazy idea to make custom oil pan with place to bolt idler, of corse it is not possible because of so many reasons... Probably welding a peace of aluminium and then CNCing it to precisely hold idler.

I don't have a problem of sharing with Keith. I will post idler design when I made it.

mirko

[kmb69]

Yep, the primary has to be completely redesigned. How do I know? 
Very similar to Brent's prototype for the DOHC. The stock Honda stuff and similar facsimiles will self destruct quickly!
The primary damper system on the 5 speeds has always been the inevitable weak point if you're making any real power.
But I am mounting a bracket in the cases to hold the idler gear. Should actually strengthen the 5 speed cases considerably.
The 5 speed is considerably simpler than the Automatic I started with. No welding - all bolt in after machining the cases a little.

[MessnerMoto]

Nice Keith I will need to look at that dumper. From what I saw on Honda picture http://forums.sohc4.net/index.php?action=dlattach;topic=168840.0;attach=365443 it looks like standard sohc damper system. But maybe I am wrong I just have that picture. If I just change outer sprocket on damper will it hold "hold" normal abuse and hp not dragracing?

[kmb69]

.....From what I saw on Honda picture http://forums.sohc4.net/index.php?action=dlattach;topic=168840.0;attach=365443 it looks like standard sohc damper system. But maybe I am wrong I just have that picture.....

Mirko, Look at that picture again. All we can see is one side of the outside of course, but it appears to be quite different from the stock damper. Look at the difference in circle diameter of the assembly pins versus stock. Also, no rotational limit stops are visible. I would speculate the inside is quite different from stock, as well as how the gear rides on the hub. The stock sprocket to hub mounting method is much too flimsy to support the gear drive.

.....If I just change outer sprocket on damper will it hold "hold" normal abuse and hp not dragracing?

No.

[MessnerMoto]

Thanks Keith! I already have a solution. I will convert modern damping mechanism from modern bikes... with springs.

[MessnerMoto]

Does anybody knows how this aluminum star is attached to steel shaft of primary drive?

I need to remove that star I will use press. But I am not convinced that it is attached to steel part just by material overlap.

[madmtnmotors]

The inner "star" hub interfaces with the outer hub with twelve rubber dampers:

http://www.cyclexchange.net/Engine%20Parts%20New%20Lower%20End.htm

[madmtnmotors]

Duh-oh! You asked about connection to the shaft, my bad. I thought it was a splined shaft?

[MessnerMoto]

It is not splined where star goes

[kmb69]

Does anybody knows how this aluminum star is attached to steel shaft of primary drive?

I need to remove that star I will use press. But I am not convinced that it is attached to steel part just by material overlap.

Mirko, The "star" is cast onto the inner hub. You will have to machine it off.

[MessnerMoto]

Does anybody knows how this aluminum star is attached to steel shaft of primary drive?

I need to remove that star I will use press. But I am not convinced that it is attached to steel part just by material overlap.

Mirko, The "star" is cast onto the inner hub. You will have to machine it off.

thx Keith.... in the end I am making my own shaft

[kmb69]

.....
thx Keith.... in the end I am making my own shaft

I am making my own shaft also.

[MessnerMoto]

.....
thx Keith.... in the end I am making my own shaft

I am making my own shaft also.

I will make a separate thread for this

[kmb69]

Here is a basic model of mine.
I'm using GoldWing "style" dampers.

[MessnerMoto]

Nice

I see you are using primary tensioner bolt and 6mm hole at the front. But I am not sure what are u are using at the back. Still thinking about it.

I am making everything. Damper will be a modern unit with springs. The problem here is that 41 tooth sprocket is smaller in diameter then in modern bikes. So it is hard to fit all. But I managed somehow. I don't have everything in 3d but I sent this for machining today

[Captain]

Here is a basic model of mine.
I'm using GoldWing dampers.

 Keith, you "MUST" use something larger than 6 mm at the front and rear unless it is anchored to the primary (re: my gear drive conversion)  as under power the load is directed and driving the carrier assembly upwards and it is only the fasteners that are resisting this.  Too small and without enough case support it will fail. Now I have brought your attention to this this, if you look closely at mine you will now understand why the bolt is so far forward and is using the channel directly under the crankshaft. You couldn't have a better support if you tried. This mounting is many times higher in capacity than the loads the engine even if blown could ever deliver to the carrier.

 Captain

[kmb69]

Here is a basic model of mine.
I'm using GoldWing dampers.

 Keith, you "MUST" use something larger than 6 mm at the front and rear unless it is anchored to the primary (re: my gear drive conversion)  as under power the load is directed and driving the carrier assembly upwards and it is only the fasteners that are resisting this.  Too small and without enough case support it will fail. Now I have brought your attention to this this, if you look closely at mine you will now understand why the bolt is so far forward and is using the channel directly under the crankshaft. You couldn't have a better support if you tried. This mounting is many times higher in capacity than the loads the engine even if blown could ever deliver to the carrier.

 Captain

Brent, It has 4) 10mm bolts, one 10mm vertical is in front of the crankshaft, and three through the sides. Two vertical 8mm bolts in the rear. Could easily do two verticals in front of the crankshaft if necessary. I am anchored to the primary on the Automatic but there is no room to anchor to the primary on the 5 speed. We're not making 200HP (yet ) like somebody I know! Pretty sure it's not gonna move.

I should add, my torque moment is 93mm versus 57mm on the DOHC.
Just checked, a Class 12.9 10mm bolt has over 9400 lbs. of clamping load.

Keith

[kmb69]

.....
I see you are using primary tensioner bolt and 6mm hole at the front. But I am not sure what are u are using at the back. Still thinking about it.
.....

That picture is not current. The bolt in front is a 10mm and Brent may have just talked me into putting a second one in there.

.....
I am making everything. Damper will be a modern unit with springs. The problem here is that 41 tooth sprocket is smaller in diameter then in modern bikes. So it is hard to fit all. But I managed somehow. I don't have everything in 3d but I sent this for machining today

That looks pretty good. I considered a similar arrangement with springs but decided to go with Viton dampers on the 5 speed and the Automatic. The CB750A has a similar spring type damper on the primary that I'm converting to a solid gear. I have yet to tear an Automatic down that did not have those damper springs busted all to hell. They're just too small in the Automatic. Maybe yours will be more robust.

[dragracer]

I'm reading all of this with much interest and fully absorbing the majority of whats been discussed. Thanks again to Brent for at least sharing as much proprietary information as he providing us thus far. His R&D has come at a cost so I respect his right to be vague on all he's done to make this arrangement work. As he said, he's not going to spoon feed us in order to protect the integrity of his product and research. I appreciate the collaboration with KMB69.

Looking forward to seeing the outcome of the project Keith is working on. You guys are progressing above my pay grade so I'll stick with bracket racing my slow SOHC.

[MRieck]

.....
I see you are using primary tensioner bolt and 6mm hole at the front. But I am not sure what are u are using at the back. Still thinking about it.
.....

That picture is not current. The bolt in front is a 10mm and Brent may have just talked me into putting a second one in there.

.....
I am making everything. Damper will be a modern unit with springs. The problem here is that 41 tooth sprocket is smaller in diameter then in modern bikes. So it is hard to fit all. But I managed somehow. I don't have everything in 3d but I sent this for machining today

That looks pretty good. I considered a similar arrangement with springs but decided to go with Viton dampers on the 5 speed and the Automatic. The CB750A has a similar spring type damper on the primary that I'm converting to a solid gear. I have yet to tear an Automatic down that did not have those damper springs busted all to hell. They're just too small in the Automatic. Maybe yours will be more robust.

Yes....broken and all sorts of exterior wear on the springs.