Author Topic: Geared Primary Drive  (Read 2274 times)

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Offline slikwilli420

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Re: Geared Primary Drive
« Reply #50 on: June 17, 2018, 04:57:27 am »
.....
I can only hope this conversion works out and is  made available to forum members at an affordable price.  Thanks again

.....
+1

What do you guys consider affordable?

Hard to say. One of those things that I'll only know once I hear a price. I know engineering is expensive work but it will be hard to justify passing all that cost onto the end user despite the number of kits made. I'd say the cost of the parts to manufacture plus a reasonable profit. Sell a lot more that way than trying to recoup engineering costs too quickly.
« Last Edit: June 18, 2018, 07:43:46 am by slikwilli420 »
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Offline dragracer

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Re: Geared Primary Drive
« Reply #51 on: June 17, 2018, 08:20:15 am »
.....
I can only hope this conversion works out and is  made available to forum members at an affordable price.  Thanks again

.....
+1

What do you guys consider affordable?


For me to justify the expense of the overall conversion, it have to be less than the cost to get a stock Sohc crank stroked. When I say overall conversion, I mean the dohc crank/ machining, the gear modification kit, and the cam chain modifications. My only goal is to achieve more horsepower to lower my Et's. A longer stroke crank is the quickest way to meet that goal with my current engine package without installing a power adder. On the other hand, the cheapest bang for the buck to go quicker is nitrous oxide.

Offline kmb69

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Re: Geared Primary Drive
« Reply #52 on: June 17, 2018, 09:57:44 am »
.....
What do you guys consider affordable?


For me to justify the expense of the overall conversion, it have to be less than the cost to get a stock Sohc crank stroked. When I say overall conversion, I mean the dohc crank/ machining, the gear modification kit, and the cam chain modifications. My only goal is to achieve more horsepower to lower my Et's. A longer stroke crank is the quickest way to meet that goal with my current engine package without installing a power adder. On the other hand, the cheapest bang for the buck to go quicker is nitrous oxide.

You've got to be kidding me! Sounds like to me, you need to get to dumping on the nitrous and/or stroking a stock crank if you're wanting a stroker. And it ain't got jack to do with collaboration!

I can't speak for Mirko, but I can tell you without a doubt at least in my case - fitting a DOHC 900 crank, the raw cost - NO profit - NO engineering recovery, to machine the idler and primary gear assembly, machine the bracket assembly, machine the crankcases, the bearings, the cam chain tensioner and guide, the cam chain, modified cam chain sprocket, the crankshaft, the material for the custom billet parts, and ancillary fittings, will exceed the price of a stroked stock crank several times. We're talking about some fair serious precision machining of components and cases to mesh those gears properly.

Even with Mirko's SOHC A crank solution, you will have to buy his kit for the stock automatic crank, probably have to have the cases machined, and then have it stroked to end up with a gear drive stroker. So it already cost more than a stroked stock crank.

Not to mention you WILL BREAK SOME MOTORS with a stroked stock crank if you are making any kind of serious power. What is the cost of that?


Offline Jerry Rxman Griffin aka MuthaF'er

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Re: Geared Primary Drive
« Reply #53 on: June 17, 2018, 10:22:50 am »
What the hell did he just say?!  :o  ;) Them sum big wurds Leroy  :)

Come on Spanky! It's just a prescription without the squiggly signature!

LMAO  ;D
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Offline dragracer

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Re: Geared Primary Drive
« Reply #54 on: June 17, 2018, 10:38:17 am »
.....
What do you guys consider affordable?


For me to justify the expense of the overall conversion, it have to be less than the cost to get a stock Sohc crank stroked. When I say overall conversion, I mean the dohc crank/ machining, the gear modification kit, and the cam chain modifications. My only goal is to achieve more horsepower to lower my Et's. A longer stroke crank is the quickest way to meet that goal with my current engine package without installing a power adder. On the other hand, the cheapest bang for the buck to go quicker is nitrous oxide.

You've got to be kidding me! Sounds like to me, you need to get to dumping on the nitrous and/or stroking a stock crank if you're wanting a stroker. And it ain't got jack to do with collaboration!

I can't speak for Mirko, but I can tell you without a doubt at least in my case - fitting a DOHC 900 crank, the raw cost - NO profit - NO engineering recovery, to machine the idler and primary gear assembly, machine the bracket assembly, machine the crankcases, the bearings, the cam chain tensioner and guide, the cam chain, modified cam chain sprocket, the crankshaft, the material for the custom billet parts, and ancillary fittings, will exceed the price of a stroked stock crank several times. We're talking about some fair serious precision machining of components and cases to mesh those gears properly.

Even with Mirko's SOHC A crank solution, you will have to buy his kit for the stock automatic crank, probably have to have the cases machined, and then have it stroked to end up with a gear drive stroker. So it already cost more than a stroked stock crank.

Not to mention you WILL BREAK SOME MOTORS with a stroked stock crank if you are making any kind of serious power. What is the cost of that?



Well now, you did a great job of letting us know the cost. Of course I had a good idea that conversion would probably far exceed anything "I" would consider affordable for "my" personal SOHC build. I understand the concept of R&D, machining of parts etc..  Keep in mind, i'm not tunnel visioned into thinking an SOHC dragbike will ever be competitive in anything but a record setting type class such as super eliminator. Given my prospective from drag racing my SOHC for over 20 years, but also owning and building and racing other much faster bikes, its simply not practical to invest tons of $$ into my SOHC bracket bike. Its a budget build to say the least. On the other hand, endurance racers, road racers and side car racers that have experienced chain failure likely feel the cost is very reasonable. I might feel the same way if I competed in any of those venues. I will however consider myself lucky that after 20 plus years of hard launches and 10 second passes, I have yet to experience a chain failure.

Please don't confuse anything I've said as bashing the concept of the geared primary drive. Its quite to the contrary- I applaud  and fully support the efforts being made to correct a flaw in an otherwise solid platform and to bring about the means by which a DOHC crank can be installed into an SOHC engine via a "kit". My only comments were directed at cost.

Remember, you ask what "we" thought was affordable, not what we thought it costs to engineer and produce the gear set. You guys have done an outstanding job thus far in making something happen. No talk, all action.

Once again, i'm appreciative of the efforts. I'm pretty sure I should just "stay in my lane" from now on.

Offline calj737

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Re: Geared Primary Drive
« Reply #55 on: June 17, 2018, 11:35:46 am »
I will however consider myself lucky that after 20 plus years of hard launches and 10 second passes, I have yet to experience a chain failure.
Dear Lord, I hope you didn't just jinx yourself there!  :( :'( :-X
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Offline kmb69

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Re: Geared Primary Drive
« Reply #56 on: June 17, 2018, 11:37:26 am »
.....
Remember, you ask what "we" thought was affordable, not what we thought it costs to engineer and produce the gear set. You guys have done an outstanding job thus far in making something happen. No talk, all action.
.....

I get it. Just kinda blown away that such a kit would be valued less than a stroked crank to anybody! If its not affordable to you, so be it. Different strokes for different folks!

.....
..... I'm pretty sure I should just "stay in my lane" from now on.

Not necessary - no offense taken.

Offline 754

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Re: Geared Primary Drive
« Reply #57 on: June 17, 2018, 11:50:55 am »
I am sorta thinking..
Racing a monster motor and changing the Hyvo every race.
 I am thinking 5 to 8 or ten races.  3 hours minimum  to change it out. Adds up fast looks like 1500 to 3000 a season just to keep chains in it......ouch...
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Offline calj737

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Re: Geared Primary Drive
« Reply #58 on: June 17, 2018, 11:59:02 am »
Probably the disconnect on "cost" is comparing what we regularly can find used, or refurbish (fairly inexpensive for most models and widely available) to something brand new, modern, and re-engineered. It is hard to emotionally swallow putting a $400 hub (Cognito) on a wheel, or a $300 oil sump on a bike that many have built for less than $1,000. Not too many will race (straight or road) for less than $7-$10k of engine work, but as these are passions and hobbies, and most can't make a living doing it, cost does matter.

I see the cost of this as well worth whatever it takes because I completely understand the effort and intricacy of it. Fortunately, I have no 750 so I won't have to pluck a wad of Bennies from under the pillow for this one... but I certainly would if I were racing a 750 on a road track. Anything to extend the reliability is well-worth the cost because the price to play, is very high. And its a no money back if you break.  :-\

These types of projects (and others like Mike's billet block, Big Jay's cranks and rods, etc) fascinate me on this site. It's very interesting to see individuals re-vamp these bikes to extract more and more from them. They will never perform as a new bike will, but a new bike will never have the character or soul of these vintage machines. So I embrace these things wholeheartedly.

But that's one dolt's opinion-
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Offline gschuld

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Re: Geared Primary Drive
« Reply #59 on: June 17, 2018, 12:10:41 pm »
Frankie,

Your thoughts likely mirror the vast majority of sohc4 guys.  But for those building something truly exceptional and at the limits power wise for these “modest” cb750 engines, I can see the interest.

I am extremely impressed with all the work that has gone into this project by a number of people.  High end over my head stuff😁

George
« Last Edit: June 17, 2018, 02:04:16 pm by gschuld »

Offline Ilja

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Re: Geared Primary Drive
« Reply #60 on: June 17, 2018, 02:52:14 pm »
Wow great work!

Well, if you make this happen then bottleneck RPM limiter (the chain) will be gone, and you can safely setup your engine to spin something like 11.000-12.000 rpm with the right light weight pistons, compression ratio, camshaft combination and a lightened crank.

Since power is torque X angular speed (RPM).... it means more power.  ;)

Mainly interesting for guys that enjoy racing these old bikes offcourse.  8)

Offline gschuld

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Re: Geared Primary Drive
« Reply #61 on: June 17, 2018, 03:39:39 pm »
Higher rpm limits will really make Mike busy with building more top shelf flowing heads to handle the extra rpm capacity. ;)

That should be a welcome change at this point from dealing with all those dinosaur RC engines😁

George

Offline bear

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Re: Geared Primary Drive
« Reply #62 on: June 18, 2018, 02:18:20 am »
We used to weld our stroker cranks before we started using the DOHC units about 15 years ago.
We broke a lot of motors using welded cranks.
Our limiting factor was how much mixture we could get through the SOHC ports.
In the end we settled on as much cylinder pressure as we could achieve and limiting our RPM to 10'000.
I have not broken a Hi-Vo chain ( cam or primary), or crank in ten years.

In my opinion and experience using a welded crank will only end in tears. ;)
« Last Edit: June 18, 2018, 02:23:16 am by bear »
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Offline gschuld

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Re: Geared Primary Drive
« Reply #63 on: June 18, 2018, 04:32:15 am »
Bear,

Did you come to the conclusion that the welded stroker cranks were simply not up to the task or the Sohc chain primary/cam chain systems were the issue at your power/rpm levels?

I’m curious if you feel a new high quality welded stroker crank is capable of less than giant power levels.  Say... 110 RWHP or so at a pump gas compression ratio with a 9500 or so limit with a more modest duration but high lift cam (125-75/CX7).  Just a ...random...thought ::)

George

Offline bear

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Re: Geared Primary Drive
« Reply #64 on: June 18, 2018, 01:13:49 pm »
Bear,

Did you come to the conclusion that the welded stroker cranks were simply not up to the task or the Sohc chain primary/cam chain systems were the issue at your power/rpm levels?

The cranks would fail George, plane and simple. I'm not saying chains where not an issue. They where, but the issue was longevity not failure.  We just had to change them out more often than we would have liked.


I’m curious if you feel a new high quality welded stroker crank is capable of less than giant power levels.  Say... 110 RWHP or so at a pump gas compression ratio with a 9500 or so limit with a more modest duration but high lift cam (125-75/CX7).  Just a ...random...thought ::)

I'm sorry George, I don't believe you can use the term "high quality" and "welded stroker crank" in the same sentence.
It comes down to one simple factor, these crank's do not lend themselves to welding.

A simple test for you, if you have the opportunity.
Pick up a welded crank by the tapered end and give it a light rap on the bottom weight with a small ballpeen hammer. The sound you get will be a "DONK".
Do the same with a std or DOHC crank (without cracks) and you will get a nice clear bell type "RING".

Anyway back to the thread...........I can't help but be impressed with this geared drive. I would love to have had the opportunity to get my hands on this type of quality engineering ten years ago.

Cheers,
Brian
« Last Edit: June 18, 2018, 03:46:48 pm by bear »
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Offline MessnerMoto

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Re: Geared Primary Drive
« Reply #65 on: June 19, 2018, 04:35:02 am »
I have a wild idea how to attach idler gear to lower case. It will not demand machining of lower case. Thats should lower the cost a lot....

I need to do FEA(finite element analysis) of lower case and everything attached. Thats why I 3d scanned the lower case... I will now exactly how much power/force "idler assembly" can handle...

but maybe it is jut stupid idea... I need to check first

Offline slikwilli420

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Re: Geared Primary Drive
« Reply #66 on: June 19, 2018, 06:23:29 am »
Looking forward to it Mirko! Ill step up to be a test subject. My motor is dialed in and running strong. I plan on next year being an even bigger one with more races on my schedule. If we can work something out let me know.
All you gotta do is do what you gotta do.

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Offline kmb69

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Re: Geared Primary Drive
« Reply #67 on: June 19, 2018, 07:08:26 am »
I have a wild idea how to attach idler gear to lower case. It will not demand machining of lower case. Thats should lower the cost a lot....

I need to do FEA(finite element analysis) of lower case and everything attached. Thats why I 3d scanned the lower case... I will now exactly how much power/force "idler assembly" can handle...

but maybe it is jut stupid idea... I need to check first

Mirko, that would be brilliant if you can make that work!
The case machining is definitely a big cost factor in how I'm mounting my bracket.
Honda actually had custom cases cast to gear drive their RCB1000.


Offline Cb750 Racer

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Re: Geared Primary Drive
« Reply #68 on: June 19, 2018, 04:23:55 pm »
Respect to you man. Can't wait to see the final product!

I have a wild idea how to attach idler gear to lower case. It will not demand machining of lower case. Thats should lower the cost a lot....

I need to do FEA(finite element analysis) of lower case and everything attached. Thats why I 3d scanned the lower case... I will now exactly how much power/force "idler assembly" can handle...

but maybe it is jut stupid idea... I need to check first
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Offline Captain

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Re: Geared Primary Drive
« Reply #69 on: June 19, 2018, 11:20:57 pm »
 FEA is they way to go and knowing what the actual lids are is imperative.
 However make sure you understand clearly the “directions” are they are being applied.
 Everybody assumes at first glance that the load is downward on the idler when under power....it’s actually the reverse and upward. Off throttle and deaccelleration is the only time it is downward..

This a major bearing on how it is carried in the cases.

Captain

Offline MessnerMoto

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Re: Geared Primary Drive
« Reply #70 on: June 20, 2018, 03:28:14 am »
FEA is they way to go and knowing what the actual lids are is imperative.
 However make sure you understand clearly the “directions” are they are being applied.
 Everybody assumes at first glance that the load is downward on the idler when under power....it’s actually the reverse and upward. Off throttle and deaccelleration is the only time it is downward..

This a major bearing on how it is carried in the cases.

Captain

Thanks for that info Brent.

... do you have idea how much is that force in down direction, approximately in Newtons? 

Offline MessnerMoto

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Re: Geared Primary Drive
« Reply #71 on: September 17, 2018, 04:32:44 am »
... I had some time to elaborate on my idea....

it goes something like this...

Three locating pins for oil pump, mounting surface of oil pump, are precisely machined compared to crankshaft position. Surface for oil pan cover is same as mounting surface for oil pump... This surface and locating pins were precisely machined because oil pump has a gear etc.....

Oil pan is bolted with 10 m6 bolts. Those bolts combined can handle 14000N of force. 10.9 M6 bolts

I calculated using some simple equations for spur gears that maximum upward force on idler gear is around 5150N if engine is making 100Nm at crankshaft. All FEA simulations I've done with safety margin... at 6250N of upward force. So you are locking at maximum displacement of parts when subjected to 6250N of upward force. Displacement is magnified several hundred times in some pictures so it can be visible. When force is in downward direction deflection magnitude is the same....

There is a lot of material around the oil pan mounting surface on lower engine case and it is really nicely spread around... I haven't run FEA on lower case but I really think it can support several times more force.

The smart part is how to locate my oil pan in correlation to crankshaft position... Actually thats easy because like I said three locating pins for oil pump, oil pump surface are precisely machined in compared to crankshaft position....

 So there will be a simple helping tool(precisely machined)... Simple plate with three holes for oil pump 15mm locating pins and three holes for 8mm dowel pins and several holes for m6 bolts. The goal is to drill three holes in lower case for three 8mm locating pins. The pins are the same like in cb750 head.... three 8mm holes on tool are guides to were to drill 8mm hole on lower case. Three holes are located where existing m6 holes are in lower case so it is just to expend them to a depth of 6mm. One would need 8mm H7 drill, I can provide. Rest of threads in this three holes will be undamaged and used to bolt pan... You can see the tool in last picture

Oil pan is modeled in the way that it is 2D job for CNC(cheap). Oil pan is AL 6082 T6...

Idler sprocket holder is made from 4320 steel. There is no space because of crankshaft etc... for aluminum version

Oil pan and sprocket holder are connected with four m10 bolts... and two locating pins. I will add also adjusting layer of thin measuring steel between pan and sprocket holder.... so one can adjust height of idler... just in case....

Oil pan will have a slot for 1.5mm rubber ring on upper edge to seal with crankcase.... Also oil pan should not interfere with exhaust

this is not final and suggestions are welcomed ;) ..... and maybe I am wrong and this is not possible :)
« Last Edit: September 17, 2018, 04:55:26 am by MessnerMoto »

Offline jus4selling

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Re: Geared Primary Drive
« Reply #72 on: September 17, 2018, 10:42:38 pm »
Wildly impressive, bravo.

 

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