Topic: project 71 cb750 with 330 wheel convertion

[sangyo soichiro]

Don't think so. Appears to me that the geometry there will have contact on the 'extra' sprocket pretty much all the time.

Can you tell me why you don't think so with a logical explanation?
The little sprocket is attached to the swing arm and pivots with it.
If you draw a straight line between the top of the front sprocket and the top of the rear sprocket,
it is easy to see that the little sprocket will clear that straight line when the suspension is raised
(swing arm rotated down).
This is not rocket science, it is geometry 101.
I'm sure he is getting a kick out of the fact that all of these experts can't see the obvious.
In the engineering field, we call that "Paralysis through analysyis"

I think you should look at this picture closer...


Perhaps when you get to geometry 102 you'll notice something different. 

[Mdub]

I think you should look at this picture closer...


Perhaps when you get to geometry 102 you'll notice something different. 


[/quote]

O.K., nice shot but not very informative. I have looked closely and don't see what it is you are trying to say.
I still see a little sprocket that pivots with the assembly allowing chain clearance.
Where is the problem?
Care to enlighten us all? I am all ears and eyes.

[sangyo soichiro]

O.K., nice shot but not very informative. I have looked closely and don't see what it is you are trying to say.
I still see a little sprocket that pivots with the assembly allowing chain clearance.
Where is the problem?
Care to enlighten us all? I am all ears and eyes.

The pivot of the swing arm is not the same as the pivot of the jackshaft.  That is, they do not share the same axis.  This makes the action of this configuration somewhat complicated.  I won't be able to fully understand it until I get to geometry 103 I think.   

[mlinder]

mdub, dunno how to explain it other than, the chain will always be on the little sprocket, and faras I can tell, will HAVE to be because the swingarm height and design will never allow a chain between front and rear sprockets without hitting the swingarm.
Straight line from top of sprockets goes through the swingarm, and won't matter at what angle it's at. It will still go through the swingarm.

I'll cad a mockup later tonight if I have the time and this hangover goes away. Easier to show with pictures.

[Syscrush]

Very measurable. The amount would depend on the angle of drive sprocket to 'tensioner', but there's math for this, and it's measurable.
I'll let Soichiro do the math for you. It's not just friction.

Is it your claim that there's a difference in power transmission between these two cases?

[mlinder]

Very measurable. The amount would depend on the angle of drive sprocket to 'tensioner', but there's math for this, and it's measurable.
I'll let Soichiro do the math for you. It's not just friction.

Is it your claim that there's a difference in power transmission between these two cases?

Yes.

[Syscrush]

Is it your claim that there's a difference in power transmission between these two cases?
[/quote]

Yes.
[/quote]
Wow.

[Frankenkit]

I think part of our issue is that our expertise is in CBs and their mechanics (in addition to basic physics) so if anyone wants to download a hayabusa manual to get a feel for its swingarm/drivechain structure and get ideas to adapt that to the much narrower 750, there's a link to the 'busa service manual here.

I tried to find an actual picture of one, but it seems 99.9% of the pictures are of stretched ones, unfortunately.

[Terry in Australia]

Hmmm, and here all along I thought this was 631's build thread. 

There you go mickey, and while it looked more of a "character assassination" session to me, with a couple of people here using all sorts of sneaky methods of digging into and exposing someone else's life, it's interesting to turn things around and watch the protagonists attempt to justify their own feats of engineering excellence, motorcycle maintenance skills, or otherwise...........

[Industrial Cafe]

Hi, I was looking for the motorcycle threads, but I came across this Jr. High School locker room instead... Where are the forums for grown ups?

no?

[Frankenkit]

Here's a step-by-step walkthrough of someone's jackshaft-to-OSD conversion.  I guess his jackshaft blew a bearing, but also the dual chain thing was bugging him.

Just putting up more visual fuel because I've never seen anything like this done and it's interesting if it'll work.  For SCIENCE!!!

http://www.hayabusa.org/forum/busa-mods/116798-jackshaft-conversion-osd.html

[333]

Very measurable. The amount would depend on the angle of drive sprocket to 'tensioner', but there's math for this, and it's measurable.
I'll let Soichiro do the math for you. It's not just friction.

Is it your claim that there's a difference in power transmission between these two cases?

Any time you take even the slightest angle of a turn, it will rob considerable power.  And your drawing shows much more angle than is on the device we're talking about.  But even with a milder angle, there is still loss.

[754]

Since the OP aint commenting..

 Terry, You missed a bunch of stuff..
 I Never said the stock fender would fit using its own brace. Mine has a fender.

 No reason you cant run dual disc

 No thick plate ever mentioned on my end, unless 1/4" is thick in your shop....could be made from scraps.

 NEVER seen one made of steel..(are we talking the same part)

 I did supply thread title so pic of it could be seen.

 I did make the one I am talking about, without a mill, used a saw, and sander., and a small lathe. Also, only help I had, was to use was a pic in a mag..

.......................................................................................

 My intention was to provide a DIY project that was thought provoking, confidence building, Simple, did not require a lot of tools.. and that several of us on here could work through TOGETHER.... maybe that is just too difficult for some or they dont have the nads to actually make a part themselves. The object was for the person doing it to have to do some minor measuring (ruler would suffice), intentionally left out so they would gain understanding of the process. I would have been there for support.

................................................................................

 Hope that explains my motive, and the offer I had made to do a bit of teaching.. The lack of pics, is partly intentional, if someone wants to build a piece, they have to show a miniscule piece of ambition, and do a bit themselves..

..................................................................................

Back to this thread, Terry comes on to complain how the newbie is treated, then proceeds to dig at another forum member, in their effort to do something for the forum.... nice..

 Feel free to correct me, if I am seeing this wrong...

[Syscrush]

Any time you take even the slightest angle of a turn, it will rob considerable power.  And your drawing shows much more angle than is on the device we're talking about.  But even with a milder angle, there is still loss.

Where's it going to rob the power? Friction in the flexing chain, friction from having to spin another idler, and what else?

[Caseygroh1]

I agree with mlinder. the chain will always be on the small sprocket. can't see how it wouldn't be, since there is pivoting involved.

[Frankenkit]

here! a 750 with a 330 on the back.Very different swingarm setup but looks very rideable, even though it might be kind interesting in turns...

[the technological J]

here! a 750 with a 330 on the back.Very different swingarm setup but looks very rideable, even though it might be kind interesting in turns...

thats just terrible...i though about a bike with extended forks but a heightened neck to maintain stock geometry but this talked me out of it it looks stupid

[Spanner 1]

Hardtails with  fat tires do not relate to this thread at all...no moving parts except sprockets and chains...!
Oh wait,  IMO....just like EVERY post I've ever made on this Forum...challenged someone about something = yes; stomped-on  = never.

[Frankenkit]

just pointing out that if 631 completely revamped their setup, this build is, essentially, possible.

[Spanner 1]

+1, also look at how SUBSTANTIAL that 'Busa mod is, box-section arm etc...WAY mo' better than OP set-up which we were asked to 'drool' over and agree as a masterpiece, or be abused....

[bradweingartner]

Wow.

I'm looking at the geometry and I'm surprised nobody else noticed.

If I'm looking at it right...the swingarm pivot and jackshaft share a different centerline. If that's the case, the 'arm' that connects the outside of the jackshaft to the mid-arm area on the swingarm would essentially make a swingarm that doesn't move.

Observe my crude MS Cad drawing 

[Terry in Australia]

Since the OP aint commenting..

 Terry, You missed a bunch of stuff..
 I Never said the stock fender would fit using its own brace. Mine has a fender.

 No reason you cant run dual disc

 No thick plate ever mentioned on my end, unless 1/4" is thick in your shop....could be made from scraps.

 NEVER seen one made of steel..(are we talking the same part)

 I did supply thread title so pic of it could be seen.

 I did make the one I am talking about, without a mill, used a saw, and sander., and a small lathe. Also, only help I had, was to use was a pic in a mag..

.......................................................................................

 My intention was to provide a DIY project that was thought provoking, confidence building, Simple, did not require a lot of tools.. and that several of us on here could work through TOGETHER.... maybe that is just too difficult for some or they dont have the nads to actually make a part themselves. The object was for the person doing it to have to do some minor measuring (ruler would suffice), intentionally left out so they would gain understanding of the process. I would have been there for support.

................................................................................

 Hope that explains my motive, and the offer I had made to do a bit of teaching.. The lack of pics, is partly intentional, if someone wants to build a piece, they have to show a miniscule piece of ambition, and do a bit themselves..

..................................................................................

Back to this thread, Terry comes on to complain how the newbie is treated, then proceeds to dig at another forum member, in their effort to do something for the forum.... nice..

 Feel free to correct me, if I am seeing this wrong...

Ha ha, so your "handy dandy, make it in your garage with no tools" fork brace actually requires a lathe to make now Frank? Geez, that's a good idea, spend a grand to make a 50 dollar brace, what a helpfull chap you are! And still no pics of the finished article mate? Why's that again?

"The lack of pics, is partly intentional, if someone wants to build a piece, they have to show a miniscule piece of ambition, and do a bit themselves.." Hmmmnnnn, that makes sense...............   

The reason I fired a shot across your bows mate, is because you jumped on the "Lynch Mob" bandwagon as you are wont to do, and I reminded you of a half-arsed engineering project that you were boasting about, (but of course haven't actually provided any pics of) because I thought that you were being somewhat of a hypocrite. I still do. Cheers, Terry. 

[754]

Well its nice to hear that you think its worth a lot of money to face the ends of 2 pieces of 3/4 bar stock, but I dont charge much for that, Plus(since you forgot) I did mention, I would help folks thru facing it, by hand. Perhaps you simply are not capable of using a square and fitting parts?.. typical 8th gtade metalworking..

 I didnt think 50 bucks INCLUDING machining, was that bad a deal, considering no one even makes a brace for those forks..

 For a pic of this, search "Pennzoil 1/4 Century test", pretty clear pic on there..marked 754 001.jpg  I have mentioned where to see a pic of this before.

 Yeah, I can see now ,why folks stop trying to help out on here...

[ColinMc]

Terry and 754...you guys need to either arm wrestle now, or whip your you know what's out on the table so we can see who's is bigger... Did I just get myself involved in this by busting on both of you?! hehe

On topic: something just isn't "clicking" in my head about this setup i'm very much looking forward to see a couple pics to show the travel of the swingarm and how things change, or a video of it moving up and down.

[sangyo soichiro]

Wow.

I'm looking at the geometry and I'm surprised nobody else noticed.

If I'm looking at it right...the swingarm pivot and jackshaft share a different centerline. If that's the case, the 'arm' that connects the outside of the jackshaft to the mid-arm area on the swingarm would essentially make a swingarm that doesn't move.

Observe my crude MS Cad drawing 

Oh it'll move...
once!

 

In all seriousness though, good point.