Cb200 "Hephaestus"

But in all honesty I do believe that I have the suspension figure out the way I want it, when it is all set up I will show you, how it works. I promise I am not trying to be curt, and you could be right, but that doesn't mean that I'm not going to try it my way first haha
 
Since the rear sprocket is below the center line of travel you'll need to run a huge sprocket in the rear to make the tension side of the chain not grind against the pivot point. Even if the swing arm is level when you load the suspension, Having the ability to travel all the way own there on full decompression may be dangerous.

A few others on the forum have had some issues with longer shocks out back. These bikes don't have much mechanical travel.

In this photo is a 17/45 sprocket. When fully unloaded, the chain barely touches the swing arms pivot.
 

Attachments

  • 2013-08-04_19-36-36_300.jpg
    2013-08-04_19-36-36_300.jpg
    1.5 MB · Views: 252
Maxd22 said:
But in all honesty I do believe that I have the suspension figure out the way I want it..........

Mind sharing with the rest of us how you calculated that out? What rake and trail does it now have? How much swingarm droop, What size sprockets will you use to avoid it cutting through the swingarm?

Just from the small pictures posted, I'd guess that swingarm droop is about 10 degrees more than you want and they barely make sprockets large enough to clear. You may want to double check that before you go any further.

ACM - I still love that little bike. It's gorgeous.
 
Sorry I was being headstrong gents, young blindness sometimes overshadows good advice. So I was thinking something like a chain tensioner used on chops, Ive seen it on a couple builds.
 

Attachments

  • Yamaha-XJ-600-by-Pimmel-Messer-part.jpg
    Yamaha-XJ-600-by-Pimmel-Messer-part.jpg
    76.4 KB · Views: 508
The shock stiffness has been something that my father and I have looked at, and are considering ordering something less stiff.
 
Maxd22 said:
Sorry I was being headstrong gents, young blindness sometimes overshadows good advice. So I was thinking something like a chain tensioner used on chops, Ive seen it on a couple builds.

you are overlooking the fact that the poor girl you put on that bike will be lucky if she isn't killed outright from the speed wobble enduced crash
you clearly have no idea what you are doing,but what you are, is actually endangering someone elses life if you put them on that ill concieved contraption
 
I really do thank you for what you have to say, you've given me a lot to think about, and in regards to your comment about me not knowing what to do; I'm on this forum to learn how, for people to help if i make mistakes, so yes I don't know exactly what I'm doing, but I'm trying. That's why I love this forum. It enables people to aspire, and to try to build new things, even if they don't know what they are doing 100 percent. If I have to re-design the whole suspension, then hell that's part of the build, and inevitably the process. I would rather not, and try to find a way to make it work with the lines I have, but I'm not ignorant enough to put someone on a dangerous machine when I've been told by educated people that it wont work. So thank you, all of you for the help, and lets fix this mistake.
 
xb33bsa said:
you are overlooking the fact that the poor girl you put on that bike will be lucky if she isn't killed outright from the speed wobble enduced crash
you clearly have no idea what you are doing,but what you are, is actually endangering someone elses life if you put them on that ill concieved contraption

Let's apply a little logic. Is that monoshock setup flawed? I certainly would change it. Does it show perhaps a bit of a knowledge gap? Sure you could say that. But since when is that a bad thing? I would rather see someone try and fail 20 different designs before finding the right one, and perhaps learn a thing or two, than never take on the project in the first place.

So being this would be what I would call a fluid representation of what he wants as a final product, and no one is going out and riding it tomorrow, saying someones life is in danger/the bike being ill conceived is a bit strong wouldn't you say?

Maybe filling this gap in knowledge, and providing for him what to be mindful of and why would greatly benefit his project.
 
You are not so far along that you can't re-group a little and get on a sound base line. The work you are doing does not require extensive engineering expertise in single track vehicle dynamics as long as you keep the geometry you started with which you know is good. You will be well served to realize that seemingly small geometry changes can have large and potentially very dangerous consequences. You can stay out of trouble simply by not making any changes to the chassis geometry the manufacturer spent so much expertise figuring out. Take off your shock, and get the swingarm and frame positioned back like it would have been before your modifications. Figure out what the suspension travel was, and then make whatever modifications are required to fit the shock you want while keeping the original geometry. That way you will end up with a bike that at least drives as well and as safely as the original. Even with the original geometry retained, you will have substantial changes with the monoshock. For example, your swingarm now triangulated is substantially more rigid than before, so loads transmitted to its pivot are much greater. Loads previously transmitted more or less vertically supporting the back of the bike and rider are now comprehensively different and severely loading parts of the chassis previously loaded entirely differently. Think about it. Even if the geometry is completely unaltered, the substantially changed loads while driving might be very noticeable. Figuring out how to deal with all of that is complicated enough without adding all the complexity of all new geometry.

Do not underestimate the consequences of small changes to the original geometry. Manufacturers know very well what they are doing. Racers are willing to go to most any lengths to improve on what the factory does, and while you see all manner of efforts to strengthen or stiffen what the factory built for street use, geometry changes are usually very tiny, and racers are willing to accept the trade-offs, or find ways to compensate for them. For example, racers commonly accept sacrificing straight line high speed stability for quicker turn in accomplished by slightly lowering the front/raising the rear, but get the straight line stability back by improving chassis stiffness and even just riding around the problem. Not a good idea at all for most normal street riders.

You are doing some very nice work. It would be a shame to end up with a bike that doesn't drive well. I think maybe a little re-think and some adjustments to what you have so far will get you headed in a better direction.
 
jpmobius said:
You are not so far along that you can't re-group a little and get on a sound base line. The work you are doing does not require extensive engineering expertise in single track vehicle dynamics as long as you keep the geometry you started with which you know is good. You will be well served to realize that seemingly small geometry changes can have large and potentially very dangerous consequences. You can stay out of trouble simply by not making any changes to the chassis geometry the manufacturer spent so much expertise figuring out. Take off your shock, and get the swingarm and frame positioned back like it would have been before your modifications. Figure out what the suspension travel was, and then make whatever modifications are required to fit the shock you want while keeping the original geometry. That way you will end up with a bike that at least drives as well and as safely as the original. Even with the original geometry retained, you will have substantial changes with the monoshock. For example, your swingarm now triangulated is substantially more rigid than before, so loads transmitted to its pivot are much greater. Loads previously transmitted more or less vertically supporting the back of the bike and rider are now comprehensively different and severely loading parts of the chassis previously loaded entirely differently. Think about it. Even if the geometry is completely unaltered, the substantially changed loads while driving might be very noticeable. Figuring out how to deal with all of that is complicated enough without adding all the complexity of all new geometry.

Do not underestimate the consequences of small changes to the original geometry. Manufacturers know very well what they are doing. Racers are willing to go to most any lengths to improve on what the factory does, and while you see all manner of efforts to strengthen or stiffen what the factory built for street use, geometry changes are usually very tiny, and racers are willing to accept the trade-offs, or find ways to compensate for them. For example, racers commonly accept sacrificing straight line high speed stability for quicker turn in accomplished by slightly lowering the front/raising the rear, but get the straight line stability back by improving chassis stiffness and even just riding around the problem. Not a good idea at all for most normal street riders.

You are doing some very nice work. It would be a shame to end up with a bike that doesn't drive well. I think maybe a little re-think and some adjustments to what you have so far will get you headed in a better direction.

So, would it be possible for me to get a shorter shock, power the front end an inch and get a larger tire in the back?
 

Attachments

  • BIKE (3 of 4).jpg
    2.6 MB · Views: 276
  • BIKE (4 of 4).jpg
    2.4 MB · Views: 260
I have a 2x4 under the wheel right now to get an idea of where I need the wheel to sit for chain clearance. Pic after lunch.
 
put 2 good shocks back on the bike in the stock configuration,with the same as stock ride height in the back
you are so lost you dont even seem to grasp what the real issues are with what you are doing chain clearance is a secondary issue ,you are totally fucking up the handling
the fact is putting a single shock on a 200 honda twin,just for the sake of a look(you are not improving it with a single shock) is just plain dumb and it is stupid when you don't know what you are doing
 
xb33bsa said:
put 2 good shocks back on the bike in the stock configuration,with the same as stock ride height in the back
you are so lost you dont even seem to grasp what the real issues are with what you are doing chain clearance is a secondary issue ,you are totally fucking up the handling
the fact is putting a single shock on a 200 honda twin,just for the sake of a look(you are not improving it with a single shock) is just plain dumb and it is stupid when you don't know what you are doing

If everyone had your mentality then we would all ride stock Japanese bikes and nothing else, no cafe bikes, no choppers, no trackers. I have been very understanding, and I refuse to humor you with any aggressive comments, I may be 18 and naive but I also understand when I don't need to waste my time with someone like you.
 
I think you might be able to get away with a smaller shock, if you can find the right one. I would also consider adding a bit more bracing from the upper hoop to the swingarm. But i think thats out of scope at the moment.

I would put the engine back in the bike so that you can measure the stroke of the rear sprocket in relation to chain alignment. Measure the shock mount at the max upper and lower bound. That should give you a good estimate on what size shock you could put in there.

Then you'll just have to find one.


@teazer Thanks! It should be a good season this year-- My fiance and I purchased the house that has my garage attached. It was in the family. Its a much shorter commute to work on my toys.
 
Maxd22 said:
So guys, I have a dilemma, the mono-shock is anodized, and I need it all black, sand blast and powder coat?
Also going to black out my motor, same process?

You can not powder coat the shock. It will add too much material on critical areas like threads. Not possible. If you have to change the color, the only way is to anodize it. Simple as that. Not that big of a deal. Its done by many, every day. We do it all the time on our suspension components.





I even like to take stock, cast parts, like calipers for instance, and anodize them. We sand blasted these prior to anodize for a totally different, dull sheen and texture, as opposed to anodizing a machined part, like your shock body.



As for the motor, most people paint them. As do we sometimes. But if you are gonna split the cases, and you want to go with something other than the cast aluminum look, yes, powder coat is a great choice. Its what we do 75% of the time that we split em.







That being said about your shock... It needs to be changed. Just like others have pointed out. Swingarm angle is way too steep. The least of your problems are going to be chain issues. It seems like you may see that now, so I wont harp on that any further.

Some people may be harsh in their responses to your build. You've taken the criticism pretty well in stride. Not everyone is going to know what they are looking at or be willing to be blunt at the risk of sounding harsh or rude. Although none of us know everything, when people with far more experience give you advice, as harsh as it may come across, take it. Those that have said the geometry is off, are on the money. It is, and needs to be addressed and changed. Im not of the camp that thinks 40 y/o tech can not be improved upon. But you cant just throw tubing, bracket, and random shocks at it. Keep it up buddy.
I have no doubt that, if you sepnd the time, you will learn the basics of geometry and how mod "X" will affect "Y".
You've done a great job with the proportions and lines. Gonna be a good lookin bike for sure.
 
Not too sure what "power the front end" means, but if you are thinking raising the front to compensate for raising the back, then - well, sort of it would be good. Lets back track for a minute. This sounds like you think you have to have the back too high, and the solution is to raise the front the same amount to retain the geometry. This is a good scheme if for some reason you simply have to live with the back being too high. In my own experience, this is often a poor way to do things. The logic is ok, but in the real world, you commonly end up with a cascade of problems that you keep on solving with a repair for the problems rather than eliminating the problem in the first place. In this case, you sound like you are resigned to having to keep some version of the shock you have now and "fixing" the resulting tall rear end problem by lifting the front accordingly. Sounds like the easy path, but you still have the other problems with the kinematics of the swingarm angle. I have spent enough time and money chasing my tail on things just like this to realize the best solution is to fix the problem at the source. Maybe you feel the space you have available for your shock is too small, and you will find a solution by "fixing" other problems that result from this. I say DON"T DO IT! Put your bike back into the stock geometry, and find a way to make a single shock work directly. Don't create another set of problems to solve. Those problems usually beget other problems that need solving, which beget other problems and so on. Just solve this one problem and move forward. If this was my project, I would make a decision on what I was going to use for a shock, and use it. Maybe I would do some major surgery to the frame I had not planned on to make space for it, and maybe I would run into additional unforeseen problems (like now there are carb clearance issues - whatever) but I would attack it from that perspective and try to see what other issues may lie ahead along that path rather than continue with where you are going now. It is a truly clever man that can see all the chess moves ahead on any strategy, but I say you are money ahead sometimes picking the lesser of evils. You may not see every potential problem on any particular path, but bad geometry is a pretty big evil!

For the record, I do not necessarily promote "always go with the stock geometry". I do not on my own bikes. It is a big subject, and like any engineering adventure, everything is compromised by everything else if you are designing your own. My advice to go back to stock geometry comes from the notion that you (like MOST people) are not really wanting to engineer a chassis from scratch. Doing that requires either knowledge or foolishness! (often both it would seem!)

You and your dad look to have some pretty good fab skills. I would find a way to keep my new swingarm, keep the stock geometry, and figure out a way to modify the frame to use the shock I have or find a different shock to make my frame mods simpler. You actually only have this one problem, try to solve it rather than creating a cascade of new ones as a solution.

FWIW, (and on a completely unrelated subject) I have done a fair bit of anodizing. I really like it - BUT. . . . Black and red anodizing fades DREADFULLY in the sun. (gold and clear are good for a long time, but what if you want black or red?) Just an FYI. If anybody says this ain't so, PLEASE let us know how to do it!!!! I have a customer bike with black anodized heads that are GORGEOUS, but are already fading - and this bike is kept indoors and only sees sun while being ridden.
 
Thank you all for the help, as far as the geometry is concerned, do you mean for the bike to stay level? or do you mean the tail sections triangulation? Would it be possible for me to lower the front end through the forks and getting a shorter shock to level out the back, effectively bringing everything level, getting rid of the chain clearance issue while retaining the frame modifications?

Essentially bring the swing arm up to where it belongs?
 
This is exactly why making changes is complicated. "Keeping the frame level". What does that mean? Well it is actually sort of meaningless. The frame has some orientation in its original configuration which results in its original geometry. In truth, as you ride, the geometry is constantly changing, so its all a bit hard to define. Fortunately, you really only need to get back to what you had. I realize that is a bit difficult now that you have eliminated a bunch of stock references on the factory frame, but I would think you can get pretty close "guesstimating" where it was. The front is as yet unchanged, so get an original shock and set up the frame and swingarm angle back to stock using it as a gauge. It does not have to be perfect, but set it back to original as close as you can. If you kept the cut off old frame parts, that can help. Just block everything up with some wood or whatever you have lying about and put the frame and swing arm in place like it would have been before you made the modifications. Then you can sort out your new shock. If it was me, I would take off the spring and complete my work. Then put the spring back on and use it to gauge what I needed for a new spring. Of course, you could be lucky and the spring will work, but probably not!

You may find it helpful to work from a completely extended suspension perspective. Normally in designing from scratch, you would be considering the ride height and whatever portion of suspension travel would be consumed in this condition, but if you are just going back to where you were, you can get the front at full extension, then estimate all the back to be at full extension and assume that you will be able to adjust your rear spring to provide the proper ride height when you are all done and riding the bike. The main point being that the max extension of the rear suspension will be the same as it was, in which case you will be able to make the ride height what it was and therefore recreate the original geometry.
 
jpmobius said:
This is exactly why making changes is complicated. "Keeping the frame level". What does that mean? Well it is actually sort of meaningless. The frame has some orientation in its original configuration which results in its original geometry. In truth, as you ride, the geometry is constantly changing, so its all a bit hard to define. Fortunately, you really only need to get back to what you had. I realize that is a bit difficult now that you have eliminated a bunch of stock references on the factory frame, but I would think you can get pretty close "guesstimating" where it was. The front is as yet unchanged, so get an original shock and set up the frame and swingarm angle back to stock using it as a gauge. It does not have to be perfect, but set it back to original as close as you can. If you kept the cut off old frame parts, that can help. Just block everything up with some wood or whatever you have lying about and put the frame and swing arm in place like it would have been before you made the modifications. Then you can sort out your new shock. If it was me, I would take off the spring and complete my work. Then put the spring back on and use it to gauge what I needed for a new spring. Of course, you could be lucky and the spring will work, but probably not!

You may find it helpful to work from a completely extended suspension perspective. Normally in designing from scratch, you would be considering the ride height and whatever portion of suspension travel would be consumed in this condition, but if you are just going back to where you were, you can get the front at full extension, then estimate all the back to be at full extension and assume that you will be able to adjust your rear spring to provide the proper ride height when you are all done and riding the bike. The main point being that the max extension of the rear suspension will be the same as it was, in which case you will be able to make the ride height what it was and therefore recreate the original geometry.

Perfect, I'll get out there and take a look at it, thank you for the in depth explanations, It has been super helpful!
 
Back
Top Bottom