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Discussion Starter #1 (Edited)
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This is a 1982 Honda cb900c and is the base of this project. while skeptical at first of the 9200 miles on the odometer, given the grime and stiffness, i think this is accurate. I chose the C platform for a couple of reasons, but primarily because of the longer frame. i'm 6'7" and want to extend the size to fit me wherever possible. However, this bike is friggin heavy. So, here's the plan; strip it down to the frame, literally. throw away those parts that are just too old, sell the parts i won't need (anyone interested, just let me know. i'll give you a great deal). replace the tranny with single stage, racing gears (no hi/lo, just straight shifting). replace the front fork, stainless brake lines, and of course the handle bars, fiberglass, etc. as for the back end; to cut weight, i was considering having a new swing arm fabricated to move the back wheel back and allow for a single rear shock v. the current dual air shock set up. anyone done this before? if so, i'd love to see pictures. i may also have the seat area lifted to, again, give me a little more room.

Folks, i know this will be a lot of work and a bunch of you will be tempted to say "scrap it" and "don't bother..." i'm new to a project like this, but have the time and money to make this a fun build. i look forward to asking your guidance through this journey and appreciate all the help i anticipate receiving from you far more experienced individuals.
 

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Geeto has asked a very good question. Leave it as a rolling bike while you work on it. Go ahead and remove the bodywork, then replace the front end. That way you still have a bike that you can move around, but much more importantly a bike you can sit on to see how it fits at various stages. Next, I would fit the gas tank and then redo the subfame so you can put the seat where you need it to be, followed up by the footpegs where they need to be. This is not a styling exercise, it is about getting a bike to fit. That means seat, handlebars and pegs. Whatever you decide to do with the drivetrain and rear end has no effect on the ergonomics at this stage.

BTW there are no such thing as "racing gears" for that abortion of a sub gearbox/ transfer case that Honda stuck on the 900C. It is just a set of gears and whatever you would replace that gearset with would not provide any difference in performance. If you really want this to be a project, then I would look at converting to chain drive and getting rid of the whole shaft drive mess. I don't think it will be easy, but could be done. Since you have explained why you want to go with the C chassis, then you could look at getting an F motor and a new longer swingarm and move the pivot closer to the rear of the engine. that would give you more room for a monoshock and linkage. I would look for the suspension, brakes and wheels off of a 1990 or later CBR1000F. They are pretty cheap and not bad pieces for what you want.

But you should really follow my advice in the previous thread and just make it a super coll power cruiser.
 

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Please don't make multiple threads for the same project!
 

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That bike weighs 611 pounds Dry, for gods sake don't get it wet!
I'd say, if you want a light-weight CB900c, jack up the stickers and slide a new bike under it.




sorry, couldn't help myself ;)
in all seriousness :I have something fairly close to that headed for my garage in about 1 hour. I'll throw a few of it's parts on my bathroom scales, and see if I can find anything on it that could be considered light enough to want to keep. Maybe I can help you identify some of the weight offending parts.

Update: Guess I can't help you, the bike turned out to be a 1982 650 Nighthawk with almost no milage and all original parts.
:| they tip the scales at 451 pounds dry and it's chain drive, so this is basically the bike You should have bought.
I'm just fixing it up as a favour for a good friend.
Best luck with your build is the best I can do for you.

 

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Discussion Starter #7
thanks. two things i failed to mention. First, when i say i want to replace the swing arm, i want to actually convert it to chain drive. yes, i realize it means taking out that "abortion of a sub gearbox/transfer case..." what i have not heard from anyone yet is whether or not, if i unbolt these components from the engine, i'm looking at the same engine block as the 900F. also, not trying to make it a 900F, really want to make this my own invention. Finally, i've seen lots of places offering Honda Racing transmissions. is this not something worth considering?
 

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You want to convert to chain drive? Take out the cb900c engine and put in a cb900f engine. Then use the F swing arm and rear wheel.

By the way, you keep talking about the C as being your choice over the F because of its size of the frame. The F's frame isn't smaller.
 

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Discussion Starter #9
hmmm. according to specs, it is longer to accommodate the larger transmission box. you're saying this is not true? the other difference in the frame was the seat are subframe is supposedly lower as well. one quick question; instead of hunting and pecking for documentation, do you have any recommendations on where to find a better source of documentation for these bikes?
 

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If you remove that secondary transmission / transfer case, I think you are committed to altering the swingarm, frame and rear wheel. The chain will be driving from the opposite side and the new countershaft sprocket location is going to be so far away from where your swingarm pivots, you would need all kinds of chain slack to accommodate the movement of the swingarm.

That's how swing arms work! The greater the distance between the swingarm pivot point and the countershaft drive sprocket, the more chain slack you will need.
:/ or plan on making it a hard-tail.
 

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... i've seen lots of places offering Honda Racing transmissions...
For cars or motorcycles?

"Racing transmission" usually refers to the gear ratios inside the transmission. Close ratio gearboxes are usually considered racing transmissions and Wide ratio gearboxes are what you find in street bikes.
Almost guarantee your bike has wide ratio gear ranges and you would never be able to alter the transmission internal gears on that bike, which outputs to its secondary transfer case via a gear and not a chain.

If you do what you plan to do, it will definitely be your own invention. You may as well remove the engine and put just that in a scratch built chassis, there is virtually nothing about the original parts that would be worth retaining. imho
 

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hmmm. according to specs, it is longer to accommodate the larger transmission box. you're saying this is not true? the other difference in the frame was the seat are subframe is supposedly lower as well. one quick question; instead of hunting and pecking for documentation, do you have any recommendations on where to find a better source of documentation for these bikes?
No what I am saying is that the logic jump from having a little more room in the cradle to having an overall longer from is both flawed and ignorant. While it may be technically true the bottom of the cradle is extended to accommodate the transmission that doesn't make the backbone any longer. I'm pretty sure the f model super sports have a longer overall frame because the part of the frame that supports the rear passenger goes all the way to the taillight whereas on the C model it stops just aft of the shocks to mount the fender.
 

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I have never heard of anybody even trying to convert a 900/1000C to chain drive, because there is no reason due to the availability ofthe 900 and 1100 F. People have converted the Yamaha XS series because there no chain drive equivalent. The only reasonable way for you to do a conversion is to put an entire F engine in your C frame. Then you could put a longer swing arm in and move it forward closer to the rear of the engine in order to shorten the distance between the swingarm pivot and the countershaft sprocket. This would make it your own, since you would need to build the swingarm pivot area of the frame and work out the rear suspension. You could also look at putting your 900 top end on a trashed 750 so you could have a different combination of parts and get an engine cheap.
 

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I just took a look through google images for 900c's and there are no, none, zero, zilch, as in not any pics of nicely done performance cruisers on the first page, at all. There are a couple of weak attempts that look like they got started and gave up, there are a couple that tried to do bobber, chopper, brat style kind of things. There are not any that appear to have given comprehensive thought to the characteristics of the bike and play to the strengths and minimize the inherent deficits. Clearly this is a wide open field.


Go for it!!!
 

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Discussion Starter #16 (Edited)
Project is progressing slowly due to the need to research and, well, stare at the bike for awhile. sometimes, a new vantage point works so i had my bro-in-law build me a rolling work bench. see pic. Bike_on_bench.JPG

first off, i thought i could salvage the rear wheel, until, that is, i noticed it's 3" smaller in diameter than the front. so, need to get a new wheel. not a big deal as there are a ton out there. Second, needed to decide on cafe seat style. most likely going with a fiberglass "Thruxton" style seat. still need a line on good options for the cushion, so if you have suggestions... third, need to paint the engine. any thoughts on a good paint that will last a long time? also, converting the shaft to chain is really not all that tough. Remove the secondary transmission and it's the same engine, gear box, clutch etc. as the other CB750/900's. but, i'll save the details for future posts. finally, i'm thinking of replacing the standard 5 speed gear box with a racing, close ratio 5 or 6 speed gear box. the only one i find online is from Nova Racing. anyone know of a place that sells rebuilt gearing?

hey, i know most of you like to light up the poster with all sorts of negatives. bring it on. only motivates me more (which i appreciate). just please understand, i'm doing this for the fun of it. and to learn. just don't make it personal. i appreciate it.
 

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i had my bro-in-law build me a rolling work bench. see pic.
nice bench.

Second, needed to decide on cafe seat style.
i'm thinking of replacing the standard 5 speed gear box with a racing, close ratio 5 or 6 speed gear box. the only one i find online is from Nova Racing. anyone know of a place that sells rebuilt gearing?
close ratio gearbox and chain conversion for a C-model? Seat being the second most urgent decision after the new 17" rear rim (which needed a swap ANYWAY if doing a chain conversion).

I am baffled.

hey, i know most of you like to light up the poster with all sorts of negatives. bring it on. only motivates me more
Also understand that the "negatives" might not be food for resilience by the pessimists - BUT actually words of wisdom. Don't ignore helpful advise just because you don't like hearing it.
 

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Discussion Starter #20
the clymer's book indicates the counter axle is different, which is expected, but only on the one side. the primary gearing is roughly the same. again, based on the book. find out when i get in there. appreciate the feedback. would like recommendations on engine paint if you have any. thanks.
 
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