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My CB750 cafe build in progress.....

vegastruckee

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Hey everyone Im new to the world of the CB750 and this forum. Im a firefighter from Las Vegas NV and really enjoy motorcycles.
I recently found a 1978 Honda CB750 Super Sport. The guy was asking $1200 but I really didnt want to spend CASH on a bike. I asked about a trade and the guy took a couple handguns for the bike. It was a completely stock bike with 7500 original miles. I gave myself a 6 week build time and a budget of $1000. Im currently $450 in and bike is really coming along well. So far I tore bike down to frame. I cleaned up the frame, swing arm, front forks and painted them graphite color. I am doing all the work myself. I couldnt find a tail section that I liked for a price that would help me stay within budget, so I made my own out of fiberglass. I made a mold out of wood, florist foam, and aluminum tape. Today I finished making the tail section out of fiberglass and am very impressed with the final product. I ordered most of my parts this week and am anxiously awaiting their arrival. I have been taking pics of the entire process. Any comments or suggestions are greatly appreciated.

IMAG1964.jpg IMAG2008.jpg IMAG1995.jpg IMAG2049.jpg IMAG1985.jpg IMAG2007.jpg IMAG1967.jpg
 
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looking good i went with same frame color on my cafe last year but have decided to change it to red this year the graphite just didnt stand out against all the black i had going on most people didnt even notice. keep posting pics as you go really like the tail piece kudos on home fab!
 
thanks. Ok so yesterday i was taking apart both the speedo and the tach to put new face decals on. I followed the directions and got the cases apart pretty easily. when it was time to take the needles off I used a fork as stated online as a good way to avoid breaking the needles......well the needles didnt break BUT the shaft from the tach AND speedo that sticks out and goes into needle did.... does anyone know if this is repairable or are both trash now. thanks
 
Shit that sucks! I can't offer any help but I feel your pain. I hate when some simple project turns into a pain in the ass.
 
Ive been looking at the aftermarket speedos and not sure what applications will work with the 750. Is the ratio 2:1 ???
Any help and personal experience would be appreciated.
 
I've read that almost all Japanese bike use 2240:60 speedometers including the CB750. The tachometer is 4:1.
 
So I've been doing more reading on this and am even more confused. If 2240:60 means 2240rpm = 60mph like I've read in numerous places, then the ratio of the speedometer drive must be about 3. If a stock front wheel is about 26" tall, that means the front tire covers (26 * pi * 2240) / 12 / 5280 = 2.89 miles per minute or *60 for 173.26 miles per hour. That must mean the drive itself has a ratio of about 2.88 to 1. Someone should unhook their speedometer cable and rotate the wheel 10 times and count how many times the cable spins. I'd do it but it's cold outside! :laugh:
 
You're right on. 5280*12=63360 inches in a mile. 26*pi=81.6814 circumference of wheel. 63360/81.6814=775.6968 revolutions of front wheel per mile. 2240/775.6968=2.8878 cable RPM/wheel RPM =gear ratio.

In this case RPM meaning Revolutions Per Mile.

I have the gear housing for my 450 in a parts bin in the garage. I'll check it out in the morning.
 
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OK so when i got home this morning i grabbed the speedometer mech and rotated it and found that you guys are correct. For each rotation of the wheel the mech rotates almost 3 times. So I think the 2.88:1 is correct.....NOW WHAT lol
 
I could be wrong, but I think Travis was trying to verify that the 2240 RPM 60 MPH speedo was right for your bike. It looks like it is. I spun mine around this morning and found the same thing. Actually the one McGyver posted looks pretty nice. I may buy one myself.

And, I thought the math problem was fun.
 
vegastruckee, if the speedo cable rotates about 3 times for every turn of the wheel, then that confirms that the 2240:60 is the one you want. :thumbsup:
 
Sooo even more reading on the topic.. One place said all Japanese bikes with mechanical speedos driven by the front wheel use 2240:60 speedometers and that 2:1 and 1:1 speedos are for harleys with transmission driven speedos.
 
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