Topic: Beaniam's 78 cb750k build.

[beaniam]

Well here's some history on my bike.  Picked it up a few months ago for $750.  Pretty clean, appeared taken care of.  Ran pretty good after a little carb idle screw adjustment.  The accelerator pump wasn't doing anything as it was all clogged and the diaphragm was full of holes anyway.  Front forks leaked (no wonder they leaked the seals were installed upside down), owner claimed the clutch slipped, had pod filters, oil cooler, 10" hangers, some other bits and pieces.  I took it for a ride but being in the middle of Wildwood city NJ I couldn't really get any sort of speed or even out of 3rd and 4th gear for that matter.  Fast forward I get it home and have horrible 5th gear racket.  Clutch was fine.  http://forums.sohc4.net/index.php?topic=76692.0  for that whole issue.  Turns out a thrust washer was in the wrong place in the transmission.

Fun time learning experience, brand new to CB's and I've gotta split the case already.





Now that the engine is back together (haven't fired it up yet, fingers crossed), I've moved on to setting up the bike how I want it.  

Day I brought it home.



I couldn't stand the hangers, didn't even find them comfortable.

Installing drag bars.



Yesterday my solo seat, fender, rear turn signals, and taillight arrived so I've been mocking up and playing with how I want stuff to sit.
As I expected the stock tank looks way too big but I'm going to run it for the time being.  I also moved the seat back about 3" after these pictures.  I plan on making a sheet metal shroud to cover the gap between the seat and tank and possible do something between the shocks and seat.  Just looks kinda empty how it is in these pics.  Also I want to make up a hinged seat bracket so I can access the battery.  I'm not running seat springs.  Don't like how they look on bikes that aren't hard tailed.  
No definite ideas of how I'm going to do it yet, just kinda threw the parts on for a basic idea.  Some tips or suggestions are appreciated.  Other than my chopping the rear of the frame off I'm not doing any additional cutting.









I have some 3/8ths round stock I'm going to make fender struts from the fender to the swingarm but I'm not sure yet what I'll do about making them adjustable for chain adjustments.  I plan on having the fender hug the tire as close as possible and probably end at the middle point of the top of the tire.  
A smaller tank is in order but I'm not sure what I'll do yet as I'm not konging the frame so it's going to stay at the angle it is now.  Dunno if a peanut style tank would look right like that.

Anyway, let me know what you think or throw me some ideas!

[MasterChief750]

just fyi drag bars are very uncomfterble for more than just a few miles.

[beaniam]

Made a few 50 mile runs, felt fine to me.

Pretty much done at this point.  Some little things here and there I need to address like how high the taillight sits so the license plate clears the fender.





Mac 4-1 exhaust, drag bars, mini gauges, oil pressure gauge, solo seat w/fabbed seat bracket and tank hold down, 83 nighthawk gas tank, pods, 130 main 40 slow jets, custom front and rear fenders, chopped rear frame, probably some other things I'm forgetting.

[Alan F.]

I just popped in from your 21" front tire thread to ask if you know more about your gas tank, which model of 83 nighthawk is it from, how well does it fit, and did you have to fabricate a rear mount?

Thanks for any info you can offer.
Alan

Edit: From a little looking on ebay it looks like it's from an 83 CB650 (same as 83-85), did you do anything with the gas guage sender or just unplug the wire?   That's a 3.4 gallon tank plus a .5 gallon reserve.

[beaniam]

Yeah I believe it was an 83 nighthawk 650 that it was off of.  I just cut the sender wires off.  Left the sender in so I didn't have a hole to plug.  The bottom rear corners of the tank had mounting tabs that I cut and ground off flush.  I also had to weld on new mounting studs for the ears on the front of the tank.  About 2" back and up an inch from the originals.  The rear mount is held down by the seat bracket I fabricated.  Basically it was one of those pivot brackets for bobbers they sell on ebay that I heated up and flattened.  I welded some nuts to the bike frame and the seat bracket sandwiches the tank bracket between the frame and seat.  I can take some more detailed pictures later.  Only downside is a lot of vibration comes through the tank because it's all rigid mounted.  I also had to remove the vacuum diaphram spring out of the petcock so fuel would flow through.  The older cb750 petcock wouldn't fit.  Had to bend the petcock mount out about 1.5" to clear the frame as well.