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Britman

Britman

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Been awhile, I have been on a Honda CB750K roll, have done four in a row. I sold the last one a few weeks ago and in the words of Monty Python, "Now for something completely different". Has not run in a couple of years, needs a lot, but after Santa comes and I wash the stink of Honda off my mitts I will get started. Gonna be going to a lot of old threads, when you turn 74 stuff just leaves your head in droves.....
 

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Just a heads up - when you put bends in the rear brake rod like you've got, it weakens the amount of application force. Besides applying the brake, you're also trying to pull the rod straight. That's an old dirt biker's trick to weaken the rear brake so it doesn't lock up as easily in the dirt. I don't think you want to weaken the brake for street use. I don't see why the rod couldn't be run straight, looks to be clearance for that.
 
Looks like the brake rod is bent to make up for the brake stay being too short. You could put a straight rod on there, measure, make and install a correct length stay.
 
Britman said:
Been awhile, I have been on a Honda CB750K roll, have done four in a row. I sold the last one a few weeks ago and in the words of Monty Python, "Now for something completely different". Has not run in a couple of years, needs a lot, but after Santa comes and I wash the stink of Honda off my mitts I will get started. Gonna be going to a lot of old threads, when you turn 74 stuff just leaves your head in droves.....Respectfully asking,what’s the Honda stink at 74?
Click to expand...
 
I don't think the length of the brake stay is an issue. You can simply change the position of the rear brake arm on it's splined shaft. Looking closer, I think the issue is (and the reason for the bends) that the front attachment point for the brake rod doesn't align with the brake arm (look at the third pic). But, being a custom build, I don't think it would be too difficult to modify that front attachment point and make it align.
 
The stay has the brake plate clocked (angled) wrong. Instead of cutting and rethreading the brake rod, they bent it to shorten it. If the stay was the correct length, it wouldn't have needed bending.



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Well, maybe not to alter it's length, but it would need a little bend to compensate for the offset between the brake arm and the front attachment point for the brake rod.
 
Welcome back Britman! I'm in between XS projects and currently building a CB750....

So, while we're re-designing your rear brake :whistle: - I might as well chime-in and add :twocents:; I think it also needs a longer lower lever-arm @ the pivot (more power).

As Jim said, the anchor could be longer (the anchor arm does appear to be an off-the-shelf TC Bros) and as 5twins mentioned, the brake rod should be shortened. One way to shorten the rod is to "de-rivet" (dremel, chisel) the rod from the clevis hanger and slide the hanger back to the desired length and then cut and re-peen or spot weld back together.

Carry on.....;)
 
Thanks one and all for the immediate comments, this site has always had members willing to help and provide input, it is good to be back. Besides the "Peyronie's Disease" in the brake rod there are tons of other issues, I really appreciate the suggestions on a remedy for that issue. I haven't even checked what the electrics are yet hidden in the fake oil tank, that should be fun. In the good column so far are, great compression, clean title, some decent aftermarket parts on the bike, and a box full of extra goodies. The seller bought the bike as a non runner, just needing general maintenance and the carbs adjusted, "Don't They All". He left it a local bike shop for over a year and it was never touched so he tried to get it going on his own, but had very little mechanical knowledge. I do have a lead when it comes to me selling the bike, he is very interested in buying the bike back if I get it up and running. I am looking forward to the experience, of course I will spend the first couple of weeks looking for the other two cylinders.........
 
That brake rod does have a slight clearance problem with that type of hardtail. It's super easy to bend the arm in towards the wheel for a better fit.
 
The Wife, Daughter, and Grand-daughter spent the entire day making Christmas cookies so I stayed in the garage other than to come in and taste at least one out of every batch. I am going to have to look at the wiring diagram closely for a bare bones chopper set up. I think there are a couple reversed wires on the switch, "IE" I have power to the coil in every key position when the battery is hooked up. The lights do work in the third key position, but no brake light switch to be found. Of course the stock ignition module is in the fake oil tank, along with the Mikes adapter plug. Sadly there is no fire to the plugs, testing the coil shows a bad secondary so the parts list has started. Carbs look fairly decent, but the choke plungers are not moving. I am going to break them down in the next few days and take a look. Overall I am pleased, I really do believe the motor is a fresh build with no or very few miles. Piston tops are still shiny, and the compression will break your leg. Starter is in place and spins when jumped, I think it might make a return. I have to go now, time for more cookie testing, damnit, somebody has to do it.....
 
Many of us use a Honda MP08 coil. They're cheap, very dependable, and easy to find on eBay for $20 or less (sometimes way less, lol). I got a bank of 3 from a Honda Goldwing 6 for $24.

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The coil arrives today so if fire shows up, might try a kick over. I am checking the cam chain adjustment and valve lash before hand. I broke the carbs down and put them back up yesterday after a good clean. V38's with brass floats and stock jetting. I got the frozen choke plunger freed up also. The previous owner said he had tried kicking the bike over with no results, the carb clean may have produced the cause. The needles were just sitting free in the barrels of the slide on the wrong side of the plastic needle hold down, can't see them doing much good. Wish me luck......
 
Have you determined exactly what year the carb set is? You will need to know that in order to know what the stock jetting should be. But, with your open intakes and straight pipes, re-jetting will be needed, and you base that on what was stock for that year carb set, not the bike year.
 
5twins said:
Have you determined exactly what year the carb set is? You will need to know that in order to know what the stock jetting should be. But, with your open intakes and straight pipes, re-jetting will be needed, and you base that on what was stock for that year carb set, not the bike year.
Click to expand...
According to the chart, 76-77 from the jetting and style. I know it will take some re-jetting down the road and will be way too lean, but hopefully it will be enough to fire up just to test the motor....
 
Yes, it should fire up but it will be very lean, especially with that carb set. While most of the 650 carb sets require mains one to two sizes bigger for mods like yours, the '76-'77 set needs more, like 3 or 4 sizes up. That's because it had such small mains stock (122.5), the smallest mains put in any 650 carb set.
 
Angle of the pic makes it look out of wack. Brake plate doesn't look to be to far out of place going by the indent at 12 0'clock. could rotate slightly clockwise, not much. Brake actuator needs to be set back a fair bit though. That will take up the slack in the brake rod

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Well it is alive, runs and sounds strong, but starving for fuel. Ordering bigger jetting tonight, garage is full of Klein jets, not the first Mikuni in the pile. I started it without the headers, just to test, will play with it a little further tomorrow with pipes and air cleaners but I am ending the day on a good note......
 
Well, good for you. You will need a size larger on the pilots as well. So, one up on the pilots (25 stock to a 27.5), 3 to 4 up on the mains (122.5 stock to a 130 or 132.5, I'd get both sizes so you can experiment), and with the larger mains, you'll need to lean the needle setting a step (lower the needle by moving the clip up one slot from the stock #3 position to slot #2).
 

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