1977 CB750 Deviant Hell Ride

Got it all wired up. Compression check and static timing done. Oddly, the only way to time the Dyna S was to flip the plate and reverse the yellow and blue wires. It contradicts the wiring diagram I'm using, but it timed. Put my XL tank on it to attempt the first start up. Gas pours out of the #4 carb. Tapped the carb and tried again. Gas pours out of the #2 carb. Tapped all four carbs, no more overflow. Ignition and first attempt to start. Wa wa wa wa wa ... nothing. A little bit of ether- started right up and died right away. Adjusted all the carbs to 1.5 turns. Still wont start without ether, now it idles for about 20 or 30 seconds seconds, but only 3 cylinders. I think the carbs are sticky and clogged. I'm going to pull them apart again and run guitar string through the idle jets and check the pump circuit. I'll also run through all of the valves to make sure I have them right.
 
Cut the bracket off of a spare XL frame and welded it here, with this beautiful rusty-as-fuck XL kickstand.

0919d78aebc376847ec1b2a5e66bf27f.jpg



Sent from my iPhone using Tapatalk
 
Still not running without ether. Plugs are getting wet, so I'm thinking it's flooding somehow. I can get it to run for a short time, 10 seconds or so, then it dies. I set the floats at 12.5mm, which is what I've found to be the number through online searching. However, that seams way too high. I'm going to reset them to where the top of the float is level to the carb body. It works for Holley, it's been suggested it works here. Someone also suggest closing three float valves, hooking a tube to the fuel inlet, then blowing through the tube while opening and closing the fourth float to see where is should be set.


Intake.JPG

It has also been suggested that the idle circuit is clogged and fuel is bypassing the idle circuit. Fuel looks as though it's blowing out of one of the venturi ports (#2 or #3) on the inlet side of the carb. #2 is the idle circuit, #3 the main. At least two of them definitely seem wet.
 
The general rule if there aver was one for these carbs is that floats should be adjusted so the metal tab that holds the actual floats is parralell with the bowl gasket surface. If you adjust them as you described you may be too low.

12.5 does sound really high, i dont know the spec off the top of my head but ill look just for funnsies today.

Do you have your accel pumps adjusted properly? Are you giving the bike throttle immediately?

Plugs are getting wet, yes it is flooding. This could certainly be due to an extremely high float or mis adjusted accel pumps. Generally a bike that wants to idle on the main does not flood, it just revs when throttle is applied.

I gotta go back and read again but it runs. Tuning for dummies: If you change or clean something and it runs better, do more of that. If you change something and it runs worse, do less or the opposite of that.
 
Your hex doesn't touch me, holmes. :p

I got the bike running and idling pretty well yesterday. Still starting on ether. After a couple of minutes of running, oil starts pouring out of the bottom of the head underneath the #2 header. Shut it down. Fuck.

I pulled an all-nighter; dropped the motor to see what was happening. I figured out 4 bolts at the front of the head were barely torqued. Just color me stupid. put it back together, into the frame, and now the bikes together. This time I stole the choke cable and mechanism I got for my truck, installed it, put a little charge on the battery, and this bitch fired up. No ether. Pure gas. It's not perfect, but it fucking runs. Now I at least have a baseline to tune it.

I also need a goddamn 20mm x 1.00 petcock, so I can use the tank meant for it.
 
deviant said:
Your hex doesn't touch me, holmes. :p

I got the bike running and idling pretty well yesterday. Still starting on ether. After a couple of minutes of running, oil starts pouring out of the bottom of the head underneath the #2 header. Shut it down. Fuck.

I pulled an all-nighter; dropped the motor to see what was happening. I figured out 4 bolts at the front of the head were barely torqued. Just color me stupid. put it back together, into the frame, and now the bikes together. This time I stole the choke cable and mechanism I got for my truck, installed it, put a little charge on the battery, and this bitch fired up. No ether. Pure gas. It's not perfect, but it fucking runs. Now I at least have a baseline to tune it.

I also need a goddamn 20mm x 1.00 petcock, so I can use the tank meant for it.
Click to expand...

Which tank, I have a few CB750 petcocks
 
YEEHAW! WORK-BOY. Good job. Looks like Kiley posted he may have one for ya, on standby.
 
Cocks what I think your calling 20mm I have both down and left outlet and the other is standard 750 I would caution the little one because of fuel starvation
047135fafdebf17e146ecb9ef9311ced.jpg



Sent from my iPhone using Tapatalk
 
You must log in or register to reply here.

DTT Light or Dark

  • DTT Light
    • www.jadusmotorcycleparts.com
    www.lostapostle.ca/
    www.sparckmoto.com

    Spread the Love

    Back
    Top Bottom