Ross’s CB750 project

[Steve G.]

  Carb balancing requires confirmation of which carb is the ‘static’ carb, the carb that the others are adjusted to,,,,which should be confirmed in any manual. 25 years of CBX ownership and restoration, I’ve got a lot of practice.

[Galactica]

  Carb balancing requires confirmation of which carb is the ‘static’ carb, the carb that the others are adjusted to,,,,which should be confirmed in any manual. 25 years of CBX ownership and restoration, I’ve got a lot of practice.

#2 carb is the static carb.  It’s fixed to the throttle shaft with no adjustment possible.  The other three are synced to it.

[Galactica]

Got a battery at Edmonds battery for $78 all in.  Earlier quote was for the wrong battery.

[Steve G.]

  That’s a good price.

[Galactica]

So I bought a ‘77 CB750.  Needs a lot more work ($) than I thought it would. 

Great turnaround from Partsnmore in Ontario.  Cheaper than other parts sites and on CDN dollars.  Ordered carb stuff Tuesday afternoon, got it this afternoon. 

Hopefully try to start it tomorrow.

.

I ordered some parts from vintage CB750.com Thursday morning.  Got them this morning (Monday).  Pretty darn good

[Runningdog]

Since Xmas, shipping seems to be a lot quicker.   I received something for the GS750 from Thailand in 4 days last week.

[stanfromhell]

Are all the cables adjusted so that the slides rise simultaneously  Needles in the same grooves? Jet sizes all the same?

[Galactica]

Dunno what’s going on.  After initial disassembly, clean, reassemble, and install, the bike ran but ran badly.  Ran better after syncing but stalled on throttle tip in.  All four cylinders firing.

Removed carbs, re-cleaned accelerator pump circuitry, re-installed.  Still ran badly.  Removed carbs, re-ultrasonic cleaned the entire rack and installed new accelerator pump diaphragm, re-cleaned and reinstalled all jets.  Re-installed carbs.  Good spark on all cylinders but now #3 cylinder is cold but has good spark. 

ARRRGH!!

[hardrockminer]

How is compression?

[Galactica]

How is compression?

I’ve not been able to check it.  My tester is for B size plugs.  The CB has B size plugs. 

I’ll need to borrow a tester.  Anyone have one I can borrow?   

Having said that, I’ve no reason to think compression is bad.  The bike does not seem abused.  It was running at the first fire-up with all four cylinders firing and hot, no smoke. But ya, compression is next on the list.

[Galactica]

So, I removed the carbs… again.  Sprayed carb cleaner into all orifices and blew them out with compressed air.  Removed the pilot jet and re- cleaned it.  Re-installed carbs.  It runs…not well, but all four cylinders firing and hot.  I reckon there was crap in the pilot circuitry.  Re-balanced carbs.  But clearly the idle mixture is bad.  I’m no good at setting mixtures so I will likely get professional help with that. 

[rz5mark]

No air leaks, those have tripped me up with old carbs.

[Galactica]

No air leaks, those have tripped me up with old carbs.

Ya, entirely possible.  Hoping not to have to buy carb holders.  I may make arrangements for Rick at Bby Kawasaki to come by and help me out.

[hardrockminer]

You can check for air leaks by spraying a bit of carb cleaner on them while the engine is running and listening for a change in revs.

[rz5mark]

Or water for a bog.