Show Posts
271
CB750 / Carbs Install
« on: March 15, 2023, 09:28:37 AM »
Hi,
As mentioned in a previous topic, Im looking into why my new 750K6 is reluctant to tickover and run, particularly no.4, along with a stiff throttle that won't return on its owm. The ignition / timing looks ok. Plugs will be replaced.
I've removed and cleaned the carbs and fuel lines. I found 2 things;
-Floats were set at around 30mm above the bowl rim. So maybe it was lean? I've put it to 26mm and will watch out for leaks!
- I was unable to see through two of the slow jets (one was no.4). Hopefully, now all clean.
I'm not familiar with Keihin, nor multi carbs set ups. Im used to single Amals! At this stage, I only cleaned what I could get to from the float bowl without dismantling them from the gantry system. I'll replace the fuel, the tank is very clean.
I'll crack on this morning. A couple of questions:
I know the carbs were not synch'd prior to taking them off. Is there a good method to getting a base setting on all 4, before re-installing? I have vacuum guages for once it's running (that will no doubt, be fun and games!).
The issue with the throttle not springing back remains a mystery. Cable run is smooth arcs. They were a little, very slightly, stiff. I don’t think this was the issue. I've flushed them through with silicon lube. They are now nice and light. Off the bike, the throttle movement on the carbs gantry is very stiff. Im not able to shift it manually. On the bike, once the cables were removed, they did operate and spring back. The springs look ok. Should I be lubricating something, or easing any clearances? Is there perhaps a 'usual cause' for this?
Thanks, Martin
As mentioned in a previous topic, Im looking into why my new 750K6 is reluctant to tickover and run, particularly no.4, along with a stiff throttle that won't return on its owm. The ignition / timing looks ok. Plugs will be replaced.
I've removed and cleaned the carbs and fuel lines. I found 2 things;
-Floats were set at around 30mm above the bowl rim. So maybe it was lean? I've put it to 26mm and will watch out for leaks!
- I was unable to see through two of the slow jets (one was no.4). Hopefully, now all clean.
I'm not familiar with Keihin, nor multi carbs set ups. Im used to single Amals! At this stage, I only cleaned what I could get to from the float bowl without dismantling them from the gantry system. I'll replace the fuel, the tank is very clean.
I'll crack on this morning. A couple of questions:
I know the carbs were not synch'd prior to taking them off. Is there a good method to getting a base setting on all 4, before re-installing? I have vacuum guages for once it's running (that will no doubt, be fun and games!).
The issue with the throttle not springing back remains a mystery. Cable run is smooth arcs. They were a little, very slightly, stiff. I don’t think this was the issue. I've flushed them through with silicon lube. They are now nice and light. Off the bike, the throttle movement on the carbs gantry is very stiff. Im not able to shift it manually. On the bike, once the cables were removed, they did operate and spring back. The springs look ok. Should I be lubricating something, or easing any clearances? Is there perhaps a 'usual cause' for this?
Thanks, Martin
