carburator float level again

[david451]

Mines a 1974 750 and prior to the carb level adjustment it was running rich on 1 and 2, on over run it was popping like it was running lean but other than that it wasn't too bad.

Took carbs off trying to do it in place is impossible, took the float bowls off and one carb was well out of adjustment " the 26mm" from the others but the others also needed adjustment to bring it within the 26mm .

Here is where it is so vague these carbs have a cut out on either side so the tool I made up "credit card" sits on the gasket it has to because of the cut out.  I imagine if the tool was thicker it might bridge this cut out

Having adjusted the carbs to 26mm from the gasket it now runs like a burst ball, its hesitating opening the throttle and surges up suddenly like it was getting a chunk of fuel and then settles off idle.

If the float is too high because I set it from the gasket then its running lean, yes/no ?

Does anybody confidently know where the 26mm is measured from the threads don't show it clearly because they use a Honda tool which is thicker and probably sits on the edge and not the gasket.

[petersy]

I don't know about the 750, but on my '74 CB550 I measure (with the carbs at 45 degrees from uside down) from the flat of the main body of the float bowl to the top most part of the float and it runs OK.
I cut a piece of paper 21mm wide (for the CB550) and use that as a measuring template.

[david451]

There is a thread on here where the guy measures the 26mm from the edge of the carb and not the gasket, Honda don't say because you use their tool which is calibrated to do the job.

I guess mine are too high now, probably need to measure the lip tomorrow and then cut a bit out my tool likely to be 28 from the gasket.

[david451]

ok adjusted the floats again 26mm from the cut out of the carb bowl is too much, the carbs were flooding, I measured the cut out and then the normal section and recalibrated to 28mm and it runs much better but to be honest I don't know why I wasted my time so have sent off for the proper tool and then I know its perfect.

My new exhausts came today a big juicy box with 4 other boxes with nice shiny exhausts. Easy pleased so I am. Might go out to the garage and look at them again for a while.

[MarkCR750]

ok adjusted the floats again 26mm from the cut out of the carb bowl is too much, the carbs were flooding, I measured the cut out and then the normal section and recalibrated to 28mm and it runs much better but to be honest I don't know why I wasted my time so have sent off for the proper tool and then I know its perfect.

My new exhausts came today a big juicy box with 4 other boxes with nice shiny exhausts. Easy pleased so I am. Might go out to the garage and look at them again for a while.

Sounds as though you're on the right track with the float heights then David.

I know what you mean about going to the garage to look at the exhausts, harmless though 

P.S. just off to the garage to admire my new gold coloured chain. so I am.

[mgy66]

Hi All,

I am in the middle of getting my 750 k1 working as best as possible for regular commute (dry run only as someone though it would be good to nick and resale my front mudguard or thinking that is more stylish/trendy without it!).

I think that the levels are only affecting the tickover, not really lean or rich mix. The float should be as high as possible without reaching the bowl gasket and making sure the pilots (shorter than the main) are sufficiently imerged into the fuel. If not, then the bike may either struggle to start or may be able to start but tickover would be affected at red lights with the need to rev up.

The idea is that you need to have sufficent drop in the levels to have the floatters opening enough to get the fuel in and replenish the bowls. I haven't measure the gap between the bowl gasket and the pilot tip but I would assume there are few mm overlap, i.e. 28mm gap or so. Would be interested if someone has measured it.

I like the idea of the credit card cut out... should call my bank to tell to resupply mine...
Cheers...