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1976 CB250 G5 Float height for 745B Carb

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rbt1548:
After being unable to get to work on the bike for a wee while I have managed to get back to it.

Before measuring the float heights I noticed one of the float was not moving as freely as the other so I removed the pin and noticed it was slightly bent with a couple of gouges on it. I tried the float with the other pin inserted and it bounces about no problem. I understand pins are not available on their own, but I am able to get stainless steel dowels the correct length and dia. 28x2.5mm, would they suffice? I notice other carbs use stainless float pivot pins so I hope they would.

One set of floats was wildly out at 26mm the other 23mm which had me doubting I had measured them at the correct place, the highest point of the float as indicated by the arrow in the picture, could someone please let me know if I am measuring them at the correct part of the float?

Thanks.

Oddjob:
I tend to do my float measuring slightly different. To me it's not the height the float is set at, more the height it actually shuts off the fuel. Ideally these should be the same as the spec figure, however in reality they usually aren't. Sometimes the needle seat wears or the tip of the float needle wears, causing a leak past. As soon as that happens your float height doesn't matter anymore, it's higher than it should be.

So I tend to connect a remote tank up to the carb with petrol in it, then measure the height where the fuel shuts off, to do this you need to position the carb upright over a bowl to collect the split fuel. If it shuts off at the spec figure great, if it doesn't alter the float tang till it does. If for some reason the fuel just won't stop dribbling past no matter how high you hold the float then the needle and seat need either replacing or some attention until they do stop the fuel.

The other way is to do the height as you are now and then test it using the above method so ensure it actually shuts the fuel off. You'd be amazing how many don't shut the fuel off when they should.

rbt1548:
Thanks for that, on thinking about it when it shuts off the fuel seems logical as there will be wear on the needle and/or the seat after a while in use.

I have a remote reservoir so will give it a go.

Any thoughts on using a S/S dowel as a float pin?

Oddjob:
You can buy some brass rod on Amazon, right size as well.

rbt1548:
Some more info required from you kind people please.

I had set the floats to the heights to the measurements specified in the manual and pic in post without much hassle, however when I turned the carbs the right way up I noticed that one set of floats were hanging down a good few mm than the other set, they are ok when on their sides on the bench for measuring but one hangs a bit lower when turned vertical.

I had a good look at the floats and noticed a second tang on each set of floats which came into contact to on of the cast pillars that the float spindle goes through, one was slightly more bent on one set of floats than the other causing the float to hang down further when the carbs are vertical.

Obviously, both should hang down the same, but one set of floats is lower due to the bend in one of the tangs hitting the pillar first, is there a distance they should be set to or is it just a case allowing a bit of free movement?, as I mentioned when measured on their sides they are spot on.

Don't you just love 50 year old bikes that have gone through a few pairs of hands!

Thanks

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