Checking Float Levels + Design of a Carbie stand

Checking your float levels.

When it comes to carbie issues, checking your floats is by no means a trivial task, and most people have difficulty doing such a thing. I was no exception, and really had trouble finding out how to accurately measure the float levels. But thanks to handyman Trevor, I now know a fairly foolproof way to accurately gauge the float levels. (still haven't freakin done it cos bunnings and me aren't on speaking terms.. but I have got an inaccurate way of doing it now)
Thanks to him and his digital camera, I was able to construct this little tutorial on not just checking float levels, but I’ll also explain floats a little bit for those who don't know about them, and would like to know a bit about them before ruining/fixing them.
You can skip questions if you don't care, or already know. It's a structured tutorial 'cos I be clever.

Let's roll:

Q. What the hell are floats?
A. The 'floats' themselves are a plastic device contained within the 'float bowls' (bowels?), which are an entire section of the carburettors. The bowl is basically where the fuel is temporarily stored before being sucked down thru the jets, into the motor and burnt. This bowl is intended to contain a set level of fuel, and this level is regulated by the little plastic floats. The floats work just like a toilet cistern.. When the bowl becomes full, the floating bauble lifts up the tab, and in turn the fuel can no longer flow through. Look at your toilet for reference (that's not a joke).

Getting off the topic of toilets:
More fuel in the bowl basically means more fuel pressure, and your bike will run richer. Less fuel means less pressure.. leaner mixture. I wouldn't really suggest using this method to tune the bike. Stick to re-jetting and changing needle heights.

Q. How does one check the float levels in the first place?
A. As you can probably see, it's all well and good to check the float level in a toilet cistern - it has a lid. Carbies (sadly) don't have clear panels or lids to check the levels (but wow that would be as cool as a glass fridge) so: how do we see how much fuel is in the chamber? Pretty easy in theory, if you ignore all other factors.



Get a short piece of 4mm diameter clear hose and hook one end to your float drain hole (shown in the pic) Lift the other end of the hose above the top of the carbs and open the drain hole. Assuming you a) have a flow of fuel to the carbs, and b) have the floats on the correct angle (bike on centre stand), the fuel in the floats will flow into the clear tube and match the hydraulic head of the fuel inside the float chamber. The level of the fuel in the hose is your float level.

Q. This is hard to do. Tell me how to measure floats easily and accurately or the cute bunny dies.
A. That's more of a threat than a question, but put down the gun and we'll talk. I see your point. Although the above method is a fine way to roughly check if your floats aren't going nutty, most find it very hard to accurately gauge the float level. Plus it's really awkward to do with everything in the way. Time for Trevor's solution: Take the carbs off the bike, take the pump and bike battery off (if you have a pump), and take the fuel tank + tap off (you already would have if you're working on the carbies)
Put them on a bench and set up a mini rig. For this you'll need a crude carbie stand (Concept of such a stand is in another post around here)
Now all you need is:


A handy-dandy float measurer jig!
Basically it's a bit of wire holding two joined lengths of hose in place. With this, you can keep constant, accurate measure of the float levels. It's a really good idea to make it so the plastic tubing can slide up and down. Just trust me on that.


Basically the pic says it all here.

The hose should be 4mm. I believe that Trevor's jig has different thickness tubing. As long as it fits on the float drain hole all is well.
I gather you know how to use the device, but just in case: Let the floats fill up, attach the hose to the drain hole, activate the pump (this is actually important!) and measure the level.
Some documentation says that the stock level is 10.5mm above the float indicator. I just set mine to the line. Worked just dandy.

If the hose just keeps on filling up, then your floats are so low that they are never turning off. This is bad and it CAN HAPPEN. It is more likely to happen with an aftermarket pump. This can cause cylinders to fill, causing hydro-lock, and petrol seeping into the oil (bad bad bad!)
Hopefully this won't be the case!

If anyone would like to post a tutorial on changing the float levels, go ahead. I don't have pictures to go with that, and tutorials without pictures aren't very nice when it comes to things like float-setting.
Thanks go to Trevor for all his ideas. The carby stand being the best one yet.

Speaking of which, here's part two: Carbie stand piccies!






This stand holds the carbs at the same angle as the bike would. Basic design, you can build one of your own from this concept.
Thanks again Trev.

Well, that's it. Comments and stuff go down there.
Cheers and good luck.

 

Yup I didn't just want to ride, I wanted to learn.

It's my thing, I'm a nerd. <!-- s --><img src="{SMILIES_PATH}/icon_biggrin.gif" alt="" title="Very Happy" /><!-- s -->

 

ehehe, yeah starter those carbs are in a bit of a shocking state. Trev told me they're his old carbs which are just in cold storage these days.