as I wrote in the "3300 low power" thread we are continuing to troubleshoot the low RPM.

It has already shown that obviously a rather small main jet (245) was installed. I will get a selection of nozzles, especially the 255 default nozzle, as well as 260, 265 and 270 to try.

Someone told me the nozzle needle also comes in two versions, one with many mounting grooves on top and one (eco?) with only one mounting groove. Which is the right one for the 3300 ?

The fuel supply is best from the carburetor comes with the electric auxiliary pump about 500ml in about 20sec, if you have removed the float bowl. That should be enough.

The vacuum can with the rubber diaphragm worries me, like everything that is not used, but also about 12 years old.
How can I check if the vacuum can still does its job properly ?
My idea would be to look with a borescope in the air intake of the carburetor to see, if when you accelerate max., the cylinder in the carburetor goes up and how far ?! Would this be a feasible idea or is it better to do otherwise?

Thank you.



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that carb comes out very easily...  i took mine out so my mechanic could clean and inspect the inner workings- including a thorough inspection of the diaphragm boot...  also, there are divots in the diaphragm that must be oriented correctly during install.

he showed me how to inspects the diaphragm.  he inspects it every time he takes a carb out, as this is a known cause for the cv carb to NOT self adjust. 

he is a harley shop owner and sole mechanic so he sees hundreds per year.   i've reached out to him to ask him your bing carb questions.  more to follow...


Thank you !

The diaphragm is old indeed but never used before, 12 years as the Crab itself.

Are there more parts to change that are fading away ?

Is the Bing common for harely d. ? Can I get spare parts from them ?

Getting spare parts in germany for bing is difficult and time consuming ....



he’s traveling on holiday, but texted - “diaphragm for sure or incorrect float height”

parts are around on innerweb for ordering your motorcycle carb parts, yes.  and a Rotax sometimes has twin smaller bings.  I found a good website in a thread on bing in the Jabiru forum here.


What is this god for ? Let it as it is, or is some tube needed there ?


 If this was not hooked up, it could present problems. This is from page 29 - installation manual.

Connect to air filter box - not the tube running from box to Bing. Get this right before making other changes....   https://jabiru.net.au/wp-content/uploads/2020/04/JEM3302-9-_Inst-03...

• The Bing carburetor has a Balance tube (also known as a “sense tube”) which connects the carburetor to
the air box. The tube runs from a nipple on the carburetor to the airspace in the air box on the “clean” side
of the air filter. This tube is part of a system or ports which “tells” the carburetor how hard the engine is
working and controls how the carburetor varies the fuel / air mixture delivered to the engine. Tuning issues
and poor running will result if this tube is blocked or connected to the wrong spot. Figure 32 shows the tube
installation. Note that the balance tube must not be connected to the air box in a location where the air is
moving fast – rapid flows produces pressure changes and boundary layer effects which mean the balance
tube gives the carburetor “bad” information, which can cause poor mixture control and running issues.

Connect that to
Air fliter. Should be with the inatall kit

I got a lot of spare parts for the bing 94 with many O-rings, but where do they fit ?

What would you exchange and what not ?

Again, if you still have the hose from Bing to airbox not connected, you still may have a problem. Forget your rebuild kit till you obtain the required standard installations.


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