Must be something I am doing wrong with these carbys. I have 3 here at the moment which I have put new kits in but all 3 of them for some reason are running rich. Anybody have any thoughts?
A few things you could check below but may not be the problem as I've taken the primer bubble off before and found a one way valve has popped out and sometimes seen a jet popped out .
These sprint carbs will over fuel if the two tangs on the diaphragm are not sealing properly (2 Fuel Pump Valves ) usually you can tell straight away by how the fuel primer works ,once fuel is in the carby each press on the primer should shoot the fuel out in a strong steady stream if not the diaphragm valves aren't sealing properly. The valves should seal as you've fitted new diaphragms but they don't always seal.
I don't know if that's your problem without looking at the carby but if you can feel air in the primer when pushed or the primer isn't pushing or a lot of fuel the poor sealing valves could be the problem.
Another thing I always do is remove the 2 metal fuel screens and blow everything out with compressed air.
If the spring in the diaphragm is longer than normal it can make them over fuel.
Hi Max, they prime as they should and start easily but they are obviously running rich because of the stuttering and black smoke coming from the exhaust. Put a good known carby on and these 3 motors run perfectly. I have just kitted another one and will see what that does in the morning.
Ok so now I have 4 out of 4 running rich. I now suspect these Chinese kits to be junk, I am so sick of Chinese junk but everything we get these days is Chinese junk
I would take the gasket and diaphragm out of the working carby after wetting the gasket with fuel or CRC so it doesn't rip then try the working gasket and diaphragm in the carbs that are flooding that will at least tell you it's definitely the new spare parts are the problem .
It doesn't sound like any of the carbs that are over fueling are missing the brass jet as you have 4 out of 4 over fueling.
When I was around 14 ,I would help my next door neighbours brother out doing deliveries to many Factories which I got paid for and it was quite common for the Factories to have manufactured seconds in the skips, we would take new parts out of the bins when the parts were at the top and it was always interesting to see what went wrong with the parts.
The problem is people that work at some Factories take new seconds (rejects) out of the bins and sell at markets and eBay. This doesn't happen much in Australia because factories lock their bins an have a surveillance camera on the bins as they don't want rejects being sold and people will say their products are faulty.
I find the selling of seconds from China is quite common these days from markets and eBay.
Max, I probably have about 10 here now all doing the same but I am not game enough to pull the one working carby I have. And this is a carby I have not put a kit in. I guess I could go to the local mower shop and get a kit from them to see if there is any difference in the ones they have
Max, I thought that removing the brass jet was to make them leaner for high altitude operation
I thought it works the opposite way Tyler , the bigger the air jet the more air pressure makes it's way down to the main jet which along with the vacuum acting on the main jet this helps to drag more fuel from the main jet , the air bleeder jet will mix air with the fuel but I thought it's main purpose is to help the fuel to be drawn up the main jet.
At high altitude I would have thought you would go to a smaller jet.
Originally Posted by NormK
Max, I probably have about 10 here now all doing the same but I am not game enough to pull the one working carby I have. And this is a carby I have not put a kit in. I guess I could go to the local mower shop and get a kit from them to see if there is any difference in the ones they have
There could be a problem Norm with the kits if they have shrunk or are cut wrong ,maybe worth getting a kit at the local mower shop just to check.
I always keep the carbs when I junk a B&S, just bung a whole carb on..... KISS principle, I know there's not a lot of thought in my process....... speedy
........................Keep your blades sharp......................
I have had it confirmed that Xi Jinping was also involved with the manufacture of this rubbish so they decided he was not cut out for manufacturing so they turned him into a president. I have been told to throw them in the bin and not waste my time with the junk.
Hi speedy, I would if I could, but I can't so I won't. I have ended up with boxes of carbys and nothing that works so I have to start kitting them. I have kitted them before but obviously this lot I got are just Chinese bottom of the barrel rubbish
I'd just put a new diaphragm and gasket over the top of an old diaphragm and gasket on a table to check the difference ,that would tell you straight away if it's cut wrong Norm.
That's interesting Tyler ,thanks for that info, the jet must lean out the fuel mix. I was going by the guy on Youtube explaining the operation at 38 minutes and 56 seconds in on the video.
Hi Tyler, drilled the jet out and a big improvement not what I would consider perfect but close enough. Running it without the cowl so once that is on I will see how it goes. I will try another one tomorrow
Advice please about how to remove that "main nozzle" mentioned above ?
Have Victa Lawnkeeper in excellent condition with 450 series 148 cc B & S motor, same plastic carby.
Problem is it is running far too rich and no matter what I do with the throttle it is revving way, way too fast even with the butterfly almost closed. Has always been like this but now I'm using it more often for mowing between shrubs because it is so light and manoeverable and don't need much power. Damm annoying to have it screaming its heart out and it is horribly thirsty.
Looks like the nozzle may be picked out but I don't want to ruin an otherwise good carby.
Would like to check the O ring or reduce the jet bore a little. Are nozzles with smaller sized bores available?
Governor and all linkages disconnected, operating the throttle lever by hand. Wide open the motor is screaming fast enough to throw the conrod, and initially when throttle completely closed it was still running far too fast.
I took out the brass butterfly and soldered over the small airhole hoping the motor speed could be controlled by having the throttle nearly closed but it bogged down running rich. Then drilled a smaller than original hole in the butterfly which helped a bit but idle was erratic/unreliable.
I reckon the main jet is too large, hence wanting to remove it and reduce the size of the bore.
![[Linked Image from outdoorpowerinfo.com]](https://outdoorpowerinfo.com/repairs/images/briggs_carb_790206/_main_jet_nozzle.JPG)
