Back story -
I was given a cheap Chinese saw because it wouldn’t oil, wouldn’t run properly and the purge bulb was broken.
I fixed all the issues with spare parts I had around the workshop and gave it a tune, but couldn’t get the H lean enough without it affecting the L side off idle.
Long and short is two fold - this it what you get with a big box store Chinese saw, where they just stick a generic carby (although in this case good walbro) on to their equipment without really caring about how it runs, but secondly it is a dependant carb - all the fuel flows through a single drilling in the carb floor controlled by the H screw. This fuel then passes the main jet and then flows to the L needle which then controls the fuel flow through the idle and progressive idle drilling’s.
This is the first time I have worked on a dependant system that I’m aware of (could very likely had it in other carbs but they were matched to the correct powerhead etc).
Anyway, here you go, a quick video showing how the H affects fuel supply to the L.
I’m sure many of you already know this, but it may also be new to some too.
Thanks to those who shared advice on the topic already, it’s much appreciated
It has been a great opportunity to learn something new, to add a leaf to the book so to speak and get hands on experience with it.
i’ll re tune it back and just have it run a little rich on H and good at and off idle - it starts, runs and cuts just fine. Not a refined tool, but, you can’t expect much and it gets the job done for the average homeowner pruning their garden. I just thought someone may enjoy seeing it in a video.
I was given a cheap Chinese saw because it wouldn’t oil, wouldn’t run properly and the purge bulb was broken.
I fixed all the issues with spare parts I had around the workshop and gave it a tune, but couldn’t get the H lean enough without it affecting the L side off idle.
Long and short is two fold - this it what you get with a big box store Chinese saw, where they just stick a generic carby (although in this case good walbro) on to their equipment without really caring about how it runs, but secondly it is a dependant carb - all the fuel flows through a single drilling in the carb floor controlled by the H screw. This fuel then passes the main jet and then flows to the L needle which then controls the fuel flow through the idle and progressive idle drilling’s.
This is the first time I have worked on a dependant system that I’m aware of (could very likely had it in other carbs but they were matched to the correct powerhead etc).
Anyway, here you go, a quick video showing how the H affects fuel supply to the L.
I’m sure many of you already know this, but it may also be new to some too.
Thanks to those who shared advice on the topic already, it’s much appreciated
It has been a great opportunity to learn something new, to add a leaf to the book so to speak and get hands on experience with it.
i’ll re tune it back and just have it run a little rich on H and good at and off idle - it starts, runs and cuts just fine. Not a refined tool, but, you can’t expect much and it gets the job done for the average homeowner pruning their garden. I just thought someone may enjoy seeing it in a video.