Chainsaw Help

NormO

NormO

New Member
Hello Everyone

I could really use some help here.
I have a Poulan Pro 42cc chainsaw that i would love to get rid of the primer bulb on and run a gravity fed tank.
I'm not sure if it's even possible though. Any thoughts would be welcome.
 
Some of the others probably know better but i have been starting my ryobi WW bike by dropping the motor onto the wheel. No priming (even though it has a bulb) and no full choke. It will even start in no choke mode but usually I start half choke.

Carbs on those little motor usually have a pump that sucks up the gas from the tank. the bulb just seems to put a burst into the carb so that it is easier to start. I think you could run a straight line from the carb to the tank where the primer is attached now and it should work. In my case i can turn the engine over twenty times or more just by lowering the motor onto an already moving wheel.
 
So I should be able to get away with just using a T connector into the line and be good to go. Sounds easy enough. Thanks for the help Deacon.
I don't plan to have friction drive though. The engine is already mounted in-frame with the throttle and kill switch attached. They even work.
 
hi !

at least it can be done and works fully on weedwackers.

my mom had a broken Primer Bulb on 2T Ryobi weedwacker. i took the 2 hoses of the Primer Bulb and put a wood screw into each hose end hole.

afaik most ChainSaw carbs arent different than Weedwacker carbs (construction and how they work)

if you would use Gravity feed fuel tank, i dont see why you would have to take of/modify the Vacuum/pulse system, anyway afaik most Vacuum systems are "internal" build in Carb body and taking Vacuum/pulse pressure from Cylinder, so there is kinda no modding available to do for it.

Gravity fed petrol tank should not effect by any harm into the Gas flow by having in place/in use already working Vacuum/pulse pressure system on the side.

Does this make any sense ? any comments, any1 ?

bye:)
m
 
What i am confused about is the second line running off the carb and back into the tank. Is it a return line? Can i just block it off? or does it need to be there in order for everything to work right?
 
hi !

Primer Circuit on Carb is different than idle Low/high Circuit. are you confusing which hose line "being 2nd" ?

is it Zuma carb ?

Primer line comes from tank into Primer Bulb and goes from Bulb to Carb body.

idle low/high fuel line comes from Tank directly into carb body.

thats how it is in Zuma weedwacker carb. does this suit your Carb model ?

try google the Carb photo and paste it into topic message...

bye:)
m
 
do you have a clutch mechanism still attached cause if you do it might be hard to turn it over with the drive./
 
Cagiva4ever the carb on the motor is a Walbro. Most Swedish saws come with these or a Tillotson. It has one line for the primer, main fuel. Then there is another much smaller line running back directly to the tank. I don't know if the smaller line just returns fuel back to the tank or if it has a higher function.
Deacon i am leaving the clutch intact more or less. I am in the process of modding it so it is a little tougher and won't slip so easy. I'm also making a slight mod to the clutch bell as well. I plan to keep the pull start intact. I'll try to get some pictures up of what the heck is going on as soon as i can get my camera back.
 
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NormO said:
Cagiva4ever the carb on the motor is a Walbro. Most Swedish saws come with these or a Tillotson. It has one line for the primer, main fuel. Then there is another much smaller line running back directly to the tank. I don't know if the smaller line just returns fuel back to the tank or if it has a higher function.
Deacon i am leaving the clutch intact more or less. I am in the process of modding it so it is a little tougher and won't slip so easy. I'm also making a slight mod to the clutch bell as well. I plan to keep the pull start intact. I'll try to get some pictures up of what the heck is going on as soon as i can get my camera back.
Click to expand...

One of the lines from the carb. is a return line and the other is the supply line, I haven't tried the gavity feed set up on one of those diaphram carbs yet myself but I dont see any reason it wont work, the fuel will be where it needs to be without having to be pumped to the carb by the engine pulse so it should work just fine.

one thing you will need to do though is make sure that the fuel supply tubing is set up in a way that the fuel can actually gravity flow into it from the tank, most hain saws and weed wackers have a long piece of tubing that is inside the fuel tank with a filter on the end of it, if a person was using one of those tanks they will need to remove that long tubing and that filter so the fuel can free flow through the gas tubing from bottom of tank and then maybe install some type of inline filter between tank and carb. if possible.

It's funny that this topic should come up right now because I plan on setting my FD project I'm working on right now this way or at least that is my plan as of now.

Good Luck.......with the project.

Peace, map
 
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Thank you for clearing this up mapbike. I hope you have success with your project as well. I am not doing a friction drive though. But that may change if i can't get it to work properly.
 
Ok. Here's the pictures of what's going on. As you can see i'm recycling as much as i can from my many kits that i have kicking around. I don't yet have the tank hooked up yet, but i will as soon as i find a suitable T-fitting. The good news is this contraption works.
 

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