272xp running strange.

[jakethesnake]

Had a box of 272 parts I’ve assembled. Finally got the parts to put it all together antivibe buffers. New fuel line. Screws ect.

So it starts and runs erratic. My question is I put a screwdriver on the carb screws and nothing changes. It’s idle is too high maybe even lean. Saw very well may have an air leak. I’m not that far along yet but I do have new crank seals and the Oiler o ring on the way. What would cause this. Even IF it has an air leak which is possible Why wouldn’t the screws on the carb change anything?

 

[jakethesnake]

I do have a Chinese carb laying around I didn’t clean the Tillotson or do anything to the carb.

I’m no saw builder I’m familiar enough with the two series though as I have another 272 to take notes from.

 

[XP_Slinger]

If the leak is bad enough, it could overrule carb settings. I would try a new fuel filter if you haven’t yet.

 

[jakethesnake]

If the leak is bad enough, it could overrule carb settings. I would try a new fuel filter if you haven’t yet.

New fuel line and filter.

 

[jacob j.]

Yep - a serious air leak will leak so much air that the carb adjustments won't amount to anything.

Check your intake block for cracks - it's likely it needs new seals at the minimum, assuming the main bearings are still good?

Anytime you have a saw that's disassembled in a box, there's a reason it's disassembled in the box.

 

[grizz55chev]

Yep - a serious air leak will leak so much air that the carb adjustments won't amount to anything.

Check your intake block for cracks - it's likely it needs new seals at the minimum, assuming the main bearings are still good?

Anytime you have a saw that's disassembled in a box, there's a reason it's disassembled in the box.

Vacuum pressure test is in order, wish I had a nickel for every time I’ve said that!

 

[jakethesnake]

Yep - a serious air leak will leak so much air that the carb adjustments won't amount to anything.

Check your intake block for cracks - it's likely it needs new seals at the minimum, assuming the main bearings are still good?

Anytime you have a saw that's disassembled in a box, there's a reason it's disassembled in the box.

I did put a new intake block on it. Yes I agree it was in a box for a reason. Maybe I’ll check the seals out. I have new ones. I think the bearings are ok I bought this saw just to have spare parts for mine but I just couldn’t leave it be. I don’t have a pressure tester so I’m winging it

 

[grizz55chev]

I did put a new intake block on it. Yes I agree it was in a box for a reason. Maybe I’ll check the seals out. I have new ones. I think the bearings are ok I bought this saw just to have spare parts for mine but I just couldn’t leave it be. I don’t have a pressure tester so I’m winging it

I use a bicycle pump with the pressure guage built in, works like a charm, pump it up to between 5 and 10 psi. If it holds for a minute or so, you’re good to go! If not, strip off all the parts like the carb, coil, fuel tank, clutch and flywheel then dunk it in a bucket of water and look for bubbles.

 

[Stump Shot]

New fuel line and filter.

Check the new filter, had one that was defective that did this. Wouldn't allow enough fuel in. Make sure your new line isn't kinked, otherwise your carb has problems or the aforementioned air leak. And check your tank vent out for proper function.

 

[jakethesnake]

For what it’s worth saw revs and spools up well but lean. I’m really thinking maybe leaky crank I feel fuel filter not allowing enough fuel would be unlikely. With the difficulty I had getting that damn raisman fuel line in there I hate to fiddle with new parts just yet. (The line is short had to put the stretch on it to get it out of the tank to install filter).

 

[Stump Shot]

For what it’s worth saw revs and spools up well but lean. I’m really thinking maybe leaky crank I feel fuel filter not allowing enough fuel would be unlikely. With the difficulty I had getting that damn raisman fuel line in there I hate to fiddle with new parts just yet. (The line is short had to put the stretch on it to get it out of the tank to install filter).

All that can be done from here is let you know what the possibility's are. You will have to diagnose from your end. If you plan to mess around with saws a bunch more in the future I would highly recommend a pressure/vac tool. It can check all these things and let you know with certainty what is wrong and get you steered in the right direction. Wish it was as easy as change part A and B, but if you start down that road you will end up with half the saw replaced and still no guarantee of it being right. Sorry, I can't do much better without getting hands on it.

 

[jacob j.]

Years ago, I found a cheap new Mity-Vac kit on Ebay, so I use that for pressure-vacuum testing and it does fine.

I think you could find one on ebay for around $22-$40.

 

[jakethesnake]

Well. Problem solved.... *s-wordty Chinese white gasket replaced with a green one I had laying around. Was sucking air from between the intake block and carb. Runs gentle now. I’m waiting on some random smalls for the oil system and should be ready to go

 

[XP_Slinger]

Well. Problem solved.... *s-wordty Chinese white gasket replaced with a green one I had laying around. Was sucking air from between the intake block and carb. Runs gentle now. I’m waiting on some random smalls for the oil system and should be ready to go

Nice! Gotta love a simple fix

 

[jakethesnake]

Nice! Gotta love a simple fix

Yeah. I shook the flywheel back and forth and could hear air sprayed the whole saw down with soap and water and yeah it was massive and obvious

 

[Stump Shot]

Well. Problem solved.... *s-wordty Chinese white gasket replaced with a green one I had laying around. Was sucking air from between the intake block and carb. Runs gentle now. I’m waiting on some random smalls for the oil system and should be ready to go

Those gaskets are terrible and for anyone reading this should be avoided. OEM or Hyway gaskets are the way to go.

 

[Stump Shot]

Yeah. I shook the flywheel back and forth and could hear air sprayed the whole saw down with soap and water and yeah it was massive and obvious

Glad you were able to figure it out.