272xp running erratically....

Help Support ArboristSite:

Paul Silvestri
Joined
Sep 24, 2019
Messages
557
Location
S.W Montana
Trying to chase a problem with this 272xp I picked up. Saw will run okay for a short while then rev high or bog down to almost quit under load. Carb seems fine and is now rebuilt. This saw doesn't have a impulse line but I'm wondering if the gasket from the carb to the cylinder is causing my issue.. the gasket has failed in one area that I think is important. I'm going to replace it but I'm wondering if any have had similar issues with this model. And no I have done a leak test yet.. was going to try this gasket first if that was a potential problem. Thanks!20210928_155415.jpg20210928_155425.jpg
 
Woodslasher

Woodslasher

Make McCulloch Great Again!
Joined
Jan 2, 2019
Messages
2,740
Location
Commiefornia
Trying to chase a problem with this 272xp I picked up. Saw will run okay for a short while then rev high or bog down to almost quit under load. Carb seems fine and is now rebuilt. This saw doesn't have a impulse line but I'm wondering if the gasket from the carb to the cylinder is causing my issue.. the gasket has failed in one area that I think is important. I'm going to replace it but I'm wondering if any have had similar issues with this model. And no I have done a leak test yet.. was going to try this gasket first if that was a potential problem. Thanks!View attachment 931928View attachment 931929
That could very well be your problem, that missing bit separates the impulse passage from the intake.
 

U&A

Addicted to ArboristSite
Joined
Jan 17, 2016
Messages
3,049
Location
Michigan
Didn’t know that saw does not have an impulse line. I had the same exact problem with a little chainsaw I rebuilt. That little gasket had a leak


Sent while firmly grasping my Redline lubed Ram [emoji231] 🛻
 
Paul Silvestri
Joined
Sep 24, 2019
Messages
557
Location
S.W Montana
Carb is rebuilt and I replaced that damaged gasket. However now it floods like crazy.. not sure what has changed. Started with H and L out one turn and went from there. Will only start with that throttle lock engaged then smoke and carry on from there. Plug is wet and gas in the filter horn. Hmm
 
Paul Silvestri
Joined
Sep 24, 2019
Messages
557
Location
S.W Montana
BAD idea! The NEW metering lever MUST be properly adjusted... OR just use the old one (and verify proper adjustment... Never know someone may have monkeyed with it).
I realize this now... Mistakes are some of the best education, if not the best! I'll take it apart and redo. I don't have a gauge for adjustment or a manual for this carb so maybe online will yield some useful specs.
 
huskihl

huskihl

Addicted to ArboristSite
Joined
Dec 26, 2014
Messages
3,161
Location
Northern Michigan
I realize this now... Mistakes are some of the best education, if not the best! I'll take it apart and redo. I don't have a gauge for adjustment or a manual for this carb so maybe online will yield some useful specs.
The lever usually goes level with either the carb body or the well it sits in. Gasket first, then diaphragm, then cover.

On the other side, the pump diaphragm (with the flappers) goes on first, then the gasket, and then the cover
 
Cliff R

Cliff R

Addicted to ArboristSite
Joined
Jan 24, 2008
Messages
2,445
Location
Mount Vernon, Ohio
The Tillotson HS series was used on many saws in that series. They can be a little "touchy" when it comes to metering lever height, especially on high hour models where there may be some wear in the bore the needle rides in.

I would also avoid non OEM rebuild kits for them. You may also find in necessary to remove the welch plug if all attempts to rebuild fail as there can be trash lodged under them that is difficult if not near impossible to remove otherwise.

 
Paul Silvestri
Joined
Sep 24, 2019
Messages
557
Location
S.W Montana
The lever usually goes level with either the carb body or the well it sits in. Gasket first, then diaphragm, then cover.

On the other side, the pump diaphragm (with the flappers) goes on first, then the gasket, and then the cover
This is just what I needed.. I rebuilt it like it was previously assuming it was correct and it wasn't.. I'm thinking the previous shop or owner swapped something and i only copied what they did. One should never assume!

Thank you so much!
 
Paul Silvestri
Joined
Sep 24, 2019
Messages
557
Location
S.W Montana
The Tillotson HS series was used on many saws in that series. They can be a little "touchy" when it comes to metering lever height, especially on high hour models where there may be some wear in the bore the needle rides in.

I would also avoid non OEM rebuild kits for them. You may also find in necessary to remove the welch plug if all attempts to rebuild fail as there can be trash lodged under them that is difficult if not near impossible to remove otherwise.

Oh this is perfect!! Thank you!
 
Cantdog
Joined
Feb 17, 2009
Messages
15,867
Location
Beautiful Rockbound Coast of Maine
I second using only the OEM kits. And the metering lever must be set flush with surrounding carb floor on these Tillotson carbs.. When I do a carb I always check the H&L passages to make sure they are clear by using the red straw on a can of WD 40 or similar inserted where the needles would be. By looking down the bore of the carb, holding the throttle plate open, you can squirt WD and and see if it flows well from the main jet on the high side and both idle jets on the low side. Also pay close attention to the little metering lever spring as they are quite fine and can't be stretched or stepped on etc. as this will render them useless and the carb untuneable.
 

Latest posts

Top