Chainsaw problems

[Zacchainsawmiller]

Gday guys I've got a baumr ag sx72 I've had it for a couple of years always ran on 25:1. Tuned the saw when I first got it got it running really well, lately I've been doing milling with it and it seems to go really well until it gets hot. At first I thought it was the air filter it wasn't sealing around the throat of the carb and dust was going straight through as well so I fitted some rubbers on to seal it and put some air filter foam inside the filter. Had stopped the problem of dust going straight through and sealed the air filter needed another tune but got it running great again until it got hot. It seems like its struggling for fuel but I've checked the fuel filter and lines for cracks and they're all in really good condition. I've replaced the spark plug with NGK and its made no difference. I realised that one of the screws to the top plate on the carb was loose so wondered if dust could had got down in there but that seems as clean as. Sorry for the long post but I'm not sure what it could be now, any advice would be greatly appreciated cheers

 

[rarefish383]

I'm not familiar with that saw , but with 2 strokes, you have to be real careful about running them lean, and a loose screw on the carb can do that. I had two of my Dad's Homelite Super 1050's. I had a loose screw on top of the carb of one and it started leaning out and I kept running it to finish the job. Melted the rings into the piston. That's how I found this site. Now I make sure I never let them run lean, especially milling.

 

[Zacchainsawmiller]

What would you recommend running it at? I've always done it 25:1 knowing that the motor should last longer. My dad has a husqy 340 he's had that for 19 years and always ran it on 25:1 and its always been a great little saw punches above its weight really.
I've been over the carb and everything looks fine, once the saw is hot it'll bog down in the revs hard then it'll struggle to get back up in the revs but once it starts to pick back up it'll rev flat knack as quick as it should then bog back down. I've tuned it flat out and am confident its where it needs to be it idles well cold revs well cold cuts well

 

[BobL]

Sorry if I dis your saw but IMHO the Baum ag range of saws are not worth the headaches they generate. With chainsaws you basically get what you pay for and any $99 saw simply cannot be made to run long term under hard conditions that milling requires. I had had to deal with a few Baums and they have all been very ordinary in the way they are made. One of my mates, 79 year old mate asked to have a look at his brand new Baum that he could not start. His son had also tried to start it without any luck. It turned out the kill switch was wired in backwards but when I went to desolder the connections my small (electronics) soldering melted the plastic around the switch so I had to fit a new one.

All that aside as far as your problem goes;
Forget the filter, the saw should still run at full power without one.
If it was a carby issue that would manifest itself even when the saw is cold although a complete carby tear down and clean would be worth doing. It might be one of the carby gaskets
The way the saw bogs loses power when hot, sounds like a possible vacuum leak.
This could be anything from a cracked impulse line to a cracked crankcase, has the saw ever been dropped?
The impulse line needs to be more that visually inspected.
It needs to be removed and pressure and vacuum applied to see if it leaks, it might just be a pinprick.
Place it under near boiling hot water and apply a bit more than the usual pressure eg +/- 15 PSI and look for bubbles.

 

[Zacchainsawmiller]

Sorry if I dis your saw but IMHO the Baum ag range of saws are not worth the headaches they generate. With chainsaws you basically get what you pay for and any $99 saw simply cannot be made to run long term under hard conditions that milling requires. I had had to deal with a few Baums and they have all been very ordinary in the way they are made. One of my mates, 79 year old mate asked to have a look at his brand new Baum that he could not start. His son had also tried to start it without any luck. It turned out the kill switch was wired in backwards but when I went to desolder the connections my small (electronics) soldering melted the plastic around the switch so I had to fit a new one.

All that aside as far as your problem goes;
Forget the filter, the saw should still run at full power without one.
If it was a carby issue that would manifest itself even when the saw is cold although a complete carby tear down and clean would be worth doing. It might be one of the carby gaskets
The way the saw bogs loses power when hot, sounds like a possible vacuum leak.
This could be anything from a cracked impulse line to a cracked crankcase, has the saw ever been dropped?
The impulse line needs to be more that visually inspected.
It needs to be removed and pressure and vacuum applied to see if it leaks, it might just be a pinprick.
Place it under near boiling hot water and apply a bit more than the usual pressure eg +/- 15 PSI and look for bubbles.

Yeah I've heard that about the baumers too had it for two years never had a problem with it until now and I've cut over 40cubic with it so its paid for itself. The air filter actually wasn't sealing off on the carb and the air filter are nasty dust was going straight to the carb, never had a problem just blocking wood because it spits chips not dust while milling. The saw has never been dropped and always looked after really well. I have checked the carb gaskets and they were in good condition

I will check over it but once the saw is cold again it'll fire back up no problems and go sweet until hot, thanks for the response anyway really appreciated guys