My 154se won't idle

[CJ Brown]

Well I finished another saw yesterday - a 1983 154SE. It had a top fin broken so I decided to do a little porting on this one - a first for me on a saw. I ended up with 121-102-79 for numbers. I used a red97 deflector to make a dual port muffler, did a small timing advance, and bored out the air filter inlet along with the carb elbow to 11/16". Even though it is quite cold today, I HAD to see if it would run, so that's where I am now. It wouldn't start so I checked for spark and didn't see any. So I swapped coils and then I had spark. So at this point the saw was flooded but I finally got it started by holding the throttle wide open while starting it. It wasn't running super great (rich) but the saw was cold so I kept the rpms up until it was warmed up a bit. At this point it would rev super quick, but would not idle at all. After messing with the low speed for a while, I decided to switch carbs. Saw started quickly and again will rev quickly when hitting the throttle - I mean it seems to run fantastic - but if I lower the idle speed down low enough to stop the chain from moving, it just dies quickly - like you turned it off with the switch.

Saw has new air filter, fuel line, fuel filter and Denso plug. All oem parts, and both carbs were cleaned and kitted. HDA120 carb. Saw passes both vacuum and pressure test, both carbs held 12psi on inlet.

Anyone have any suggestions what to check next?

 

[jacob j.]

It sounds like it may not be getting good impulse - Check the intake block to see if it has any cracks. If it's good, then pull the saw over
with the spark plug out and feel with your finger for air wooshing out of the impulse channel.

Also, make sure your intake gaskets are all lined up correctly.

 

[CJ Brown]

It sounds like it may not be getting good impulse - Check the intake block to see if it has any cracks. If it's good, then pull the saw over
with the spark plug out and feel with your finger for air wooshing out of the impulse channel.

Also, make sure your intake gaskets are all lined up correctly.

Okay I will take it apart tomorrow and I will swap out the intake block and install new gaskets. I will also check the impulse channel as you suggest. I will check back in tomorrow and post results. Thanks JJ

 

[CJ Brown]

Followed @jacob j. 's advice this afternoon and checked everything he suggested. I think I had a slight gasket leak between the intake block and the carb as there was signs of wet fuel on the bottom of the gasket. Installed new gaskets and put everything back together and saw fired right up. Adjusted idle speed and low speed needle and she purrs like a kitten now. Another lesson learned - thanks JJ!

 

[jacob j.]

Excellent - nice work getting her figured out.