McCulloch 250... easy start... stalls immediately

[sliceoflife]

I don't see anything that looks concerning to me. There are some vertical lines/scratches, but they seem superficial... Scoring would actually mean channels/gouges, correct?


As for the last paragraph, Thank you. I suspect this MAY be the culprit and might break up the Carb to check it (new kit not arriving for two weeks, so it'd get a lot of time to soak in carb cleaner). I watched a rebuild youtube for this carb and then pulled the adjustment pins as they were not seating equally which the video said may indicate they'd been switched... this wasn't the case, the L pin's o ring was just completely obliterated and the H pin's o ring was bad but still intact. So I'll be swinging by harbor freight for some o rings on my lunch. The other warning in the video was exactly what you suspect... if the needle is being held open by a mismatched needle/seat or if the rubber on it is completely trashed, it would cause symptoms like what I feel like I'm seeing (ludicrous amounts of gas going through the carb)... so that'll get checked. And if that's not obviously the case, then I'll wait for the rebuild kit to get here and replace what I can.


Double checked and turns out I actually have an HL-63G, Not E. Only difference seems to be that the filter gasket from the kit won't fit my carb... and it seems there's no easy source for one that does (all reports from HL-63G rebuilds report having to reuse the original gasket). I suppose I could cut my own replacement, but hopefully it's not too bad for me to reuse.

 

[Okie]

I would not leave it in carb cleaner for long period of time.
Usually first time I go into a carb I do so with a minimum of soak and just replacing some gaskets and clean the needle seat with a Q tip and spray on carb cleaner from a can.
I sometimes at first just use 50/50 mix of warm water and vinegar or even dawn dish soap mix.
If using vinegar leave in soak about 30 min, remove rinse and using low pressure air NOT OVER 25 PSI and do not direct inject high pressure air into any of the port holes and then back into the cleaner for another 30 min. If using the 50/50 vinegar mix do a final rinse soak using spoonful of baking soda in water to neutralize the vinegar acid on the aluminum. If the vinegar is not neutralized with baking soda it will keep re-acting on some magnesium or aluminum and make it feel gummy on the surface and turn black on some carbs so best to neutralize.
Carb cleaner from a spray can is ok.
I have a heated Ultra Sonic that is really good for cleaning carbs when I get into the contrary ones.

If you direct inject high pressure air you can loosen or blow out welch plugs plus ruin other things or send unseen things into orbit.

Them cork gaskets are usually re-useable if care is taken when removing the plate, peck on the cover gently with a screwdriver handle with the screws loose and or soak in hot water first. Replacements small cork gaskets are not easily made by hand.

 

[sliceoflife]

All Good to know, Thanks again.

 

[mg1944]

Your description makes it sound as though it is very lean, even to the point of running out of fuel at high speeds. I normally start with both H and L out about 1-1/4 turns and work from there, acceleration should be fairly crisp when you hit the throttle and it should just begin to 4 stroke when running wide open unloaded. Often they need to be quite rich (really 4 stroke unloaded) to supply enough fuel under load.

Mark

"It should clearly 4 stroke out of the cut and clean up when you put some load on it."
could somebody translate that for me? I haven't got a clue what it means, and I've been around saws all of my 65 years. might as well be Swahili.

 

[Okie]

"It should clearly 4 stroke out of the cut and clean up when you put some load on it."
could somebody translate that for me? I haven't got a clue what it means, and I've been around saws all of my 65 years. might as well be Swahili.

Search around on-line and you will find some you-tube videos with how it should sound.
The 4 cycle sputter is how the Mac should sound out of the cut indicating that it's running somewhat rich, termed 4 cycle sound, instead of a 2 cycle scream.

 

[Old2stroke]

The amount of fuel required for proper combustion in a 2-stroke is dependent on the load on the engine. When the engine is running fast but not cutting, the fuel/air mix is too rich and it makes a rough, bubbly sound commonly called 4-stroking. When you stick the chain into some wood, the engine is seeing that as a load and the air/fuel has to be right for that condition, being right means that the exhaust note should change to a crisp, clean sound. When starting the first cut with a cold saw, the A/F mix will be way rich from all the choking and should make that obvious 4-stroke sound when you first start cutting and if the carb is properly adjusted, you should hear an obvious change in exhaust note as the saw gets into the cut and cleans out all the residual fuel from the starting process. It's hard to pick out the difference in exhaust sounds with some saws and beware of saws that have rpm limiting ignition as they sound very much like the 4-stroke sound when they are running at full throttle with no load. If possible, listen to a concrete saw, they seem to always be running under RPM limiting.