# McCulloch PM610- starts and idles..dies upon accleration except 'milking' it up?..



## mowisme (Jul 10, 2011)

It only idles- try to rev it up and it cuts out or kills..If I keep burping the trigger at small intervals I can get rpm's up-but only for second or two. Things I've done(1) Checked screen in muffler- cleaned it-wasn't that bad thou (2) bought a new wabro carb-set screws at 7/8 out on 'H' and 1 turn out on 'L' (3) fresh gas mix at 40:1 (4) can't recall if new..but plug was from other running saw. P.S. exact same symptons with new carb as old. I also checked fuel line for kink or air leak..nothing wrong with line. My only assumption is bad seals? but if bad seals why would it start after 2-4 pulls? Also good compression by bicep check..will get meter reading. Gene


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## Roanoker494 (Jul 10, 2011)

The issue you describe indicates a carb\fuel delivery problem. A bogging issue is almost never, if ever, traced back to a air leak. Symtoms of a air leak would cause the engine to race when started or turned on it's side. Need to completely disassemble the carb, clean it out and install a fresh kit. My guess would be trash in the high side jets, bad pump diaphargm and\or sticky inlet needle. I would also pull the fuel filter out and blow air through backwards, may want to pull the line loose at the carb and blow through it a little in case there is trash stuck in it. Make sure the line is not in the fuel and the cap is off the tank or you could get a shower in gasoline and exploded fuel tank, as how I know.


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## mowisme (Jul 10, 2011)

*thanks ..*

I cleaned the old carb couple times to no prevail..so just bought new one. Line is clear..but I'll do as you said and blow back thru it. I did make some progress. I opened 'Both' screws to about 1 and 3/4 out. way more than specs..but did run sorta good? had full throttle but idle wouldn't get low enough. I turned 'L' in little and it got lower but not enough..little more and it died out. I'm wondering if maybe I got a intake leak below the carb mount somewhere? thanks again.


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## rob066 (Jul 10, 2011)

Just a thought. Set your low to where the saw starts and accelerates smoothly if you can. Then adjust the idle screw to your liking. Your saw may be richening out and flooding at low speeds because the idle screw is set to low. You may be compensating for the idle with your low screw and not the actual idle adjustment.


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## heimannm (Jul 10, 2011)

Hey Gene - Continue to open up the H jet untill is rev's and runs up to full speed with power. In fact, keep going on the H until it starts to slow a bit, even a little 4 stroke with no load and it should have plenty of power in the cut.

Even 1 to 1-1/2 open on the H is not too much. Beyond that you may have to readjust the metering lever as it certainly sounds like it's not getting enough fuel. As Roanoker noted, seal issues would be more like reving out of control, changing speed on it's side, etc. Lack of power & failure to speed up indicates it is not getting enough fuel.

Mark


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## mowisme (Jul 10, 2011)

*thanks all*

I'll work with it tomorrow..tired..time to put it to rest for a day. Thanks much. I'll let you know how I come out.


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## Sprintcar (Jul 10, 2011)

heimannm said:


> Hey Gene - Continue to open up the H jet untill is rev's and runs up to full speed with power. In fact, keep going on the H until it starts to slow a bit, even a little 4 stroke with no load and it should have plenty of power in the cut.
> 
> Even 1 to 1-1/2 open on the H is not too much. Beyond that you may have to readjust the metering lever as it certainly sounds like it's not getting enough fuel. As Roanoker noted, seal issues would be more like reving out of control, changing speed on it's side, etc. Lack of power & failure to speed up indicates it is not getting enough fuel.
> 
> Mark


 
Great advice from a man that has forgot more about saws than I will ever know. Carb tuning comes with experience and don't feel bad if you don't get it spot on the first time. A few things I have learned over the years;

1. Adjust both the Low and High jets until just seated, open to 1 to 1 and 1/2 turns open. This will get you in the ball park.
2. Crank the saw and set it down for 5 to 10 minutes. This will allow the saw to come to operating temps. NOTE, if it won't idle for five minutes you may have other issues.
3. Adjust the Low (L) jet for HIGHEST idle RPM. Readjust the idle for an RPM just below clutch engagement, the chain does not move.
4. Check the transistion from low jet to high jet. The saw should accerlate smoothly with no burbles or bogging. If the saw staggers, burps or bogs readjust the Low jet in 1/8 turns to richen the low side. In some cases a too rich low side adjustment will cause the saw to bog and not make a smooth transistion from the L circuit to the H circuit.
5. Operate the saw at NO LOAD WOT, wide open throttle, you should hear four stroking with no load across the saw. Four stroking can be described as it sounds like the saw is missing. This is caused by not all of the fuel delivered to the combustion chamber is being burned and the excess is being forced out the muffler.
6. Using a good piece of wood at the start of the cut the saw should four stroke at the initial start and then clean up, noticeable change in sound as the torque rise and cylinder temps rise in a loaded condition. This takes practice and listening to what your saw is doing.

Hope this helps, I've only blown up a couple saws doing this, O.K., three or four. There are numerious threads and web sites that have audio of the correct method of tuning two stroke carbs, give a listen and go practice.


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## NORMZILLA44 (Jul 10, 2011)

Speaking of great advise, I remember a guy who showe'd me step by step, a fuel line replaceme't for a 044 step by step. I still remember that how ya doing Sprintcar?


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## imagineero (Jul 11, 2011)

tried replacing the fuel pickup? They're pretty cheap. 

Shaun


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## mowisme (Jul 11, 2011)

*thanks on advice..*

The pick-up is like new yet. The end has a foam like element that pops out of a rubber cup. I'll look at it again..clean it too anyway, but it seems to be at this point carb adjustment. I did get it to run on high after bringing screws out to 1.5 turns out. Just not dialed in right yet. I'll look at it when time permits. thanks


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