# McCulloch PM610 Which spark plug and how do I get it to run smoothly and without cut?



## PinkyPerky (Dec 14, 2012)

Hi
I have a McCulloch PM610 chainsaw Model 600041B Ser No 11-077584 which has electronic ignition so there isn't much to adjust.
This was a new present from my parents when I bought a plot to build a house. It did a lot of work (though not for such a beast) but hasn't been used for over 10 years.
I have got it to start and even run several times for about 10 minutes (without the chain on) but sooner or later it just dies and doesn't want to start again 
It is not as smooth as I remember it but there is no smell of fuel so I don't think it is over-choked.
I have cleaned the spark plug and the filter and used a new mix of 40:1 McCulloch two-stroke oil. The carb adjustments haven't been touched yet. I am about to clean the muffler and the fuel line filter.
Can anyone say precisely which spark plug to use?
Suggestions on what to check to get it running better would be helpful
I have misplaced the outer bar plate - does anyone know what the part number is for this model and series, as the part catalogue I have downloaded may not be the right vintage.


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## heimannm (Dec 14, 2012)

Most likely you will need to remove the carburetor and give it a good cleaning, install a new kit with gaskets and diaphragms, new needle, etc.

Check the condition of the fuel line, could be soft or could have a crack that allows it to draw some air depending on how it moves. A new fuel line and filter would be a small investment at this point.

Outer bar plates are the same on all 10 Series and 600 Series saws, 64330 (set of two) or 64325 (individual plates) is all you need to know.

Spark plug should be AC CS45T or equivalent. It would be odd that the spark plug causes rough running but it can't hurt to try.

Mark


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## PinkyPerky (Dec 15, 2012)

heimannm said:


> Most likely you will need to remove the carburetor and give it a good cleaning, install a new kit with gaskets and diaphragms, new needle, etc.
> 
> Hi Mark
> Thanks for the reply.
> ...


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## russhd1997 (Dec 15, 2012)

I was having the same problem with my PM 610. I swapped the carb with my good running Timber Bear and still had the same problem. I exposed the coil, cleaned the surface of the magnets on the flywheel and coil and adjusted the gap between the coil and flywheel. I have since run about 6 tanks of fuel through it with no problem. 

A Champion DJ8 or RDJ8 spark plug also fits.


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## Chris-PA (Dec 15, 2012)

Make sure the plug wire is not rubbing on the flywheel and intermittently shorting out. Been there!


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## PinkyPerky (Dec 15, 2012)

Hi
Thanks for the comments so far.
Today I retrieved the fuel pipe from the tank. Filter was clean and the pipe appears fine.
Before I remove the carb I need to purchase a set of seals. I don't think I'll need a new needle as being the sole owner I know how little use it has had.
I looked at the carb today. It has a name Walbro at one end which is embossed with 21-245 2-3. Anyone recognise it and know what kit I need?
Where is the coil?


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## bplust (Dec 15, 2012)

The coil's next to the flywheel (on the opposite side of the saw from where you mount the bar and chain).

The carburetor is a Walbro HDB. So you need a Walbro HDB carburetor kit. Any dealer should be able to get them.


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## russhd1997 (Dec 15, 2012)

PinkyPerky said:


> Hi
> Thanks for the comments so far.
> Today I retrieved the fuel pipe from the tank. Filter was clean and the pipe appears fine.
> Before I remove the carb I need to purchase a set of seals. I don't think I'll need a new needle as being the sole owner I know how little use it has had.
> ...



My carburetor is a Walbro too. It has HDB cast into the side of it. A complete rebuild kit will have a new needle in it. 

The coil is under the cover over the fuel tank. To adjust the gap between the coil and flywheel insert a business card between the coil and flywheel magnets.


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## PinkyPerky (Dec 16, 2012)

How thick is a business card in mm?


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## heimannm (Dec 16, 2012)

0.25 mm or 0.010" is normally the correct adjustment. Those saws are prone to having the spark plug wire or kill switch wire short out due to the long route past too many moving and fixed parts. 

All of the 600 Series I have looked at (at least the ones that I remember) have the Walbro HDB carburetor.

Mark


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## PinkyPerky (Dec 16, 2012)

Thanks


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## John Lazar (Jul 9, 2016)

If you can help I would greatly appreciate it. Concerning my Mac Pro 610, I had it running great and after a couple weeks storage, will not even make a sound and just turns over. Using a spark site tool, and also confirming by looking at the spark plug which is new, there is a visible continuous spark. Tried new fuel and even starting fluid and no sound at all of even an attempt to turn over. Any possible reason what to do next?


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## Brushwacker (Jul 9, 2016)

PinkyPerky said:


> Hi
> I have a McCulloch PM610 chainsaw Model 600041B Ser No 11-077584 which has electronic ignition so there isn't much to adjust.
> This was a new present from my parents when I bought a plot to build a house. It did a lot of work (though not for such a beast) but hasn't been used for over 10 years.
> I have got it to start and even run several times for about 10 minutes (without the chain on) but sooner or later it just dies and doesn't want to start again
> ...


 I would try a new sp plug and make sure it is correctly gapped. To wide a gap can be a problem. It is common for electronic ignitions to go bad at or near a couple decades, and your symptoms are logical for either these parts failing. Old fuel often causes problems in the fuel system but if it runs 10 minutes normal before faltering ignition components sound more likely to me.
I have a 610 would make u a great parts saw. It ran excellent until a loose screw got into the flywheel, broke some fins and took a fair chip off the case between the flywheel and oil pump. I have all the parts it needs,( + 1 or 2 others parts repair 600 series power heads) and was going to patch the case and bring it back to running condition, haven't yet got to it. I don't know about now but a year or so ago ignitions for these were selling $30+ used to + 65. on new.


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