MCCULLOCH The official McCulloch thread

[MedicineMan]

When the trigger was in idle position, the throttle rod was touching the uninsulated portion of the off switch wire, grounding out and killing the spark. When the trigger was pressed it would move the rod away from the uninsulated end so it would perform like it was supposed to.

 

[Dream]

First couldnt get the points to open.
Turned out to be a TINY steel shaving bridging the points strap to the adjuster screw clamp.
Still no spark.
Pulled the coil wire. That looks rough, but wasnt open.
Then I noticed the primary terminal on the coil was loose where it was soldered on, so I pried it off.
Now I'm getting 14 ohms across primary to ground terminal, but still not happy with secondary side.
Any ideas?

 

[MedicineMan]

That what was puzzling me when I was starting my nap. It would run perfect at anything past 1/4 throttle but die without a sputter if I let the trigger in to a certain point. I kept thinking fuel/air and trying everything related to those two. Started trying to think out of the box (something simple stupid) and when I woke up it fell on me like a pile of bricks.

 

[MedicineMan]

Those readings seem very high. Maybe someone Like @heimannm will chime in but I thing the primary should be 1-2 amps and the secondary 8-12 Ka. or in that vicinity

 

[MedicineMan]

Want me to send you a coil to try? I'll ohm it first.

 

[MedicineMan]

oops I meant 1-2 ohms and 8-12 Kohms.

 

[MedicineMan]

My skills as an electrician align with my ability as a photographer.

 

[Dream]

oops I meant 1-2 ohms and 8-12 Kohms.

LOL!
I understood what you meant D.
Ive been trying to solder this tab back on. Cleaned it multiple times, bit it keeps wicking oil and crud up the post.
I did get a read of about 1 ohm across the primary. Secondary is still flaky.

 

[MedicineMan]

 

[MedicineMan]

These are in the range of readings I usually get when I test a Mac coil

 

[MedicineMan]

That's the coil I'll send, complete with dirt grease and mold.

 

[Dream]

That's the coil I'll send, complete with dirt grease and mold.

It'll already match the "patina" on this one.

 

[MedicineMan]

Just let me know. You can text your address. Might check the condenser in case I need to throw one in the box. I only have old used stuff but can check to make sure it charges and discharges.

 

[Vinnywv]

That what was puzzling me when I was starting my nap. It would run perfect at anything past 1/4 throttle but die without a sputter if I let the trigger in to a certain point. I kept thinking fuel/air and trying everything related to those two. Started trying to think out of the box (something simple stupid) and when I woke up it fell on me like a pile of bricks.

What a good find. You mustve had a great dream. Lol

 

[Dream]

What a good find. You mustve had a great dream. Lol

I looked at mine since that came up, and its REALLY close.
I can see where a little tweak would cause it to contact.
Think I'll put a little heat shrink on it at some point.
Good find!

 

[Al Smith]

A lot can be said about solder joints which on oily stuff can be a chore .It's got to be physically clean and chemically clean else if it does stick it could be a "cold " joint .A cold joint on the low voltage side will be nothing but trouble . A suggestion try using something like brake cleaner first and let it dry as it evaporates .Be careful not to get in the fumes .Then use a little bit of acid flux with small solid core electronic solder which melts easier .Some like to use a 35 watt pencil iron ,I use a 100 watt Weller gun type .Like many things the only way to get good at it is to do it .I've been at it for a long time from printed circuit boards to radiators on bull dozers .refrigeration tubing joints using silver bearing solder which is almost as strong as silver brazing .BTW that stuff cost over 40 bucks a roll .

 

[edju1958]

I had a similar situation on my SP125 as well.I got it fired up & then it'd start cutting out when I throttled it up.I went through the carb & it did nothing.For some reason I had to pull the recoil off & found a bare spot on the switch wireAs a quick fix I found a small diameter fuel line & put that over the switch wire & all was good.I got the new switch wire from Bob J.,but still haven't put it on,.That was about 1 1/2 yrs.ago.This is still in my head - when I was first starting out working on saws about 5 yrs.ago,a saw shop owner told me that a fuel delivery issue can mimic an electrical problem & vice versa.Never forgot it.(And it can be difficult to discern between the 2)

 

[heimannm]

Around 1 ohm on the primary, 9-10K ohm on the secondary would be the correct range.

Mark

 

[Dream]

Around 1 ohm on the primary, 9-10K ohm on the secondary would be the correct range.

Mark

The coil seems to be good, I just cant get it to stop wicking crud up the post and ruining the joint.
Ive cleaned it with brake cleaner etc.
May just keep at that and see what happens.

 

[Al Smith]

Two thoughts .Maybe if you buried the coil in a coffee can full of oil dry, kitty litter it might suck the oil out of it .Another which I've done is bake the coil at low heat ,like 200 degrees it will drive moisture out of it .Did that on a points type Mac coil and it fixed it .