First, this thread will be of little use to anyone because it relates to an obscure saw, but I thought it came out cool and maybe will be an inspiration to others in similar circumstances. I have a McCulloch-branded clone of a Zenoah GZ4000 (the subject of this thread: http://www.arboristsite.com/community/threads/my-first-strato-porting-job.250199/ - made by Jenn Feng), and it has a "Smooth Pull" easy start system. I didn't initially mind it really, but the end of the big spring broke once already (it was VERY difficult to repack), and I knew it was only a matter of time until it went again. The increased compression after the mod didn't help. I had a spare, but gave it to a friend as I thought the design was weak, and figured the next time it broke I would defeat the easy start system anyway.
So today it broke, but not the way I expected! The assembly kind of jambed up too and would not retract:
The big spring was still intact. So now I was in a pickle, as the saw is from 2005 and parts are not available. While it is GZ4000-based very few parts will swap, including the recoil assembly or internals. I looked around at my piles of parts, and could not help noticing that a Poulan Wild Thing starter pulley was darn close:
Even the spring width and extension on the bottom of the pulley was the same. The problem was that the Poulan pulley was intended for a wider, shorter center post. I looked around and noticed my collection of spent CO2 cartridges, which have been quite useful stock in the past. The 3/4" OD and ~0.650" ID were about right. So I used a step bit to bore out the Poulan pulley, but not all the way through:
I put a 3/4" flat washer in there, but had to drill the center out to 7/16", which was a bit difficult. Here is the CO2 cartridge tube:
It looks a bit short because it will need to clear the spring at the bottom, or the end of the spring may not seat properly. Here is the tube test fit into the pulley:
I used the spring from the Poulan, but I think either would have worked:
I needed a bit of a spacer at the top, and found the nylon washer from something - an old plumbing fixture I think. I had to drill the center out to 7/16" too, which was again annoying:
I glued the tube inside the pulley with JB Qwik, as it is not under much stress. Here it is finished:
I used the McCulloch line which is a little thinner, and I will probably replace it once I get some more. It started and ran perfectly, and feels much better than the Smooth Pull did. The saw will get a lot more use now, as I've been kind of avoiding taking it to the woods due to the weak starter.
So today it broke, but not the way I expected! The assembly kind of jambed up too and would not retract:
The big spring was still intact. So now I was in a pickle, as the saw is from 2005 and parts are not available. While it is GZ4000-based very few parts will swap, including the recoil assembly or internals. I looked around at my piles of parts, and could not help noticing that a Poulan Wild Thing starter pulley was darn close:
Even the spring width and extension on the bottom of the pulley was the same. The problem was that the Poulan pulley was intended for a wider, shorter center post. I looked around and noticed my collection of spent CO2 cartridges, which have been quite useful stock in the past. The 3/4" OD and ~0.650" ID were about right. So I used a step bit to bore out the Poulan pulley, but not all the way through:
I put a 3/4" flat washer in there, but had to drill the center out to 7/16", which was a bit difficult. Here is the CO2 cartridge tube:
It looks a bit short because it will need to clear the spring at the bottom, or the end of the spring may not seat properly. Here is the tube test fit into the pulley:
I used the spring from the Poulan, but I think either would have worked:
I needed a bit of a spacer at the top, and found the nylon washer from something - an old plumbing fixture I think. I had to drill the center out to 7/16" too, which was again annoying:
I glued the tube inside the pulley with JB Qwik, as it is not under much stress. Here it is finished:
I used the McCulloch line which is a little thinner, and I will probably replace it once I get some more. It started and ran perfectly, and feels much better than the Smooth Pull did. The saw will get a lot more use now, as I've been kind of avoiding taking it to the woods due to the weak starter.
