I gutted my 7900 muffler before even running the saw when new. Thankfully I had a small MIG gas bottle from when I installed the stainless exhaust on my truck. It is a tri-mix: helium, argon and CO2. So, I quickly ground down the pinch flange on about 1-1/2 sides of the muffler. Used a cordless 4-1/2" grinder to take off as little as possible. The rest of the pinch flange will side as you use a mallet to separate the two halves. Once apart I salvaged the crack-pipe flange and tacked it to the inside of the muffler at the inlet. Slide it back together then weld up the flange seam which doesn't take long since it is roughly 1-1/2 sides. Admittedly it is nice to have the gas and 0.023" stainless wire. I just had cheap wire I got off of Amazon but it works well. I will Makita was still making these saws. Ran the 7900 last weekend with a 32" bar. Very nice running saw. I am going to take a shot at modifying the carb next - drilling out some jets and things.
Alpina C50 chainsaw has a muffler with a divider in the middle and the divider has a tube with a dense wire mesh inside. The only way gasses can escape is that wire mesh. I used the same technique as you to open the muffler and remove the divider completely. The problem I have now is that I can't press back the seam airtight as it was, so it's leaking heat in many spots. I heated the seam and used pliers to press it back. Maybe I should heat it again and hit it with a hammer.
I gutted my 7900 muffler before even running the saw when new. Thankfully I had a small MIG gas bottle from when I installed the stainless exhaust on my truck. It is a tri-mix: helium, argon and CO2. So, I quickly ground down the pinch flange on about 1-1/2 sides of the muffler. Used a cordless 4-1/2" grinder to take off as little as possible. The rest of the pinch flange will side as you use a mallet to separate the two halves. Once apart I salvaged the crack-pipe flange and tacked it to the inside of the muffler at the inlet. Slide it back together then weld up the flange seam which doesn't take long since it is roughly 1-1/2 sides. Admittedly it is nice to have the gas and 0.023" stainless wire. I just had cheap wire I got off of Amazon but it works well. I will Makita was still making these saws. Ran the 7900 last weekend with a 32" bar. Very nice running saw. I am going to take a shot at modifying the carb next - drilling out some jets and things.
Alpina C50 chainsaw has a muffler with a divider in the middle and the divider has a tube with a dense wire mesh inside. The only way gasses can escape is that wire mesh. I used the same technique as you to open the muffler and remove the divider completely. The problem I have now is that I can't press back the seam airtight as it was, so it's leaking heat in many spots. I heated the seam and used pliers to press it back. Maybe I should heat it again and hit it with a hammer.
Yeah sometimes that happens. Maybe a form of soldering rod could be applied to the seem could help you out in sealing that up.
Just fit a stihl 460 muffler they fit real good
That is good to know and I will give it a try. Thank you