dolmar 6400 muffler mod

[havenodog]

Hi guys;
  Just got finished with a muffler mod on my dolmar 6400 from home depot. Incidentially they had a great deal on a used one in great condition here in Carlisle PA. for $205. The mod took me about an hour to do and was really quite simple. All you do is remove the muffler and pry open the flap that holds the two halves together. I used a regular flat headed screwdriver. Once you have the two halves apart, discard the "guts of the muffler and put the two pieces back together using the anvil end of a table vise and a piece of round or square steel stock to pound the flap back. You can also use the end of a large punch if the end is flat enough. Afterwards I drilled a 5/8" hole about an inch below the muffler mounting holes and took a dremel and smoothed out all the edges. It would have been nice to weld  a washer and screen over the hole but I don't have anything to do that kind of welding with. Afterwards I started it let it warm up and tached it to about 13,000 rpm WOT with bar and chain. Jets are set and man this thing is a screamer. It's got a 20" Arbor pro bar on it with an Oregon round chisel chain 3.75 .050 guage. If anyone out their has a 6400 that is looking to get more power out of it try this. It works great. Thanks for all your great posts.  Greg

[Cut4fun]

There is a 13,500 rev-limiter built in these saws. So make sure you dont run into the limiter on the carb adjustment(will sound like it has a miss or cutting out). i have mine set a 13,330K and you can push right up to the limiter, just dont bump it, it will run 12,600K when you hit limiter and retard timing and be in a lean condition.

[havenodog]

That's a good looking muffler Cut4fun. What did you use to cut the hole in the side? Did you split your muffler or do something else?                                                                               I was going to go a little higher than 13,000 but thought it wouldn't make that much difference in the cut. What do you think? Anyway It's a great saw. Just one question. If you put a 7900 top end on this saw are the muffler dimensions the same? I'd love to run a 24" bar on this saw for the bigger stuff. I've got a Waldkerized 353 with a 16" bar for the smaller wood. They say in the specs that you can run up to a 32" bar on this saw but that seems to be too much for a saw of this size. Any comments? Thanks

[Cut4fun]

JMO, i wouldnt go over 24" with a stock 6401. Mine started off stock 6401 too and has a modded 7900 on it now. You can get the stock 7900 topend and parts for the change over for 190-200. Muffler is the same, hole on other side was cut out to match the stock side hole using a dremel. It was opened up and baffle removed too.
The guy that did the mods did all the work, plus port matching everything to the exhaust port to muffler. Plus he has all the right tools. I can run a 32" on mine and can not tell any difference from running my 16" on it. It just eats and spits wood. 13K is good.