Some probably seen the thread on the Bush Hog HD-12 where I found a Kohler K341 to do an engine swap with. Got everything swapped and once I had it running realized the governor wasn't working. I pulled the engine apart and found the governor gear wasn't on the shaft. Almost like someone pulled the retaining screw for some reason and it fell off and thankfully just rested in the corner without taking anything out.
Fast forward to getting it all back together and running good. I had taken the tractor to the Menges Mills show last weekend. It has been running good other than the bad battery. Went for a longer ride pulling a trailer and than later went for another ride to pick up a disc plow and it was almost like it loaded up to the point it all but died and almost sounded like and engine that started to run backwards. I shut it off and it fired right off and was good till we got back.
Once we got home and went to unload it off the trailer it just didn't seem right in the mid to top end. I than realized I had a mopar coil which requires an external resistor so I thought the points may have gotten burnt up causing poor timing. So I ordered a proper coil, also got new points and I also got a carb kit since the float bowl was leaking a little.
All of that prior I had a straight pipe on the engine but I was tired of all the noise so I wanted to put the original muffler on since I was going to be working on it again. This muffler is the same one I had on when I had the Wisconsin in the tractor and that engine seemed very anemic in power.
I got the new points installed and set the points gap at .020 per the manual. The old ones didn't look too burnt but they definitely didn't look the best. I also got the new coil and carb kit installed. Fired it up and it started easily and idles perfectly. Ran the throttle up on it and it sounds like it is fighting to reach top speed and it was shooting 3 to 4" blue flames out of the muffler and also when bringing it down to idle it would pop with a larger orange flame. Shut it off and it would backfire with an orange flame also.
So I figured the timing may be off since backfiring is usually a sign of timing being off especially with flames since that is a sign of un-burnt gas in the exhaust. I had to pull the flywheel shroud off so I could get to the timing marks and mark them with white chalk. I got them lined up and set the points with my continuity / voltage tester where it just broke continuity and tightened everything down. Fired it back up and it seems to start even faster now but still shows the same signs in the upper rpm with the flames out of the muffler and popping after shutdown.
I didn't notice these issues when I had the straight pipe on so I am wondering if the muffler could be causing these problems? Obviously if the muffler was clogged it would make it hard for the engine to run. I didn't think to look in to the muffler (not that I would have been able to see anything) before I put it on and welded it to the pipe. I might take a sharpened metal rod and poke a could holes in the baffle if I can. I would like to see what you guys think.