THE PORTAL HUB - Pinzgauers, Haflingers, Volvo 303s and more!

Has anyone had success with a non OEM muffler? Mine pops and backfires. I'd like to build something a bit quieter for as little $ as humanly possible =)

I built a "cherry bomb" silencer for Lurch - it's a bit loud as it is basically a straight through pipe, but if you are looking for something quite your biggest issue will be to find a silencer which has less than a 2 inch diameter pipes in and out. Haflingers have 1.25" pipes from the manifolds and the exit pipe on the standard silencer box is less than that.

Most usual reason for popping and backfiring is due to air leaks and have too rich a mixture. i.e. there is still some unburnt fuel in the exhaust gas as it leaves the cylinder, then it sucks in some more fresh air when you take your foot off the throttle. The gas mixture then becomes correct of it to ignite and it goes "bang"!

John
Lurch has the Heat exchanger heating system.

If you have an RV supply place or RV dealer near by, you might take a look at the various resonators for Cummins and Onan generators. They are usually fairly short and have small diameter in/out pipes. Just might work.

Skidoo, quad and side x side mufflers are another option.
Soni in NM used a skidoo one but not sure of model

Or your contactpoints are bad...or the ignition timing isnt on point or a bit late it backfires in the exhaust

Jim l rebuilt this engine. I'm hoping he set the timing properly... I have confidence in the man. I'll check to be sure.

It has an aftermarket hack job exhasut as is. I believe it's time to remove and replace over the winter.

OEM mufflers do not pop and backfire (through the exhaust rather than inlet)- that is a function of your tuning settings - ignition and fuelling - worse case are valves not sealing on compression and letting fuel mix into the exhaust. Without fixing this any muffler will pop and backfire.

Pop and backfiring is unburnt fuel being burnt (exploded in the exhaust). The reasons for this can be varied - retarded timing, too rich a mixture, intermittent ignition, leaking valves etc. I have a Landrover V8 that was timed and tuned perfectly but it started backfiring and then blew the muffler apart with a huge bang. The LT lead to the coil came away from its connector making intermittent contact so every now and then no spark to individual cylinders but of course fuel was still going in and then out of the non firing cylinder into the exhaust but then ignited by the next firing cylinder.

So get you fuelling and ignition sorted before worrying about the muffler.

My Haf is 762cc and is tuned to standard specs - so 7mm before TDC as per the handbook - ensure mixtures are correct and you should not have an issue.

PS when I had my Haf last tuned it had hi hydrocarbons in the exhaust - tappets were too tight stopping the valves from completely closing allowing unburnt fuel into the exhaust - not enough to pop or backfire but enough to lower performance and hi hydrocarbons in the exhaust.

So get your tuning sorted first.

Garry