H Backfires Deceleration

[AgTires4295]

Hey all, Ive been enjoying the H for awhile and have added a few mods. One recent was a chrome straight pipe to spruce it up from the old canned muffler.

I drove the H for the first time at night since the switch to a straight pipe and noticed a very uniform response. Upon deceleration from full throttle and/or going downhill, it backfires, throwing light flames and pops like a shotgun blast. It's quite entertaining as I never noticed this trait before with the canned muffler but is this normal? I have it timed pretty well so I'm not sure what's what.

I'm hoping to not cause any damage but it seems as though this may be normal. Any input?

[Jim Becker]

Sounds normal to me.

[Rick Spivey]

They tend to run rich, so the excess fuel is detonating in the straight pipe. The original muffler would have, well, muffled this, and had baffles to stop the fireworks show.

[AgTires4295]

Thanks for the responses. I figured as much but wanted to be sure. The fireworks show was fun on the long downhill deceleration.

[v w]

The H was ok but I liked the M. It had a louder pop. I would leave the throttle full and close quickly just to hear it. Close the throttle slowly if the pop bothers you. This does nothing for the downhill however. Vern

[Urbish]

Sounds normal to me.

Pretty much any carbureted engine running with nothing but a short straight pipe from the exhaust will backfire and pop. This is a consequence of not having any back-pressure and the fact that a carburetor briefly allows an over-rich fuel ratio into the engine during deceleration. Don't run that thing under any low-hanging dead trees

[AgTires4295]

I love the responses. Many thanks, gents! I definitely enjoy the show. It gives the H a neat characteristic that my A and Cub (straight pipe) don't have.