Hello all,
I am far away from my D4/7U and D2/3J at the moment. If possible, could you give me the OD dimensions of the pony and main exhaust pipe that come out the top of the hood on the D4 and also the same dimension for the main pipe on the D2. I also am thinking of modifying a spare exhaust manifold I have for my D2 and having the pipe come out the top of the hood like on the U series D2’s. The dimensions would be used when ordering Spark Arrestors for these machines. Thanks in advance and hope you all have a great day. 👍👍.
Joe Giraud

The D2 pipe dimensions are 2-1/2" OD for the main and 1-1/2" for the pony, these are a pair of the Hapco spark arresters I bought for one of my D2s, they were sold as pictured. 3AA for the big one 1AA for the pony. I don't have a D4 to measure.

Thanks Josh. 👍👍👍

Josh, does that spark arrester on the pony cut down on the bark? I dont mind the big engine sound but the pony is brutal. Interesting, Grant.

Spark arrestor on the pony helps a little, I still would not start one without earplugs.

i know the hotdog style muffler off a 5hp briggs and stratton fits in the pony exhaust just nicely. and it makes a fair difference to the noise.

yeah they deafen you without it.

it might sound strange but a bit of copper pipe works well as a muffler. especially if you cap the end and then come down a bit and drill several holes equal to the pipe area. so yes you need to use Pir2