drilling spree exhaust

[Fraser4204]

Hello, I have an 86 spree and was thinking about drilling a few holes in the end of my exhaust for more power/ top end. If I decide to do so, do I need to upjet or tune anything else so that Im not running lean?
Thanks

[Bear45-70]

You want to drill the baffle inside the muffler. Be advised that these things are labeled "do not modify" to make the EPA happy and it may well be louder if you start drilling the muffler.

[Fraser4204]

I was thinking of drilling holes in the end where the tip is. the screws holding the baffle plate on are too rusty and I can not get them off. My biggest concern is that if I drill holes, how do I compensate for the extra pressure and heat. Do I need to increase my air/gas flow, upjet, etc. Thanks

[Bear45-70]

I was thinking of drilling holes in the end where the tip is. the screws holding the baffle plate on are too rusty and I can not get them off. My biggest concern is that if I drill holes, how do I compensate for the extra pressure and heat. Do I need to increase my air/gas flow, upjet, etc. Thanks

That is not a baffle plate. That is a heat shield. All the baffles are internal. Drilling the back end of the muffler will not help. All the baffles are in front of there.

[Fraser4204]

In that case what is the best method? Do I drill holes through the outside of the pipe a few inches away from where it meets the cylinder port. And how many and what size? Also, do I need to increase air flow or upjet?

[fastplastic]

or... you could just look for a 87 muffler which flows better drilling holes doesnt really do anything for you

[Fraser4204]

or an aero exhaust. Drilling holes will definitely do something. I ran it for a short time without the pipe and i was going 4 mph faster

[Wheelman-111]

Greetings:

Running with no pipe at all?! No doubt it sounded faster, but I'd like to see that GPS reading go up 4 MPH. If it's faster, it won't be for long. The exhaust pipe prevents unwanted oxygen from being re-aspirated and admixed with the intake charge. Without it, the engine will run extremely lean. Even a leaky gasket with an exhaust installed can bring on all manner of top-end woes. I suggest you don't risk it again.

I agree with the previous remarks asserting that drilling a pipe will have no meaningful effect on performance. However it may have a very negative effect on Neighbor Relations.

[fastplastic]

Greetings:

Running with no pipe at all?! No doubt it sounded faster, but I'd like to see that GPS reading go up 4 MPH. If it's faster, it won't be for long. The exhaust pipe prevents unwanted oxygen from being re-aspirated and admixed with the intake charge. Without it, the engine will run extremely lean. Even a leaky gasket with an exhaust installed can bring on all manner of top-end woes. I suggest you don't risk it again.

I agree with the previous remarks asserting that drilling a pipe will have no meaningful effect on performance. However it may have a very negative effect on Neighbor Relations.

Thank you...

[wiguy05]

Drilling holes will definitely do something. I ran it for a short time without the pipe and i was going 4 mph faster

[honda spree 86]

what i did drilled out baffels nothing happened drilled out a hole right next to it then got results it also sounds really good, and i did a pulley mod i got it to top speeds of 36 but lost take off. i will be puttin a preformance head on it and upgrading the carb with my brothers dirtbike carb

[fastplastic]

no thanks to the drilling of exhaust though, fact proven that does nothing.......

[Bear45-70]

Untuning the tuned exhaust will never make you faster. These are 2 strokes not totally "don't give a d***" 4 strokes.

[fastplastic]

Bear maybe one day they will get it lol

[that guy]

Build a new expansion chamber exhaust 2 get results as stated above drilling holes will NOT help.The noise will give the illusion that u r going faster when in fact u are probably going slower.Another option is 2 buy the exhaust that tazland001 is manufacturing