Tinkering with stock exhaust

[Harleyriggs1]

It will probably run hotter in the long run, the exit remains the same but now doesn't have the feeds that would initiate the flow into that tube as pressure builds, and now the pressure release will be more of a pop sound.

What if I was to gut the muffler then put that cap on the same way

 

[Street Ryderz]

What if I was to gut the muffler then put that cap on the same way

You then create a trap after a certain point in the rpm range where the gasses can't escape fast enough and it hampers rpm climbing, builds heat and then the engine feels sluggish.

Exhaust designs are complicated and multifaceted for a reason with high and low pressure area's, baffles and such trying to reduce noise levels but still allow the proper velocities and volumes through and these bicycle engine exhaust are a double chamber within one body so when you gut them out yes you can gain some initial acceleration just as a dump pipe would do but it's a very small gain vs the consequences as I've seen those glowing from the heat trapped in there.

Back pressure is not really the right term when it comes to a 2 stroke and the exhaust because it's really pulsing waves the same as the intake side, the exhaust pressure as it leaves the cylinder into the head tube creates a vacuum behind it due to it's velocity and this aids in pulling through the transfers the next fresh charge of a/f from the case up into the cylinder but without the reversion of that pulse/wave alot of that charge is lost out into the exhaust as a dump pipe would do hence the struggle to build rpm's, but with a proper head tube length and a canister/chamber the reversion takes place and acts as a block trapping the intake charge in the cylinder until the port closes instead of a physical valve doing this job like a 4 stroke.

This is why tuned pipes/expansion chambers are a big deal to a stroke engine, the tuned pipe will not only act as a block to trap the intake charge in the cylinder for better cylinder fill it will also push most of the lost charge back into the cylinder actually over filling it at it resonant point and this is the hit many refer to or where the engine just kicks in and pulls hard and smooth over a certain rpm range, but again very highly calculated volumes with convergent and divergent sections for high and low pressure zones all timed ideally perfect for that specific engine.

 

[alextheguitarman]

I don't know any tricks that will do anything for you with the stock exhaust, except make it louder. If I understand the state of your stock exhaust, you may need to chuck it in a vise, and then get maybe a needle-nose vice-grip pliers on the remaining internal tube and pull it out. It may take some elbow-grease. A tuned expansion chamber exhaust is really where you can get a big performance gain though.

But once you've settled on an exhaust system, you'll need to adjust your main jet for best performance at WOT, and after that, work with the needle position for your mid-range mixture. Just remember, any changes you make to the exhaust may require you to rejet the carb.

Which carb are you running?

Full disclosure - I have limited experience myself with the HT engine. I have mostly "book-knowledge" at present and more experienced members will be able to help more, and make us both more knowledgeable.

I took the cap of the stock muffler completely off, and the horsepower and speed most definitely is significantly more. There is no question.