Well was bored today.
So I went out to hack up an 89 silencer and adapt it to a power pros pipe.
Goal: Is to see. If it will quite the machine down with out sacrificing power output.
The stock silencer is forest approved so it would be nice to have if ever ridding in an area that required it. A lower db out put would also be nice for those areas that require it.

The stinger ID has to be increased all the way into the chamber to be effective for power out put. The OD of the out put piece is fine for it's length.
One issue is the this design is not a baffled straight thru design.
I think you may find the pictures of the inside interesting.
Once it is mocked up I'll run a DB test to see how it does. The pipe it's self may get a wrap to quite it down a little just not sure yet.

Few more
Wife said dinner ready so do the inlet later

Took one more pic showing how the inlet is offset. This tube also had a sound wrap in it.
I removed this baffle tube and packing.
The I'd of this tube was to small and would choke down the inlet.

The inlet ID must be maintained all the way into the chamber.

Hopefully the inner turbine core will not have to be removed. Should be enough chamber volume to offset the exit velocity.

This set of pics show what was removed.
#1 is all removed.
#2 is the inlet baffle & packing material
#3 is the inlet pieces so I could remove inlet baffle and adapt larger dia inlet
#4 is the outlet baffle core piece cut to the top of the turbine cone. The piece is where a tab was welded the the core. This was broke loose inside the pipe.
#5 tab,
#6 next page, broke piece of inlet baffle banging around inside of pipe.

#6 broke piece

Decided to go out while cool this morning and do some measuring and come up wit a plan for new INLET pipe.

I thought it through a little while the coffee set in and got me thinking. So first I should log the stock dimensions for a bend and the tubing size needed. As I measured up a few things I had a what IF moment. We all know Honda does what the do for a reason, we also know I'm a Back Yard Hacker. What I came up wit was relocating the inlet on the silencer for a better bend radius since I will be using a larger dia tube. Now knowing the monkeying around you have to do getting the silencer on and off this may not work and again it may. The save a lot of aspirin taking on babble of Inlet to power rpm math and theory I will just stick to pics of hacking.

For those a little more interested, Stinger ID/ Inlet ID and it's length as an effect on the Engine's peak power rpm at a given port duration and pipe type. Gas law stuff, yuck. The rest bla bla bla, happy CO?

You can see from the pics why I cut the stock inlet where I did as mentioned above.
You will also see and watch for the Inlet ID where it enters the baffle chamber. This has not been cut yet due to first need to design the Inlet runner.

Enjoy the pics

more pics,
First log stock numbers
Second log new proposed numbers

more pics
Relocated fixed points and inside look of inlet relation to turbine core in baffle camber.

more pics
The rotation of the end cap reference marks
Tomorrow I will source tubing and build a few inlets and make a determination on baffle inlet dimensions.

To hell with the rest of it, that turbine bit is the most interesting.
I ran spiral mufflers on my formula race car. We had to meet a 105db noise limit to race. High frequency noise does not go around corners very well.
CO

You should use the 0-60 app and do a run with your noisy pipe and one with the conversion, will be interesting to see if any difference

Oh, I plan on it. Hoping to do this week along with some other stuff. One issue I have is that CO's 350 runs faster than my pilot. Must be the better air.

When I raced the "Stock" class I took my stock Pilot silencer and drilled a series of 3/8 holes about 1/2" apart through the backside of the muffler through all the layers except for the outer layer of the front side then welded up the holes on the back side and repainted, ran it a few tanks of gas with the spark arrestor clean out plate removed so the shavings could blow out.

I also took a factory pipe, using a cut wheel on a die grinder cut it along the Rolled Crimp Weld so I could split the pipe in two, removed the guts tig welded back together.

Everything looked stock but run much better uncorked.

The 350's running the factory drive clutches with the after market springs (raised the engagement RPM) would kill me on the hole shot but that's about it.

Thanks for tips "H"
Got more?

Short circuiting the flow path through the muffler and increasing the volume inside the main body of the pipe is about it.

Other thoughts, its almost as if the pipe engineers designed a kick ass pipe section then turned it over to the sound engineers and they put the insulation on the inside then never returned the pipe back to the design engineers for testing to see what affects the changes made. If they had I think we would have seen a larger bodied pipe on the Pilot OR maybe they did it to tame the Engine increase reliability?

One pipe I autopsied and modified the perforated metal that covered the insulation had partially disconnected and had bent out into the flow path causing a good amount of flow restriction, sort of like sticking your hand out the window in a moving auto mobile

Shame the retired engineers wont stop by and share the thought processes involved with designing the Odysseys and Pilot

Thank you for the follow up comments.
I agree it would be nice if they logged on and gave us some direction.
Wonder if they do log in and laugh at us at times.
If so, wish they would throw us a bone every once in a while.

They should be very proud that they designed such a machine for the times. I for one have enjoyed my Honda's since 1980.

That's 40 years of proud ownership and brand loyalty.

Prior to that had yamahammers and susuckyies. Not real fare both served me well though my younger years. Favorite suzuki was my TC 90 fist rotary valve. That suspension was put on my first Honda atv.
First yahama was a chappy, used for paper route many good years on that on. First lesson on to hot of plug range.

Sorry for memory lane. Got see if I I can dig up my old race pics of the Honda. Back in the film days.

I wish Lee would pop in from time to time.
CO

Source the parts I needed for the muffler today.
Found a good source for lots of great parts.
Any way time to start hacking

More pics

More pics
Well it's in paint. Ha ha ha rattle can drying on back porch.

Last ones
Do some sound testing tommorow. It for sure is quiter then the atvr silencer.

For those wondering how to test. What i come up with is 200,000 divided by stoke (79) for a given test rpm of 2532 or 2600 rpm. Then hold your meter 20" from the exhaust exit at a 45 degree angle. Then take a reading sooting for a max of 99.

Do my test this morning. So far so good.
The first test is with the hack job 89.
I set up a test station according to requirements for test Db on atv for forest approved areas.
The app I'm using is an approved app to be +/- 2%. That of course subject to AHJ.
The first pic what I came up with for some states. Oregon being what I found to be the strictest of all. If some one knows more please post.

After a bit I will install the atvr none approved spark arrester silencer and test. Then an atvr approved spark arrestor made by big gun. It has a screened cap.

More pics

I would like a few notes on this. Some may wonder why take the time to rework the silencer. As most know my Engine is not stock and even if it was it would or should be factored in. If to restrictive it could lead to piston crown over heating. We have all seen that to many times. So I had to factored that in. That may take another post or two. So CO should be happy, no babble.

I opted to maintain the inlet ID of the stinger and radius of the atvr into the silencer. The silencer outlet size was fine.
I like the way the stock clamp is so I tried to do that as well to keep a stock looking appearance.

Next week I will make a few calls and see if I can get park ranger to do a test to compare.