The Hodaka Club Forum

looking for some input for my 95 combat this factory baffle was missing when i got bike and it had a rigged up baffle and wanted to make somthing that
looked better.what i have is a 7/8 id tube 9 1/2 long that will fit into factory pipe i was wondering if it would hurt to close off end
a little like the factory combat did to add a little back pressure or if i should run as is. any input is welcome

here is what i am going to try 1st

My understanding is that the CW stock pipe isn't all that bad as a tuned exhaust. While it probably needs the narrower stinger (narrower than the outer body) it doesn't need back pressure. Two stroke tuned systems use sonics to create negative pressure waves at specific rpm points to improve scavenging and intake charge retention. Back pressure is not, per se, an intention of two stroke tuning. What your flap arrangement would do is help muffle noise and deflect sparks, and that is probably what the original system was all about if it had such a flap. The original stinger should have been perforated and glass packed because aside from the technical need for a stinger somewhere in a tuned exhaust, it also needed a silencer. Someone who has actually seen a stock CW system can verify how the pipe was perforated and packed. I would speculate that the stock system was fifty-fifty silencer and stinger by intent. A solid body stinger such as you show here will be noisy with or without the flap because it isn't configured as a silencer.

Jack and Bronco, here's one I built which with packing is tolerable noise wise.

Max

ok my 1st design looked close to hodakamax i used ceramic fiber packing and it didnt do a lot for sound maybe just a little more bass sound
i guess i was thinking it needed a little more back pressure .but it sounds like i dont maybe i will stick with the 1st one i made ?
the one in bike when i bought it was just a perferated pipe with washers welded on ends and no packing at all. i guess i could try wrapping
that one also and do a comparision

here is what stock unit should be just cant afford $175.00

here is unit with holes

The holes are necessary to allow sound to pass back and forth into the glass packing, making it a muffler.

The gizmo you show with the flap is a spark arrestor, not a stinger or silencer. Spark arrestors do tend to muffle sound by strangulation, but their intent is to stop sparks from being blown out the pipe. The flap on the end of the spark arrestor is a spark deflector, and while it probably does up the back pressure, as does all the other business in the way of dinks and bends and bullets, the back pressure is a by product of spark arresting, not tuning. Unless you are trying to build a spark trap, I would not bother with the Krissmann insert, and just make a silencer much as did Max.

The one you already made with holes looks functional but needs more holes. The ceramic packing will be fine but is louder than glass. Don't know why since glass strand and ceramic strand are very similar. Maybe it has to do with how course the strands are.

Could I use fiberglass mat that I have that is for
Body/boat repair

Could I use fiberglass mat that I have that is for
Body/boat repair

Yes you can use fiberglass repair mat but I would expect it to not last as long as it should. You can buy glass repack material from bike catalogs. Or use your ceramic. You can even use steel wool. Almost enything will work, some better than others, some last longer than others. What you are creating is a baffle full of dead air spaces that bounce sound waves around so much they loose definition.

I have always used just plain old fiberglass house insulation , works great and never had it blow out , there is always a chunk laying around any construction site .

Rich

thats for the input guys
would you expect a rejet after adding baffle? mine bike is running rich after doing baffle so i ordered few more jets of the smaller size
i can feel more power at lower and midrange

here is lastest update bunches of holes and 2" outercasing will try fiberglass also

here is lastest update bunches of holes and 2" outercasing will try fiberglass also

Looking very nice. That should tone down the note.

its is way queit now compared to what it had maybe a litttle to much
here is what i am seeing bike was running rich change 45 pilot jet to 40
left 180 main jet in for now bike does not sputter at wot like it did before
but it does not seem to reach the high rpm it did before i assume that is
coming from my new baffle? the lower and midrange seems better and the noise level
is way better.is there any thing elese i should do ?
i guess i could swap main jet back to 190 or larger untill sputter comes back
and then drop 1 size from sputter ?
youtube below of old baffle sounds

https://youtu.be/D9r-AF4YKxkdown

here is youtube of new baffle sound

Nice work, looks good!

Max

Bottom line here is that changing the exhaust system can require rejetting.

update
after some trail and error i got a decent baffle that is not to quiet
i had made baffle with 1/4 holes and that may have been issue
bike was queit but didnt seem to rum as well ,also i made part 12 1/2"
long and accordding to math i found stinger for my bike should only
be 9 1/2 some i change lenght and instead of drill the holes i used some perferated
tube with tiny holes that i robbed from an old dg muffler. also made cone shaped adapter
from pipe to baffle . bikes seems great now
not ear busting loud any more but just toned down enough that folks next door
are not complaining .also dont see any loss of power that i can tell
thanks to all who gave some input