silencing the super combat

[fullchoke]

Mine makes too much noise. It runs good, but I generally ride it only at Hodaka days Bad Rock because it is too loud for camping and trail riding, which is all I do. I don't race. Is there a good clamp on silencer? and can I leave the carb alone? I want to ride it more and it doesn't say it has an approved spark arrestor on the pipe either.

Thanks,
gm

[Zyx]

Stock pipe? I doubt it has a spark arrestor. How to remedy noise will depend on which pipe you have. Even then, most 'silencers' aren't all that quiet. There are a couple made specifically to reduce noise if you are willing to modify your pipe. The Snorkel is quiet by comparison but looks goofy. The Super Trapp is adjustable so you can keep adding baffle plates until you get the sound you want, but you may find them restrictive if you try for very low noise. Two strokes are lead by nature because of the tuned exhaust.

I have the HT3 with two silencers. One is the original FMF shorty, the other a spark arrestor Turbine II. Both sound exactly the same, which is to say they are fine until you get on it.

[fullchoke]

It looks like the stock pipe. It has passed inspection at the last 3 Bad Rocks. It is loud at idle, really barks, it annoys me most at idle. We also have a 98 super rat, it is much quieter at idle. Maybe I can pack the end with steel wool or something but I doubt it will help much. That is why I asked about a slip on. I hate the looks of them, but the sound is worse. Quieter the better but I don't want to lose any power either. I kill the engine enough as it is, as I've always been a 4 stroke rider until my son wanted a Hodaka. I enjoy how light and nimble they are but the decibels are disappointing.

[bchappy]

Looking at the schematic the Super Combat has a "sound absorber" wrap around the "inner pipe".
http://www.strictlyhodaka.com/Parts_List_R2_s/2165.htm
My Super Combat has an HT3 pipe and I have never had the stock pipe so I am not sure what the material is. Have you checked to see if yours has the wrap on it?

[Zyx]

The wrap is usually long strand fiber glass. Repack kits are available from several sources.

Just looking at the schematic, which shows little detail, the "inner pipe" might have a diffuser in it, not much more than a perforated cone, which isn't technically a spark arrestor. If it was USFS approved as built, it would have language stamped on the outer pipe of the silencer, but it would also have a spinner in it, like the current design of the turbine core used by FMF. The stock street trail bikes had such finned bullets inside, but they were also marked as spark arresters.

If it barks at idle, it probably needs to be repacked. I have used fiberglass mat from the auto store, intended for body repair, but glass is glass, and it is available locally. It may or may not last as long as what is intended for the purpose, but if it works, that's what you are looking for. I would not use fiberglass insulation. Too fine strand, and will blow out quickly.

Pull the inner pipe and take a look. There is probably nothing left inside but goop. Clean it well, wrap it with glass mat, put a twist or two of wire to hold it in place, and put it all back inside. The glass need not be packed tight. It is the porosity that muffles, so work with it and see if it is better. I used to wrap firmly, but not super tight.

[fullchoke]

I looked at the schematics again and it looks like the tube at the end of the pipe is open at both ends and you could then use the wrap. The screen inside my pipe is blocked so everything must pass through the the fine screens. If I tried to wrap those fine screens, I would effectively plug the pipe. It also appears that 1 screw holds it in, where mine has 2 screws. The pipe itself looks original, but the fine screens were added to act as a spark arrestor, so my pipe internals looks different.
If the tube is open on both ends and the coarse screen is wrapped with fiberglass that would not be considered a spark arrestor and would be the reason that is not stamped on the pipe.
I appreciate the suggestions, I will look for an add on, ugly or not I'll have to get used to it.
gm

[Zyx]

Not sure what you mean by screens are blocked, and everything passes through fine screens. If you have it apart, perhaps a photo or two to illustrate. It would forward the discussion to see what you have.

Cone screens are not, technically, a spark arrestor. It may well act in that way, but would never pass a tech inspection. The Bad Rock inspection isn't a tech inspection, it is a fun ride with a reasonable attempt at safety. No one checked my silencer to see if it was stamped as approved by USFS. It did pass the "stick" test, but that was the only test made.

The inner pipe should be a perforated tube, smaller in diameter than the outer tube. How many screws hold it in place doesn't mean much. Probably started with one, now it has two. The question is, what is inside when you disassemble it? If someone has made a non-perforated insert for it, using only some fine mesh screening across the hole, it could be a home brew of some sort, and would explain why it is loud. Or perhaps the perforations are so clogged with carbon that it now looks like a solid tube.

Even if it is a solid tube, you can always perforate it with a drill. It would take time no doubt, but not hard to do. Once perforated, you can pack it with glass. If the tube is in fact perforated but clogged, burn it clean, then pack it.

Since you have a silencer that could well work with a little effort, I don't see the immediate need to hang something on the end of what you have. If you really want to use an aftermarket silencer, at least cut off what you have and replace it with a length of stinger to attach the new device to so it won't be unnecessarily long.

[fullchoke]

I'll try to explain it better. It is soaking in gas right now and it is after dark so I'll have to take a picture tomorrow if I'm not clear.

Picture a tube made of fine screen that is closed off at one end. One end blocked off totally, no screen. The other end of the tube is the exit of the pipe, it is open. It is a single tube, not one tube inside another. If I pack anything around the screen I will have no flow. I know a picture is worth a thousand words.

another way...It is like a cone screen, as you mentioned, but instead of coming to a cone the tube stays a tube, but is blocked off solid. Exhaust gases must pass through the sides of the tube(fine screen)before they exit. Therefore packing the tube would block the flow, just like packing a cone would do the same thing.

The relevance of the screws is just the difference with the schematic tells me the end of the pipe isn't original and the spark arrestor was probably added.

On a side note...We didn't check the Super Rat's pipe before we left for HD's. We had just bought the bike, and brought it as a spare as my son couldn't get his CW started before we left. The SR passed the inspection but I looked tonight and I didn't see anything but a coarse screened tube and some packing. So I don't know what stopped the stick except luck. We are going to need something for this pipe too.

gm

[Zyx]

I think I understand from the description, and no wonder it is loud if all there is is screen. Either a home brew insert, or something from the loud rock and roll music generation.

This as a DG unit. Very simple, not a spark arrestor, just a silencer. Very similar to the original unit welded on the stock pipe, but not rebuildable unless you modify it by cutting the tack welds, and attaching the end cap with screws.

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There are three tiny tack welds holding the cap, and there is already a screw hole so rebuilding would be simple. I would weld this one on your pipe as the original was, and perhaps shorten it a bit so that when welded it looks original. It is as effective as any such silencer. Idle is quiet. This same unit comes welded to the RD350B aftermarket exhaust which is okay for street use.

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[fullchoke]

Thanks Shorty for all the ideas. That muffler looks good on your RD350. It would look good also on my Super Combat, and I might be able to get a spark arrester in their too. The spark arrester is very important for where I would ride this bike. With that in mind I found a super trap type spark arrester on ebay. It may be a a little bulbous on the end of the pipe but it would only add 3". If it doesn't muffle enough I can put the spark arrester back in with both ends open and pack the tube with the fiberglass mat and attach the disc type spark arrestor back on the end.. The current spark arrester I have was sold all over ebay yesterday. Today I can'y find ONE. It was an insert in another brand pipe. Anyway I'm going to try this one from Chirco Performance. If it works I'll use it on the Super Rat too.

gm

[Bullfrog]

Arizona:

Have you tried inverting your pictures before you upload them? They are good and useful photos . . . but dang, that upside down thing is distracting.

Ed

[Zyx]

It is a programming fault of iPad. They all look right side up to me, no matter how I manipulate them before posting, so I can't tell which ones post upside down. Even on the iMac, they look correct. Something to do with the iPad being able to detect up from down, so no matter which way you turn the pad, it flips the view. Why it does not also identify in code which way is up, I don't know. How it consistently gets photos upside down instead of randomly sideways, I also don't know but you would think the geniuses at Apple would get it straight after eight or more system updates.

I may try turning off the gravitation detection next time to see if that makes a difference.

[viclioce]

If you have an internal baffle which can be wrapped, you might try something I have used in the past. Wood stove door gasket. You can get it in any length, cut to your measurement(or estimate) and wrap it around the outside of the baffle. Used it on my street bike, a Susuki VL1500 with Vance & Hines exhaust. It works well and lasts a very long time! I think I paid about $7 for 12 feet and was able to wrap both baffles twice!

The one I used was flat & about 1/2" wide. I removed it after 5 years of use and over 40K miles and it was still 95% all there! Great solution at a cheap price, and it will trap anything big enough to exit the pipe as a spark when wrapped around your baffle! ; D Victor