KA100 Exhaust Pipe Maintenance Cleaning

Quick search didn’t yield much. Any tips on keeping the internals of the KA100 exhaust clean? Any specific tools for cleaning? Cleaning intervals? I’m noticing some carbon buildup at the exhaust exit in the perforated section. Thanks.

Soak in a caustic soda solution should get rid of the carbon

This is one of those things I read in the manual and scratched my head over. Tried to take the cap off to inspect better and I cannot get it to come lose. May try soaking in caustic soda which seems to be all I could find on internet…but wondering if buy a new pipe every year is a better solution.

A couple of bucks for caustic soda and a few more for some pvc piping and glue to make a container seem a better deal to me, then buying a whole new exhaust.

The chrome end usually gets pretty caked on there and will probably require some blows to remove it.

The main thing you want to be sure of is that the baffle cone inside the pipe expansion chamber is clear. It takes a lot to clog one up, but it’s good to check.

Heat removes the carbon deposits too. Some have BBQ’d their pipes or placed them in a fire.

All that said, accounting for your time it could be worth replacing it annually if you like.

Personal decision really.

In the past I’ve had one pipe for breaking in and another for racing. But rebuilds were much more frequent with those particular engines.

Bill, by caustic soda, I’m guessing you mean like a drain cleaner with sodium hydroxide? So let it soak then hit it with a wire brush?

Yes the active ingredient in the product I use is sodium hydroxide, a painting preparation cleaner.
Left the pipe in the solution for a couple of days, stirring occasionally and didn’t need to use a wire brush.

Thoughts on the state of the exhaust? Managed to get the end cap off. Took a round punch and gently went around the perimeter working it off slowly.

Looks pretty good to me, minty. I’d leave it. Make sure you look down through the entry to the pipe as well to confirm all the holes in the baffle cone are clear.

That looks reasonable, I am not sure at what point carbon buildup makes a noticeable performance difference. Cleaning in caustic every so often is a maintenance/cosmetic thing for me. I use a full synthetic oil in my KA so there isn’t a lot of carbon build up, but I’m impressed with how it cleans the surface rust off.
The engine does have a noticeable snap in the exhaust sound again after i clean it, just like it was when new, so it makes me feel good.

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That is always very satisfying.


Atleast twice a season the top 5 are pulling caps at our track for tech inspection. So far all the pipes look pretty decently clean and no one so far locally has made adjustments to the pipe internally.

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Thanks to all for the input! I’ll clean up some of the loose debris, probably from tapping on the cap to get it off, and put all back together. I’ll pull it from the head and check the inlet to the exhaust this evening.

Bill, how often are you doing this cleaning? Also, can you elaborate on the PVC container you made to do this cleaning?

@mtbikerbob not as often as I should, generally do it before a big event. probably once a season.

I bought some 4 inch PVC storm water pipe and capped one end, and put a threaded cap on the other to make a tube, so I can store the solution for multiple uses. I just hang the header end off the top and it mostly fits.
Currently looking for a 4 inch tee, that I can cap so I could put the whole thing in completely. but I’m not sure if that will leak as I wont be able to glue the tee on (needs to be removable to accommodate the bend)

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Are you guys using a powder? Or diluting a liquid? I want to give this a try but I don’t know what to get.

Put a flathead screw driver against the edge of the chrome cap, at a steep angle, then bang it with a hammer. Rotate the pipe, do it again, etc, etc. After 5 or 6 bangs it will pop right off.

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The stuff I use is a powder that water is added to.

Now is probably time to mention that Caustic soda or Sodium Hydroxide is classified as a “Poison” or S6 rated in the old language.
I’m not sure how Chemical labels work in other parts of the world, however here in Australia using this level of chemical comes with guidelines that require gloves, face shield, aprons and possibly a respirator to be used when using this product.

Contact with your skin, will make it feel soapy which is an indication that the caustic nature of the solution is turning the fats in your skin to a soap. Which is not ideal.
Getting this stuff in your eyes or accidentally drinking this would not be a fun time.

Mixing up a powder or a liquid concentrate against the label recommendations will wildly vary the strength of the solution and therefor its toxicity.
As this forum is open to all I would suggest if you are under 18 get a parent to help/ supervise.

Just revisiting this topic…Has anyone tried other methods of cleaning the pipe? Sandblasting or some sort or agitating with small rocks for cleaning?

When I had a snowmobile we used to have our exhaust systems ceramic coated. I am assuming this would not be allowed but haven’t seen that specifically addressed.