A35 coked up exhaust port and pipe

So I managed to get my exhaust pipe off my TX50 using this wrench:

Don't know why I didn't think of it to begin with. DUHH..

Anyway here is what I found in the exhaust port:

The port looks really coked up but it's not. The exhaust port is tapered like that. See below.

Exhaust pipe/muffler:

I ran the bike without the muffler and it runs better and doesn't smoke (as bad) but will sometimes stall at idle. Probably from not running an exhaust and it's sucking in some air.

So is this carbon buildup considered bad? Or would cause excessive smoking?

What's weird is the intake port is 17mm. The exhaust port is about 17mm as well but the hole at the jug is much smaller then tapers toward a larger hole. Is this meant to be some sort of a restriction or is there a reason for the exhaust port to be shaped like this. Does that make sense? (edited)

Re: A35 coked up exhaust port and pipe

All that carbon buildup is probably the result of burning excessive oil/ or transmission fluid/whatever. Clean the port and the pipe out. Your piston looks like it has some scoring, you'll probably need to look into that sometime in the near future. Almost all exhaust ports are shaped like that. The port size on the bore side has a lot to do with the power the engine makes. A larger port could produce more peak power, but you would loose power lower in the powerband. The piston ring ends prevent the port from being much wider. Wide ports will reduce piston ring life. Since it's a stock cylinder designed for a restricted moped and small children's motorcycle it's set up to produce mild power, but over a wide rpm range.

Re: A35 coked up exhaust port and pipe

engineers reasons rarely trickle down to the consumers

could be as simple as "make it 2 hp, no more, no less"

that pipe looks decent, but the baffle part is probably bad off.

i've taken a long drill bit and punched holes in the separator plates, to allow more time between cleanings.

i recently took an oxy / acetylene torch to a stinger baffle, amazed how clean it got, may not work for the whole pipe.

crud was gummy oily sludge, could only push it around with a scraper.

kudos on your photo skills, i'm still taking 10 photos for 1 decent one.

Re: A35 coked up exhaust port and pipe

I took a Dremel wire brush attachment , flathead screwdriver to clean out the exhaust port. As far as the muffler. I filled it full of kerosene and lit it up . then filled it full of Drano and its soaking overnight. If that doesn't clean it out then I'll poor it full of muratic acid no more than 30 minutes. Works good on rusty gas tanks. For awhile anyway. I did take about 10 photos then deleted the bad ones!

Re: A35 coked up exhaust port and pipe

Inserted a vinyl cap in the intake of the exhaust pipe and filled the muffler full of Drano and let it sit overnight. Then flushed it out with a water hose. I flushed allot of junk out of the muffler. I have not installed it yet to see how well the bike runs.

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