Hi Guys,
73 CT3, Just started first time in 30 years after much work. Very little exhaust. Seems to be seeping out. I'm thinking the exhaust is clogged. I'm wondering how to inspect it. I'm sure it's not as simple as running a coat hanger or a roto rooter through it. I can work on any other component of these bikes. Never dealt with exhaust.

From what I saw in the crankcase and the carburetor, there's probable a mouse nest or something in it. Nothing visible from either end.

Help!

Tsmitty

Remove what you can out of the end & see how that looks but is probably further in. Looks like there's two parts but blockage will be in the second part. Might have a spark arresting bit down in that second part but not sure. I throw mine in the log fire. But complete system idealy need burning out in a bigger fire or gas burner to get it REALY going then compreesed air to send it through. In an ideal modern world i guess ya not meant to polute things but short of buying a new old stock exhaust i doubt any chemical will clean it like burning will. Check the exhaust port too considering how bad you describe it. Here's some pics of my various problems in the last 10 years for a laugh if i can find them. Might just be links to hit.
photos.app.goo.gl/h1NbvKpgpQXVBBVg9 Yamy 100 twin LS2 right side pipe-& left much the same.
photos.app.goo.gl/3zMaSZ4Cg3JkoTXk7 Burning something Yamy landscout i think.
photos.app.goo.gl/7rkHvm8jY4UdSRUk8 RMX250 Mouse family.
Video from when i fitted a cheapy chinese carb. Poor old girl, what a a way to be woken from hibernating. Tis a "70 AT1 with a 175 top end. Plus a clean exhaust of course lol.
Here's the fitting of the new carb. Was quite a few years ago years ago now but nothing's changed--except i've got older haha.

Sorry to clog your post up with my rubbish but hoper to see yours running good sometime.







www.cmsnl.com/yamaha-ct3-1973-usa_model8420/partslist/B-03.html

So where the exhaust leaves I removed the pipe and it looks new in there. I'll take it off tommorow and check the curved end. I tore the whole engine apart so everything internal is good.

Thanks for the post!

Remove the baffle ,( there are two parts ) , run it and see if that helps .

I have the outlet pipe off. Any idea on how to remve the silencer?

So, I used lye and water. Soaked for 3 days. Thick brown liquid and a blister on my foot from spillage. Still plugged. Filled it up with concentrated degreaser. 24 hour soak. Lot of ugly coffee looking liquid.

Put it in the bonfire. Smoke, then flame after 15 minutes. Flame burned for about 15 minutes. Let go for another hour to be sure. Let cool, tap, tap tap. 1/3 cup ash. Repainting tomorrow!

Have another that I rebuilt, and when I got it the exhaust had a bunch of gunk come out. Used brake/parts cleaner. Runs "okay". Think I'm going to burn this exhaust also. Can't hurt.

IMO just burn the exhaust. Probably needs reapainting anyway when restoring. I have three CT3's and repainted all three. Could have saved an extra paint job. Live and learn!!
Tsmitty

“IMO just burn the exhaust. Probably needs repainting anyway when restoring.”

Yep. I’m about to do a huge bonfire with a pile of dead branches and pine logs accumulated over the past few years. That bonfire will see at least 4 OEM exhausts. 400, 360, 175, and 125. All of which currently have aftermarket expansion chambers at the moment.

Schu, you should add a bonfire with Enduro exhausts burning out in the middle of your avatar! Several years ago I cleaned out my JT exhaust the Schu way.

I just burned my exhaust out, it was similarly clogged with gunk. I burned it out in my Solo fire pit with a little help from a propane burner.