Chief tuning question, exhaust shaking when started

[Lipdog]

I found this video on YouTube https://www.youtube.com/watch?v=i-qOz6blud8 and realized that none of these other Chiefs shake when started like mine does. My bike rides well and I stay on top of the plugs and ignition parts. Though it's hard to tell with modern gas, the plugs look clean - neither too rich or too lean . But when I start the bike, the rear exhaust section shakes the fender pretty hard. I'm thinking it's a tuning question. Does anyone know specifically what would cause this?

[PaulCDF]

Specifically no; but I'd start with the basics: Check that rear fender and exhaust fasteners are tight.

[Rubone]

Raise your idle speed.

[ChiefTwoKicks]

Happy Holidays to all... I once had a '46 Chief that shook the rear fender (and the exhaust tailpipe mount), causing similar damage back behind me unexpectedly. I first noticed that my license plate bracket kept vibrating, seemed weird... but I started sniffing around and also found the exhaust pipe tab/mount at the very rear of the fender was also cracked. I really never felt or heard vibration, so when I found both the license plate bracket and the pipe mount broken (not exactly at the same time, but sort of back to back. After a very extensive search I only thing I could find was the rear transmission mount bolt only slightly loose... maybe a half turn from really tight. Tightened it up, and I never had anymore vibration... or at least cracked or broken tabs behind the center post of the frame.
I'm guessing here, but with your rather brief description of starting your bike and some of the shaking, it led me to wonder... I totally agree, pretty much what PaulCDF says above.

C2K

[Lipdog]

I’ll definitely check the trans and fender bolts. The rear section of the exhaust slips onto the front section with no clamp, so the rear section seems to move much more when the bike is idling.

[Lipdog]

I had the bike out yesterday and noticed a couple of things:

- The exhaust still shook, even though I tightened the trans and mounting bolts (they didn't really need it). I tried to adjust the idle mixture and it didn't really seem off. But if I retarded the ignition at a slow idle it smoothed things out and stopped the shaking

- The rear section of the exhaust (with the muffler) slides over the front section to hold it up in the front, and is bolted to the fender at the rear. There are no other mounting bolts or clamps. There is a tab on the inside of the exhaust near the shock tower that had been mostly removed, but I could fashion a bracket and screw it into what's let of that tab on one side, and to the frame on the other side. How are the rear exhaust sections usually mounted?

[pisten-bully]

213722E8-CF0F-4679-8A70-51B175C17CE5.jpeg

[pisten-bully]

this one, too:

CBDFD7AD-F841-4249-BC4E-8E9FC1C9F560.jpeg

[Lipdog]

Thanks PistenBully. I think that's what I need. I just found that part on the Jerry Greer website: 5/16''-24 X 1.375''. I'll try to find it at the hardware store and then replace it with the correct cad-plated part later.

[TH47Indy]

The one I bought from Greer's wasn't Cad plated. Maybe the originals were not plated?

[Lipdog]

Gonna be raining for a bit here anyway. I just ordered the right parts from Greer. I'm hoping they do the trick. Thanks again.

[TH47Indy]

If your exhaust isn't welded together as one piece, you may also need this part: https://jerrygreersengineering.com/p...1947&modelid=2

[Lipdog]

If your exhaust isn't welded together as one piece, you may also need this part: https://jerrygreersengineering.com/p...1947&modelid=2

I thought of that too, but from the photos of restored bikes on Greer's and Kiwi's websites, no one seems to use them. And they look like two pieces.

[TH47Indy]

It can be tought to see it up close in most of the pics on Greers and Kiwi's site, especially when in chrome. I beleive that may be because the ones you are seeing have been welded together into one piece.
Here's a pic of mine, that was welded together.IMG_0542.jpg

[Lipdog]

Update: The last guy left the exhaust mount just ahead of the shock off. He also sawed off the vertical bracket on the muffler that mates with it. I bought the mount from Greer and I had to make a stainless bracket, threaded into the muffler on the stub that's still welded on. I couldn't weld a new bracket without needing to replate the whole muffler, and I didn't want to do that. The two cap screws don't look great but they are mostly hidden. But the good news is that adding this bracket solved the shaking problem.