Carbs still falling out of holders on 78 Street Tracker

[Frank47]

Everything came in. Removed seat & tank. Installed tygon hoses. Clamps from JBM were pretty large so got smaller ones at Autozone. Carbs still falling out. Turning new carb holders so large side was at bottom made no difference. Still considering strapping carbs to engine or frame for support. Any suggestions on this greatly appreciated.

 

[gggGary]

pictures?
Checked your timing and advance?
Points bikes with linked carbs are kind of famous for blowing the carbs off.

 

[Jim]

Pictures of what you have going on?

 

[DogBunny]

I too would like pics. Until then, I suggest using ARS brand boots with the stock carb holder "cages" which look something like this:

and I promise that your carbs will not fall off.

 

[5twins]

Yes, I've run nothing but pods for the past 20 some years and never had the carbs fall out. Yes, I have "popped" them out a time or two because the timing was off a touch and the engine backfired through them, but they've never fallen out by themselves. I use original ARS boots and the shrouds, and also original clamps with Allen bolts instead of the Phillips screws they came with (Yamaha even sells them this way now). Once the heads on the original Phillips screws get a little buggered up (which they usually already are when you get them), it's difficult to make the clamps tight enough. And I do make them tight, pretty much as tight as they'll go. I tighten them up until the two clamp halves touch. I recommend original clamps too. The aftermarket replacements are junk. They're not as strong and use a smaller diameter screw.

 

[Frank47]

I too would like pics. Until then, I suggest using ARS brand boots with the stock carb holder "cages" which look something like this:
View attachment 251407View attachment 251408
and I promise that your carbs will not fall off.

Thanks, do you have a source for the shrouds? Old ones pretty beaten up.

 

[Adamc]

Yes, I've run nothing but pods for the past 20 some years and never had the carbs fall out. Yes, I have "popped" them out a time or two because the timing was off a touch and the engine backfired through them, but they've never fallen out by themselves. I use original ARS boots and the shrouds, and also original clamps with Allen bolts instead of the Phillips screws they came with (Yamaha even sells them this way now). Once the heads on the original Phillips screws get a little buggered up (which they usually already are when you get them), it's difficult to make the clamps tight enough. And I do make them tight, pretty much as tight as they'll go. I tighten them up until the two clamp halves touch. I recommend original clamps too. The aftermarket replacements are junk. They're not as strong and use a smaller diameter screw.

I’m with 5T here. My bike is currently set up without the butterfly brace on top of the carbs (BS34), running UniPods. The only thing holding them to the inlet rubbers are the shroud clamps. At the moment my bike is backfiring flames out the left carb; but they stay in place even with violent backfire!

 

[Vincenthdfan]

Yes, I've run nothing but pods for the past 20 some years and never had the carbs fall out. Yes, I have "popped" them out a time or two because the timing was off a touch and the engine backfired through them, but they've never fallen out by themselves. I use original ARS boots and the shrouds, and also original clamps with Allen bolts instead of the Phillips screws they came with (Yamaha even sells them this way now). Once the heads on the original Phillips screws get a little buggered up (which they usually already are when you get them), it's difficult to make the clamps tight enough. And I do make them tight, pretty much as tight as they'll go. I tighten them up until the two clamp halves touch. I recommend original clamps too. The aftermarket replacements are junk. They're not as strong and use a smaller diameter screw.

I had a fuel injected Suzuki DL1000 V-Strom that would occasionally cough back and blow the V-Twin carb bodies out of the intake boots way deep up under the fuel tank.

After a couple of limping it home episodes with throttle bodies barely feeding the intakes remotely, I resorted to safety wiring the throttle bodies to the intakes...those suckers werent going anywhere anymore! Between that at a little bit richer tune with a Power Commander in the fuel injection stream, never had another problem with it.

 

[DogBunny]

Thanks, do you have a source for the shrouds? Old ones pretty beaten up.

Can you provide a picture of yours?
Old ones are always a little rusty, and the "fingers" are often a little bent, but straighten them and they'll work fine.
I don't think anyone sells new shrouds, but you can usually find them on eBay. Most sellers call them carburetor holders, or some call them carburetor clamps or intake clamps. Try different search word combinations.

 

[5twins]

The shrouds, just like the manifolds, are right- and left-handed, and also come with or without the notch for the vacuum nipple ......

I suppose you could cut the notch if need be but just know there are ones already notched out. I managed to find a N.O.S. pair on eBay for cheap many years ago because my originals looked pretty ratty. The new ones had a nice, gray finish to them but they turned brown and rusty looking in short order, lol. I don't know what Yamaha uses as a finish on them but the heat must affect it. One of my new ones, lol .....

If you want them to stay nice looking, I guess some heat resistant paint of some sort will be required.

 

[Frank47]

Can you provide a picture of yours?
Old ones are always a little rusty, and the "fingers" are often a little bent, but straighten them and they'll work fine.
I don't think anyone sells new shrouds, but you can usually find them on eBay. Most sellers call them carburetor holders, or some call them carburetor clamps or intake clamps. Try different search word combinations.

Left one after straightening gently with linesman pliers. Now have done both & will try them on new manifolds after I get back from trip Thinking might work better if I connect manifolds to carbs on the bench & then bolt up to engine.

 

[DogBunny]

View attachment 251497
Left one after straightening gently with linesman pliers. Now have done both & will try them on new manifolds after I get back from trip Thinking might work better if I connect manifolds to carbs on the bench & then bolt up to engine.

Yours look fine. I don't think it's a big deal, but the end of each finger is supposed to flare out a little -- see 5twins pic of the NOS one, or the one you haven't straightened yet.
In your initial post, you mentioned JBM clamps. Are you using JBM manifolds? I'm pretty sure they won't accept the stock shrouds.
I think putting the manifolds on the carbs before bolting to the engine is a bad idea.
I looked at a pic you posted in a different thread. I think you might be using BS38 manifolds and shrouds with BS34 carbs. No wonder your carbs are falling off.

 

[5twins]

Yep, that would certainly do it .....

..... but I'm pretty sure he has BS38 carbs.

 

[DogBunny]

View attachment 251504

View attachment 251505

..... but I'm pretty sure he has BS38 carbs.

Yeah, I think you're right. I was looking at the wrong pic...

 

[Frank47]

Busy, cruise, Covid. Got it all back together today by using hair dryer to soften up carb holders (suggestion from neighbor who has worked on Harley’s for years). Popped in, tightened up auto style clamps, new filters. Started right up, rode to beach. Read posts about mixing oil & gas for air filters, but decided to just use cheap 5w20 from Walmart. Seems to work ok.

 

[mrtwowheel]

Love that graphic on your tank Frank.