First Bike - No Idea What's Going on

GLJ

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The red caps are where the fuel normally comes into the carbs. For whatever reason he brought the fuel into the crossover nipples.
Reason for the crossover is you have 2 petcocks. If one side of the tank empties before the other you can still get fuel to the other carb.
Will it run the way yours is, yes as long as you have fuel in each side of the tank.

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Jim

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Just read Greg's comment. It's prolly best to change it over to the correct way that he shows. Both ways would prolly work, but with the loop at the top, low head pressure in the tank "might" not feed correctly... like low fuel on reserve.
 

5twins

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His carbs have #125 butterfly plates. That makes them '73 or older. The single choke makes them '72-'73. The "claw" style cable arms make them '72 or older. I'm thinking they're the original '72 carbs.
 

Silviculturalist

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His carbs have #125 butterfly plates. That makes them '73 or older. The single choke makes them '72-'73. The "claw" style cable arms make them '72 or older. I'm thinking they're the original '72 carbs.
I genuinely couldnt find anything as specific as this so thank you. Maybe my googling skills are just getting bad.

Any suggestions for how to proceed fixing the vaccum problem? I've taken it apart and blasted it out with carb cleaner in case there was a bit of dirt hiding somewhere, all the internals look pretty much brand new so I think it was freshly rebuild right before the bike got handed over to me. No holes or anything in the diaphragm as best as I can tell. And I replaced the butterfly shaft seals as of last year.

Is the best I can do at this point to put them back on the bike, start it up, and spray some carb cleaner around it and see where it stutters?
 

5twins

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If by vacuum issue, you're talking about how quickly your slides fall, check the choke plunger. If it's not sealing or partially open, the slides will drop very quickly.
 

Silviculturalist

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Alright one more update for today. Did a lot of little tinkering with these things and dont know what is actually relevant or not so i'm just going to vomit out a bunch of things I saw.

Removed choke plunger. It was very black so I cleaned it up real good, no change in how fast the slide falls.

Swapped the right (good) side diaphragm and slide to the left carb, still fell just as fast.

Put the carbs back on the bike and started it up, sprayed carb cleaner all over the left side carb but there was no stuttering.

Took the pod filters off and plugged the top hole on noth carbs, Right side slide basically stopped moving while the left side one moved up and down even harder.

Sprayed carb cleaner into both carb intakes, right side caused stuttering while the left side shot the rpms up.

Both carbs have 137.5 main jets with all the other jetting bits being stock as per the manual with the jet needle clip on the 4th space from the top and both mixture screws are turned out 3/4 of a turn.

There is a noticeable difference in the sound from the left exhaust while the bike runs, sort of a lower possibly slightly slower "thumpier" sound.

The bike also wont start unless I have the throttle cranked all the way open, not sure if thats really an issue but I would assume you shouldnt HAVE to do that.
 
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