73 carb jet help please

[jkocr2]

So I'm having some trouble getting my carbs dialed in. I previously had them running good but realized my throttle shaft seals were leaking. I replaced those and did a resync of the carbs and then it felt like it lost some low to mid range power. So I tried upping the pilots tonight and now I can't get the carbs in sync. The left side will dial in but the right wont idle down nearly as low and I have to open the butterfly more than the right.

I have pods and stock mufflers without baffles

Currently
Two up on the mains
One up on pilots
Needle position in slot 3

Previous with Leaky throttle shaft seals
Previously had it running good at
One up on mains
Stock pilots
Needle position in slot 3

 

[5twins]

Did you center the butterflies before tightening the mounting screws after replacing the throttle shaft seals? It sounds like the right one may not be centered and is binding. That would make it stick open slightly and that would hold the idle high.

 

[jkocr2]

Yeah it's centered. It's not sticking open. I had it running good after replacing the seals but felt like I lost some low mid range. That's why I tried to up the pilots. I was getting some pop on decel. It's now not syncing up after I messed with the pilots tonight.

Should I try and go back to stock pilots abd richen the mix screw?

 

[5twins]

Well, you should always try the mix screws before switching pilot jet sizes. Sometimes they do the trick, sometimes not. They only have control over about 25% of the pilot circuit flow so that's why they don't always have enough adjustment to cure things. If they won't do it, then you change the jet size. Are your new pilot jets the same type (BS30/96) as your originals?

 

[jkocr2]

Yeah jets are correct type. I'll try the stock one's tomorrow. As for the low midrange. Should I put the needle back to slot 4

 

[5twins]

Sure, try everything and anything. Although the upper midrange may not like the richer needle setting with the larger mains. These early carbs were set up richer from the factory than the later ones. For minor changes, you may not need much re-jetting, if any.

 

[jkocr2]

ok, i think i'll try and put it back to stock everything and see what happens from there. maybe just richen up the mix screws to decrease the popping on decel. now that i look at the jet charts i do see what you're saying that these years were quite a bit richer from the factory.

 

[jkocr2]

Sure, try everything and anything. Although the upper midrange may not like the richer needle setting with the larger mains. These early carbs were set up richer from the factory than the later ones. For minor changes, you may not need much re-jetting, if any.

Put everything back to stock. Even leaned the mix 1/4 turn and now I'm getting big time break up down low and up top..should I raise the needle one slot? Seems like I never got that even with the larger main. But the clip was always in slot 3. I've gone back to the stock main and clip to slot 4.

Left plug is totally black now and right looks ok

 

[jkocr2]

Uhm just realized I left my vacuum plugs off when I was syncing the throttle cables. But why would the right plug still be black. Still thinking I should raise the needle clip but I guess I should ride it first with the vacuum plugs back on.

Oh another day of tuning tomorrow I guess

 

[5twins]

First of all, you said you have pods, but not what kind. If they're the cheapo K&N copies, they can cause all sorts of tuning headaches much like what you're experiencing. All that popping doesn't sound right for just some minor mods. Have you checked for air leaks (besides the uncapped vacuum ports, lol)?

 

[jkocr2]

They are uni foam filters. yep checked for leaks with the carb cleaner while idling...no change in idle.

I'll have to work on them some more tonight after work.

 

[jkocr2]

First of all, you said you have pods, but not what kind. If they're the cheapo K&N copies, they can cause all sorts of tuning headaches much like what you're experiencing. All that popping doesn't sound right for just some minor mods. Have you checked for air leaks (besides the uncapped vacuum ports, lol)?

so i set everything back to stock and it would still not run right even with the vacuum plugs back on. so ive set everything back to how i had it running the best.

needles in slot 3
one up mains (get very very tiny hint of surging when cruising at 60mph or above that may have been there before)
pilots stock
mix screws out 1/8 turn rich past stock setting.

bike seems like it pulls good through all gears for the most part but wants to die when i come to a stop. if i blip the throttle it will rev back up and sit at the correct idle. left plug still looks quite a bit darker than the right, which looks a little lean. also the idle screw is definitely turned in more on the right vs. left

i'm at a loss. i should of left my leaky throttle seals in there

 

[5twins]

Are the float levels correct? Almost dieing and recovering at a stop is a sign of too much fuel in the bowl. Popping is a lean sign. You may have one carb float too high and one too low.

 

[jkocr2]

Are the float levels correct? Almost dieing and recovering at a stop is a sign of too much fuel in the bowl. Popping is a lean sign. You may have one carb float too high and one too low.

I just checked them the other day when I had the bowls off messing with the pilots. Could a needle have gotten stuck I wonder. It's also dripping gas out of the right vent up top but it's sporadic. But the right cylinder seems leaner than the left.

Everything was running great till I had to go and mess with the Damn throttle shaft seals... grrrrrr

 

[5twins]

Your float bowls have over flow pipes in them. If the fuel level gets too high and over the top of the pipe, gas should come out the nipple on the bowl bottom. Gas should never get as high as those upper vents. I don't know what you've got going on but it doesn't sound good, lol. It does seem like the carbs are intermittently over-filling. It could be bad float needles and seats, maybe worn and only sealing sometimes, other times not. Some of these early '70s carb sets are just plain wearing out now. I'd keep my eyes open for a cheap later linked set.

 

[jkocr2]

Got things pretty much synced up. Took the bowls off and rechecked float height and it was good. Cleaned out overflow drains and all other jets...now my right bowl is leaking from the gasket after reassembly

Ordered some new ones. I also think part of my syncing issue was I was doing it on the sidestand and not the centerstand....not sure if that would make a difference or not but it seemed to.....or its just in my head....oh how I love the carburetor..not!

 

[5twins]

Yes, I've found carbs can act funny when at an angle. My SR500 is easy to flood if I try starting it on the sidestand, never does when started on the centerstand. When you check the floats, you should measure twice on each one, from each side for each float "bulb". Many times they are twisted or tweaked on the bracket and sit at different heights. You won't know this unless you measure from both sides.

 

[jkocr2]

Yes, I've found carbs can act funny when at an angle. My SR500 is easy to flood if I try starting it on the sidestand, never does when started on the centerstand. When you check the floats, you should measure twice on each one, from each side for each float "bulb". Many times they are twisted or tweaked on the bracket and sit at different heights. You won't know this unless you measure from both sides.

Yep, I had to twist them a bit to get them right. Thanks for the help and suggestions. Hopefully the gaskets will fix my leaks. Ill check the floats again when I change the gaskets

 

[5twins]

If all the carb stuff checks out and you're still running points, it might be a good idea to check the points gap, timing, and condenser condition on that rich side. Maybe the spark is weak or off time slightly.

 

[jkocr2]

If all the carb stuff checks out and you're still running points, it might be a good idea to check the points gap, timing, and condenser condition on that rich side. Maybe the spark is weak or off time slightly.

I'm running a pamco