carb first timer

[CoreyF]

Thanks to all for the courage to undertake breaking down my carbs. The forum is a great resource and enjoyable reading.
I put in replacement diaphrams from JBM, new choke seals, tee o-ring fix and gave them a cleaning. Piece of cake.
Here comes the question.
I hooked them up to the gas tank - on the bench - to check for leaks. Looking in the venturi from the airbox side it's wet, a puddle where the needle goes into the main nozzle. Is that right? I'm trying to avoid off and ons with the carbs.
The float height for an '80 is 23mm

[motoman]

Originally Posted by CoreyF

Thanks to all for the courage to undertake breaking down my carbs. The forum is a great resource and enjoyable reading.
I put in replacement diaphrams from JBM, new choke seals, tee o-ring fix and gave them a cleaning. Piece of cake.
Here comes the question.
I hooked them up to the gas tank - on the bench - to check for leaks. Looking in the venturi from the airbox side it's wet, a puddle where the needle goes into the main nozzle. Is that right? I'm trying to avoid off and ons with the carbs.
The float height for an '80 is 23mm

Upside down with bowls off fed from a fuel supply above carbs is what is needed done checking that float needles are sealing.
23mm is a 'ball-park' figure given in specs. The actual fuel levels(3mm down from carb body casting) is what matters for an end result.....if you want levels all the same, which they NEED to be. Varience of float needle internal spring load tension dictates ACTUAL fuel levels.....and they DO vary.

[CoreyF]

Started it up. Started right up. But, when I rev it up the rpm's stay up, gradually lowering to around 2000 and backing off the idle adjustment doesn't seem to have any effect. The plugs are black. I did do a check of the float level with a clear hose. Was I too cocky thinking I could do this taking the carbs off and put 'em back only once? Besides changing the diaphrams with the JBI alternative I changed the jets by the book to 115 - 120 - 120 - 115. What they were was 110's on all four

[phatts27]

Maybe you just need to sync the carbs. There's a how to for bench syncing and instructions for a homemade sync tool available on this site somewhere. Also, check for vacuum leaks.

[MarkD]

CoreyF.--- Not sure if my problem was like yours is, but check out my thread "unwanted revving issues", and see if there is any useful info there.

[motoman]

Originally Posted by CoreyF

Started it up. Started right up. But, when I rev it up the rpm's stay up, gradually lowering to around 2000 and backing off the idle adjustment doesn't seem to have any effect. The plugs are black. I did do a check of the float level with a clear hose. Was I too cocky thinking I could do this taking the carbs off and put 'em back only once? Besides changing the diaphrams with the JBI alternative I changed the jets by the book to 115 - 120 - 120 - 115. What they were was 110's on all four

Actually, too bad you didn't know to check that the carb bank on there is ACTUALLY 80Standard also. 80-81Specials and Standards had different configured metering rods, with teeny-tiny letter/number designations at top on side of metering rods. Special carbs used 110's across all four. If that WERE the case with yours, the 2 and 4 step richer WILL make for black plugs and rich running.

[CoreyF]

Thanks MarkD, I'll follow your lead and pull out the K&L pilot jets (2-2-2-2) and replace with the previous (1-2-1-2)
Motoman, while I'm in the carburetors again I'll confirm the code on the metering rod. By that do I look at the top of the needle or slide? And I checked the book for main jet sizes for various yeas and models and didn't see any that have 110's across all four, according to Clymers. Not that facts could have been misprinted (ha)

[motoman]

Originally Posted by CoreyF

Thanks MarkD, I'll follow your lead and pull out the K&L pilot jets (2-2-2-2) and replace with the previous (1-2-1-2)
Motoman, while I'm in the carburetors again I'll confirm the code on the metering rod. By that do I look at the top of the needle or slide? And I checked the book for main jet sizes for various yeas and models and didn't see any that have 110's across all four, according to Clymers. Not that facts could have been misprinted (ha)

Clymer's has MANY mistaken listed stuff, including some torque specs(insert swingarm bearings) as just one.
That numering/lettering is on the side/top of metering rods. In other words, you have to remove them from the slide(careful removing the clippy, as the man-cave can 'eat' it).
Anything K&L needs to be eliminated if intending to get to run and tune correctly......especially the main/pilot jets. Just a word to the wise.

[CoreyF]

I've taken out the K&L stuff in the carbs and put back the Mukini 110 mains that were in there and new genuine float needles from Jets-R-Us. Seems there has been a stretch of members going through difficulties to gain from their experiences.
Since my 11 is quite unmolested, engine matches frame 3H5-004892 (G), I am curious that the numbers on the needle jets are 5GL16, from what I've read are to be found on different models/years 11's.
And from what I've read here and elsewhere suggested main jetting is something other than 110's. Could someone confirm these two questions?

[3Phase]

Corey,

Someone replaced the '80G Standard carburetors with a set from an '80 or 81 Special or rebuilt the '80G carburetors with the wrong needles and jets. They'll work but they're a hair lean for the Standard's larger rear wheel.

Unless you can find a complete set of four unobtanium 5IZ7 needles to use with the '80/'81 Standard's staggered 115-120-120-115 main jets, I suggest you leave the needles and jets alone and just ride it.

Remember it's lean so try to keep it below 120 MPH sustained.

.

[CoreyF]

I haven't done 120mph since my new xs1100E in'78 when I wa 25yrs. old. I remember the telephone poles going by like fence posts.
Thanks for the input. Good idea to know what carburetors I'm dealing with.
Now to try synchronization.

[3Phase]

Corey, it'll be a little anemic but you'll like it when it's synchronized.

Someone had done the same thing to my '80G before I bought it too but at the time I didn't know Jack about the different needle shapes so I tried replacing the 110 mains with 115/120 mains.

Low-speed is fine because you're mostly using the 42.5 pilot jets.

Mid-range is too rich so it wastes fuel and that's where you spend a lot of your riding time.
A Special needle is shorter and pointier than a Standard needle so it clears the main jet sooner and goes full-open before the engine in the Standard can really use it. With the 110 mains that's not too bad but with the larger jets it's not quite rich enough to blow black smoke but it does create an invisible cloud of unburned fuel that makes your eyes water and children and small animals cry.

High-speed is fantastic!

.

[CoreyF]

Stuttering and popping.
Just got back from a mechanic that "synched" my carbs. He was frustrated that he couldn't do better. Turns out the bike did not run well when the mercury sticks were all even. The #4 idle screw position had no effect all the way in or 2 turns out. The pops on #3-4 side, likely #4. I can see all four carb boots oscillating between vacuum and back pressure (normal?) Just the facts ma'am.
I'm going to recheck float heights with a clear hose before I remove the carbs and recheck the insides.
BTW new boots, hoses and clamps

[Ken Talbot]

It sounds to me like you've still got at least one dirty carb, #4 for sure. If the pilot screw adjustment does nothing from two turns open to full closed, the primary circuit on that carb must still be blocked. As you sync the carbs at a very low RPM, having a blocked primary circuit will cause no end of grief.

If #4 is dirty, it is a good guess that one or more other carbs might also be dirty.

[CoreyF]

I now know I have 3H5-00 bodies ('80G, found the stamp) with 5GL16 (SG, LG) jet needles.
It ran pretty OK to begin with but the diaphrams had a number of holes.
As can be seen I don't work real fast. When did I start this project, April, May?
I've re dipped the bare carb bodies, another can of carb spray, cans of contact cleaner, fishing line and guitar string, compressed air, pre synch, mercury stick synch and it runs like a champ . . . . 2k RPM and up.
After it warms up there's considerable hesitation and stumble up to 2k as when starting from stopped.
Where do I focus my attention? I'm thinkin idle jets, adjustment hopefully.
Is this low end symptom consistent with idle jet adjustment?