Just fired it after a rebuild. . . . Carb tuning?

[alfredo]

I just started it up for the first time. Made my heart flutter my friends. So, I am running straight pipes and 38 carbs.

I started it up and with the choke on. It idles very high. The little nipple holes on the carb holders aren't capped and if I plug them with my fingers the bike smoothes out and lowers its idle. Also, I have the air filters off.

What should I do to get this beast to idle properly? Anything else I should do before taking it out on the road?

 

[Ironsled77]

Start with plugging the holes. Put on air filters n fire it up! See if you can idle down the choke and see if it runs!

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[littlebill31]

The carb holder barbs need to be plugged. It will run way to lean, thus the high idle. They are used to attach a manometer to synch the carbs. Which you need to do. Use "blind plugs" to cover the barbs. Or use a piece of tubing to connect both. Either way you do not what them open.
So, synch the carbs and follow the "dead cylinder" method to set the mix screws. Then it should run pretty good.

 

[Sundie]

lol - yeah, plug the barbs. Should run and idle right away, pretty much.

You should only need choke for about 10 seconds, from cold.

- put the air filters on
- cap the nipples
- put tank on prime (or if no vacuum petcock, just on)
- start bike (possibly on choke)
- set idle to ~1200.

they should be *close* to balanced - i set it all before i shipped them back to you.

That's about it.

 

[alfredo]

thanks sundie!

 

[jims428]

Hey Sundie,
If you are not giving away any trade secrets could you give a simple example of how you balance the carbs without putting them on a bike?
I plan on trying a rebuild on a spare set of 34's and it would be helpful to get them close to start with.
I do have a sync gauge to use afterwards.

 

[Sundie]

I have a sort of home made attachment for my shop vac - i actually balanced his carbs on a bike in the garage, which had even compression.

The shop vac method works fine as long as it's big enough to actually build a vacuum - and you can fiddle with the idle position a bit to restrict more - the objective is just to get even vacuum, so if you turn down the idle so that the plates are more closed, it doesn't matter that you have less than the engine will actually pull, or that you'll adjust the idle back up when on the bike.

 

[retiredgentleman]

Hey Sundie,
If you are not giving away any trade secrets could you give a simple example of how you balance the carbs without putting them on a bike?
I plan on trying a rebuild on a spare set of 34's and it would be helpful to get them close to start with.
I do have a sync gauge to use afterwards.

Here's a simple way to sync carbs on the bench. Cut a strip of paper about 3 or 4 inches long and about 1/2" wide. Slide the strip of paper under each of the butterflys to achieve equal amount of drag.................go back and forth adjusting the centre screw. The paper is a used as a feeler gauge and is quite accurate. Later when you use the manometer, you'll find it is very close.

 

[xjwmx]

Here's a less subjective way. Buy a popsicle. When finished, put one stick under each throttle plate. Lift the throttle lever, and when both sticks begin to see-saw at the same time, it's synch'ed.

 

[littlebill31]

Xjwmx, kinda what I do, but I use coffee stirers. I have plenty lying around.

 

[alfredo]

What about doing this on the bike?

 

[littlebill31]

Without it running, put a long straw thru the air filter side. Hold the butterfly open and slowly release it. You are doing the opposite. So the butterfly, coming back down, will push the straw out. Keep adjusting 'till both straws move at the same time. It's very primitive though. Running, a manometer.

 

[Sundie]

What about doing this on the bike?

Dude, i would be *very* surprised if this is something you have to worry about right this second. Like i said, i balanced them on a bike here, and if they're more than maybe half an inch of vacuum out, i'd be surprised.

 

[alfredo]

Dude, i would be *very* surprised if this is something you have to worry about right this second. Like i said, i balanced them on a bike here, and if they're more than maybe half an inch of vacuum out, i'd be surprised.

Agreed. I was just curious about how to do something like that on the bike. I am most certainly going to do as you suggested amigo.

 

[Sundie]

So is it running yet?

 

[alfredo]

I went out and put the pods on last night, had my daughter hold the carb holder plugs closed and it started in choke, idled a little high. Then I turned the choke off and it died. Having to look at the local hardware store for nipple plugs today after work.

 

[littlebill31]

You can connect both plugs with one tube. Some say it equalizes the carbs, but either way it closes them. Kinda looks neat with colored tubing and cheap price.

 

[alfredo]

ahhhh. so if I can't find the bind plugs, just connect them. great piece of info.

 

[5twins]

I use vacuum plugs or caps from the auto parts store, 5/32" size is perfect. They sell them in 5 or 6 packs for a few dollars. Nice to have spares because they do split, fall off, or get lost sometimes.

 

[alfredo]

I use vacuum plugs or caps from the auto parts store, 5/32" size is perfect. They sell them in 5 or 6 packs for a few dollars. Nice to have spares because they do split, fall off, or get lost sometimes.

auto zone here I come.