No throttle response

My 1982 Seca 750 with YICS motor just idles. Brand new plugs (ngk bp7es). Plugs are perfectly tanned. I took the carbs apart to bench synch them. I put them back on and no response throttle wise. The bowls are full and I'm getting 12.8 on the battery while running. Still no response when I give it throttle. Just stays idle. Anyone have any idea what the heck is going on with this thing? LOL

 

Cable not connected or snapped, or the assembly that the throttle cable attaches to got jammed when you installed the carbs.

 

Got to be Cable and/or Linkage related.
Work the Linkage by hand and see if she accelerates.

If you got the Throttle Linkage connection at the Carbs hung-up when you put the Carbs on ... the Engine would race to high revs.

See that the Throttle Cable Sheath is seated within the U-shaped Bracket on the front of the Carbs and that the Cable isn't just sliding without lifting the Carb Linkages.

Common error.
No points off for making the mistake first time!

 

Cables installed wrong ? Choke on Throttle, Throttle on Choke ?

 

Hi Bridan, what revs you got when you checked the battery? cos that reading is well low.

 

its about 1500 rpm's i fixed the throttle cable it was out of its holder @ the carbs and now its farting through the exgust,,
my guess its to lean?? would a weak battery make it fart through
the exgust? or is it carbs

 

It's the charging rate that is low, this will affect the starting / running of the bike. Pull the plugs, clean & adjust, check for strong spark before you look at the fuel issue.

 

If the bike is capable of making 15-hundred rev's. My guess is that your Mixtures are off.
If you don't have a Colortune Plug ... Set the Pilot Mixtures to a Base Value of 2.75 Turns out from a soft bottoming out.

This Base will set you up for doing Plug Chops and determining if you are too Rich or Lean.
Seeing how the bike comes off-idle when you crack the Throttles will tell the story.

If there is a hesitation before the Main Fuel Jets kick-in ... you're LEAN.
If there is a bogging-out and a stumble ... you're too Rich.

Once you arrive at this stage of tuning ALL adjustments to the Pilot Mixtures are MINUSCULE!
A hair either way will change the Mixture for the better or worse.
To give you some perspective the adjustment In or Out will be within the width of a Dime.

Make yourself a screwdriver that FITS the Slot on the Pilot Mixture Screw with NO free-play!
You need a tool that will move the Screw either way with great precision!

Begin a routine of inspecting the Spark Plugs.
Examine the color of the Ceramic that surrounds the Center Electrode.
Tweak individual Carbs to achieve a Dark Tan to Medium Brown.

Once a Plug shows the right color ... leave that one alone and concentrate on bringing-in any of the others not having the Tan to Med Brown.

If you encounter a Plug that is CLEAN ... Beware!
Clean is too Lean and can cause serious damage to the Piston Crown in short order.
If you have one too Lean ... enrich the Mix and "Back-into" the desired coloration after you have insured that Hole isn't burning Lean any more.

The Engine is Aluminum.
The Engine is not designed to run in a Lean condition.
The threat of overheating and sever damage is great if you don't correct a Lean condition immediately.

Once you get the bike to Idle and Throttle-Up without hesitation ...
Begin a series of Plug Chops.

Plug Chop;
The Plug Chop is a method of "Fine-tuning"
After you have the Bike running.
After the Idle is good and steady.

The Optimum Performance you will get from your Bike is done via Plug Chop.

You can do it all in one sitting or across several outings.
I have done both.

But, to be successful the Carbs need to be cleaned and functioning perfectly.
The Plug Chop is a read on the way the Mixture is being burned by observing the Plugs.
Each Plug has a story to tell about how its Cylinder is being fed.

The process is one of making a minute adjustment to each Pilot Mixture Screw needing to be adjusted resulting from the read on the Plug.

My last Chop on the 900 was done after running the bike "Normally" for three days.
The Plugs were very light and the Bike "Felt" like it was being held-back.
A read of the Plugs indicated that each was still a bit lean. One leaner than the three others.

Individual adjustments to the Carbs had me add Richness to all four with an additional bit to the one too lean for its own good.

Now, the Bike is running real well.
Is this the end of the tuning.
No!
I'll ride the bike for a day or two and observe them again.
Once I get the coloration to be light brown, I'll be satisified.
I know, from checking the read ... they're still on the lean side ... but, NOT critically lean as to cause an overheat or other damage resulting from being too lean.

I'm in the Zone of great performance.
All I'm really doing now is playing with my bike.
It's fun to do after getting dialed-in. You tweak in search of perfection.

Another tweak or two ought to do the trick.

 

wow thanks rick

sorry for being a noob, but to do all of this work to the carbs do i have to take the off of the bike each time to ajust them?

 

Nope but you do have to remove and flip the tank around so ti sits where your seat is and have someone hold it there, or just take it all the way off turn the pilot screws and place it back on. (unless you have a really neat screwdriver and very very nimble hands to get up under there and still make presice adjustments.

 

Leave the Carbs on the bike. Now, you are into the Tuning phase.

I made a tool to tweak. I love the little thing!

Craftsman Pocket Screwdriver. The one with the Pocket Clip.
Remove Pocket Clip. Place tool in vice.
Measure one inch up on the plastic handle from the shank.
Hacksaw that baby right off so you have a one inch handle.

Grind shank off at one and a quarter inch.
Chuck it in the drill.
High-speed rotate the tool and sandpaper the plastic top.
Nice and smooth; bevel a nice curve on the top.

Grinder time again.
Using a spare Pilot Mixture Screw to fit the screwdriver to ... grind a new blade end on the screwdriver that fits the Pilot Screw with GREAT precision.

Back to the vice.
Place the screwdriver in the vice with the new blade at 6-'n-12 O'Clock.
Hacksaw a small groove in the length of the handle across the top. (12:00)
Lay some white paint in the groove for a visual reference.
Let dry.

Bingo!
Your own special Tweak too that will fit-in under the tank without having to do anything but lift the tank up a bit to see what you are doing!

 

How about a pic of said device or is it one of them 29.95 deals while supllies last LOL!!!