‘78 GS1000 Throttle Valve Adjusting Screw

[DeegzARG]

Yes, the idle screw you mentioned is accessible from outside the float bowl. 

I have a manual but can’t find the exact details I’m looking for. I’ll have to go through it again and hopefully I can find some more info. 
 

 

 

[Gixer1460]

Most workshop manuals will have an exploded carb diagram (usually not the best view) all labelled, A maintenance section for everyday tuning and a specifications section that usually details carb settings!

[DeegzARG]

Thank you! I’m going to have a thorough look at the manual and let you know what settings work best for me!

[BigT]

The pilot fuel screw (not an idle screw) does not appear in the manual, or diagrams, because it is "factory set" and covered with a cap at the factory.

You set it at 3/4-7/8 turn out from lightly seated for stock/ airbox. 1 -1 1/4 turns out if you've got headers, pods,cams, etc

lightly seated because it's very easy to break the tip of the needle off in the carb body. Check to confirm that the needle has a long tip and the hole in the carb body is open to the carb bore.

set the pilot fuel screw as above and tune the idle mixture with the pilot air screw on the side.  Easiest to do with a Colortune, but high idle method works well 

Remember, this only sets the idle mixture. Off idle is cutaway, then needle/needle jet up past half throttle, then the main jet over half throttle

[BigT]

On 10/7/2022 at 8:06 AM, DeegzARG said:

Thank you Gixer1460! That illustration is perfect. I’m a newbie with these carbs so that’s very helpful.
 

Questions about the air/fuel mixture idle jets; should they be perfect? I noticed one of them is in rough shape compared to the others. Should I replace that and is it something that I can walk into any bike shop and pick up or are these special order items. 

Yes, you should replace that screw, and check the hole in the carb body where the tip fits. 

And, go back up to the carb cleaning link I posted, because years of experience says cutting corners means you'll be cleaning them again

Edited October 11, 2022 by BigT

[DeegzARG]

Didn’t have a chance to pull the carbs until today…….for the third time  

BigT,  I’m glad you mentioned to check the hole in the carb body, one of them was clogged with a broken tip. I managed to get that out. Weird thing is that it was the second carb that was blocked but I’ve been having an issue with the third cylinder,third is the one that’s not  heating up to temp. 
 

I’ve reassembled the carbs and hopefully I have a chance to try it out this evening. 

[BigT]

Well, I hope you followed the tutorial before reassembly. The small passages in the carb body don't clean by spritzing carb cleaner thru them

3rd cylinder? Third from left, as you sit on the bike?  Be sure the vacuum port is either capped, or connected to the fuel tap

[DeegzARG]

Just a quick update for future reference. I followed the steps as instructed by BigT and everything came together nicely. Bike is sounding incredible, idles beautifully at about 1,100rpm. Doesn’t seem to have any issues and the third cylinder is heating up like the others (really appreciate all the folks that commented on this thread as it helped me out a TON) I will keep an eye on the bike in the next couple days and hopefully it continues to run well. 
 

Next step is to vacuum sync the carbs to dial them in better and I should be good to go. 
 

Does the tank have two vent hoses and one vacuum hose?

[BigT]

The tank has one overflow  hose for the fuel sending unit.

The carbs have 2 vent hoses for the float bowls and one vacuum line on the #3 carb, it connects to the vacuum port on the fuel tap