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Tips on setting idle screw correctly?
- Thread starter chrisd1984
- Start date
That's one option....cleaning the threads on the screw and lubricating it are another. The spring will keep it where you put it.
Specdog
XS400 Addict
That is a nice screwdriver, but it isn't long enough for the DOHC carbs. That is why I made mine... 
So why do they call you shorty? LOL
For the same reason they call 300 lb farm boys "PeeWee" or "Junior"...
use either small drill bit, like a 3/8s, or a wood screw. If you have a drill bit with a stop, have it stop before 1/4inch. The cap is just that, a drill bit bigger than half of the opening size will start to spin the cap out, Same with a solid core wood screw. you don't want to go deeper than a 1/4 inch. The screw head is just under there, so be ginger, when pulling it out. there is a hole in the middle of the cap so the screw or the drill bit will bit in easily.
http://www.mtsac.edu/~cliff/storage/gs/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf Scroll down a bit and you will find it complete with pics
Not sure myself, but I think this exchange might be on the same subject and might help:
No. Turning them out or counter clockwise makes them richer and the opposite for leaner. I would start by turning them in gently till they seat then turn them three full turns out to start with. I use a small properly fitting screw driver with a mark on it so I know when I have gone a full rotation. I would make sure you sync the carbs with a manometer after you do this then fine tune from there. If you need to go out more than four turns to get a good idle to 1/4 throttle mix. You will need to go up another step on the pilot jets.
Alriiiiiight, well got to them and did the standard 3-31/2 turns out from a gentle seat and they run to doodoo. Would it work better to lessen the gap on the butterfly valves in the carbs? Or keep them with that gap and just go to bigger jets? If bigger jets, is it best just to order a bunch and mis match them to see which work?
You are over thinking this. The number of turns out for the pilot screws is just a starting point to get the bike running well enough to ride it. Get the bike warmed up by riding it fairly hard for about 20 minutes. Then adjust each pilot screw in or out as required to find the highest idle. Reduce idle speed back to stock using idle speed screw and adjust pilot screws again to find highest idle. Keep repeating until you have it as good as it can be. Then adjust pilot screws in until idle speed drops. Then turn back out 1/2 turn. Then sync carbs.
If you end up having the pilot screws less than 1 turn out, the pilot jets are too big and should be reduced 1 size. If more than 4 turns out, increase pilot jets 1 size.
If you end up having the pilot screws less than 1 turn out, the pilot jets are too big and should be reduced 1 size. If more than 4 turns out, increase pilot jets 1 size.
Yeah, I ran it and tried makin adjustments and it's just way too high of an idle and hangs up at high rpms and I'm at like 4 turns out so I'm assuming I will need new jets... But what's the next size up from stock?
See what you have first. stock is 42.5 next would be 45 then 47.5 most often 45 is enough but do what dave said.
Alright so I ordered some new pilot jets... These are found actually inside the carb correct? And just so I know prior... When I out the new pilot jets in I will just gently seat them correct? Or it there a certain way on putting them in?
The idle screw, also known as the idle mix, is top between the carb n the engine. Nice pic of an older model on pg 1 of this thread. The newer ones were cap'd to keep people from messing with them. From the factory they were set at 1 1/4 turns. We know if it has enough gas it will start. So we recommend 3 turns for initial start up after a rebuild or other maintenance. Upgrading the jet, which is in the fuel bowl, to 45 is something people do when they think the bike is starving due new muffler, or air filter design change or some change like that. The jet goes in till it is tight, the pilot idle mix screw will go in softly, and back out right away. There is more postings for people who have tighten that one too much. Dont be that guy.
Its been awhile, the jet might be on the air filter side of the carb. (Memory not the best) it is listed on the manual, under carbs.
Its been awhile, the jet might be on the air filter side of the carb. (Memory not the best) it is listed on the manual, under carbs.
