confused! Carb tune sequence?

Carb cleaned and new parts in place. I'm struggling with the process of final tuning. Float bowls and bench synch done, reinstalled on bike.

I have YICS tool (homemade), plug colortune, and vacuum carb tune ready to go.

What is best sequence to best perform the synch? I've got vacuum to deal with, I've got plug color to deal with, I've got butterfly idle to deal with, I've got idle mix pilot screw to deal with.

How do I make this thing purr? I keep reading and getting more confused.

 

VALVE CLEARANCES IN SPEC FIRST. Then vacuum carb sync, then mixture tuning.

Vacuum sync="butterfly idle."

Pilot screws=pilot mix=ColorTune.

Vacuum sync first, then tweak mixtures as needed. ColorTune is a way to fine-tune the mixtures, AFTER the vacuum sync.

Block YICS for vacuum sync and ColorTune (at least that's what Yamaha recommends.)

 

first of all, a good set of CLEAN carbs are in order. Then, you MUST verify that your valve clearances are within spec. After those two items are good, then you can proceed to your carb adjustments.

I typically do a bench sync while the carbs are off the bike. This will get you close enough to run the bike when they're installed. Second, I set my mixture screws to 2 1/2 turns out from soft set. With all the before mentioned conditions, your bike should start and idle (it may be a rough idle, but it will idle). Then I adjust the idle mixture screws to allow the best idle (read as highest idle without messing with the idle knob of the carb set).

Right now is a good time for you to shut down your bike and install your YICS tool and vacuum hoses to your manometer.

Next I use my homemade manometer to vacuum sync the carbs. Make all my adjustment to make sure that all of my carbs are equal vacuum.

Then, I start using my colortune plug. Very small adjustment are needed at this point. I turn out my mix screw until I get an orange flame in the cylinder. Then I turn the screw back in until I start getting a blue flame (it will be a mix of blue with just a hint of orange). This is where I found that my 650 runs the best.

Once you adjust all the idle mix screws, then I just verify that my carbs are still in sync just one more time. After these procedures, my bike typically sings like a sewing machine, and is extremely easy to start in the morning.

I need to engage my fuel enrichment during the cold starts. Then I am able to lower it to halve within the first 30 seconds or so. By the next minute, I can turn off my fuel enrichment and the bike will be as smooth as butter.

 

Thanks for the progression. Another question, as I've a homemade YICS tool (per specs on XJbikes) how do I know for sure that the tool has indeed blocked off the ports?

 

(You don't?)

The biggest "issue" with homebrewed YICS tools is often the lack of a seal between the tool and the head right where the tool is inserted. The tool needs to have an airtight seal against the side of the head so that it simply doesn't cause a major vacuum leak.

As for whether or not it blocked the ports, that is simply a matter of the spacing being correct; and then do your rubber bits "swell" enough when your version of the tool is deployed to ensure the passages will be blocked?

You can test it by "engaging" the tool with only one "passage-blocker" inserted into the passage in the head and watching how well it fills the passage when you activate it.

 

Interesting that in all the threads on building ones own YICS tool the topic of vacuum seal does not appear ..... maybe I just missed it. So working on a YICS tool fix to make a tight seal.

thanks for the help.

 

Get a piece of coat hanger wire and bend a hook (L) and feel, and measure for yourself.

If the first rubber lands exactly on the hole, or further outboard, you don't need an "outside" seal.

In fact - you could make a tool that plugs #4 and #2 only, and #1 & 3 would "breathe" into a very small, closed cavity, simplifying the tool.

The Noobs can stuff it with an oily rag for their first tune-up.