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Old 07-15-2002, 11:33 AM
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Mike Hart Mike Hart is offline
XS-XJ Guru
Join Date: Jul 2002
Location: Seattle, Washington
Posts: 1,025
Post Norm Kokes' Home-made YICS tool

Norm Kokes' Home-made YICS tool

Parts to build a YICS tool
  • 1 - 16" long section of #6x32 threaded rod
  • 7 - 5/16" washers with a 1/8" hole
  • 1 - 3/4" fender washer with 1/8" hole
  • 1-1/2" section of rubber gas line hose - approx. 3/8" O.D. and
  • 1/8" I.D. cut to 1/2" long (3)
  • 1 - #6x32 wing nut
  • 1 - #6x32 lock nut
  • 12" of 1/4" I.D. copper tubing

You can pick up all the parts at ACE, Coast to Coast or Hardware Hank stores The rubber hose is standard gas line 3/8" O.D. with a 1/8" inside diameter nylon reinforced The copper tube should be cut with a tubing cutter so the ends stay square, you will have to drill the ends open after cutting as the tubing cutter will squash the ends down. don't try to bend the treaded rod too sharply, make a gradual bend or the rod will snap. (I warned you) Better yet use a propane torch and heat the rod section (red hot) and it will bend just fine. Total cost of all hardware should be $3.00 to $4.00 total.

The later models of Yamaha (1982 & newer) use a YICS ( Yamaha Induction Control System) which is basically a vacuum balancing system in the intake manifold. A gallery is located just below the intake passages connecting all four intakes together via small air passages (approx. 1/8" ) the gallery itself is approx. 3/8" in diameter and 16" long on the 1100's. ( one of these days I'll convert to metric )

To balance the carbs and set the idle mixtures properly the YICS must be rendered inactive so a true vacuum can be established. A special tool is required to seal the YICS passages while this adjusting is going on. The tool incorporates three rubber hose sections to act as seals, they are located in such a way as to isolate the passages from each other.

To use just remove the gallery plug, it's located on the left side of the engine just below the carburetor inlets, should be 12mm. Slide the tool all the way in until the fender washer come in contact with the tube. Now while holding the bent part of the treaded rod tighten the wing nut till firm. Hook up your gauges or carb sticks. Start the engine and allow to warm up. It is normal for the engine to idle slower than normal so you may have to increase the idle speed to 1000 - 1200 rpm. Now proceed to adjust the idle mixture on each carb for maximum rpm. should be approx. 1- 1/2 turns out. Sync. the carbs for even intake vacuum balance. Shut down and remove the gauges & YICS tool tighten the gallery plug to 100 inch pounds ( firm but not gorilla ) reset the idle speed and your finished!! How it works, tightening the wing nut squashed the rubber hose sections and causes them to grow in diameter sealing against the gallery walls. the section closest to the wing nut is positioned directly under the #1 cylinder passage sealing this on from #2,3&4 the second seal is set between #2&3 isolating these two and the end seal is between #3&4 so intake vacuum is now independent and not shared by the other cylinders. BTW the YICS system helps the cold start back fire that the non-Yics machines are prone to. You can achieve similar results on the older machines by connecting the carbs together. just get some rubber gas line and two tee connectors remove the rubber plugs from the balance tubes and hook the four carbs together using the tees on #2&3 and the rubber hose. You'll notice a slightly faster and smoother idle.

Reprinted with the kind permission of Norm Kokes

I hope this has helped.

UPDATE: 06-28-09 by T.C.

I was preparing to do some tuning on a fellow Xsive's XJ this coming July 4th weekend, and so I set out to make this tool.
I encountered some shopping problems. Both the local hardware store and LOWES did not carry the #6x32 threaded rod in 16" lengths, only 12". They also didn't have those nifty little threaded joiners like they have for other larger sizes! After browsing around I found that I could use something called a "T" Nut, designed to put a threaded section into a piece of wood that you could screw in the bolt, etc. to secure it. They have them in the small #6x32 size, and would allow about 3.5 turns from each end of the threaded rod to hold them together for a 24" long section. I used some wire cutters to cut off the large disc end so that I had a small disc and the threaded section. Then I used some thread lock and joined the two sections together.

The above parts list wasn't as descriptive as I think it should have been, so here it is again, hopefully with more info so you can acquire the correct parts:
  • 2 - 12" long sections of #6x32 threaded rod
  • 7 - #6 washers with 5/16" O.D. with a 1/8" hole
  • 1 - 3/4" O.D. fender washer with 1/8" hole
  • 2-3" section of rubber gas line hose - approx. 3/8" O.D. and 1/8" I.D. cut to 1/2" long (3 pieces)
  • 1 - #6x32 wing nut
  • 1 - #6x32 Lock Nut/Cap Nut
  • 12" of 1/4" I.D. copper tubing

Here's a photo of all of the parts separate:

And here is the tool actually bent and assembled.

Mike * Seattle * 82 F'n'XJ1100 *

Last edited by TopCatGr58; 06-28-2009 at 09:13 PM. Reason: Updating Info and adding Pictures

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