What is a YICS tool?

What is this YICS tool? What is it used for? I was curious since I have a 1986 Yamaha XJ700S that has YICS embossed on its valve cover.

Can someone tell me anything about this tool?

 

Here is a short and sweet explanation, others will be able to expand a bit:
The YICS tool is used to fine tune the carbs individually. It goes into the head of the engine on the carb side and blocks off the ports that help to level out the flow between each cylinder. They are available from the dealer, at a healthy cost. Many on the board have one or have made a knock-off that does the same thing as the original. Unfortunately I don't have a pic available, but if you go to the sticky threads and find the thread about the YICS tool rental you should be able to find a ton more information. Hope this helps.

 

Which models have YICS? I've got an 82 650 maxim.

 

Someone else can provide a list, but yours should be a YICS engine, as I have the same bike and it is. I believe the cam cover and the side covers say Yamaha YICS, as an easy identifier.

Anyone else want to chime in?

 

YICS is a performance and fuel efficiency cylinder head design that promotes better/more complete combustion chamber "filling" and "mixing", and thus more/better combustion efficiency via a cast-in passage (or "sub-intake ports", as Yamaha calls them) within the cylinder head. These YICS sub-intake ports have approximately 1/4th the cross-sectional area of the main intake port runners. These smaller YICS ports tie into and enter the main runners just above the intake valve seat in the combustion chamber and at such an angle that their air/fuel "charge" is directed around the outside walls of the cylinder/cylinder head/combustion chamber, which results in a swirling effect as the mixture is drawn in and then compressed via the piston.

These "sub-intake ports" are connected via the YICS cylinder head passage. Since only one cylinder is on the (downward) intake stroke at any one time, the YICS sub-intake port FOR THAT CYLINDER also draws in some air/fuel mixture charge from the other three sub-intake ports and carbs. When a piston is moving down in the cylinder bore during its intake stroke, the vacuum created operates on both the main intake port (for that cylinder) AND on all the other sub-intake (YICS) ports. But since the area of the sub-intake port is so much smaller than the main intake port, this sub-mixture moves through the YICS passage/port almost 4 times faster than through the main intake port. Thus the cylinder "filling" and "swirling" effects......

According the the factory marketing gurus, the end result of this controlled turbulence in the combustion chamber is quicker, more complete burning of the air-fuel charge, and thus, all (well, at least "more") of the power contained within the fuel is liberated on every power stroke of the engine.

Note that in all of this discussion by Yamaha, that the underlying theme is "greater fuel efficiency", and NOT more power or performance--------although the two do go hand-in-hand.

YICS was used on all XJ550 models, 1982-up XJ650 Maxim and XJ650 Turbo models, all XJ700 non-X models, all XJ750 models, 1983 XJ900RK, and 1982 XJ1100 models. The 1980-81 XJ650 Maxim and 650 Midnight Maxim models, as well as the 1982 XJ650 Seca models, did NOT use the YICS system. It has also been reported by some owners that some very early model 1982 XJ650 Maxim models did not use the YICS system.

YICS bikes have front lower (oil pump) covers on both sides that have a rectangular "YICS" emblem in them below the cast-in YAMAHA wording. Non-YICS models have the oil pump covers with only the YAMAHA wording cast into the cover.

YICS bike also use a valve cover that has the word YICS cast into the top surface, while non-YICS models are blank or are cast "YAMAHA" (or "YAMAHA 5VALVE on 700-X/750-X models) on the valve cover.

YICS is probably a good feature, and probably does provide some moderate advantage in fuel economy and performance, just as the factory claims. It makes carb synch a bit more difficult, as a YICS passage "blanking" or block-off tool must be used when doing a carb synch, and it's also not a bad idea to clean out the YICS passage port holes every once in a while, and to replace the YICS passage bolt Sealing Washers every once in a while; but other than that, it's a pretty simple and problem-free system; as Yamaha likes to say, "we did all this without adding any moving parts!".

Here is the YICS blanking tool that I offer that is needed to properly tune/synchronize the carbs on a YICS bike.


vv7) Reproduction YICS Port Blanking "Block-Off" Tool---this is the tool you'll need to perform a proper carb synchronization on any YICS motor......without it, you're just wasting time. This block-off tool is used to isolate each cylinder from the others while perfoming a carb synch. Updated version of the factory #90890-04068-00 tool. Some people claim that this tool is NOT needed to perform a proper synch; we disagree, and so do the Yamaha engineers who designed the YICS system. Quality aluminum tool features a snap-open and shut trunnion handle design like the original. This is NOT a cheap home-made tool and has all the proper seals, dimensions, and high-temp insulators as an original factory tool. IN STOCK!

HCP93 reproduction YICS port blanking tool, each:
$ 37.00


c5) Yamaha YICS Port Clean-Out Tool----the YICS chamber runs side-to-side in the back of the cylinder head, and is accessed via a 12mm bolt on either end (this is the same chamber that the HCP93 synch passage-block-off tool fits into). This chamber has four tiny passages in the top, one for each cylinder. These passages can accumulate soot and other material over time, effectively clogging or reducing their capability to pass the fuel-air mixture through them, and thus compromising their function. This YICS port probe & clean-out tool has a spear point that can punch through the toughest accumulation of carbon build-up, and has marked notches on the extension rod to indicate exactly how deep into the chamber the tool must be inserted to easily locate the passages. Convenient plastic handle allows for ease of use. A very handle tool to have around!

HCP1282 YICS chamber Port Clean-Out Tool:

$ 14.95


http://www.xjbikes.com/Forums/viewtopic ... t=135.html

 

please pm me about the yics tools

 

MrCarb....you got mail!

 

looking for same said tool... any info would be great thanks.

 

Here they are!:

vv7) Reproduction YICS Port Blanking "Block-Off" Tool---this is the tool you'll need to perform a proper carb synchronization on any YICS motor......without it, you're just wasting time. This block-off tool is used to isolate each cylinder from the others while perfoming a carb synch. Updated version of the factory #90890-04068-00 tool. Some people claim that this tool is NOT needed to perform a proper synch; we disagree, and so do the Yamaha engineers who designed the YICS system. Quality aluminum tool features a snap-open and shut trunnion handle design like the original. This is NOT a cheap home-made tool and has all the proper seals, dimensions, and high-temp insulators as an original factory tool. IN STOCK!

HCP93 reproduction YICS port blanking tool, each:
$ 37.00

 

excellent sign me up... where do I purchase???

 

Igor....send me a PM and I'll send you all of the ordering info!

 

I would say this is correct as all the YICS bikes in the fuel economy thread get 10+ MPG better then the standard engine.