The cheapest YICS tool

... that's not wood or a bit of pipe or a length of oily rag.
10mm allthread.


http://www.900-xj.com/forum/viewtopic.php?f=198&t=20414&start=15

 

I thought I was the only one. I've done the same thing except I wrap 4 sections of the all thread with hi temp electrical tape to give it a better seal.

 

The French do it naked.

I'm kicking myself, having just paid for and taken delivery of a YICS Eliminator, because I'd noticed when I pulled the oily rag out, the bike didn't run quite as well (although it was better than before) as it did with the YICS blocked. I thought I'd better get something more substantial than rag, that I can leave in place if needs be.

In my workshop I have 2M of 10mm threaded rod. Gah.

Ah well, I intend to do a comparison between the two, and if the allthread gives exactly the same results as the Eliminator, that's useful info.

 

the cheapest tool is not using one, it seems to be the opinion of many it is not needed.

how would a threaded rod work if you can not expand the "rubber" as the real tool does when you clamp it in place

I do assume the 10mm rod is the same size thread as the port plug bolt.

 

It seems that engines vary - over on the XS1100 forum, the YICS-equipped versions seem to benefit from being blocked up, and the XJ900F owners in France seem divided on the issue, with some reporting success, others saying it's no big thing. High-milers report more of an effect, from what I see. The naked threaded rod is v.close to the bore size and I assume the baffling effect of the threads is sufficient to create enough of a restriction to be beneficial. The YICS port plug is 12mm thread, iirc. Personally, I'd be leary of leaving a naked threaded bar in the channel, as vibes will surely cause wear and tear, so not a good idea.
More than one way to skin a cat, as it turns out.
As I wrote above - there was a slight but noticeable difference in running when I removed the oily rag and restarted the engine. Proved that it was actually doing something, but a hardware solution seems better to me. It turns out my engine benefits from being set up with YICS blocked (I'd tried it without any blockage, and while it seemed to work, it wasn't as good as it could have been).

 

Everyone is divided on the issue, regardless of which YICS engiene is being discussed. Most of the division centers on whether or not a person understands and appreciated Constant Velocity carburetors and the advantages that the YICS system provides in the combustion chamber.

 

Us non-YICS owners are curious as to what the advantage is and if we should get a second XJ that is a more recent model with the YICS system.

 

The YICS system does two things. It allows for a slightly leaner mixture at the carbs (the difference is pulled from the three other carbs via tht YICS passages) which helps reduce emissions (EPA rules were tightening in '82) and slightly increases fuel mileage. The YICS system also swirls the intake charge in the combustion chamber, which promotes a more complete burn and an increase in power.

 

So it (in away) combines all 4 carb intakes and balances them?

 

Somewhat. The throttle plates are what balances the carbs once they carbs are synched, just like an all other multi-carb systems.
http://www.xjbikes.com/forums/threads/yikes-all-about-the-yics-system.14757/

 

After reading the article it really is important to have a tool that completely blocks those passages then to get the full benefit of the yics system and have your engine run truly smooth.

 

I'm going to try it with and without. Set it up with, run it without for a few hundred miles, note mpg and behaviour, then the same again with the Y-Elim in place. I suspect that YICS might work better on younger engines than high-milers, but I'd be interested to see if there's a benefit that might offset some wear and tear in older carbs.
I know I was getting 45mpg (imp) with decent power when I bought the bike, but that was pre-HD mufflers, and I wasn't hanging around, either. I need to see how these are actually affecting things by putting a figure of sorts on it. A couple of the French XJ9 riders were reporting 54 and 56mpg (imp), with it fitted, which is pretty good, but they might have been 'sensible' riders.

 

Looking forward to your figures. I have 3 to eventually tune so the info will be helpful

 

As long as all of the passages are clean. Which sounds like another article in itself.

 

Is there an article on how to make sure all passages are clean? if so, I need to read it. if not when I get to that part I will have to figure it out and post what I try.

 

You can clean the main passage with a bore-brush, but the small passages require that you remove the head to get them clean. I had mine apart last year and found the passages to all be very clean (just a thin coating of carbon) after more than 20,000 miles. I can't see then being plugged up unless the engine has gone through a lengthy period of running very rich.

 

I have to change my head gasket this year so I will try and check them out. There is over 50 000 km on it and it has never been cracked (1982 xj550 maxim). I am actually a little scared to open her up because of this...lol