yix port....

im lookin at my young friends xj650 seca rj varient, an 81....while I can see where a common drilling might be in the head connecting all the intake ports, (hump in the casting) if there is an acess, it seems to be a cast in cap closing it.
The inlet manifold has vac. port nubs.... is this a YICs head? If so, ...well, do I have to drill a hole for acess? That makes no sense....
The more I get into this machine, the more im impressed.

 

Mutt, Generally if it's a yics engine it will say so on the valve cover, or engine side covers.
Some engines have 2 yics ports, 1 on each side of the heads. Some only have 1. It's a threaded plug that takes a 12 mm wrench.
Look at this pic it shows where mine is, I have 2 One on each side.
Some engines don't have yics ports.
Hope this helps.

 

grazie, mate- no yics port here....im all for simplicity. I was looking at that circular casting to the rt of the head nut , above the point of yr arrow.....

 

be sure to check both sides, it may have only 1.
But if it doesn't you have it made no yics tool to buy.

 

My 81 Maxim does not have YICS... I think it was something new for '82.

 

My '81 750 Seca has it on both sides. Was this something that was tested on the 750 before it was incorporated into the 650?

 

From what I remember seeing somewhere, it was started on the 750's and than added to the 650's later. Not sure if it was the seca's only.
I also read it's purpose was to eliminate cold start backfires.

Woot, do you experience any cold start backfires, since you don't have the yics?

 

I believe the YICS experiment started in 1981 (Stamped Dec 1980) with the XJ550.

All the others are just copies. :wink:

 

thought I would add a closeup picture of the YICS gallery. This is my 1982 xj750rj cylinders. Hope it helps the subject!

 

mine dont have it!

if it dont have it

it says yamaha instead

of yics on valve vover.

nice pics nick!

 

Nice pic there Nick...Thanks, I haven't had the head off of my bike. Now I see why some people are experiening carbon build-up in the YICS port. Those are pretty small holes that lead to the gallery.

 

Thanks for your comments on the pic!
dcmilkwagon, that is the narrowest part of the YICS porting.
Here's the view from the intake valve side.

 

ya gotta love serious motorcycle enthusiasts....this site is a great resource.....pics worth a buttpile of words.....

 

Nick, nice pics. Are you in the middle of this tear down right now or are these just old pics? If so what all are you doing to your baby?

 

Thanks again on the pic comments, they are current.
I've been itching to get back on a bike for some time, and figured this would be the one, and I knew it would nickel and dime me to death.
I bought this bike last summer, it was completely dismantled, wasn't sure what was missing, everything was covered in years of dust and sawdust.
I made a parts washer, cleaned things up, did a parts listing, and said ohhh $@#*. Spent a lot of time and money on Ebay, dropped a few bucks at the local yamaha shop for new bearings and seals. Still lots to do, but feel like the end is near, just need the cold weather to go away!

 

I was thinking the other day that I might try to find a spare engine for mine. Tear it down all the way and rebuild it. Then when it's ready, slap it in my frame, then rebuild the other one. Might be good to have a spare around. :wink: