YICS Tool Rental?

Re: SECA 400 YICS

Richard:

Thanks for your reply, and your research.

The Seca 400 is a twin, and yes, it's a YICS engine. But it doesn't have the passage on the back of the heads like your fours appear to.

I just bought the bike, returning to riding after a 20-year absence, and it's my first street bike. I'm still familiarizing myself with the Seca, trying to get everything cleaned, lubed, and adjusted before putting it on the road.

I assume that leaving the YICS passages open throws off the carb synchronization procedures?

Thanks again for any advice you can offer.

HH

 

HH;
Just a stab in the dark, but are the heads interconnected some how, or have some sort of tube between them? If not you may not need the tool. As long as the two are not connected I see no need for a tool. But it kinda doesn't make sense if there not connected why the YICS. I still haven't found anything, I'll keep trying.

 

Richard:

I think I found the answer, in a review of the Seca 400 in Cycle magazine back in 1982...

"Yamaha features its YICS...on both the Maxim and Seca 400s. However, unlike the four-cylinder Yamahas equipped with YICS, which use a bolt-on tube to house the waiting charge, the 400 YICS engine has its chamber cast and drilled directly in the cylinder head."

So my YICS passageway is cast into the head, and not accessible from outside.

In other reading about the YICS, I remember something about YICS not really functioning at high RPM, because there wasn't time for the charge to transfer between cylinders.

I've never synched carbs before, but would it be possible to do it a relatively high RPM, thus overcoming the YICS connection?

Just wondering...

Thanks again for your help-
HH

 

The whole point of the YICS is to improve the low speed operation.
They still use this today on the Banshee ATV.
What happens is at low speeds the air coming in is stopped by the closing of the intake valve. It then reverts back through the carb picking up a second fuel charge. Then, when the valve reopens, the air goes through the carb again picking up a third fuel charge.
Now admittedly the amount of air that reverts is smaller than the entire fuel/air charge, so you do not get a 3 times rich mixture, but you may pick up a 1.5 times rich mix.
The resulting ricness creates a pretty pronounced dead spot in the 2 stroke twins.
The YICS passage connects this sudden pressure to the vaccum being created in another cylinder, thereby preventing the reversion, or at least making it manageable.
I think you will still need to try and synch as close as possible at idle, but rechecking and synching at say 2-3000 rpm will put you right on the mark.

Hope this helps.

 

Nachoman:

Thanks for the info and advice.

I'm getting my Seca ready to put on the road, and want everything to be right. This will be my first time synching carbs, so I wish I didn't have the YICS to deal with, but I'll work through it as best I can.

Thanks again!

Regards,
HH

 

I have thought about setting up a pool of spare YICS/R tools that could be rented. Pay a deposit and a rental fee. Get your deposit back when the tool is returned.

I ave used tool pools form other forums where special tools are required (like timing belts on 944's). It works out pretty well if you can plan the work.

I have tried to put the price point low enough that most folks can buy a YICS/R outright.

If there is any interest I might be able to add a few tools to the next batch and keep them arounds as loaner/rentals.

 

The problem with this design of tool is that it does not seal the #1 port from atmosphere. It does isolate #2,#3 and #4.

It needs a seal at the washer/flange on the handle end. Otherwise your #1 carb will have a vacuum leak while syncing.

 

It also improves charge agitation in the intake tract because the YICS port is tangental to the intake tract.

 

It is not a big issue.

The tool has four seals. Assuming it is inserted from the left side of the engine; When clamped the 3 inner seals expand to seperate the carbs from each other and blocks the YICS passage. The 4th seal on the handle end is a press fit against the engine head and seals the YICS passage from the #1 carb to the bolt you removed.

Once in place sync, mixture and idle are just like any other bike.

 

Here is an OEM tool:

http://plan9.dnsalias.org:88/xj/photos/ ... C02077.JPG

Here is the one I make:

http://plan9.dnsalias.org:88/xj/product ... C02453.JPG

It is intended to be functional copy of the OEM tool. But the dimensions would still apply. I'll need to get the dimensions from a drawing since I haven't memorized them :wink:

 

Hi all, first time here, and currently restoring an 82 XJ750RJ. Can anyone recomment the best/easiest/cheapest sync guages for a first-time user? After having idle up & down issues, I cleaned the carbs and noticed the mixture screws were all set at around 4.75 turns out rather than 2.5. Is that crazy? I reset them to 2.5 and eyeballed the fuel screws to make the butterflies even. This has created more of an up/down idle problem, thus the need for the YICS tool & guages now.. But I did write down the original position of the fuel screws, so I may go back to those settings with the new 2.5 mixture settings and see how that works while waiting for the YICS tool in the mail.. (Got lucky on eBay; $58.) When I'm done, I'll offer it to whoever needs it. Maybe someone can send me pressure guages and I'll send them back with the YICS tool when I'm done? Let me know.. - mcane7@yahoo.com - Mike

 

I just made a yics tool tonight... should work ok I think, I need a larger washer for the handle end; I couldn't find one around tonight. And I still need to bend the handle.

I have everything here to make another one.
It cost me 11$ for everything but I ended up with enough stuff to make two. Not that I need to, but at least when it comes to lending it out I wont have to part with my only one.
Its not pretty but it should be functional.


here is a pic

 

Nice job Aschulhoff, good going. I've made my own, but I sure like Injuhneer's unit, pretty. I might even buy one if I get serious 'bout fixing bikes on more than an occasional basis.

 

Yours appears to be missing a seal on the adjuster end. If you look at the factory tool you can see it has 3 internal seals and one external seal.

If they aren't spaced correctly and have the seal on the outside the sync won't work.

 

And if the seals aren't a hi-temp material they will melt and get stuck in your motor.

 

Okay, so I've gone and bought all the little do-dads to make my own tool. The only thing that I'm having difficulty obtaining is the high-temp silicone hose (3/8" OD). I found some at McMaster-Carr but they have three different types: Firm, Soft, and NSF51 Soft (whatever that means). Can anyone recommend which type I should acquire?

Also, once I get it all assembled, how do you actually use it? Just back off on the wing nut until things are just snug but not tight (so that the tubing is not swollen), insert into the YICS chamber fully, and then tighten down the wingnut until the tool won't move?

For the end seal...facing the motor side, next to the big flat washer....I'm just using a rather large flat rubber washer that I got in the plumbing dept. at Ace Hardware. Hope it won't melt!

 

Thanks for the tool design, getting all the stuff together to put one together. I am really glad that I came across this site, alot of outstanding and useful information. I appreciate the posting, again thanks....

 

Has anybody found a source for high-temp silicone hose for this tool yet? If not, let me know. I might have a source for Mil-spec silicone aircraft-grade hose.