Yics or not?

ok im comfused, i have a 80 xj650 midnight maxim, modled as 1981. And a parts bike thats a 80 xj650 models as a 82 yeAr. According to everything ive read they should be none yics engines. But! On the side covers both say yics, the valve covers only say yamaha. Ill be ordering head gaskets and intake boots hopefully soon and need to know witch i have,

 

The side covers were interchangeable, so possible that they were swapped out.

Considering the age of these bikes, anything is possible regarding a swap. Best way to tell is post VIN and picture of the side of the engine. We can tell ya for sure what it was and is with that.

 

If the valvecover does NOT say YICS on it, then it is not a YICS engine. The YICS valvecovers fit differently than the non-YICS valvecovers, and they won't interchange with each other.

As jayrodoh points out, the same does not apply to the engine side covers, which are fully interchangeable between YICS and non-YICS engines.

 

Thanks Chacal for the clarification, I only have the YICS version at the moment.

I need to get online and find a vendor that still makes a 710 cap. Can't find that anywhere...

 

710 cap will this fit
http://kalecoauto.com/index.php?mai...2&products_id=44&zenid=,FMB5-PPT09qzt3DZHm113

 

Ok thanks! Was just making sure. Foumd it strange that both bike which i got from the orignal owners. Would have swapped out side covers. Both seem all original when i got them. The midnight having 5,000 miles and the reg maxim having 3,000 miles!

 

Dood! Two xjs with under 6000 miles?! that's awesome. Add them together and it's still less than a third of what's on my odometer! Get them running and your kids' kids can ride them!

 

OP,
Post a picture please. Very unusual for two bikes from a original PO with such low milage to not have the correct covers. The right cover is usually not disturbed unless the case is being split. Do both bikes have engine guards?

Gary H.

 

I purchased my 1980 - 81 XJ650J model YCIS in Tokyo Japan. It has 23,000 miles on it and runs like a champion. Carbs are Hitachi and came with open air/fuel mixture screws. I have found very few mechanics that will work on these bikes because of the variations in synchronization and air fuel adjustment. I also found that European models were factory set and Yamaha warned against mixture adjustment. With that said, I have found that the ideal adjustment for the Hitachi carbs is; starting from stop to 2.5 turns out. I also bench synch my carbs then vacuum inspect the synchronization after all is said and done. The bike came new with blank side covers and only indicated that it was a YCIS model on the right side of the valve cover. With that said, expect anything and be surprised at nothing. These were some of the best bikes (in my opinion) Yamaha ever produced.

 

The 650J is a '82-'83model. YICS = Yamaha Induction Control System.

Gary H.

10/4/2015: This has been edited to reflect a correction.

 

1980-1981 xj650 maxim are non YICS
1982-1983 xj650 maxim are YICS

1982 xj650 Seca non-turbo is non YICS

 

I know the "J" designation should make it a '82. Is it possible he actually has a '81 because he purchased in Japan? A member recently posted he has a '85 Xj750X (I looked it up...who knew?) I learn something new everyday.

Gary H.

 

Maybe

 

Just to clear things up. I am forwarding a couple of photos. Please note the month and year of manufacture. Also note the type YICS on the engine cover. I purchased this bike new at a factory distributer.

 

JYA5N...'82 YICS manufactured in 7/81 right?

@deepearth: Nice pics and thanks for buffing away the dust (orange cord) so we can see things clearly.

Gary H.

 

Correct JYA5N800 date of manufacture 7/81. I believe it was destined to be shipped and sold in the USA as the sticker indicates it was manufactured to Federal Standards. I'm in the process of cleaning the old lady up and giving her a facelift (paint). I was in the Army at the time and stationed in Japan. The original price at purchase was $2000.00 American. The military shipped her home duty free the following year. This bike and I have had some great times together.

 

So it was made in 1981 for the 1982 (J) year. 1982 would be a YICS engine

 

Think it was destined for USA market? Easy check -- is the speedo in MPH or KPH?

 

The speedo is MPH/KPH. MPH is indicated on top while KPH is below. My owners manual was in Japanese. Sadly it has been lost along with the English version I bought when I got home. I do have a factory service manual though. It has alot of useful information.

 

If mph is on top, then it was for usa

 

service manual in english?

 

YICS ports on the head and barrel?

 

@k-moe: think the yamaha engineers ran test with them on each then plugged the head and decided the block was better? Orrrrrr....is there a YICS engine somewhere out there with open ports on the head and plugged block ports. Hmmmm... i wouldn't be surprised. Ok, yes i would.

Gary H.

 

Maybe, but I doubt it. Any amalgamation of thay sort would not have been sold to the public.

 

I know...maybe i didn't ask that correctly. Nevermind.

Gary H.

 

Note my edit. One can be made to fit on the other, but would serve no purpose.

 

+1.
Gary H.