The easy way to tell if you’ve got an “FYK” engine (1985 US K100)

[frankenduck]

If you haven’t heard that acronym before it stands for Finest Year K.  It refers to 1985 United States K100s which have “Euro” cams which are “hotter” than the cams in 1986+ US K100s and put out something like 5-7 more horsepower.  However, the 1985 K100s were not compliant with California emissions standards so from 1986 on all US model bikes had “de-tuned” cams and fuel tank venting back into the front of the engine block in order to be California compliant.

The California cams (11311461525/11311461526), as well as the normal or “Euro” cams (11311460045/11311460044) do show up in the parts catalog but, unlike most parts that changed over time, there are no from/to dates so you can’t decode your VIN to figure out what engine/cams you have from the production date.
   
Since part numbers aren’t cast into the cams, you can’t simply inspect the cams to tell which you have.  (If you’re a real mechanic with a real shop you could measure them and tell the difference but most of us aren’t.)

Anyhow, since part of the changes on US bikes from 85 to 86 was to add the venting line from the gas tank to the front of the engine block, the easy way to confirm if you’ve got an FYK is to look at the front of the engine. If don’t see the gas tank fume vent fitting on the front of the top of the engine then you’ve got an FYK.

I’ve attached a couple of pictures copied from Fleabay K100 engines for sale as visual aids.

[wmax351]

Interestingly, a lot of people in europe, with the euro cams, bought the milder, CARB compliant cams for the improved low end torque.

[frankenduck]

I guess the grass is always greener on the other side of the pond. :laugh

I'd really like to see a dyno comparison of the same engine with both sets of cams.  Would be interesting and educational.

[billday]

Confused. Per the VIN decoder, and per what it says on the title, mine is an '85. But I have the vent line on the front/top of the block. So that makes mine an '85 with post-'85 cams?

[frankenduck]

Production year and model year are usually different but 85s were early on so things may have been more dynamic in terms of how/when production changeovers occurred.

What month was your bike built in?

[billday]

October 1984

[frankenduck]

With that production date it seems that it would likely be an FYK.  Maybe somebody swapped engines???

[argent brick]

Anyone know of a way to decode the VIN more than just month and year? Maybe a way to tell what came on the bike from the factory?

[frankenduck]

There's no 100% accurate way to tell what came on your bike from the factory.

For example, my K1100LT decodes to a 10/92 production date.  Looking at the from/to dates in the parts catalog my bike, being built after 9/92, should a have had a 50A alternator.  It didn't, it came with a 32A alternator. (I suspect because they wanted to use up all of the inventory of 32A alternators on hand.)

[billday]

With that production date it seems that it would likely be an FYK.  Maybe somebody swapped engines???

Doubtful -- the tank matches (I mean it has the nipple for the tube and the tube with the one-way valve).

[frankenduck]

Ya never know.  Those 85 tanks are odd.  Even though they have the fuel level sender up in the left front the metal in the bottom of them is stamped in the middle of the back for where the newer fuel level sender goes which seems odd to me.

[billday]

Another factoid... I just found this "84" cast into the top of my engine block, normally hidden by the lower half of the air box. The ring around the '84 must indicate the month of manufacture but I don't know how to decode it. This engine also has the nipple cast into the top/front of the block to receive the California vent from the fuel tank....  So, my FYK is the right year but the wrong engine to have the mythical Hot Cams.... bummer!

[frankenduck]

I knew about the year cast into the block.  Not sure how decipher the ring around it. I lost my secret decoder ring.

This is from an FYK w/o the vent port.

[branandfox]

Chassis number   0041905
Vehicle code   0513
Series   K589
Model   K 100 RS 83 (0502 ( 0503 )
Body type   K 100 RS 83 (0502
Catalog model   USA
Production date   1984 / 11
Engine   0513)
Transmission   
Steering   
Catalyzer   NONE

 Dont believe I have the vent hoses either. As Im ripping her apart Ill let you guys know. But I believe I Don't have the vents. So I should have the hotter cams. which seems right to me, I always feel there is a little more power than stated on the records for my 85

[billtr96sn]

Bit of a thread ressurection, but the 'coded ring' is easy to figure out.

It is divided into 12 spaces, one for each month, and they have centre punch  marks in them. One space= January, two =Feb etc etc.

That one above has 10 centre punch marks so = October.

[jjs1234]

First time poster here....


I have the vent hose, however the sticker on the bottom of the seat says 49 states compliant... :yow


What gives

[Laitch]

I have the vent hose, however the sticker on the bottom of the seat says 49 states compliant... :yow
What gives

Welcome, jj. My guess is that California was the holdout—not compliant enough for the pristine air of the San Fernando Valley.

[jjs1234]

 Just trying to figure out what that means, if I have FYK or  I should go source out some cams for my next build.

[Laitch]

Just trying to figure out what that means, if I have FYK or  I should go source out some cams for my next build.

The photo of a "fume vent" in the first post of this thread and the explanation about it isn't enough to determine FYK in your case, jj? Considering the age of the bike, if the sticker actually is on the seat, maybe you've got a different seat. That seems an odd place to put an engine compliance sticker though.

Maybe it's a chiropractic compliance sticker.

[koapono]

here's picture of decal located on fender, under the seat of my 85 K100RS, top right corner indicates 49 state compliance so does that make it a FYK in that it is not california compliant?.

[jjs1234]

From CA.gov:

A vehicle manufactured to be first sold in all states except California and meeting only federal emission standards.
These vehicles cannot be registered to a California resident who acquired or purchased the vehicle with less than 7,500 odometer miles unless the owner qualifies for an exemption

But I have no idea.

[Laitch]

A vehicle manufactured to be first sold in all states except California and meeting only federal emission standards.
These vehicles cannot be registered to a California resident who acquired or purchased the vehicle with less than 7,500 odometer miles unless the owner qualifies for an exemption.

Another tragic example of the consequences of eating weed brownies while writing regulations.

Anyhow, since part of the changes on US bikes from 85 to 86 was to add the venting line from the gas tank to the front of the engine block, the easy way to confirm if you’ve got an FYK is to look at the front of the engine. If don’t see the gas tank fume vent fitting on the front of the top of the engine then you’ve got an FYK.

Taking the easy way would be my way, jj.