New Member Opening a Big Can of Worms

[bikerphil]

Perfect time to get rid of the YICS, put on XS jugs and pistons, they are easier to find. Another option, if that's the only bad cylinder, is to change that one piston and the cylinder sleeve. You'll have to pop the jugs in an oven, and of course find a sleeve.

[DGXSER]

Honestly, it is somewhat sad but true that you may find a cheaper answer in buying a "parts" bike or a used engine than in finding and buying all the parts you may need to fix all that back up.

[Guy_b_g]

I've been eyeing these for a while..can't afford them right now, but maybe just what you need...appear to be in excellent shape, and cheaper than most other solutions.

http://cgi.ebay.com/ebaymotors/ws/eB...#ht_1199wt_958

[ny.phill]

I'll be sure to watch that auction, but it's a little rich for my blood. I've got a few things on ebay that could be promising and of course i'll be touching base with andreas as i always prefer to keep money in house when i can =)

So i'm reading up on it a little bit, but if i use the XS jugs and my XJ heads, would i still need to seal the intake side port of the yics?

Tomorrow I should have the primary and the crank out... hopefully no more surprises with all the bearings.

Thanks again for all the help guys, much appreciated!

[Guy_b_g]

Perhaps someone else can chime in on using xs cylinders with an XJ head, I don't have enough knowledge of the XJ to answer. Is it even possible?

Reason this seemed like a good deal to me is that the pistons are already matched to the cylinders..no cylinder work should be required, and there can't be more than a few miles on those pistons and jugs judging by the lack of blow by and condition of the pistons. Hard to find a set that nice. Also Wiseco pistons are of good quality. $149 is actually less than you would spend on a full set of new rings in most cases (if you can find them).

Just my thoughts, and of course you always take a chance when buying on Ebay...though the seller has very good feedback.

[bikerphil]

if i use the XS jugs and my XJ heads, would i still need to seal the intake side port of the yics?

Yes you will need to plug the ports on the head, here's how to do it...

http://www.xs11.com/forum/showthread...ight=yics+plug

[DGXSER]

Very interesting Phil, I had never seen that before. Looks like a decent option to the YICS Eliminator if your going to be pulling the head off anyway.

[ny.phill]

I've finally gotten around to finish taking the cases apart and spent some time almost getting frost bite cleaning them off. It is COLD up in here in the Northeast!

My bearings don't look too terrible. The only one showing some copper (brass? i forget) is one of my rod bearings. None of them look "great" so I need to look into how much new bearings will run me. And seals. And gaskets. Nothing like buying yourself engine bits for xmas =)

I did get my new countershaft the other day which has some lovely square dogs on them. I also found a guy with a clean set of jugs and pistons off of a 78 xs1100 and got the cams along with it for a knockout price. Not sure if i want to swap the cams just yet, I need to read up a bit more on that.

Is there anything else I should be doing before I really start putting it back together? planning on backcutting the 1/2 gears, 2nd gear washer swap, new bearings/seals and probably rings.

I really don't ever want to take this thing apart again so if something needs to get done, now is the time right?!


New 1st gear in foreground, old one in background


Lower Case Bearings


Upper Case Bearings


Worst of the Rod Bearings... you can see it a little here but it looks worse in person

[Guy_b_g]

The '78 jugs and pistons are gonna lower your compression some, so you'll have less performance than you would if you had gotten the newer ones. They raised the height of the piston dome to compensate for the extra capacity in the later combustion chambers.

I have a full set of bottom end bearings I'll let go for the price I bought them for, which is to say $100 for the full set plus shipping. By a full set I mean it is an OEM complete set still in the box with all the the sizes included. You can always resell the ones you don't use.

If you think my price is too rich you can check ebay...

http://cgi.ebay.com/ebaymotors/Yamah...#ht_1610wt_958

http://cgi.ebay.com/ebaymotors/YAMAH...1#ht_898wt_958

[Guy_b_g]

Sorry... I should have clearly specified what I have...rod bearings.

[ny.phill]

Lower compression? that's the opposite of what i want!!! Oh well, I suppose getting rid of the YICS is a decent trade off as long as i'm not losing too much squeeze.

Guy_b_g: PM sent concerning the bearings. Graci

I'm also curious if you guys have any recommended places to get the valve shim tool. It's just under $20 shipped on Amazon which doesn't seem too bad I guess. Amazon Link Here

I'll post some more pics when i make some progress somewhere with this project.

[natemoen]

The compression change is not much. It is low 9:1 for the lower version and mid 9:1 for the higher compression version IIRC.

I got my valve tool on ebay with 8 shims for 15 bucks shipped.

[Guy_b_g]

Nate,

The compression ratio change is more than you might expect...how much more I don't know...maybe someone here who does can chime in.

What you aren't taking into account is the combination of parts being used.

The later head had larger combustion chambers...and to make up for the resultant lower compression, they raised the piston domes on the later pistons. Even with the taller domes the later engine gives up a tenth of a point of compression to the early engines...as you pointed out.

Now take the larger combustion chamber of the later engines, and the lower domes of early pistons...and the effect is no longer to cancel out the larger chambers..instead it compounds the problem, (making the combustion chambers effectively larger still)...again...I'm not sure how much, but it's definitely the wrong direction to go for higher performance.

[natemoen]

Yup, your right. I wasn't thinking about the combination of the 2 designs.