Whats the difference

[imanightsurfer]

Can some one tell what the difference between a xj1100 and a xs1100 as far as engines and so forth? Is there a difference in the power of the engines?

[mro]

Think the order of power is:

XS 78/79, (9.2 compression) then

XS 80/81, (9.0 compression, carbs not quite as adjustable and timing fixed at factory.

then came the XJ

the Xj,................got the "ickys"



mro

[TopCatGr58]

Originally posted by mro
the Xj,................got the "ickys"

mro

Hey Surfer,

That's "NEW" Guru TechSpeak for detuned for emerging after gas shortage era emissions controls and mileage. The XJ still has plenty of power for a Liter+ bike, but like MRO said, just not quite as much as the early XS's!

I see in your handle that you have one of each! Are you trying to decide which one to invest your $$ into for increasing the performance?

I tried doing a search in this forum and the Member's lounge, I remember a thread talking about the differences, or commonalities of the XS's and the XJ's, but can't seem to find it?

The basics of the engines are very similar, but the early years had smaller valves but higher cam lobes, the newer engines changed the pistons to reduce the Comp. Ration a tad, again for Emissions and such crap, the XJ has the YICS system built into the jugs and head, the ALT is different=brushed, the XJ has lots more electronic doo dads.
T.C.

[imanightsurfer]

So can engine parts be interchanged crank, cam, soforth? ive got my xj the way i like it but would like to have a little more power.

[imanightsurfer]

I cant find the specs on the 80 xs does someone know the specs?
And could i just change pistons to get the higher compression and put the bigger cam. found the xs in an old shed looks are rough but not as bad as the xj was when i found it. But fired right up after switching carbs and tank and pulling dead mice out of nest in the air box. The guy said he hadn't started it since 89. Oddometer says 12,000 miles barly broke in

[mro]

Hi ya imanightsurfer

Bottom end 10M motors and top end XS's are interchangeable.
Cylinders same dia. and height, but XJ has extra mounting studs for yicks head.

(have not checked XJ bottom end, but all XS'es from rods down are same, and think internals of XJ are probably same too)

Cams interchangeable year to year.

More power? Really don't know if you will get noticeable improvement with out serious mods, but 78/79 cams/pistons put into an XJ sounds like it might boost it some. (would plug yicks)


There have been posts by several guys that have or are in the process of putting a more modern set of carbs on there XS's.
The new carbs claim to add some HP, and I can "see" that.

Also a few have gone and put FI systems on there bikes. Have yet to hear the definitive answer on how much or little improvement .

My 80G (stock) is fun to ride just like it is. Ride it every day.

mro

btw, do have another XS thats fast.........., fast for an XS.

[mro]

yicks?

Do you have a yicks tool?,
if not check out the tech tips, shows how to make one.


mro

[imanightsurfer]

Thanks for the info I dont know if I would of got the xj up without this page and all the help I've found here. No dont have the tool yet but copied the pics and directions so I will have.
And Agin Thanks Alot!!!!!!!!!!

[MAXIMAN]

Originally posted by mro
......then came the XJ

the Xj,................got the "ickys"



mro

Mine doesn't have the "ickys"...hehehehehehehehehe

[MAXIMAN]

MRO

that's YIKES

and the YICS ports are actually in the block too.

[MAXIMAN]

Originally posted by imanightsurfer
So can engine parts be interchanged crank, cam, soforth? ive got my xj the way i like it but would like to have a little more power.

nightsurfer

here's howya get more power out of an XJ.




But seriously ...short of blowing your pension on a 25 year old bike...the easiest most cost effective way to get power out of any of the Elevens is a highly modified exhaust (4-1 header or gutted baffles like GNEPIG) ... a modded air box or individuals...with a re-jet. You should be able to pick up 10-15% from this alone.

[mro]

MAXIMAN, is da XJ guru

Looked at parts, found that XJ has same crank as XS and same pistons as 80/81 XS.......

the rod is different part #
does have a "Y" in part #,..................so has to do w/yics???
just don't see how.

What/where yics ports in crank case???


mro

[posthuman]

http://www.xs11.com/forum/showthread...threadid=11245

What/where yics ports in crank case???

I prefer the way the Xj looks over the xs, however it's just a bit sluggish, not too bad and certainly functional, but not exactly thrilling.


So I'm VERY interested in XJ performance mods


VERY

[Brian_D]

here is the link started by Dan Hodges on the H.P. difference between 78 E & later models
unfortunately it does not provide any detail on the XJ, but it does provide some good insight on the XS.

[Jerry]

Some differences in the XJ engine as opposed to the XS:

XJ has the YICS (Yamaha Induction Control System) ports cast into the head. Idea was to swirl the incoming charge for more complete combustion. Easy to identify the ports cast into the cylinders, as there is a bolt on the left-hand side of the engine that must be removed, and the YICS tool installed, before synchonizing the carbs. Both the cylinders and heads have this extra passage. Bolt head is below #1 carb inlet.

Second, the timing curve is different, therefor the CDI 'black box' is unique to the XJ. Timing comes in full at a higher RPM, so timing is retarded in comparison to the XS engine at under roughly 4,800 RPM. The XJ, like the '81 XS, uses a boost sensor which converts vacuum into an electrical signal which the black box uses to compute the timing curve. Coils are the same as the '81.

Third, the XJ carb inlet bells is 54mm as opposed to the XS 11's 52mm. Choke (enrichment circuit) is cable operated vs the XS's lever operated mechanism.

4th, the XJ uses an oil level sensor, mounted in the oil sump, instead of the XS oil pressure gauge. There is an extra wire that goes to the XJ sump for this sensor.

5th, the XJ uses a brush-style alternator, a bit of extra power for the LCD display. This makes the engine shorter on the left side, where the pick-up coils are on an XS, and longer on the right side. Stock pipes are a bit wider to accomodate this difference, though after-market system seem to fit OK without problems.

Cam specs...I don't know, though the different cams appear to be interchangeable between model years.

As far as I know internals, like pistons, valves, gears, clutch, et all are the same and interchangeable between the XS and XJ models.

The XJ has quite a few other differences in electronics and cosmetics, to say nothing of the linked braking system and (adjustable) square handlebars. If you have any questions in those areas, just ask.