10.5 to 1 compression?

[XS1100_OEM4ME]

9.2

Looks like 9.2 to me 81 +.

http://www.xtreemedecals.com/yamahai...1100_1981.html

[yamahansolo]

Sorry dude that info is incorrect!!! Go to the section on this site that has the origional yamaha info the 78 79 have higher compression heads and smaller valves the 80 and newer have 9.0 to 1 trust me that other site is wrong!!! I have been here a while and have a screaming fast bike!!!

[yamahansolo]

Ok dude I am on a droid so I don't know how to copy and paste yet but go to the top of the screen look at adds and brochur8es then click on the 80 model. Read thbe specs 9.0to 1. Also the 78and79 had more timing. Even if a 80or newer ha a big bore they can't beat a 78 or 79.

[mro]

Problem with trying to "up the horses" on an XS is that it gets pricey.
You can have your cams done ($300.00+)
Big bore kit ($600.00+)
Above close to a waste of time w/o the head done and new exhaust,
then maybe some new carbs ...

get radical with chops chain drive ...
a squirt of nitros ...
or a turbo ...
Then go out and watch one of the new super bikes pass you while it's going 150 MPH +++

mro
You would have a pretty fast XS tho
And they do stomp on hardleys pretty good
And with most of the above mods will take a V rod too.

[yamahansolo]

I have taken 3 vrods they are sh%*. They top out lower thaN an xs

[XS1100_OEM4ME]

HD's

You beat some HD's? I never considered HD's as anything to race. We are talking 30 year old yamaha tech. and HD is still trying to catch up? My V max was fast QTR but my 1100 has more class and style.

[TopCatGr58]

Hey there OEM,

Don't feel bad, we find mistakes on sites and even in Printed products of expected authority...ie. Clymer's Manual!

Here's a link to the OFFICIAL YAMAHA site:
http://www.yamaha-motor.com/sport/parts/home.aspx
Just select Motorcyle, then year, and then model. They don't post things like the specs sheets on every year/model....but the ones for the major engine change is on the 80G Service DATA page.

It's been debated that the 10.25:1 ratio that WISECO promises was only for the 78-79 engines partly due to them having a smaller head dome, so the more prominent domed Wiseco pistons created more compression.

I put the small 1179cc kit in my 81SH. Stock compression is stated to be ~142 +/- 14 PSI at sea level. However, after I got it broken in, I tested it, and it came out to ~180 psi, which is very close in my humble calculations to close to the stated 10+:1 ratio. I've retested it several thousand miles later and it wasn't artificially elevated due to excessive carbon buildup from the gentle breakin !
T.C.

[rpgoerlich]

I put the small 1179cc kit in my 81SH. Stock compression is stated to be ~142 +/- 14 PSI at sea level. However, after I got it broken in, I tested it, and it came out to ~180 psi, which is very close in my humble calculations to close to the stated 10+:1 ratio. I've retested it several thousand miles later and it wasn't artificially elevated due to excessive carbon buildup from the gentle breakin !
T.C.

Interesting stuff as I tested my 79SF when I got it with 56kmi and it was 180-185psi. The PO tells me it's never been into through the 45kmi he put on it. My 80 & 81 are running 150-165psi.

[XS1100_OEM4ME]

Thanks, TC

Yes, there are many spec's on the internet, some right, some not so much, just tried to pass on a link to one, right or wrong, dont know

[DiverRay]

And just so you all know, you CAN get a "stroker" crank for the XS. I must say, my "balanced" crank(14K RPM), with 4 shot peened rods, was almost $900! It's still in a box, as I'm trying to get one of the '79's running so I can sell it, and put time into the '78. I DO have the 1196 kit AND a ported head for it. Yes, I will have a nice looking "hot rod", and I know the larger modern bikes will outrun it. My thing is, they just don't have the CLASS of an XS!

[XS1100_OEM4ME]

Yes Driver!

I get you, They can buy a box rocket that will do 9's out of the box or 190 mph, yes tech has come a long way, but CLASS is forever and cant be duplacated! The XS1100, like the first musle car (GTO, owned 3 of them) is and always will be a first!

[crazy steve]

And just so you all know, you CAN get a "stroker" crank for the XS. I must say, my "balanced" crank(14K RPM), with 4 shot peened rods, was almost $900! It's still in a box, as I'm trying to get one of the '79's running so I can sell it, and put time into the '78. I DO have the 1196 kit AND a ported head for it. Yes, I will have a nice looking "hot rod", and I know the larger modern bikes will outrun it. My thing is, they just don't have the CLASS of an XS!

Ok, you got my curiosity piqued; how much stroke? Is this a new piece, or a weld-and-regrind deal? Your max rpm will be reduced a bit, but it should fatten the mid-range very nicely... And how big overall with the big-bore kit?

'78E original owner

[XS1100_OEM4ME]

DiverRay

"Stroker" most often means longer stroke? That would mean less RPM and more torque? Guess you have a short stroke kit for less displacement, shorter rod's, higher RPM? Shot peened rod's are just rods that have been surface blasted with shot to add to rpm hold up (after magnaflux I hope). They would have to be shorter for a 14,000 RPM motor. Where did you get this stuff and how does it work?

[81xsproject]

Ment 14,000 RPM

I see your two posts are only three minutes apart. For future reference, you have like 5-10 minutes that you can edit a post if you make a mistake or have a change of heart.

[DiverRay]

My crank was "just" balanced. To have it stroked was going to be another $600 to $800. Rods were supposed to be fully inspected, and yes, they do need your old crank to stroke. My problem with that is I would have to buy new rods if I had the crank stroked even 2mm. They would have cost about $2,000, so that was out.