Need Help with Displacement Question

[Truspeed]

How's it going, I'm new to the xs11 board and have just purchased a 1980 xs11 for $750. This motorcycle has sat for about 13 years and has 9K miles on it. The seller didn't want it because the carbs were stuck from varnish, yet he didn't know it. I have decided to "soup" it up over the winter into something I can really be proud of but have a few questions. Some of these questions may seem obviously stupid to some of you, but only being 17, I have not had much experience with motorcycles yet, other than a 75 Honda CL 360, and I don't have very good access to the internet. I would like to increase both the displacement and compression on my new bike while replacing what looks like a slow oil leak on the head gaskets. I have taken a look at the Wiseco website and have not had much luck in locating the piston package as talked about in one these messages. I was wondering if anyone new somewhere else that I could possible look for them. I would considder doing this if I can't find somewhere to bore out the cylinders and get ROSS or Je to custom make some high-compression pistons for me. What is the maximum bore amount, or dimensions of the largest possible combination of displacement/compression? I would also like to install a larger mm flat-slide carbuerator but have noticed that the intake ports on the head are only about 26mm, is there some place where I could get this ported and polished? With a high compression ratio, would I also have to replace the connecting rods and crankshaft to accomodate for it and to withstand it? I'm also looking into installing a nitrous kit for it, if anyone has had any experience with nitrous on a bike, please let me know if it makes a substancial increase in power and if it is safe, etc. I plan on putting a lot of time and effort into this motorcycle and would like to do everything right and do it once, and as far as performance parts, I would like to retain the stock broad powerband as much as possible so that I don't just get a horsepower "peak" somewhere. I also plan on putting a lot of money into this new project of mine so that I can have a "sleeper cycle" to kick the pants off of all those crotch rockets. If this seems a bit confusing it is because I am at work and am writing this as fast as possible. Any advice is appreciated, Thanks.

[sixtysix]

Check out this thread:

http://www.xs11.com/forum/showthread...=&threadid=965

Shak did what any reasonable person would and bought a good used Bandit 1200.

Several of us here have both,

You will have an insane amount of $$ just getting a bike that has been sitting for 13 years to run, stop and look good. that does not include any performance mods you may want to try check out my tech tip on What to look for in a neglected XS.

Good luck with your new project, the XS11 was the Hayabusa of it's day.

[TopCatGr58]

Overbore Kits

Dear Truspeed,

First of all, have you ever ridden a properly tuned XS11?? They have plenty of power and speed fully stock. The model designation was not for their displacement, but the fact that they were the first production stock bike to turn a 1/4 mile in 11 seconds!!

Secondly, as for the big bore kit, go to the link below, scroll down to the last page 14, look for XS1100 and you'll find two kits, the 1179 and 1196, and they rate the comp level at 10.25 to 1, vs. the stock 9:1.

Wiseco PDF file for Overbore kits

With only 9K miles on the bike, it could be in pretty good shape internally if it was stored properly, and you wouldn't need to bore it ...YET. Yamaha doesn't support it anymore, so you can't get standard oversized pistons for it. The big bore kits, even the lesser one takes the bore to 74mm diam, which is at least 1.0 mm larger than the maximum oversize they state was made. The 1196 adds another 0.5mm. I have the 1179 big bore kit in mine due to improper storage for 9 years, got rust in the cylinders, had to get it bored to clean it up. I also put Individual filters on it, and am running 4-1 pipes, both mods required a rejetting of the carbs, but the cams are stock, didn't polish the ports or anything fancy like that. And after it was broken in, I did comp checks, and got readings around 180psi, at sea level, divided by 14.7 for 1 atmosphere, yields 12.25 comp ratio to my surprise.

We have a nick name for the crotch rocket riders,...zip-splats cause many of them don't know how to handle that much power, so they go 'zip' and then splat against some retaining wall, or another vehicle or such!! Your XS11 should be able to keep up with them in the straights to about 130MPH, which is wreckless driving in most states if caught. Try to grow up a little!!

As for the NO2, don't know anything about it for our bikes, just that you can't get any parts to beef up the lower end, and the XS11 power plant is stronger than it's frame, it'll push it easily in all 5 gears to redline and beyond, so I can't see where it would really be needed.

Remember, its' a 20+ year old bike, and you can't get parts for it very easily, and so if you are wanting to keep it for a while and have it driveable, just get it tuned up to it's best, save your $ if the cylinders are in good shape until you wear it out for a few years, then invest in the big bore kit since that will be the only way you'll be able to keep the engine going when the stock rings and cylinders wear out. Of course you might want to buy the kit now, incase they stop making it the not too distant future!!

As for your slow oil leak, it's probably coming from the Valve cover gasket, not from the head gasket region and a tear down may not be required, again depending upon the comp tests and the preservation of the cylinders. Hope this helps, and hope to see you for a long time on the Forum.

[procamper]

well, let me start off with a congradulations on your new purchase! properly cared for and respected, it will be fun for years to come!

One thing you might not be counting on is the power that your XS can put out in its stock form. I belive the engine produces 95 horsepower at the crank. To put this in perspective, that cl360 you rode probably put out around 20HP. Even the top 600cc sportbikes today(ninja, cbr, yzf) are "only" putting about 100hp to the rear wheel. Considering that these "crotch rockets" have to rev to over 10,000 rpm, and the xs only revs to 8,500 means that the XS's power comes on faster, and earlier in its powerband. Translated onto real world terms, this means quicker and easier launches.

properly tuned flat-side carbs will increase horsepower, however, as with most hop-ups, you have to make sacrifices. In this case, you have to realize that flat side carbs are designed to work well at one throttle setting--WFO (that would be wide f ing open). REALLY not good for drivablilty or maintaining that stock pwerband your looking to keep.

NO2 is an oxidizing agent. As highschool shop tought us, the best fuel to oxygen ratio roughly equivelent to one gallon of gas to a semitruck load of air. When an engine is given a dose of NO2, it is increasing the amount of oxygen in the mixture. this will increase power substantially, however as I said before, you have to make sacrafices to make power. This time, you have to realize that increasing the amount of oxygen in the mixture without increasing the amount of fuel will make the mixture lean. A lean mixture will burn MUCH hotter than the normal mix which could mean you could be looking at a termainal case of piston soup if used for too long. This is especially true if used in air cooled engines.

personally, when asked if my bike is fast, I respond truthfully, "its fast enough to get stupid on" which is entirly true. It will cruise happily all day at 80mph, with me in total comfort, it will go scaryfast on deserted backroads, it will even make most rockets eat yamaha dust!

[tiel]

Power & Speed

I agree with the other posts, The XS11's in their day and even today are extremely powerful machines. I have heard it hundreds of times before, "Its a Sleeper" " I just like knowing that its there!" Speed/HP is like a $100 bill stashed in your wallet, sure you like to know its there, but you will get the itch to use it!! I often wonder why the need to get somewhere faster than anyone else is so important? I in my younger days also had the NEED FOR SPEED! all it got me was alot of traffic fines, loss of driving rights, etc...


I'm sorry if this sounds harsh! but its kinda meant that way..

Try to just enjoy the air in your face, the serenity, the un-obstructed sights around you and the feel of your girls arms wrapped around you.


Like the other posts, Welcome and I also hope to see many many posts for along time to come!

[Truspeed]

Thanks for all of the good information, I appreciate it. Although after reading sixtysix's "What to look for in a neglected XS" I am somewhat scared of what I baught because for 1) the original carbs on the bike almost looked as bad as the one in his picture 2) My spark plugs were slightly rusted, and 3) just before I posted my original question I had recieved a set of used carbs from a local junk yard and started the motor without changing the oil, etc. which was incredibly stupid of me because I knew I should have at the time but eagerness to hear this bad boy run got the best of me and obscured my ability to think in a logical manner. I know that when I first started it it had a lot of power and sounded really smooth, however after shutting it off and turning it back on the next day it had a loud poping sound out of the muffler (by the way I have a Kerker exhaust system) like POP...POP... etc. which leads me to believe that I have caused some cylinder damage to one of the cylinders :-( After school today I will continue to take off the heads (I have gotten to the point of taking the cam sprockets off and yes, I do have a Yamaha shop manual for it) and hope for the best. The muffler packing/end cap is missing and I can't seem to find a replacement insert for it from Dennis Kirk or Kerker/Supertrapp. If anyone knows a place that I could find one, it would be much appreciated. Does anyone here have a Mr. Turbo turbo charger and can tell me if there is a significant lag with it? Thanks again!

[Truspeed]

I got the head off last night and all of the pistons/cylinder look okay. The only thing out of order is that cylinder numbers 3 & 4 have light brown colored valves and numbers 1 & 2 have black colored valves. My guess is that numbers 3 & 4 were running lean and 1 & 2 were rich. Any ideas please feel free to post them.

[TopCatGr58]

Brown vs. Rust!?

Originally posted by Truspeed
I got the head off last night and all of the pistons/cylinder look okay. The only thing out of order is that cylinder numbers 3 & 4 have light brown colored valves and numbers 1 & 2 have black colored valves. My guess is that numbers 3 & 4 were running lean and 1 & 2 were rich. Any ideas please feel free to post them.

You also mentioned in earlier post your plugs were rusty, which ones, all or only 3 & 4 ? The light brown may be rust. If the bike was sitting on sidestand, that would have allowed fuel to drain from those carbs, or allowed that side of tank to rust easier, and then it came thru the fuel lines into the cylinders, you said you did test fire it before changing oil, and doing general cleaning!?!? You will want to clean, inspect, and possibly recoat the tank, clean the petcocks, screens, etcs. to remove the rusty gunk that accumulates in the bottom of these tanks after so many years sitting.

Hope you have a valve lapping set, since you NOW have the heads off, you'll want to recondition the valves & valve seats, with only 9 k miles on the rings, they should be able to handle the increased compression from newly conditioned sealing valves!!! I hope you got a gasket kit, you're going to want to use a NEW head gasket, not the old one when putting it back together. I also hope you have a low scale torque wrench that reads accurately from 0-75 lbs, vs. standard wrenches that start at 10lbs? The the valve bearing cap nuts require only 7ft/lbs torque; the cam sprocket bolts I think take 14; the head nuts 25...check the manual for sure!

And, since you were in a hurry to get the heads off, you might have forgotten to check your valve clearances before you pulled the cams?? Would have made it easier to check, and then replace the lifter shims now that you have the cams out! Good luck, hope it stays healthy after you get it back together!

Nobody here on the forum has ever mentioned having a TURBO on their bikes, there was a prototype that Yamaha came up with, but never followed with production, due to either emissions standards, or performance....in that it didnt' really do much vs. the normal aspirated one since it was a rather high performance engine in it's time!