Need more power!!!

[Dan Hodges]

Hey Tod,

A few years ago I did a rollon race with a guy on a V-rod, was doing about 50mph had it in 3rd, we punched it, he jumped a little ahead and I was right there, but didn't remember to shift, topped out at 8.5k, FINALLY remembered to shift to 4th, was catching up to him, but we had to shut it down. I was surprised at how quick it was. And I have 1st hand experience at DUMPING the clutch at 5 k, when I was at the race track trying to run the 1/4 mile, thought I was near the end of my clutch fanning process, and dumped it, and almost flipped the bike backwards onto myself!

Hey Chris, I'll see you at the Rally weekend after next, and we'll see if we can find some place to have a little run. I'm no racer, so there's a good chance you'll probably beat me, but it'll be fun to see what they'll do.
T.C.

A tricked out XS will beat one of the original V-Rods which had 1130 cc's but I don't know about one of the new ones which have 1250 cc's as I've never encountered one on the highway but my guess would be probably not as they are putting about 115-120 horses to the ground and weigh about 620 pounds wet. A killer XS will put about 95 hp to 100 hp to the ground and weighs about 580 pounds wet and so with the same weight rider the 1250 cc V-Rod would have the edge. When it comes to racing motorcycles every 15-20 pounds is a tenth in the quarter mile and so rider weight is a giant factor in a motorcycle race.

[trbig]

And for the ones saying the XS11 had no tuned intake... This is a quote from the article posted in the members section of when the '78 came out.

The carbs plug into an airbox which includes internal velocity-stack-type intake tubes, so changing the air cleaner arrangement may have an adverse effect on intake tuning.

Just thought I'd stir the pot a little... I think what is thought of as intake tuning these days is a far cry from what they had 30 years ago, but I still believe there was very little of ANYTHING just thrown on the bike without having been tested a LOT. I think the snorkle, length of velocity stacks, size/shape of airbox and filter area.. were all considered in the tuning (Yup, I said it) of the intake.

Tod


Tod

[yamahansolo]

if you go back and read the 1st article about the xs in motorcyclist you'll see when jody talks about his portion of the ride. when he launched the front wheel came up two feet! .
and i never said i launch at 2,000 rpm's that's dumb. but if i am cruising in 5th and roll on the throttle it pulls very hard!

my neighbors vrod is one of the first ones and it has about 200 lbs of chrome! ha

and there is no stumble with my pods. i have the mikes xs ones. i used the emgo's on my xs750 and they stumbled alot below 3ooo.
if you look at all the old race bikes in the mags and they all are running with no box. instead they have the aluminum velocity stacks. i mainly wanted to use them to move the filters towards the battery more to get rid of the huge dead space there. you can see the ugly white battery there.

TC i guess you forgot about what bruce said last year at the dinner table about how strong the 78' and 79's are with a kerker.

this thing busts your ears at 8000! here is a video. this was me hitting 95. last year. no stumbles.

[Dan Hodges]

You Can Tune An XS But You Can't Tunafish

And for the ones saying the XS11 had no tuned intake... This is a quote from the article posted in the members section of when the '78 came out.





Just thought I'd stir the pot a little... I think what is thought of as intake tuning these days is a far cry from what they had 30 years ago, but I still believe there was very little of ANYTHING just thrown on the bike without having been tested a LOT. I think the snorkle, length of velocity stacks, size/shape of airbox and filter area.. were all considered in the tuning (Yup, I said it) of the intake.

Tod


Tod

Any modifications that changes the vacuum signal to the carburetors will effect the slides rate of lift and the length of the intake tract will effect torque peak of the engine, with shorter raising the torque peak and longer lowering it. The XS employs what is referred to as an independent runner system meaning it doesn't have a plenum chamber like that used in cars or the V-Max and subsequently independent runner intake systems use larger carburetors than systems using a plenum type manifold. A motor is nothing more than a wet air pump and the more air and fuel it can pump and burn efficiently the more power it will make and the more air it pumps the larger the air box and supporting inlet/inlets needs to be. An 1196 spinning the same rpm as an 1100 needs more air if both are operating at the same level of volumetric efficiency. The stock air box is restrictive but it will feed a stock motor sufficeiently however if you increase the VE of the motor by a significant amount it will need more air. The air box tray can accomodate 4 one inch holes and this along with a K&N drop in filter will flow all the air that an 1196 XS spinning 9,000 rpm @ 100% efficiency can use. If you use pod filters with a stock engine you might make a couple more horsepower on the very top end if you can get the jetting right but you won't with the stock needles and slides but it will be down on power every place else particuallary at low RPM and this is due primarily to the removal of the velocity tubes in the stock air box. If you ditched the CV carburetors and replaced them with cable operated smooth bores and had enough dyno time to figure out the correct length velocity stacks/tubes you could improve the top end hp but smooth bore/race carburetors don't take kindly to low rpm operation unless they are very small (28 mm) and then they won't make any power on the top end. The fuel injected bikes of today have velocity tubes and some like the R-1 have variable length tubes that are electrically operated and get shorter as the rpm increases and longer at low rpm. I have a new fuel injected FJR-1300 and it has velocity tubes and a very big air box but as yet I haven't determined if it is larger are smaller than the air box on my V-Max but I will.

If you like math you can crunch the numbers and figure out how much air an 1100 cc motor will pump and then you can determine the CFM of the 34 mm carburetors and their velocity tubes, then you are ready to measure the air box voluum and the CFM capability of the intake snorkle based on it's size.

No, all of this stuff is not rocket science but it does require some thought because much thought was given by the engineers who designed it.

Much as changed in the last 30 years about the science of the 4 cycle engine and I realize that when I look at my FJR along side my beloved XS but at the end of the day the basic principles of the 4 cycle engine haven't changed all that much.

[tw1980]

Well Dan the more I play with this bike the more I think you've got most of this stuff pegged.We had a rally here this weekend and I got to ride with a bunch of well running stock xs11's.After all my work and mods I would give my performance improvements a B- at best.Although I had more high rpm performance,it didn't seem to be of that much benefit unless I was prepared to drop a gear. Well tuned xs11's perform well and it's hard to improve on yamaha's design.Better high rpm performance and lower 1/4 mile times do not = more fun.This winter I'm thinking maybe turbo and if that doesn't work maybe R1 engine next winter!OK guys now you can let me have it

Terry

[aussixs11G]

more of a good thing

Originally Posted by trbig View Post
I'm glad you are a bit scared of them at top speed. I wish I was... I find myself wanting more... and that's exactly why I won't get a newer bike.

THIS APPLIES TO ME TOO!!!!!!!!!!!!!!
(though I am thinking about a Honda VTR 1000...........)

[yamahansolo]

i am scared of 8000 rpm's i n1st and 2nd especially cause sometimes it pops out of 2nd... (i need to do the mod) over 120 it seems stable but hey it's 30 years old... what happens if an important bolt snaps or the wheel decides to come off...

i would love to get an xjr motor and stuff in there or if someone wants to send me an xjr1300 i'll take it!

[T99Ford]

quote: you won't with the stock needles and slides

Ain' dat de truth, though!

[roccet]

wow i have read every post.

all i can say is .. What??? so some say the bike isnt fast enough . Are you kidding me? I have had crotch rockets, cruisers , even other yamaha bikes like the seca and the seca turbo. , even my mad max bike the Vmax.
I have not been as pleased with a bike as much as i have with my XS1100.
The only drawback to this bike i have had is there is no radiator to cool long hot runs down. other than that. I don't find to many bikes that pull on me and even the new crotch rockets i play with a bit but i just give em a hint that the bike has power then i shut it down before they really get a jump into hyper drive. I don't really need any more power and the power it has is more then plenty to waste any Harley i have ever encountered. Yes my bike is well tuned and has some goodies so i guess i get a whopping extra 10 hp or something ridiculously low but all the hp i need and then some.

[MindWebs]

power has a price.

yes we have torque coming out the wazoo..

but i've gotten into this argument before and my 11 falls flat on it's face at 115mph

BOTH of my 250cc bikes do 108MPH

what's wrong with this picture?

i have gone through the 11 as i have gone through the 250's.
I'm give'in her all she got captain, but she hasn't got anymore (Scotty).

i'm at a loss.. it's got me baffeled...
finaly i said:
"Whatever, screw it, i'll go to jail at anything over a buck anyway"

and i'm a little happier because of it.

[yamahansolo]

i have had minbe over 115... and it still had more to go...

i think maybe all the head work might make alot more top end hp but it must lose alot of trq. i'd like to see some dyno numbers on it though.

kind of like if you put 60cc heads or 64cc heads on a 305 chevy instead of a 350. you might get a hell of alot more air in there but you'd lose too much compresion and i wonder if that's what the people with the new hedsa have done.

all i can say is i hope it doesn't keep raining this weekend!

[trbig]

but i've gotten into this argument before and my 11 falls flat on it's face at 115mph

I am currently having exhaust/muffler problems. It keeps cracking at the point where the collector joins the muffler. This system is off of a standard on my XJ, and it doesn't quite fit, so that may be a large part of my problem. When the system is closed after being welded, my top speed is over 130. When there is an open crack there, with nothing else different, my top speed is 115-118.

If everything is good to go on the engine, I'd do some looking at the exhaust.

Tod

[Ivan]

I have had the same results as Tod. I haven't had a stock exhaust, but the Jardine Spaghetti exhaust really helped mine. The old Mac with the drilled out baffle sucked. The Cherry Bomb was a vast improvement on the top end, but had NO low end, and the Jardine is a great compromise between. Its quiet too.

I have seen 130 with mine, and the 79 with the unknown 4-1 with no holes in the baffle and the stock FD, well that was still pulling above 130, pretty sure I could have redlined it in fifth, but the road was too short.

[stoked]

It's funny how a bike can feel fast. My buddy let me take his busa out and I could tell is was a much swifter bike, but honestly it was so smooth both in it's supsension, fairing, and torque curve, the seat of the pants didn't feel that much different. Now I had a Buell X1 for about a year and that thing felt faster than anything I've ever road on. But that Busa would spank it above 60 mph like it was in reverse.

[Rstyduck]

So, all this talk about the XS11 being slow is about a "Stock" bike with some engine mods?
Not a modified bike with a rank engine?
I liked My stock 81 XS11 Bagger, that's why I bought the basket case I have now.
Real bad shape, dirt and water in the spark plug less, exhaust off engine.
The bike I enjoyed riding that I think an XS11 wouldn't catch is the 2008 MT-01 1700cc.