Super Technical Questions.

[dogyear58]

I have been a XS1100 owner/lover for a long time.
The best thing i ever did was go to the 17" rim
Standerd rim on a special (full dresser).
everything just works better. it rides better
x specialy with the old lady on the back.
the pegs don't hit the pavement
when ya lean er' hard.
The walk off stand works way better.
and you gain 6 mph so you lose a tiny bit o tork.
you can tell this bike was made for the 17"er.
But,what I want to know is how to get rid of
the horrific front end noze dive.....and real HP.
I hear 95 hp engin and 65 rear wheel,insane.
Shaft drive 34.5 % ? loss I heard thay(s.d.) only lose
up to 15 % HP.........................

[AlanB]

Hi Dogyear,

I have seen three of these bikes (Stock!) on a dyno; all made between 70 and 75 horse at the back wheel once their "issues" were worked out.

The factory figures will have been taken right off the crank, and are probably with "no losses"..... No alternator, no primary chain, etc............... The factory figure is not achievable anywhere in the real world, never mind twenty-some years after it was made!

There are a couple of bikes on here pushing over 90 BHp at the wheel; Maxi has several sets of dyno sheets posted of his big-bore bike, and the sheets for my own bike with modern carbs and modded exhaust have been posted as well.

There is also at least one bike with both of those sets of mods, plus a chain-drive; it has not seen a dyno, but I would bet on over the magic hundred at the tyre.

That enough for you?

AlanB

[DiverRay]

Lets start at the front....
Progressive fork springs, no air. That should fix the front end dive. You should be running heavy duty springs if you have the O.E.M. full dress kit.
95 HP was the '78 XS1100. They started to drop slightly from there. The '79 is close, but the specials never did run with the standards, IMHO.
To get the most out of what you have, just a few easy steps.
1. Drill about six 1/2" holes in the air box. these should be in the CENTER of the filter, as the air filter sucks the dirty air from the inside, and the outside of the filter is clean air.
2. Adjust the pickup coil "air gap" to .008". this will allow the pickup coils to give a little more, and the spark will be a little better. A new set of coils, as from Mikes XS, can also give you a "hotter" spark.
3. Check your exhaust system. If you have the original still, KEEP IT!! . The O.E.M. will give you more bottom end than any header, and the junk that is available today will NOT give you any more power. If you do have the original, what I did was drill four 1/4" holes on the flat of each muffler. This increased the noise just slightly, but let it breath better at high RPMs.

[dogyear58]

X zost

The exhaust has been changed to a 4x2 with X-over pipes
and the power band droped from about 3300 down to
2700??? so how can you sa such a thing.

[skids]

Re: X zost

Well, here is another weird thing...I have a 78E with K&N pods and a 4-1 Jardine exhaust that pulls real hard below 3Krpms. In fact, 2500 rpms feels real good! Love that bike.

Originally posted by dogyear58
The exhaust has been changed to a 4x2 with X-over pipes
and the power band droped from about 3300 down to
2700??? so how can you sa such a thing.

[dogyear58]

ya skids

yaa. dude as soon as I changed the pipes right away
I note's the 2500 come on. norm 4 cill-allmost 3400
I got a 79 all tric't up with a 4 to 1 full hdr. and it does'nt
have that kinda lo end......

[TopCatGr58]

Hey Dog,

What DiverRay was saying is that you can't get NEW pipes that are any good for low end anymore! The Jardine cross over 4-2 pipes you have are aged, and not available from Jardine anymore, only 4-1. Jardine grouped the cylinders better with the crossover technique, and so you have good lowend.

Most of the new pipes now, 4-1 are tuned more for mid/hi end power range, and come on line around 4K and above!

You and Skids can consider yourselves lucky to have those pipes!
T.C.

[79XS11F]

Well there really is no issue with that anyway cause these engines love to run in the mid to top RPM range and if in good shape can handle it no problem. I rarely run around under 5 K unless on a residential street where noise might be an issue.
Rob

[LoHo]

So, the goal here is to tune them up to the felony-speeding range? I understand loving performance, but why lose any MPG so that you can go 140mph instead of 120mph? Is the goal and increased range in the middle gears for throttle response and roll-on power?

[TADracer]

Doing one modification will affect something down the line. Every change you make must be given the 'what if' thought process with the understanding that a modification will usually result in a trade off somewhere else. For instance, what if I cannot get a good 4-2 exhaust system like the original and I am forced to use 4-1's because of availability? then, I am forced to trade off low end torque for top end power....or am I?

If you want to get that 'who turned on the rocket motor at 2,500 RPM' feeling again then advancing your camshafts a few degrees should do the trick. Of course, the trade off is that your power curve will flatten and your bike may nose over a few hundred RPMs before the red line. But if you do not care if your machine can do 140 then whats the concern?

Bottom line, tune your beast for the kind of riding you like to do and forget about the rest.