Bigbore kit for xs1100?

[mrbsyammy]

I reiterate what Crazy Steve said above. Remember that the things you add/change alter the balance of a fine machine from the factory. Add a header, you change the balance....add pods, you change the balance, and so on and so on. Most external mods change the power curve to higher RPMs where you will never use them on the street/highway, making for most of the common complaints like 'my motor bogs until 4,000' or there is a big flat spot in lower RPMs'. You will get the most 'bang for the buck' doing smaller tuning things. I have been tinkering with my XS since 1980 and the three biggest 'bangs for the bucks' I have done to my 79 Special are slotted cam sprockets, mild head porting and a carb swap.

If you have a bit of shop capability, a drill press, degree wheel, dial indicator and TDC locator you can slot your sprockets and tune your stock cams to help bring the power band back to a more useable range. Most of the effect will be gained adjusting the intake cam and the exhaust has little effect.

Concerning the head, if you have a die grinder and a few stones/burrs along with an accurate burette you can port XS1100 heads yourself on a workbench. The runners are somewhat restrictive and in the intake runner there is a large ramp cast in just in front of the intake valve that can be smoothed and shaped for better flow. The exhaust runner is very small and can be widened out a lot. Give your valves a 30 degree back grind and that will have the effect of opening up the seats a lot. This can be done with a drill press and a small grinder jigged up on the drill press table. Use the 'quarter rule', that is if you remove more than the amount of metal from a runner that exceeds the size of a quarter then you probably took out too much. Port match your intake runners to the manifolds and open the exhaust runner to a diameter that is about 1/8" smaller than the exhaust gasket. Even your runner volumes using a burette and some tinted rubbing alcohol but, leave the combustion chambers alone! You can feel the difference in performance but remember, whatever you do here is not reversible.

Swap your carbs for some from a 1999-2002 Kawasaki ZRX-1200. Pretty much a plug and play deal. Do a search on this site and you will find out a lot about this.

Will all this give you 10% more horses? Nope. Will you feel the difference in performance? Yes you will. What these three changes can yield (providing you are willing to do the tuning dog and pony show once a year) is a machine with better than average performance that holds a good tune for a long time and has power that can be dialed in to come on at 2,500 RPM instead of the usual 3,500 RPM, no stumbles or flat spots and can get over 40 MPG.

Works for me!

Lots of great info, I have built many performance engine car wise so will that equipment work on cycles? I have everything you mentioned but for car engines? And as I stated I do have an extra xs1100 engine short of carbs so that's my Ginny pig per say. I have well over 10,000 cycle parts here but mostly Honda so that sucks..lol Oh! I forgot I also have an 80 xs1100 bike too so I'll leave mine pretty much alone except for minor things and would it be the best to use the 79 xs engine instead of the 80 or wouldn't that make that much difference? 79 is better correct? Hell I have little to no money in the 80 and the 79 engine was free so even IF I make a catastrophic mistake I won't be loosing a lot of money and if I don't have what I'll need for any type of machine I have a friend that has about any machine you can think of and would enjoy helping me for cheap. So again this has to be more labor then money on this project. I'm going out and replace the head gasket on the 79xs so any little things I could do like whats the best timing on a pretty much stock engine short of 4 into 1 exhaust K and N filter that's it.?
Till then and Thanks again Mr.Bill

[James England]

Personally, I like to put green Dyna ignition coils on bikes too.....

[TADracer]

What He Said

So as a power-adder, a big-bore really won't add much power (a few HP) unless you also improve the breathing, and things like a professional ported head and aftermarket cams are definitely not lo-buck. Very careful tuning is the best path to power on a budget, with particular attention paid to ignition timing, both initial timing and the timing curve.

I reiterate what Crazy Steve said above. Remember that the things you add/change alter the balance of a fine machine from the factory. Add a header, you change the balance....add pods, you change the balance, and so on and so on. Most external mods change the power curve to higher RPMs where you will never use them on the street/highway, making for most of the common complaints like 'my motor bogs until 4,000' or there is a big flat spot in lower RPMs'. You will get the most 'bang for the buck' doing smaller tuning things. I have been tinkering with my XS since 1980 and the three biggest 'bangs for the bucks' I have done to my 79 Special are slotted cam sprockets, mild head porting and a carb swap.

If you have a bit of shop capability, a drill press, degree wheel, dial indicator and TDC locator you can slot your sprockets and tune your stock cams to help bring the power band back to a more useable range. Most of the effect will be gained adjusting the intake cam and the exhaust has little effect.

Concerning the head, if you have a die grinder and a few stones/burrs along with an accurate burette you can port XS1100 heads yourself on a workbench. The runners are somewhat restrictive and in the intake runner there is a large ramp cast in just in front of the intake valve that can be smoothed and shaped for better flow. The exhaust runner is very small and can be widened out a lot. Give your valves a 30 degree back grind and that will have the effect of opening up the seats a lot. This can be done with a drill press and a small grinder jigged up on the drill press table. Use the 'quarter rule', that is if you remove more than the amount of metal from a runner that exceeds the size of a quarter then you probably took out too much. Port match your intake runners to the manifolds and open the exhaust runner to a diameter that is about 1/8" smaller than the exhaust gasket. Even your runner volumes using a burette and some tinted rubbing alcohol but, leave the combustion chambers alone! You can feel the difference in performance but remember, whatever you do here is not reversible.

Swap your carbs for some from a 1999-2002 Kawasaki ZRX-1200. Pretty much a plug and play deal. Do a search on this site and you will find out a lot about this.

Will all this give you 10% more horses? Nope. Will you feel the difference in performance? Yes you will. What these three changes can yield (providing you are willing to do the tuning dog and pony show once a year) is a machine with better than average performance that holds a good tune for a long time and has power that can be dialed in to come on at 2,500 RPM instead of the usual 3,500 RPM, no stumbles or flat spots and can get over 40 MPG.

Works for me!

[James England]

I ran an XS1100 with nitrous for over a year. I had 50bhp jets in it, although I started out with only 25bhp but rapidly went for the bigger ones. I used a complete kit which is still manufactured in the UK.

The XS11 is ideal for nitrous because of its unconventional drive train, with 'backwards' rotating engine and the shaft drive. It makes it almost impossible to wheelie due to the nitrous kicking in. What happens is that when the nitrous is activated, the swing arm pushes downwards onto the road and the back end of the bike lifts, rather than having the front end lift up, wheelie and effectively lose the nitrous power on the front raising up off the road.

Nitrous is either completely off or completely on. It's meant to kick in at full throttle openings and is activated by a micro switch on the mechanical side of the throttle so that as soon as full throttle is reached, the cable-operated lever clicks the switch.

There are two solenoids, one for fuel and one for the nitrous, plumbed into the inlet manifolds with colour coded lines to avoid confusion, with the fuel injector closer to the engine, so that the blast of the compressed nitrous adds additional 'push' to the fuel into the engine.

I mounted the bottles (two small fire extinguishers) at the rear of the bike from the US indicator mounts which are usually blocked off with grommets on European models. I painted them black to avoid undesired interest from following police cars.

The fuel taps MUST be modified to give full, gravity-fed fuel at all times, by drilling them out internally. A fuel pump is NOT advisable, as it could fail. Gravity fuel flow is more than adequate. Effectively, the taps are on full flow permanently and the 'off' diaphragm vacuum aspect of them bypassed permanently. This is vitally important with nitrous because, in the event of fuel starvation due to inadequate flow, or the failure of any fuel pump unnecessarily fitted, the nitrous oxide will act as a cutting torch and literally cut through the head or valves or pistons. Fuel starvation means a guaranteed engine destruction. For this reason, the fuel and nitrous solenoids must be absolutely top quality and wired into the electrical system absolutely securely and via un-fused wiring. They can be connected so that the nitrous solenoid will only operate if the fuel solenoid is active. Otherwise, failure of the nitrous solenoid means a super rich fuel intake with fuel going through the carbs as normal and fuel being injected into the manifolds too...not disastrous. Failure of the fuel solenoid however, means fuel starvation which will equal new engine. Cheap nitrous kits are therefore to be avoided at all costs.

When using the nitrous, the system is first armed using a bar-mounted master switch. This activates the system and allows the micro-switch to operate both solenoids at full throttle. The nitrous is meant to kick in when the normal carburetion is struggling, not when it is doing its normal job, as it were. You do not want nitrous kicking in at even mid throttle openings.

I fitted heavy duty clutch springs only and never had clutch slip.

When it kicks in, the effect is instant. My first use was as I overtook a car. The back end of the bike rose to full extension of the shocks as the swing arm was forced onto the road, and I thought the clutch was slipping as the revs rose immediately to red line. It wasn't slipping and, when I looked into the mirrors, I saw the car I'd overtaken about a quarter of a mile behind me! That's was only with 25hp jets. With the 50hp jets, the effect is even more mind-blowing.

On a Dyno, my bike accelerated from 60mph to 120mph in approx 2 seconds.

Nitrous oxide is extremely cold and the engine actually runs cooler when it's operating. It's also very smooth power delivery and not at all uncivilised (apart from the sheer speed).

I ran mine through loads of gas refills for about a year, with no adverse incidents of any sort. The place I bought mine from (still in business here in the UK) said they often increase the bhp by 75% over original and even 100% on lower mileage engines in perfect order.

Nitrous refills are cheap enough and I got mine filled locally via a hospital supplier.

The UK manufacturer was looking into using the frame of the bike as a storage system for the nitrous, although I don't know if he ever achieved this.

As a mod, nitrous is good in that it does not affect running when switched off, unlike high-lift cams or similar. It also achieves results which are completely impossible by normal tuning methods. Standard airbox and filter can be used (I did). There is a less drastic option of putting the jets into the airbox instead of the manifolds but it's not as awesome.

I loved it......


BTW UK insurers will accept the nitrous being fitted, on the understanding that it is never used......???? Err...right....I'll fit it but never use it, right?

[jetmechmarty]

Is that Pee Wee's bike?

Yes, it is.

[Prisoner6]

Also,

James (member JamesEngland) had an XS11 running with nitrous. See his posts #6 and #12 in the thread below:

http://www.xs11.com/forum/showthread.php?t=37608

Maybe James will chime in on this and tell us more??

[Prisoner6]

Well ...

Nitrous has been done on the XS11 ...

Here is one example:



And here is the story behind it:

http://cycles.evanfell.com/2011/02/race-inspired-yamaha-xs1100-with-a-past/

[MPittma100]

N20

Seems that could be plumbed right into the existing vacuum ports on the intake boots fairly easily. The problem would be a place to put the tank and the controls.

There is a small bottle ("Sneaky Pete"). A kit would need 2 solenoids - one for fuel and one for gas. Don't know if the system could be run on "gravity" fuel. May need an aux pump. A system may not be too hard to assemble?

http://www.nitrous.info/motorcycle-nitrous-injection-system.htm

MP

[XJOK2PLAY]

JW has The Navy Bike. Try and keep up Bobby.

We are meeting him in Little Rock.

I know that, Greg.
I was actually talking to him... Not you.
When I quoted it, it was supposed to have his comments, where he was bragging on it.
Sorry for the confusion.

[motoman]

Was my thoughts also BA80.........hell, just strap the bottle on passenger portion for a quick occassional thrill

[BA80]

Lot's of ways have been mentioned to make more horsepower. Problem is that the more horses you have, the more they eat.

By the time you did big bore, carburetor, cylinder head, camshaft, and exhaust mods, you would have a ton of money and much effort in the bike. Probably be tuning it forever.

You would end up with a bike that only wanted to go fast and probably would not have anything in between slow and fast. So there goes driveability and gas mileage. Not to mention what you may tear up in the drive train.

If you are not satisfied with the 95 HP that you already have. And you don't want to lose all those other things, then maybe there is another idea to gain horsepower and keep the bike pretty close to stock.

I'm thinking..................................NITROUS OXIDE!

As a rule you do not want to add more than 1/2 of existing HP with N20. 95+47.5=142.5 HP total. One should get some pretty good adrenaline rushes with that much sudden kick?

Question is.......Who makes a kit for a bike? Surely someone does. Might be worth looking into. Just saying.

MP

Seems that could be plumbed right into the existing vacuum ports on the intake boots fairly easily. The problem would be a place to put the tank and the controls.

[BA80]

Well.......guess we'll see in a few weeks from now?
You planning to ride the Navy bike to NC, right?

Maybe we'll have to see how well it runs out on the way there....huh?

JW has The Navy Bike. Try and keep up Bobby.

We are meeting him in Little Rock.

[XJOK2PLAY]

The 78 and 79 engines are quicker than the 80 - 83 and they have smaller valves.



That engine doesn't run any better than the stock 79 engine in my bike. I rode with Russ a lot when he was on that bike. 97cc doesn't make much difference in the grand scheme. The Navy Bike has also been converted to the 2H7 TCI and has a centrifugal advance. It would run a lot better with a good exhaust on it I think

Well.......guess we'll see in a few weeks from now?
You planning to ride the Navy bike to NC, right?

Maybe we'll have to see how well it runs out on the way there....huh?

[MPittma100]

More XS11 Horsepower

Lot's of ways have been mentioned to make more horsepower. Problem is that the more horses you have, the more they eat.

By the time you did big bore, carburetor, cylinder head, camshaft, and exhaust mods, you would have a ton of money and much effort in the bike. Probably be tuning it forever.

You would end up with a bike that only wanted to go fast and probably would not have anything in between slow and fast. So there goes driveability and gas mileage. Not to mention what you may tear up in the drive train.

If you are not satisfied with the 95 HP that you already have. And you don't want to lose all those other things, then maybe there is another idea to gain horsepower and keep the bike pretty close to stock.

I'm thinking..................................NITROUS OXIDE!

As a rule you do not want to add more than 1/2 of existing HP with N20. 95+47.5=142.5 HP total. One should get some pretty good adrenaline rushes with that much sudden kick?

Question is.......Who makes a kit for a bike? Surely someone does. Might be worth looking into. Just saying.

MP

[BA80]

He needs a good stock Special system for it if you run across one.