Head porting? Is it worth it?

[natemoen]

Thanks a lot guys I'll have to look into all that y'all have said. I'm building this motorcycle for a friend that was killed in the line of duty. He loved xs1100 as much as any one I know and also loved drag bikes so I plan on build a over to top bike that is both. Any help is very appreciated.

sorry to hear of your friend. Where was he/what was a part of?

[skipper]

Capton, in some ways you're right, at least about if you screw up you've lost a head (sometimes you can salvage a small error by re-shaping, you'll not salvage a big error). That's why I said you have to find someone who KNOWS how to use a "bench". A good flow bench has a probe to tell you where the air is flowing, how fast it's flowing and which way it's flowing (turbulence will reverse the flow direction). You have to keep checking and cut SLOWLY, and you need to know where to cut! That is why good port jobs cost so much.
As to gains, if one adheres to the rules, the gains on the bench seem to translate directly to power gains, at least in my experience. One must pay close attention to turbulence as once air speed exceeds the speed of sound it becomes a different animal.

[yamahansolo]

You should also check with the Guy from austrailia. He got about 110 or 114 to the wheel. There was a video on yoiutube. I can't remember guard screen name he also had the smaller bore kit.

[crazy steve]

Just buy this one.... http://phoenix.craigslist.org/wvl/mcy/2536990585.html

147 HP.... or so he says...

[motoman]

With those hp numbers..........I want THAT big bore kit............yea, right.....

[Poprock]

Geezer's polished stainless steel valves flow better, especially the intakes. I'm running them on an otherwise stock SG and they make a noticable difference in low-end torque. And they're the least expensive significant engine mod you can make, IMO.

[Incubus]

Turbulence once you pass the SPEED OF SOUND!!!!

What the hell have you done to that XS.....

Patrick

[skipper]

Gee Patrick, your exhaust gasses are way above the speed of sound,,,from your lawn mower!! That's why you fit a muffler.

[pase]

He was a cop that was shot in rockdale, ga last 5/8/10

[natemoen]

RIP Officer Mahaffey. My condolences to family and friends.

http://www.odmp.org/officer/20396-de...lamar-mahaffey

You need any help let me know!

[oldyam80sg]

Sorry to hear an officer down and is no longer with us.Also i tried the drag racing thing back in the early 80's-a lot of issues if you want to drag race an XS1100-among other things-gearing as that limits what you can do with these.I have a Goodyear racing slick on a stock XS1100 rear wheel that is barely used.And if you want to race-start safety wiring things and look for a dead-man switch to kill power to the bike if you fall off.

[pase]

I plan on taken a dead man switch and putting it under a custom seat pan that's being made or me. Thanks

[James England]

Forgive me for mentioning something again that I've posted before, ages ago....you may not have seen it. Before that though, please pass on my condolences to DS Mahaffey's family. What a brave man and what a terrible waste. To someone in the UK, reading about what happened is like a different planet.

Since you are trying to make a drag racer type machine, just put nitrous oxide injection on your standard bike. For other modifications, it's the old 'law of diminishing returns' ie it takes more and more money to get less and less improvement. But, with nitrous, you get an immediate (and variable) massive increase in power which is completely reversible and has no effect on the standard running of the bike (unlike high-lift cams etc).

I fitted as system myself to an XS1100 I had and ran it for a year (and countless fire extinguishers of N02) on a completely standard F model. At first, I put +40BHP jets in and, two days later, took them out and put +80bhp ones in. As a precautionary measure, I put 10% stronger clutch springs in. I also had the petcocks drilled out so that there was never any danger of fuel starvation

I've never experienced anything quite like nitrous. My system kicked in at a predetermined (user-selected) throttle position (usually full throttle is best) with a microswitch. When the nitrous kicked in it was like a rocket going off at the back of the bike. My bike never once wheelied (already discussed here as to why not) but just pushed the rear wheel down onto the road. I never once met any other bike, or vehicle which could burn me off at traffic lights. On a rolling road, the bike accelerated from 60mph to 120mp in under 3 seconds.


Apparently, with nitrous running, the engine runs cooler because the nitrous oxide is so cold. It's also very smooth running. The biggest danger of engine destruction is if there is gasoline starvation. If the fuel is cut off or reduced whilst the nitrous is being injected, the nitrous acts like a cutting torch and just slices through things ... hence drilling the petcocks. I lost reserve and prime and they were permanently 'on'.

When I sold the bike, I took the system, off and sold it separately because the buyer didn't want to use it. The bike ran perfectly. Between gas bottles, it ran standard and with no incident at all.

[natemoen]

Do you have any pics James of the NO2 and how you had it plumber?

[James England]

Do you have any pics James of the NO2 and how you had it plumber?

I only have a grainy b/w photo of the bike (a Martini) in an old bike magazine that published an article about it.

With nitrous, there are three sub-systems....1. Gasoline and 2. N02. 3. Electrical to power solenoid valves

When the microswitch kicks in, it electrically activates two solenoids (fuel/N02) which are plumbed into the inlet manifolds. Basically, it's two small bore plastic pipes of different colours which attach to two nipples (nitrous one is actually a jet) per manifold which you just drill and tap in.

When the solenoids open, the nitrous squirts under pressure from the tank (fire extinguisher) through the solenoid and into the inlet manifold nipple (jet). The gasoline just goes in neat from the tank petcock by gravity/suction through the pipe and into the manifold nipple right next to the N02 one. You put the gasoline nipple nearer the cylinder head than the nitrous one, both in a horizontal line on the manifold. This means the pressurised nitrous pushes in the extra gasoline into the cylinder.

The solenoids have to be ultra-good. If the fuel one jammed, it's bye bye engine. If the nitrous one jams, it's not a problem, just misfire due to too much unburnt gasoline. All wiring to power the solenoids is shared, so, if a fuse blows, neither operate. Nitrous without extra gasoline = disaster. You must have both on the same power supply and wired up with no risk of wires coming off.

I fitted the whole system in a couple of hours. The solenoids were anodised pink (for fuel) and blue (for nitrous). Same colours for the pipes. It all looked very space-age and certainly felt like it in operation.

The first time I used it, I drew level with a car on a straight, at about 60mph. Then I twisted to full throttle and heard the engine revs go up to max very suddenly, accompanied by a feeling like a kick up the pants. My first thought was "damn! the clutch is slipping". Then, when I looked in my mirrors, I saw the car I'd been level with was now about 1/4 mile behind me! I'd love to know what the car driver thought.

The nitrous always reminded me of the speed increase when you hit nitrous on a video game! With body feelings.....