I have not found it so I guess it does not exist. After market intake.

[Hotwheelbill]

I have not even been under the tank yet on my '95 ST1100 but wanted to know what options there are for any air intake mods other than just the round K&N filter? Is there any room for anything other than stock?

 

[saaz]

There is. You can drill extra holes to increase flow, but you will need to rejet the bike, otherwise it will not run that great. The end result is more power, use a bit more fuel.

Have a look at http://www.steinborn.org/st1100.html

 

[DaBear]

Thanks, saaz. After spending half of my adult life figuring out the jetting on street two-strokes, this is terrifically interesting reading.

 

[Blue STreak]

If you want to get the most out of a less restrictive intake and jetting, you probably want to look at less restrictive exhaust, too. Unfortunately, Staintunes don't come cheap, and Two Brothers are just too, too loud.

 

[STPaulK]

Be aware that others have also tried modifying the airbox, jets, pipes and mixture and found little or no gain over stock. The wording on steinborn.org ("claimed 17 hp", "somewhat stronger midrange") and lack of dyno charts at each step along the way does not instill confidence that all their work really yielded solid results. You also should note that their mods wound up also being altitude sensitive (and they had to compensate.)

The ST1100 had been around for so long that it stands to reason that someone would have found the magic mods to yield substantially more horsepower by now. I believe there is none as Honda did the proper engineering to begin with (IMO). If I were you, I would spend money, and time, on lighting, louder horn, music, risers....whatever instead of trying to milk something that others wasted their time pursuing. Or spend the money on a Hayabusa. /rant off/

 

[George]

My thought on this is that cams would be the first mod. None are available. A good Southern California hot rod shop would be your best bet. Bring money.

 

[RainyRider]

Well, maybe one shouldn't mess with an ST1100....
But.... installing a free breathing air cleaner, porting the intake manifold, rejetting, and modifying the exhaust (slightly less restrictive) on my ol' Road Star gave it a serious kick in the butt... and, gas mileage improved from 44 to 48MPG....

(BTW....That was an excellent writeup on CV carbs...)


'91 ST1100
'05 Road Star 1700

 

[saaz]

I have been there done that with modifying a GS1000 (ported head, cams, exhaust etc) I spent as much on the engine as the bike was worth. I would not do it now, as it is better to change to a more suitable bike, and cheaper. The ST1100 is engineered from the intake right through to the exhaust to deliver a flat powerband with the torque we all like. I have staintunes on, and a K&N, no retuning required, and minimal noticeable power changes (ok, slightly better down low, no effect up top). Any changes I would make would cost a fair bit, and I would loose the characteristics that I bought the bike for. But then the modified GS1000 had better power down low and everywhere, better fuel economy...but in todays money I would need to spend $5000 or so.

 

[Martin_b]

The stock air filter on the 1100 is not the restricting part of the intake system. Switching to a K&N does nothing for the motor. And many people say the K&N does not filter as well as the stock unit. So, you might just save your money.

The real restriction to the 1100 is the size of the air intake at the back of the air filter housing. Making some holes around the side of the housing will take care of that but if your bike is like most 1100's, it will hardly run after that mod. A serious amount of rejetting is required if you fool with the air box. And to get the jetting right again requires access to a dyno and numerous runs to sort it all out.

The exhaust system on the 1100 isn't really very restrictive. And due to the nature and tuning of the intake system, changes there also do nothing for the power curve. And I've yet to hear an aftermarket system that wasn't too loud for my taste.

But, there are some things you can do. First, make sure that the carbs are in perfect condition and synced properly. You'd be amazed what this can do if they are off a bit. Second, rejet just enough to take care of the EPA mandated leanness. On my 92 ABS ridden here in the Silicon Valley, this meant going up one size on the slow speed jet from a #38 to a #40, raising the stock needles .5mm, going up one size on the mains from a #125 to a #128, and turning the mix screws out to 2.5 to 2.75 turns total. The result was an improvement in low and midrange response (crisper throttle response) and an overall increase in torque and HP of about 3 to 5. Nothing to really write home about, but nice. The main difference was the bike is now more responsive and has a bit more grunt, right now.

The last thing I did was to eliminate both the PAIR system and the fuel vapor recover system. Both these smog systems operate and run by vacuum taken off the intake ports and the carbs themselves. There are two intake ports where vacuum taps are located and 5 spots on the 4 carbs. It's my belief that these vacuum systems have a tendency to soften up the carb response and when they are removed, things get crisper and more precise.

 

[Hotwheelbill]

The stock air filter on the 1100 is not the restricting part of the intake system. Switching to a K&N does nothing for the motor. And many people say the K&N does not filter as well as the stock unit. So, you might just save your money.

The real restriction to the 1100 is the size of the air intake at the back of the air filter housing. Making some holes around the side of the housing will take care of that but if your bike is like most 1100's, it will hardly run after that mod. A serious amount of rejetting is required if you fool with the air box. And to get the jetting right again requires access to a dyno and numerous runs to sort it all out.

The exhaust system on the 1100 isn't really very restrictive. And due to the nature and tuning of the intake system, changes there also do nothing for the power curve. And I've yet to hear an aftermarket system that wasn't too loud for my taste.

But, there are some things you can do. First, make sure that the carbs are in perfect condition and synced properly. You'd be amazed what this can do if they are off a bit. Second, rejet just enough to take care of the EPA mandated leanness. On my 92 ABS ridden here in the Silicon Valley, this meant going up one size on the slow speed jet from a #38 to a #40, raising the stock needles .5mm, going up one size on the mains from a #125 to a #128, and turning the mix screws out to 2.5 to 2.75 turns total. The result was an improvement in low and midrange response (crisper throttle response) and an overall increase in torque and HP of about 3 to 5. Nothing to really write home about, but nice. The main difference was the bike is now more responsive and has a bit more grunt, right now.

The last thing I did was to eliminate both the PAIR system and the fuel vapor recover system. Both these smog systems operate and run by vacuum taken off the intake ports and the carbs themselves. There are two intake ports where vacuum taps are located and 5 spots on the 4 carbs. It's my belief that these vacuum systems have a tendency to soften up the carb response and when they are removed, things get crisper and more precise.

Great info. I will print and save this.

What did this do to your milage? That is my biggest consern of late.

 

[saaz]

What Martin did should not adversely affect mileage, as all it does is bring the tuning closer to what is standard in other markets. We don't have the PAIR or other things in Australia, and run the #40 slow speed and #128 main standard. Running on the lean side can adversely affect fuel economy.

 

[Martin_b]

Around town, I got a bit of a drop. Maybe 1 or 2 mpg. But then I'm heavy handed on the throttle anyway. On the highway, I've gotten as good as 44 or 45 with long, steady state droning. Not as good as the 50+ that some get, but then I'm 260 lbs without my gear, run an XL Clearview, and my cruising speed out on the open road is usually around 80 to 85 mph. 'Not exactly conducive to good gas mileage.

Frankly, I wouldn't worry about it. Riding style has far more effect on mileage than these slight mods. And remember, those #40 slow speed jets and the #128 mains are the stock sizes in Canada.

 

[sennister]

If you are interested I have a aircover that has been drilled to allow more air flow. It happens to be on my bike now but I have been thinking about pulling it off. I really don't notice any difference although I never went through the trouble of rejetting so that would explain it. I picked it up from someone on this site a year or two ago. I was really after another item that he was selling and since he combined shipping it wasn't a big cost to try it. Plus I didn't have to drill my original one in case I wanted to go back. The one thing that it did do for my bike is make it louder on acceleration.