ST1300 Stock Window Modification - Reduce BackPressure

[BPD65]

Hi all, I'm resurrecting this post from back in 2008 https://www.st-owners.com/forums/showthread.php?7767-1300-Screen-Mod/page4
Came across that post and gave it a try this weekend.

Issue:

• Back Pressure created from windshield height
• Increased wind on passenger
• Increased wind on arms of rider
• Increased Drag from a Top Case (I have a GiviV46 on back) and noticed the bike seems to drag when its on.

Solution:

• WindScreen Modification on height (see thread).
• Pretty simple modification, you just need M6 1.0 bolt and M6 locking nuts (4ea) and a piece of 1 1/4 aluminum cut to length. More details in post above on "how to".

Results:

1. I found it works as advertised.
2. The pressure behind the screen isn't as great
3. The wind travels under the extra 1" and UP (most people reply, curious if it would be colder. No. At speed, the air comes up from the base and follows the air up to the top of the screen and over the rider ..why? because it's coming up from the fairing).
4. Passenger gains the wind over the top of Rider 1 because it's 1" higher and more airflow over top.
5. Drag seems less

So is it just mental?
Well, I tested the bike (screen full up) on the same street / same direction
Maintained speed of 65mph

Before : reading on mpg was 47.1 - 48.3
After Mod : reading on mpg was 54.2 - 58.9

Granted, wind speed would play a role at the time of testing etc. BUT what seems intriguing to consider is when tunnel tests for aerodynamics were done in the factory. Gauranteed it didn't have a top case on the bike. So, intuitively, makes sense to me and worked for my needs.


Hope you find it successful.


Staying on the right side of the grass oPoST1:,

Brian

 

[STGuy]

That mpg is enough reason right there!

Hi all, I'm resurrecting this post from back in 2008 https://www.st-owners.com/forums/showthread.php?7767-1300-Screen-Mod/page4
Came across that post and gave it a try this weekend.

Issue:

• Back Pressure created from windshield height
• Increased wind on passenger
• Increased wind on arms of rider
• Increased Drag from a Top Case (I have a GiviV46 on back) and noticed the bike seems to drag when its on.

Solution:

• WindScreen Modification on height (see thread).
• Pretty simple modification, you just need M6 1.0 bolt and M6 locking nuts (4ea) and a piece of 1 1/4 aluminum cut to length. More details in post above on "how to".

Results:

1. I found it works as advertised.
2. The pressure behind the screen isn't as great
3. The wind travels under the extra 1" and UP (most people reply, curious if it would be colder. No. At speed, the air comes up from the base and follows the air up to the top of the screen and over the rider ..why? because it's coming up from the fairing).
4. Passenger gains the wind over the top of Rider 1 because it's 1" higher and more airflow over top.
5. Drag seems less

So is it just mental?
Well, I tested the bike (screen full up) on the same street / same direction
Maintained speed of 65mph

Before : reading on mpg was 47.1 - 48.3
After Mod : reading on mpg was 54.2 - 58.9

Granted, wind speed would play a role at the time of testing etc. BUT what seems intriguing to consider is when tunnel tests for aerodynamics were done in the factory. Gauranteed it didn't have a top case on the bike. So, intuitively, makes sense to me and worked for my needs.


Hope you find it successful.


Staying on the right side of the grass oPoST1:,

Brian

Sent from my SM-G920V using Tapatalk

 

[W0QNX]

I ride with my cut down to the dash stocker most of the time. I like it just fine with the dash being the top of the wind block. I will say that gas mileage jump won't last. Mine varies at most 2 mpg over time with the shorty versus full screen. My average runs right at 44 mpg on the road.

YMMV

 

[Clutch]

I tried Catmandu2's version of this mod with fender washers and it works great. Easy peasey and angle is adjustable.

 

[Oldbikefixr]

Backpressure on the stock windscreen is amazing. On my ride home from purchasing my 2006, I was hit by light rain on the first and last half hours of the trip. Was surprised to find rain droplets on the inside bottom half of the screen. After the weather warmed up, I got into the routine of cleaning bugs off both sides. Smaller insects, gnat size and a little larger, were smashing into the same area.

 

[Honda-st-team]

Great Info Thanks

 

[Catmandu2]

Backpressure on the stock windscreen is amazing

I was always amazed to see, on my old Honda interstate fairings, rain coming over my shoulders and hitting the inside of the windscreen. Raking the ST's windscreen a bit makes a noticeable reduction in backpressure. I have tried this with both the oem screen and my Clearview GT medium, with good results. It has to be done safely though,, as you don't want the screen coming loose while passing an 18 wheeler. Some time,,, I am going to tape some yarns to the bike in a few places,,, just to observe the aero flows,, Cat'