Author Topic: Vent flaps for engine heat  (Read 8955 times)

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Offline DaveSz

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Vent flaps for engine heat
« on: April 23, 2017, 12:11:55 am »
Hello COG!

I love my 93 Connie w/103K, purchased in '14 with 62K.  Joined COG, and much appreciate it.  New to forums.  This is 1st post.  Usual J-box issues when I got her, but she ran great otherwise, and I started touring.  Just the usual maintenance. However, I just couldn't stand the heat in July and August.  Not much help from the stock plastic scoops on the sides.  She cooked me from boots to upper legs. 

Tried sealing more inside, around the engine, hoping to make the big side vents more efficient, but no luck.  Left side almost no hot air at all exiting the vent, and the right side had a little, that just slid back along the side panel, and onto my leg.  The vents weren't working much, probably due to shape of the fairing itself.  Too high of pressure in the vent at normal riding.  Heat coming out of her everywhere.   Considered air wings and heat shields, but neither appealed much, or did anything to make the vents themselves function better.  Thinking about the cooling flaps that I'd seen on aircraft engines, which are opened to help cooling while taxiing, I decided to try something similar.  Vent flaps.. 

Made several sizes and shapes, and finally settled on 9" high, sticking out 4", and attached by two screws each, into blocks with T-nuts behind the side panel, for quick install/removal.  Have had them on through last summer, and just installed them again.  They work.  Above 35 mph.  At speed, there is now a bunch of hot air coming out of both vents, into the flap pressure shadow.  150 degF air stream ends up passing 2" outside of my leg (except in strong crosswind).  Why they stick out 4".   Boots, ankles, shins, thighs get air slightly above ambient temp, flowing back-to-front behind the fairing and my cut down CBailey screen.  Nothing but cool air down at the carbs, with the vent flaps on.  And they help in the rain, too.  In winter, vent flaps off, she is still really warm, but I carry the flaps in the side cases in case I go south.  5 minutes to put them on when crossing the Florida line...

Have added bar risers, and a few other small farkles, but nothing that improves my summer riding like the vent flaps. $10 of 0.025" aluminum from Lowes.  Pretty homely looking, but cool at last, and riding all summer.   Will try to attach photos....

DaveSz
DaveSz
1993 C10 w/113K
1996 Honda CBR600F3
1987 Honda VFR F2
1985 Honda 650 Nighthawk

Offline Bob H

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Re: Vent flaps for engine heat
« Reply #1 on: April 23, 2017, 12:28:43 am »
Engine heat in hot weather is my biggest gripe about the C10.  IMO the fairing was designed by styling only.  No thought to the fact that no one really wants to sit behind a radiator on a hot day!  Engineering was allowed to make modifications only such that the engine doesn't actually overheat, and rider comfort was only addressed as an afterthought when it was too late to make meaningful changes to the design.  (I do like the bike otherwise; I must as I've still got the '88 I bought new!!)

Looks like you have made a very effective mod!
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Offline DaveSz

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Re: Vent flaps for engine heat
« Reply #2 on: April 23, 2017, 12:11:55 pm »
Agreed.  The vents looked like they should work, but just weren't placed or shaped right. And inside the left side is restricted.  With that big I-4 engine, engineering functioning vents and keeping the thing from getting seriously wide was tough.  The guys doing the vent design lost the argument with the rest of the design committee.  Engine doesn't overheat, just the rider. 

I have 2 old Hondas with full fairings, that do it better, but each is a bit different, and certainly not perfect.  My 87 VFR has a narrow engine, the pipes are low, and the heat off them does not use the vents.  And the vents face a bit to the rear.  In the fairing shadow, so to speak.  Not perfect, but when running hard, they work quite a bit better than Connie w/o the flaps. 

My little CBR600 has the same problem of an I-4 engine, but the vents are very large, and the rider is sealed away from the heat better by the panels and tank.  Kind of like the under tank heat shields for the Connie.  Pushes the heat lower, and helps. 

The vent flaps are easy to make and try.  My first vent flap effort was 12" high and stuck out 5", and was seriously ugly, but really worked.   Just some old roof gutter flashing, glued on with 3M Extreme brand double-sided tape, to test the concept.  The stuff is seriously sticky.  Will hold it on forever.  Rode it around out in the countryside for a week, testing.  Shortened to 9" for the 2nd effort, and still sticking out 5".  3rd was 9"  and only stuck out 3".   Too small.  Pulled some heat out, but just concentrated it on the side of my legs.   

Went back to the 9" x 4" that is on it now, used stiffer aluminum, but still with the 3M Extreme double-side tape, for a couple weeks.  Finally drilling holes and adding the ABS blocks.   Have been thinking about trying some more aerodynamic looking flaps, but these are simple and hide well in the side cases.  And anyhow, these days I don't think so much about the engine heat!
DaveSz
1993 C10 w/113K
1996 Honda CBR600F3
1987 Honda VFR F2
1985 Honda 650 Nighthawk

Offline ron203

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Re: Vent flaps for engine heat
« Reply #3 on: April 23, 2017, 12:34:18 pm »
Very ingenious. My C-10 roasted me in the summer in GA. Well done. (and thanks for joining the club.)
Ron
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Offline GeorgeRYoung

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Re: Vent flaps for engine heat
« Reply #4 on: April 23, 2017, 04:47:35 pm »
Good stuff. You've proved that not all the good ideas have already been discovered.

Offline JimBob

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Re: Vent flaps for engine heat
« Reply #5 on: April 24, 2017, 12:22:59 am »
Neat!


So you're saying with these on airflow ends up coming in the sides by the carbs, pulled forward across engine and then out the fairing vents? PRetty cool (pun intended).


If you want to make them more attractive, shape them parallel to the fairing vents (kind of a parallelogram shape). Surprisingly that shape really makes add-ons visually fit (tried it with some air wings I made myself).

Offline DaveSz

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Re: Vent flaps for engine heat
« Reply #6 on: April 24, 2017, 01:22:03 am »
Can't say for sure air from the carb area goes forward past the engine and out the vents.  Could be pulled down below the carbs?  But they are getting cooled by ambient air drawn in, and not getting cooked by hot air flowing back past the engine onto the carbs (and me) anymore.  Have stuck a bare hand down and felt the carbs a bunch of times, and they are surprisingly cool, with the vent flaps on. 

At work we always said you could touch stuff up to 150 degF  without pain .  Today, riding south on US33 at 65 mph, showing 70 degF for ambient, I couldn't  keep my bare hand in the airflow behind the right side vent flap for more than a few seconds.  More like 170 degF there. just trailing off the flap.   

For sure, it would be great if somebody comes up with a more efficient, and visually pleasing, size and shape.  Further lowering the pressure there.  As long as they can still be taken on/off quickly.  Would miss that heat when I'm coming home late on a summer night!
DaveSz
1993 C10 w/113K
1996 Honda CBR600F3
1987 Honda VFR F2
1985 Honda 650 Nighthawk

Offline SamSam

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Re: Vent flaps for engine heat
« Reply #7 on: April 24, 2017, 08:03:01 pm »
Backer air wings are the single best add on in my opinion.  Cool in the summer warm in the cool weather.  Check them out!
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Offline Katsi

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Re: Vent flaps for engine heat
« Reply #8 on: May 17, 2017, 01:22:42 pm »
Great idea.  By the way, I'm trying to match your design.  Assuming that the 9" is the vertical edge - when you say that they stick out 4" are you talking about the distance from the faring or that the flap itself is 4"?  For example, If I were to get a piece of aluminum and cut it to 9" x 4" and gave it say a 1" mounting surface that would make the flap only 3" and thus impossible to angle out 4" from the bike.  If the flap itself were say 5" that would give it an angle of roughly 95 degrees which is just shy of perpendicular from the faring. 

Or, are you saying that the height is 4" and the overall length is 9"?  And if that is the case, what amount are you allowing for the mounting base? 2" would give a 7" flap which sticks it at just about 8" for the over all end finish length.   I don't have the faring in front of me to measure the actual hole but it seems larger than 4".  and that does not match your pictures.   :-[

Or, is it 9" x 4" with a 2" base and angled out 4" from the inside of the fearing opening - or the plastic closest to the bike?  Hope that makes sense.

Just trying to wrap my head around this is all.
« Last Edit: May 17, 2017, 01:26:00 pm by Katsi »

Offline Pbfoot

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Re: Vent flaps for engine heat
« Reply #9 on: May 17, 2017, 01:35:55 pm »
Unless you have gas tank insulation, these blocking pieces will cause more harm than good.
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Offline Katsi

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Re: Vent flaps for engine heat
« Reply #10 on: May 17, 2017, 04:19:42 pm »
Unless you have gas tank insulation, these blocking pieces will cause more harm than good.

OK, I'll bite.  Why?  Not trying to be a smart a**.   

It makes sense to me that these wings create a low pressure area around the natural vent which allows the heat to escape without being blocked off by a higher pressure created by the vehicle just moving along.   So wind coming through the radiator can blow pass the motor and out the vent because it is now the path of least resistance instead of that path being between the ferings and motor and onto your legs. :(     

Offline DaveSz

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Re: Vent flaps for engine heat
« Reply #11 on: May 18, 2017, 01:39:11 am »
The vent flaps on my Connie now were made from a piece of 18" x 6" aluminum.  First I cut it in half, so it's two pieces of  9" x 6".   Then I clamped it in the vise the long way, with 4" sticking up, and made the bend so the mounting flange is 2" x 9", and the flap part is actually 4" x 9". 

The vent opening itself is 7" vertically, and the flaps are 9" vertically, ending up an inch above, and below.  I rounded all corners, but a bit extra off  the bottom flange part, just to make it fit a bit better, and not cover the cute red pin stripe on my '93. 

Of course, by pulling the hot air out of the vents, the heat under the tank is greatly reduced.  Carbs are cool, with ambient drawn in.  Inside of my legs is cooler than the outside.  And my boots are cool.  Heat flow is completely changed.   The flaps create a pressure shadow.  Hot air (170 degF) is coming out the vents.  Not being blocked by the flaps.

Try it.  You'll like it! 

DaveSz
1993 C10 w/113K
1996 Honda CBR600F3
1987 Honda VFR F2
1985 Honda 650 Nighthawk

Offline DaveSz

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Re: Vent flaps for engine heat
« Reply #12 on: May 18, 2017, 01:59:00 am »
Took off the left flap, for a picture. 
DaveSz
1993 C10 w/113K
1996 Honda CBR600F3
1987 Honda VFR F2
1985 Honda 650 Nighthawk

Offline Jim

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Re: Vent flaps for engine heat
« Reply #13 on: May 18, 2017, 12:36:36 pm »
That's a great idea.  Thanks for pics. :great: 

After looking at your setup I was thinking my tip-over bars would be in the way.  But actually, it looks like they would provide mounting points so I would not have to drill into the fairing.

Offline DaveSz

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Re: Vent flaps for engine heat
« Reply #14 on: May 18, 2017, 07:04:43 pm »
Jim,

I started testing the vent flaps by sticking them on with 3M extreme double sided tape.  Hated to drill through the thin fairing.  But later, when I was satisfied with the flap performance, I just drilled right through vent flap, tape,  and fairing at the same time, when preparing to mount the ABS blocks and T-nuts.  Would recommend just taping yours on till you are satisfied they are the the right size for your Connie.  And if you have the tip-over bars to help "support" them in the wind, the double side tape would work pretty well.  You may want to try making them a bit bigger, or a bit different shape.  5" flap would move the heat further outboard than the 4" ones.  Easy to cut down later.     All I can say for sure is, don't cut them any smaller than the 9" x 4" that  I'm using.   

And when you are happy with them, post a picture showing how you fitted them in front of the tip-over bars!

Stay cool....


DaveSz
1993 C10 w/113K
1996 Honda CBR600F3
1987 Honda VFR F2
1985 Honda 650 Nighthawk

Offline oldsmoboat

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Re: Vent flaps for engine heat
« Reply #15 on: May 20, 2017, 02:21:16 pm »
I actually had to look down yesterday to be sure my foot wasn't on fire.  And it was only in the 80s.

Offline Jim

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Re: Vent flaps for engine heat
« Reply #16 on: May 23, 2017, 10:40:07 am »
Picked up a couple of cushioned split clamps from Grainger to mount the flaps to my tip-over bars.  For $2.70 each, these work great.  The clamping screw pops out so it doesn't have to be removed, only loosened slightly, to get the clamp off/on the bar.  Did the right side last night with a 9 x 4 piece of cardboard.  Worked fine this morning except the angle of defection with respect to actual wind flow (not the surface of the fairing) was about 22 degrees.  I'm going to increase the width from 4 to 5 inches so I can get a higher angle plus be able to cut a 1" slot in the outer edge to fit around the top-over bar.  This will give the stability I need so the flap does not have to touch the side of the fairing and will only have 1 attachment point.  Thursday is supposed to be 90 degrees so that should be a good test out on the highway.
« Last Edit: May 23, 2017, 11:05:56 am by Jim »

Offline connie_rider

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Re: Vent flaps for engine heat
« Reply #17 on: May 23, 2017, 01:25:59 pm »
Dave, You have a clean machine there.
I like to see the continuing inventions on the Forum.
You seem to be onto something, but I have a concern that the vents could break the fairing if you bumped them.
Be careful...

Question; Are all of your original heat shields in place? (located; sides and top, under the fairing)
In particular; I'm wondering about the one on top of the engine. (located forward of the valve cover)
It's purpose is to prevent airflow over the top of the engine.
Many have lost or removed that piece when doing valve adjustment's, and may be suffering more heat, because of it.

Explanation: At 1 time, I had 2 Connies.
1 was {more} hot to ride. The other normal.
I later discovered that the upper piece was missing.
Buying and re-installing that piece helped quite a bit.

Ride safe, Ted


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Offline DaveSz

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Re: Vent flaps for engine heat
« Reply #18 on: May 24, 2017, 04:01:08 am »
Hi Ted,

Thanks for the suggestion, based on your two bikes.  My top heat shield, from radiator to valve cover, is in there.  Can reach in the front, over the radiator, and put my hand on it.  Rainy day tomorrow, so I'll lift the fuel tank and make sure the heat  shield fit is OK.  Did a valve adjust in January, and anyhow need to check the wells to see if the new well seals have any oil leaks.  Will take a picture, and look for any needed extra sealing.

The vent flaps I'm using are  made from 0.025" aluminum, and it is springy, and not really rigid.   T6 or similar, I'd guess.  $10 piece from Lowes.   I can bend it back an inch without any lasting distortion, with one finger.   But they never have bent  on their own while riding into the wind.  Put them on early last summer, and have bumped them on the Jeep bumper in my home garage, more than a few times.   Four motorcycles in one bay, plus a lot of other less interesting junk.   Never worried about the fairing breaking that much, as I put the ABS blocks on right away, when I drilled for the screws, and the fairing panels don't seem to have any significant flexing when you wiggle the vent flaps by hand.  And no apparent cracks around the vent flap screws during the last year.   

DaveSz
1993 C10 w/113K
1996 Honda CBR600F3
1987 Honda VFR F2
1985 Honda 650 Nighthawk

Offline DaveSz

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Re: Vent flaps for engine heat
« Reply #19 on: May 24, 2017, 03:41:39 pm »
Picked up a couple of cushioned split clamps from Grainger to mount the flaps to my tip-over bars.  For $2.70 each, these work great.  The clamping screw pops out so it doesn't have to be removed, only loosened slightly, to get the clamp off/on the bar.  Did the right side last night with a 9 x 4 piece of cardboard.  Worked fine this morning except the angle of defection with respect to actual wind flow (not the surface of the fairing) was about 22 degrees.  I'm going to increase the width from 4 to 5 inches so I can get a higher angle plus be able to cut a 1" slot in the outer edge to fit around the top-over bar.  This will give the stability I need so the flap does not have to touch the side of the fairing and will only have 1 attachment point.  Thursday is supposed to be 90 degrees so that should be a good test out on the highway.

Hi Jim,

Didn't think of a clamp like that for your vent flap, though I've seen lots of them in factories.  Great because it will allow you to try different angles, sizes, materials for the flap, without any  scars on your Connie.  Quick adjustment, or total removal.  Good choice! 

I think you will find the 5" size works better, particularly in a crosswind.  4" is enough otherwise.  For sure there have been days when I was riding south in a wind from the west, when I'd have liked that heat pulled a little farther outboard.   

Dave
DaveSz
1993 C10 w/113K
1996 Honda CBR600F3
1987 Honda VFR F2
1985 Honda 650 Nighthawk

Offline DaveSz

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Re: Vent flaps for engine heat
« Reply #20 on: May 25, 2017, 12:14:32 am »

Question; Are all of your original heat shields in place? (located; sides and top,  under the fairing)
In particular; I'm wondering about the one on top of the engine. (located forward of the valve cover)
It's purpose is to prevent airflow over the top of the engine.
Many have lost or removed that piece when doing valve adjustment's, and may be suffering more heat, because of it.


Hi Ted,

Pulled the tank, to get a good look at the top radiator heat shield.  Didn't get a very good picture, but you can see the heat shield in the attached. 

The top engine heat shield itself looked OK, but the rubber "edging" around the shield did not fit so well in places.  It was distorted, and left a short gap of up to 10mm wide opening.   Room for hot air to leak back onto the valve cover, if I didn't have the vent flap to keep the area between engine and radiator negative.   

Would be good to have a supply of new rubber edging for the engine heat shields.    Just needs to have the gaps filled a bit better.  I put some sticky foam strips in a couple obvious leaks, but they don't stay in place very long.  Perhaps modifying the shape of the shield?  Slap some ABS glue on it, and strips of ABS, to extend the  shield  to fit the opening better?  Could only help. 

Oh, and the plug wells were dry!

Dave
DaveSz
1993 C10 w/113K
1996 Honda CBR600F3
1987 Honda VFR F2
1985 Honda 650 Nighthawk

Offline Jim

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Re: Vent flaps for engine heat
« Reply #21 on: May 25, 2017, 10:37:57 am »
Dave, took your advice and updated to 5" flaps.  Still using cardboard with just a single mounting point and still very little defection.  Today will be the highway test on the way home, 90 degrees with 20 mph winds which I'll get from all direction at some point so I should get a pretty good idea of how things will behave with turbulence.
« Last Edit: May 25, 2017, 10:41:38 am by Jim »

Offline connie_rider

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Re: Vent flaps for engine heat
« Reply #22 on: May 26, 2017, 12:41:04 am »
Thanks Dave. That looks kee-rekt.

Ride safe, Ted

14 Connie (Traveler II) / 03 Connie (Buddy)
Gone but not forgotten; 87 and 00 Connies..

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Offline Jim

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Re: Vent flaps for engine heat
« Reply #23 on: May 27, 2017, 05:00:32 pm »
Ok, proto-type installed.  If it works, the large bolt will be replaced with nylon all-thread and a knob for easy removal/install which right now takes about 30 seconds.  Used an old acrylic clip-board which just happened to be 9 inches wide and had finished sides and nice rounded corners.  Only had to cut the 5 inch width and that side is up close to the fairing.  I'll give it a workout and see if it stays in place and doesn't flex too much (or shatter).

Offline ron203

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Re: Vent flaps for engine heat
« Reply #24 on: May 27, 2017, 05:48:42 pm »
Looks great. Did you do two or just the one proto-type?
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