Flapper removal; effects of

Started by MikeScoot, July 08, 2020, 02:51:51 AM

Previous topic - Next topic

injuhneer

#20
I guess I have to take a look at the badge on my bike.

I was actually considering metal leaf to cover the raised letters then enamel to paint the relief. I did this once on an old tuning fork badge that turned out nice.

Sorry for the OT post.
- Mike O
1982 Yamaha XZ550RJ

MikeScoot

#21
That sounds like a good method.
Here's mine. If you look closely it's far from perfect, but looks great (to me) from an average viewing distance.
Both Luthers had their dreams,
But I've just got one Vision.
Theirs got them into strifes,
Mine just takes me fishin'.

The Prophet of Doom


pinholenz

Take-aways so far from this discussion is that the jury is out about flapper removal, and pod filters have poor laminar flow and are very noisy.

So, from collective experience, is the oiled foam of the UniFlow/UniFilter air filters for the XZ550 any quieter than the foam pods?. At least the UniIlters resemble the shape of the airbox-with-flapper air filters rather than the only other available rectangular air filter.

https://www.motorcycleid.com/uni-filter/direct-factory-replacement-air-filter.html?urlId=126700658
Only one '82.5  eXtreme Zen 550

Walt_M.

I have the Unifilter in the stock airbox without the flapper and it is not offensively loud to me.
Whale oil beef hooked!

pinholenz

Only one '82.5  eXtreme Zen 550

MikeScoot

#26
@ Mike injuhneer;
I'm currently looking at places to add more intake to the airbox.
The alloy duct used by the flapper setup (now completely removed from mine) seems to outlet around the middle of the top of the air filter. I'm wondering just how important - if at all important - it is to have the fresh air fairly evenly distributed around the filter.
There are plenty of areas on the airbox lid where openings could be made and also on the lower half of the box.
I'm thinking it probably doesn't matter too much at all where they are but am considering a large opening on the very bottom at the front of the box's lower half - approximately the same size as the existing opening at the top rear.

Thought on this from you , and others, would be most welcome.

Cheers,
Mike
Both Luthers had their dreams,
But I've just got one Vision.
Theirs got them into strifes,
Mine just takes me fishin'.

jefferson

Openings on the bottom part of the airbox will allow unfiltered air into the motor. I always thought that an opening on the front of the upper portion would allow cooler denser air into the box as it was closer to the outside airstream.

MikeScoot

I'm looking at mine and air introduced at the front of the lower part still has to pass through the filter. Mine already has a small hole there (forward of the front crankcase vent hole) -presumably to allow any fluids (water) to exit the box. Maybe you have a different type of box? Will triple check mine later.

The top front of the box would work too, but there may be the possibilty of rainwater coming in during higher-speed riding. Not sure.
Both Luthers had their dreams,
But I've just got one Vision.
Theirs got them into strifes,
Mine just takes me fishin'.

jefferson

I stand corrected. I had to go get an airbox and see. It's been ages since I had one opened up.

Walt_M.

Air is funny stuff but like plumbers say, poop doesn't flow uphill. And as tuners will tell you, air flows from high pressure areas to low pressure areas. If you just  randomly start making holes in your airbox you might be letting air out rather than in. Sometimes enough is enough.
Whale oil beef hooked!

MikeScoot

#31
lolol but if the inlet to the airbox is outrageously smaller than the combined carb throats then it most likely has a restrictive effect on the negative side, but an increased swirl around the cavity before the element on the positive side. Now those Yamaha engineers probably didn't make it that way for no reason, but it is likely that they did it to lower noise and emmision levels and, perhaps, to improve fuel economy.

For some folks it's just fun to tweak certain things. :-) Wasn't it Phil Irving who said "You never know where a limit lies until you go beyond it."? Hopefully one does this without 'crashing and burning' lolol :-)
Both Luthers had their dreams,
But I've just got one Vision.
Theirs got them into strifes,
Mine just takes me fishin'.

injuhneer

As you make holes bear in mind that the original inlet had multiple design purposes. One of those was keeping large debris and water out of the airbox.

The area by the steering head is low pressure at speed because of the objects in front of it. The radiator blowing heated air being among them. This means that the sides or rear are better places for additional inlet. You could put a deflector in the air path to trap debris or moisture but that is bending the air again.

Lower holes put the air closer hot air sources (engine, exhaust, radiator). I chose to make the secondary flapper on mine to be in the lid above the frame level and midway between sources of heated air (radiator and rear exhaust). I'll deal with the rear exhaust soon because I am making an air-gap heat shield to protect the R/R and reduce heat soak in the mid-rear frame section (reduce heat on the R/R, battery and rear shock).

- Mike O
1982 Yamaha XZ550RJ

MikeScoot

#33
Quote from: injuhneer on July 14, 2020, 09:15:32 PM
As you make holes bear in mind that the original inlet had multiple design purposes. One of those was keeping large debris and water out of the airbox.

The area by the steering head is low pressure at speed because of the objects in front of it. The radiator blowing heated air being among them. This means that the sides or rear are better places for additional inlet. You could put a deflector in the air path to trap debris or moisture but that is bending the air again.

Lower holes put the air closer hot air sources (engine, exhaust, radiator). I chose to make the secondary flapper on mine to be in the lid above the frame level and midway between sources of heated air (radiator and rear exhaust). I'll deal with the rear exhaust soon because I am making an air-gap heat shield to protect the R/R and reduce heat soak in the mid-rear frame section (reduce heat on the R/R, battery and rear shock).

All good points. Thanks.

I've reconsidered putting an opening at the front bottom and am now thinking that, along with the places you suggest, an opening in the top of the box above the middle of the top filter plate (same place the aluminium duct releases air) might also be an option.

I have removed the actual flap but left the alloy duct in place for the time being because without it the fresh air would be released onto quite a small section of the filter element. With fresh air released above the middle of the filter top plate it might distribute more evenly.

Will test simply without the restrictor flap for the time being.

Cheers,
Mike

Both Luthers had their dreams,
But I've just got one Vision.
Theirs got them into strifes,
Mine just takes me fishin'.

fret not

Fluid dynamics
The guys at the salt flats seem to think that calm (not turbulent) air is needed to enter the carbs.  So they spend time 'smoothing the flow' of air.  Actually, that is the big issue for going fast regardless of whether it is into the carbs or around the 'body' of the vehicle.  Laminar flow is the goal, quiet air.  Smoother = more efficient/less drag.

The factory spent time designing the air box, so consider if what you change makes a beneficial or detrimental difference.  For those of you with the inclination and technical abilities there are computer programs for CFD (Computational Fluid Dynamics).
Retired, on the downhill slide. . . . . . . . still feels like going uphill!

MikeScoot

Quote from: fret not on July 16, 2020, 04:09:40 PM
The guys at the salt flats seem to think that calm (not turbulent) air is needed to enter the carbs.
Yes, turbulent air would have fluctuations in pressure. Not sure of the correct fluid dynamics term, but it would be fighting with itself. and not as able to move from one place to another quickly and efficiently.
Quote
The factory spent time designing the air box, so consider if what you change makes a beneficial or detrimental difference.  For those of you with the inclination and technical abilities there are computer programs for CFD (Computational Fluid Dynamics).
Thanks for the heads-up. Have recently finished installing a new (for me) workstation here. I'm thinking it would take a fair amount of time getting to know the software and then describing what it should analyse, but might look for some open-source stuff later, for fun :-)

In the meantime a local bike shop has asked me to sort-out some troublesome bikes for them, so I'm pretty happy to get some extra work! :-)
Both Luthers had their dreams,
But I've just got one Vision.
Theirs got them into strifes,
Mine just takes me fishin'.

MikeScoot

Also very happy to inform that my bike goes like a cut snake with the flap removed! Couldn't really wish for more power from a bike like this (for my purposes). Excellent! :-)
Both Luthers had their dreams,
But I've just got one Vision.
Theirs got them into strifes,
Mine just takes me fishin'.

The Prophet of Doom

Quote from: MikeScoot on July 17, 2020, 05:44:08 AM
Also very happy to inform that my bike goes like a cut snake with the flap removed! Couldn't really wish for more power from a bike like this (for my purposes). Excellent! :-)
Told you so.  Glad you like it.

MikeScoot

lololol

Well, I'm not wishing for it, but I reckon I AM going to to get even more 'happy horsepowerings' by opening the box even more. Have a spare airbox here, so nothing to lose at all - as long as I give an old motor the respect it deserves and don't go throwing anything nuclear or interdimensional in there.

Pre-emptive catastrophe question here; Anyone got a freshie motor they want to sell? Just joking - I swear I'll keep things on the mild-mannered side. Muhahahahaha
Both Luthers had their dreams,
But I've just got one Vision.
Theirs got them into strifes,
Mine just takes me fishin'.

The Prophet of Doom

I'm dying for someone to try one of those Microburst nitrous kits on their vision.  That would be exciting