Is anyone running a flapper motor without the flapper? If so, what is the effect?
The actuating mechanism on mine interferes with fitment of a common air filter so I'm wondering what the effect of removing it might be.
I'm surmising that it (absence of flapper) would reduce the fuel richness when the throttle is opened from idle, but am interested to know the REAL effect.
Thanks in advance.
Mike
The real effect would be the worsening of 'Vision stumble', the condition for which the flapper added to cure. I do not have a flapper on mine but I don't have stock carbs either.
There's no such thing as a "flapper motor". The early 82s had a gravity flapper, and the vacuum mechanism was released as a mid-year modification. You can see what's different in the booklet "XZ550 (11J) Intake and Carburetor Modification Kit 1982 Models". Same motor though, and essentially the same carbs, but with a different top.
You can definitely go flapperless. #3 came with no flapper at all. It howled like a banshee on full accell, growled like a lion on decell. Only suitable for hooligans, but goes like a scalded cat. It took a lot of pissing about to re-jet and set the accelerator pump properly.
I dabbled with the vacuum flapper, but I'm going back to flapperless on the super-mod.
Quote from: Prophet Of Doom on July 08, 2020, 07:01:51 AM
... Only suitable for hooligans, but goes like a scalded cat ...
:P So then, might it be said that real men don't have flappers? :P
Sounds like just my cup of tea! Just what the doctor ordered! Right up my alley. A match made in heaven! Would suit me down to the ground.
Thanks for the info.
And, while you are sorting your jetting, you can get rid of the YICS. It is there to improve low rpm rideability due to the lean mixture settings. Quick question though, do you have to pass emissions testing? If you do these mods, it won't.
YICS is gone already as is vacuum fuel pump, and it will be with GREAT pleasure that I remove the flapper too.
Emissions test? Last time I did one of those was at the doctor's. The nurse, who had to stand there and make sure I didn't pull a swifty with the sample, laughed her head off when I asked her to help out a bit. But seriously, na - no problem here with that sort of thing :-)
I suspect the flapper was added by the factory to cut down the intake noise. These days we wear ear plugs to prevent hearing damage from the wind noise in our helmets. It is amazing any of us survived all that noise. I have had several bikes over the years that made more noise from the intake than exhaust.
As an added bonus, when the popo pull you over for a loud exhaust, you say nah mate, the exhaust is extra quiet - that's my highly modified super noisy intake and there are NO standards for intake noise. They won't know what to make of that and will wander off in bewilderment looking for easier targets - like fully patched Harley riders who don't even do their own maintenance. No impounding for you!
Quote from: fret not on July 08, 2020, 10:12:27 PM
... It is amazing any of us survived all that noise. ...
What's that, Mike? Can't quite hear what you're saying. Lousy audio on this forum.
Quote from: Prophet Of Doom on July 09, 2020, 02:29:47 AM
... when the popo pull you over for a loud exhaust, ...
What? You mean stop? lolololol Surely you jest! :P
When I was doing my carb swap, I briefly tried a set of pod filters with no airbox. Not only did it run poorly, the intake roar was unpleasant at best. Kind of like riding an industrial shop vac, and not in a good way.
Quote from: Walt_M. on July 09, 2020, 06:53:51 AM
When I was doing my carb swap, I briefly tried a set of pod filters with no airbox. Not only did it run poorly, the intake roar was unpleasant at best. Kind of like riding an industrial shop vac, and not in a good way.
lololol That conjures up a few really weird, but very funny, mental images! :-) And disturbing noises!
I've always believed, rightly or wrongly, that the engineers at the factory put a fair bit of effort into ensuring their air inlet tracts and exhausts have pretty damned good fluid-dynamic characteristcs. That's not to say that removing some of the odd add-on afterthought bits is a bad idea.
Pod filters have always seemed a bad idea to me. The main reason is that they greatly reduce the volume between the filter element and the valve/s to about as low as it could possibly be. This would surely cause HUGE fluctuations in pressure, wouldn't it? Greater volume in this area would, I think, enable more constant pressure which would, to my mind, be much more desirable. I may well be entirely wrong about all this though - just as I was about making an excellent and luxuriously appointed spacecraft from the tin-foil lids from milk bottles when I was a kid.
Well the flap changes the velocity of the incoming air. Why? Given that it is above the air filter and that the air filter will laminate most of the airflow it has to be about the box volume above the filter.
I added a second flap to my bike's air box. At the rear with a half-dozen 8mm holes. The flap is EPDM and acts like a check valve. The big flap really could help the lower-mid -> mid but really kills any resonant behavior because of its mass. I added the second flapper to allow the air in pulses at low speed then acting as a check against the air-box to prevent any rebound from low to mid-range.
With no jetting change there is a little flat spot about 2400rpm and it is only there is a slow throttle roll-on. Roll it quickly and there is no hesitation.
Given that I live in an area about 4500ft in elevation the jetting could use a tweak to cure that flat spot and give a little better pull above mid-range but with the helper flap added I see no reason to remove the main flap. I used a bit of the same EDPM to fix the flapper hinge.
I may change my mind later but that is my current rationalization. ;D
Also consider that the YICS box is a rudimentary resonator. That too has its effect but is limited in frequency/range (like a Helmholtz resonator).
So, what RPM range do you think the YICS system should resonate?
Quote
Well the flap changes the velocity of the incoming air. Why? Given that it is above the air filter and that the air filter will laminate most of the airflow it has to be about the box volume above the filter.
Yes. The velocity past the flapper would increase the more it were closed (assuming revs were the same). It would also cause a reduction in both pressure and (therefore) flow (through the carbs), wouldn't it? The reduction in pressure would cause more fuel to be issued into the airstream due to the increased imbalance on either side of the jets/nozzles.
I too have been considering 'opening up' the inlet/s to the airbox and am interested in what you mean by "rebound". Also interested in why you went with a fairly modest increase in intake opening to the box.
Cheers
Ps I'm not sure that chasing beneficial resonance from the YICS would be fruitful. The condition of the hoses and a few other variables would make any benefit fairly unpredictable. If indeed there was a benefit it would only affect a fairly narrow rev/load range and, potentially, have a detrimental effect at other revs/loads, wouldn't it?
Cheers again,
Mike
Quote from: fret not on July 10, 2020, 02:02:43 AM
So, what RPM range do you think the YICS system should resonate?
All the Yamaha YICs implementations were targeting improved VE. I'd need to take some measurements to calculate the resonant frequency.
Right after I typed that comment I had a thought of making a variable resonator using a sensor and an Arduino controller. LOL!
Quote from: MikeScoot on July 10, 2020, 03:03:57 AM
Yes. The velocity past the flapper would increase the more it were closed (assuming revs were the same). It would also cause a reduction in both pressure and (therefore) flow (through the carbs), wouldn't it? The reduction in pressure would cause more fuel to be issued into the airstream due to the increased imbalance on either side of the jets/nozzles.
I admit to experimenting. The consequent observations are incomplete but I agree. The flap would change the pressure above the throttle plates during the transition. These carbs need the velocity of air to work. The stumble is in the transition. The flap would change the air behavior to compensate for the momentary pressure change. Jetting can hide the stumble by compensating for air or fuel but that moment between slower moving air on pilot with the throttle plates closed (or nearly) and the rush of accelerating air through the venturi is still there. It is how air behaves, right? The rapid change in pressure in the venturi means air density drops for a moment as the air behind accelerates and the air in front (engine facing) gets sucked in.
It seems that the engineers were looking to put a large carb on to ultimately feed the motor for higher HP. The problem then is low speed operation. CV carbs would be less susceptible. They resolved the problem in the V-Max with V-Boost and CV carbs: smaller carbs resulting in higher inlet velocity and CV to adapt to the demand. The passage between cylinder pairs in V-Boost to open pairs of carbs to pairs of cylinders at higher RPM solved the volume problem. And yes I have been contemplating fabricating a V-Boost for this engine with two smaller CV carbs and a controller operated passage between cylinders. Just for the fun of it (I am thinking two Venture carbs or smaller and a PIC or Arduino to count revs and modulate the stepper for the passage butterfly).
Quote
I too have been considering 'opening up' the inlet/s to the airbox and am interested in what you mean by "rebound". Also interested in why you went with a fairly modest increase in intake opening to the box.
Cheers
I wanted to observe the pulsations in the airbox with a simple mechanism. The small holes were to make it easily reversible with epoxy or a different airbox lid. I have been considering a couple of transducers to do logging. One on a YICS port, one in the airbox. I also wanted to observe if the volume of the airbox contributed to any reversion (bounce/rebound) of air at lower RPM or is adequate to absorb those pulsations.
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Ps I'm not sure that chasing beneficial resonance from the YICS would be fruitful. The condition of the hoses and a few other variables would make any benefit fairly unpredictable. If indeed there was a benefit it would only affect a fairly narrow rev/load range and, potentially, have a detrimental effect at other revs/loads, wouldn't it?
True. It won't do a lot except in a specific RPM range. My thought was that the YICS passage and a correctly size chamber might be an answer to the stumble. Or not.
Quote
Cheers again,
Mike
I suppose that EFI is an alternative. I had been looking at the Speeduino project other applications. Looks like it might be a good option along with some other EFI bike bits. Ninja 650R throttle bodies look like a near dimensional match for the OEM carb.
Or just skip all that and buy an FJR1300.
Anyway...
Quote from: injuhneer on July 11, 2020, 11:15:44 AM
Or just skip all that and buy an FJR1300.
Anyway...
lololol That would be understandable. These things are blo0dy cantankerous!
I've had a bit of a break from doing anything with mine for the last few weeks while getting a few other things done. But I did get a few things done to the bike over the last couple of days. The most rewarding of which was refitting the ducktail and its Yamaha Badge. I spent a LOT of time on the badge and it has come up very nicely indeed.
Spring will be here soon and I'm looking forward to riding my decrappified Maxini in the better weather.
In the meantime, the next thing on the list for me is removal of the flapper and opening up the airbox a fair bit. I have another (airbox) here so there's nothing much to lose and, perhaps, a lot to gain - not the least of which will be an increase in that glorious intake roar!
Thanks for all the info in your last post and good luck if you decide to go ahead with the Arduino fun.
Cheers
Quote from: MikeScoot on July 12, 2020, 04:21:00 AM
The most rewarding of which was refitting the ducktail and its Yamaha Badge. I spent a LOT of time on the badge and it has come up very nicely indeed.
I've got that badge to do also.
Any pictures / methods to share?
Quote from: Prophet Of Doom on July 12, 2020, 04:47:47 AM
I've got that badge to do also.
Any pictures / methods to share?
Ah, yes. I'll write myself a note and endeavour to get some pics tomorrow. But in the meantime - I used traditional enamel paints. I did this mainly because of their high 'solids' content as I wanted to build a slightly rounded gold face on the lettering - also because of enamel's excellent flow and levelling. I should add that my first attempt, which was to roll the face of the letters on a flat plate coated in wet gold paint, was a disaster. So from there I resigned to doing it carefully using rather expensive long, soft-bristled brush. I had the gold enamel mixed to my liking by the kindly chaps at the local spraypainter's supply shop. The first attempt at this resulted in a bit of paint winding up on the flat surface below the lettering but I decided to press on and carefully overpaint it with black (again using a very fine brush and magnifying spectacles) after I was happy with the gold. I built several thick layers allowing a couple of weeks between each, then flattened the just the very tops with 1200 paper and added another thick coat of the gold. I gave it another couple of weeks sitting on top of an LED worklamp to harden more and ... I'll post some pics within a day or two :-)
It might sound funny, but that one badge has been the most troublesome part of the whole bike project - including single-handed engine changing.
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.
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.
Very tidy
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
I have the Unifilter in the stock airbox without the flapper and it is not offensively loud to me.
Nice one, thanks.
@ 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
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.
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.
I stand corrected. I had to go get an airbox and see. It's been ages since I had one opened up.
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.
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 :-)
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).
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
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).
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! :-)
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! :-)
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.
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
I'm dying for someone to try one of those Microburst nitrous kits on their vision. That would be exciting
Ooo-La-La! You just love pulling blown motors apart and fixing 'em, don't you?!
Would be great fun while it lasted though!!! Woo-Hoo!
"That big mushroom cloud sure looked like it was over New Zealand?"
"Yeah. And WTF is that? I didn't know there were motorcycles in low-earth orbit!"
Quote from: fret not on July 16, 2020, 04:09:40 PM
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).
I have a nice module for Inventor that does a pretty good job. Finding time to model the airbox is another problem.
Quote from: Prophet Of Doom on July 17, 2020, 07:27:59 AM
I'm dying for someone to try one of those Microburst nitrous kits on their vision. That would be exciting
I seem to recall mentioning a while back in some thread that the YICS ports would be great for that purpose.
Are there any dyno charts stored on this site?
Quote from: pinholenz on July 13, 2020, 08:26:25 AM
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
Goog to know about the UNI filter. The stock Vision filter is not available from Yamaha.
I had not found the UNI filter when I needed one so I stripped the paper media off a spare and cut UNI foam to fit.