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Is there a better Air Filter for Kawasaki FR651V out there ?

#1

7394

7394

Just wondering if I can get a better air filter.

See K&N makes one, but don't think that is a step ahead in regards to filtering. I use them on Harleys, but Harleys don't have to filter out the dust & debris.


#2

cpurvis

cpurvis

Do a cross-reference of your filter number (not engine number) on Donaldson, Baldwin, Wix, and Fleetguard websites.

I agree with your assessment of K&N--they're designed to flow a lot of air, not do a better job of filtering.

Some of the Kawasaki's have a very good filter on them, a can with a cylindrical element. If yours doesn't have this kind of filter, I wonder if one could be retrofitted to your engine?


#3

B

bertsmobile1

Commercial Kwakas come standard with duel element Donaldson, the cylinder being referred to above.
The outsides get replaced about 4 to 1 against the insides.
Standard fitment on all earth moving equipment and will just about bolt directly on.
If you do go that route, get some longer connecting tube and fit the filter as high as possible and if possible mounted to the roll bar.
Mounted as Kawasaki do it removing the blower housing becomes a major chore and so you don't end up cleanng the cooling fins any where as often as you should.


#4

7394

7394

Mine is the FR engine, so the Donaldson only came on the FX series engines, I believe. I think it could be retro fitted, but would be mounted on the engine cover, & as Bert noted would make the checking the cooling fins more of a chore. I check end of every mow season.

K&N said on the phone their filter is not the usual cotten gauze they mainly are. The one that is made for my FR651V Kaw is a dry filter made of Non-woven Synthetic material, does not need oiling (as that would be a mess) but is washable with warm water.

Still don't think it is a good option.

I'll do a cross check on those sites & see if I find anything. Thank You both.


#5

7394

7394

Search results: We recognize the part number entered; however, we are currently unable to suggest a replacement.


#6

primerbulb120

primerbulb120

My FX600V has the Donaldson commercial air cleaner, except it only has an outer filter, no inner one. Works great. I think it will bolt onto the carb of the FR651V, but not sure about the blower housing mounts.


#7

primerbulb120

primerbulb120

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Click on the pictures to enlarge them.


#8

7394

7394

primerbulb120- Thank You for taking the time to post all the great pics. :thumbsup:

"Looks like" your hose to elbow on carb would go right on my carb / elbow. But the blower housing would have to be extensively modified. Mine has a flip up end cap that covers my current air filter. If I cut it off, I would have to also block it off to keep the air inside for cooling.


1) keep the air from just blowing out the back uselessly

2) once modified, mounting the Donaldson would need a landing to mount it to. A cover from an FX would work.

Looked up a Donaldson set-up last nite, they are very proud of them.

Your pics really gave great visual to doing this.


#9

B

bertsmobile1

The filter mounts to the carb with flexible hose.
So it does not have to sit on top of the blower.
I mounted a couple off the ROP because I got sick of spending an hour extra pulling the %*## thing off the blower every 3 months to service the mower.
Down side is that was the last time I replaced an element.
Other little tricks were to fit a finger guard off a CH Kohler that bolts on to the blower housing then trimming the debris guard so the blower housing pulls off over the guard.
I think there is an optional Kawaka finger guard , this is a worth while modification.
The fuel pump mounts were changed to bolts from the inside of the blower housing, with a nut on the housing clamping it in position so the fuel pump then has 2 nuts and come right off quickly and longer lines fitted so it can be set aside without undoing anything


#10

B

bertsmobile1

And if you remotely mount the filter then you can just cut a hole in the filter cover flap.


#11

7394

7394

More food for thought, Thanks Bert. I think this a very do-able mod. If I could find some of the parts used (not the filter element tho). To run the dual stage filters, re-jetting the carb would be required.

Think that is why primerbulb120 only has the outer filter on his, which would be fine as well.

FXAIRFILTERBRACKET.gif


#12

B

bertsmobile1

You just missed out, the Surplus Center had 300 of them a month or so ago.
You might like to search there they may have a few left.
I bought 20 of them for 1/4 what they cost down here.
Stens do a copy well down here they do any way & also both filter elements.

As for rejetting, a load of cods whallop.
On a vehicle that does 10,000 rpm you might need to worry about it but on a governed engine that goes up to a whopping 4,000 rpm, restrictions to the airflow is minimal.
When you have a quick think about it the new filter has around 4 times the surface area of the std filter.
Honda tried to stop people fitting snorkels to their 160 & 190 engines by claiming they needed rejetting and making the kits 1/2 the price of a replacement engine.
Fitted dozens of them withut any jetting changes with not a stick of a problem, except the filters don't clog so I get less service calls.
Probably contravine clean burn exhaust regulations because the engines run a poofteenth richer but not seen problems with any of them.

Just be careful what tubing you use.
I use convoluted tubing from Tractor supply shop, for connecting remote tractor filters, not real dear and conforms to curves.
Just make sure it will not suck in.
Suction pump tube will also work quite well but is a bit stiffer & harder to route around bends.

If you are worried about running rich, buy a Color tune from Gunsens UK and check the burn before & after you fit the filter.


#13

7394

7394

Thanks Bert. I'm doing searches, found complete set-up 'used' w/ metal blower hood from FX691V

But hood looks slightly different on the curves nearing the heads. Mine is poly-plastic whatever & has smooth curves around, the FX691V metal one has actual corners.

Seems anything FX is a 2 barrel, & any FR & FS engines are 1 barrel carbs.

I just have to plan wisely, just had a new up-graded roof added to the house. (pockets are feeling it).


#14

7394

7394

I see several 'used' kits, but am having trouble finding the intake hose size at the carb/elbow end.

If I can verify the measurement there & what model it is, I'm gonna be doing this mod.


#15

B

bertsmobile1

Tractor shops are your best friend.
Lots of mouled hose with different sizes at each end for just this reason.


#16

7394

7394

Good idea Bert, Thanks. I'm also gonna check out the graveyard (way out back) at my local Dealers, might find enough parts to piece a set up together.

I see plenty on evil-bay, but would prefer to get my hands & eye balls on things before I dig into my pocket.

Bert- Also been thinking about checking my engine cooling fins yearly, thus having to remove the blower housing, & with a Donaldson mounted to my housing.
I would only have to loosen the hose clamp at the carb/elbow & normal bolts loosened, grass cutter shield removal, then just pull the whole works off as 1 piece.


#17

7394

7394

Well, talked to my Toro Dealer & he told me he can't even order the high altitude (leaner) jets (if I should need to lean down my FR carb.)

& of course he told me that I can't do the Donaldson Swap, It's not made that way he quoted, no ship. That's why I want to do it, Kaw says it would be a great up-grade (done correctly), but they don't sell to the public & had no sources.

Anyhow if I can't find a source for Kaw FR main jets, #122, & / or #120 then I have to put this project on hold.


#18

B

bertsmobile1

Firstly the rubbish about fitting leaner jets is just that, rubbish.
The Donaldson filters flow air a whole lot freer than the original Kawasaki filter and to be honest, a slightly richer mix would be a lot better for your engine long term.
EPA regulations specify way too lean running so don't bother about jet changes unless you find it is starting to load up your plugs.
Mower makers are FORCED to specify leaner jetting by the EPA when fitting the bigger filters same as Honda is FORCED to include leaner jets in their snorkel kits that no mower shop ever fits.


#19

7394

7394

Bert- Thank You for the reply. I believe you. Right now I have nice coffee colored spark plugs. Nice burn. I know slightly richer runs cooler that Lean.

I'm running the OE pleated paper filter with the(non-OE) FS foam pre-cleaner. That pre-cleaner is a joke, more junk /chaff gets under it that on the outside of it.

I have a donaldson complete set up on the hook. That has intake hose I.D. of 2.00" which is what my carb elbow measures out with my dial caliper.

Changing jets is not an issue, I do it all the time on the bikes, I just worry if I were to need to re-jet, then I at least need a source for main jets.


#20

7394

7394

Ok, just bought a used FX691 Donaldson canister assembly complete, including hose. Should be here in a week.

Still no joy searching for leaner main jets, but couldn't I try using just the outer Primary filter alone on new spark plugs to get a 'read' on fuel/air mix (burn) ?


#21

B

bertsmobile1

Getting back to your earlier thread, the filter is quite heavy and requires some clever bracketry to hold it so it does not shake like a maracca and end up tearing a lump out of your blower housing , which ain't cheap


#22

7394

7394

Good point Bert, I will have to factor that into the bracket fabbing.

The Donaldson Outer filter on it's own is said to be able to pull 95 cfm of air. Don't know if that is more or less than current oem paper pleated ?


#23

cpurvis

cpurvis

7394 said:
Good point Bert, I will have to factor that into the bracket fabbing.

The Donaldson Outer filter on it's own is said to be able to pull 95 cfm of air. Don't know if that is more or less than current oem paper pleated ?
Click to expand...

A 651cc 4-cycle engine running at 3600 rpm needs about 40 cubic feet of air per minute.

The best thing you could do is put a restriction gage (Filter Minder) on your new air filter. Maybe you'll get lucky and it already has one. They're really the only accurate way to tell when your air filter element needs to be replaced.


#24

7394

7394

Thank You cpurvis- Yes I planned to add a restriction meter to the intake elbow. No, it doesn't come with one. But familar with them from excavating equipment.

OK my Kaw engine FR651V is 726cc

Donaldson's site specs the outer filter # P821575 to be able to pull 95 cfm, while filtering out @ 99.9% efficiency.

And if I add the inner safety filter # P822858 that number drops to 86 cfm

Just curious as to how much diff the oem Paper pleated filter on my engine pulls or needs to be able to.

Reason I'm wanting to know is, I can't find any source if I need to drop the main jet down a size or two, to lean it out running the Donaldson set-up. Kaw makes them called High altitude jets. # 122 & # 120. My Toro Dealer won't even try & find them, he is a non-believer of modding.


#25

cpurvis

cpurvis

Why would you need to lean the mixture when running the bigger air filter?

Smaller jets are needed when the density of air decreases from what the carb was calibrated for at the factory. Installing a higher capacity air filter doesn't cause a decrease in air density, like an increase in altitude does. Fuel needs to be mixed with air by mass, but carburetors mix it by volume. Putting on a higher capacity air filter doesn't change the density or the volume of air going into the engine.

I'm with bert. I think you can forget about the jets.


#26

cpurvis

cpurvis

If bert and I have failed to convince you on the need for new jets, try this place. I don't know if they ship or not but they've never failed me.

https://lawnparts.com/


#27

7394

7394

Thank you for the quick reply. My thought was the Donaldson Filters are so much more restrictive than paper pleated, & could cause a rich condition. But to yours' & Bert's point, I would be adding much more filtering media.

I just wanna line up all my ducks for winter, when I get on this up-grade.

PS: Thank you for the link, & the enlightenment as well (You too Bert.)


#28

B

bertsmobile1

Now I have not done this , so I might very well be sinking my own ship here.
But if you check the jets for the commercial series engines that are supplied with a Donaldson against the residential jets me thinks you will find they have the same part number,
If not check the choke size and if the carbs are the same size buy the jets for the commercial engine.
Just because a filter can flow 100 cu'/min does not mean it will flow 100 cu'/min as the air flow is determined by the demand from the engine.
This demand is not static either.
Most of the time your engine will never be running more than 3/4 throttle


#29

7394

7394

Bert- Good point, I looked into that, & every FX651V & bigger has a 2 barrel carb.

my FR651 has a 1 barrel carb. And in mowing I run it wide open (supposedly @ 3600 rpm).

Spoke to Donaldson today & the tech sent me some different ways they get an engines air intake max needs. 1 way is to measure the HP (in my case 21.5) x 2 cylinders= 43 CFM @ 8" H20.

I kinda got lost on the last part about the H20 ? , but he said the filters I listed here were way overkill for my set-up. That I could use filters 1/2 the size. I told the tech that I'd prefer to have oversized filters. He said that would make em last longer, & no negative effect 'cept to my wallet.

Plus he gave me the part # for the correct "Informer indicator") restriction gage for my engine.

Alternative Method
Engine Horsepower Formula
English Units
Airflow (CFM) = HP (SAE) x SA
SA = (Specific Airflow) per Horsepower


#30

7394

7394

Here's an old thread about this swap.

http://www.lawnmowerforum.com/showthread.php/33775-Stock-air-to-canister-air-filter-system


#31

cpurvis

cpurvis

What did the Donaldson guy say about jets?


#32

7394

7394

Nothing about the jets, I asked & he said to talk to Kaw about that. Kaw says it is tampering with. :confused2:

This mod has me hot one day, & the next day cold. Everytime I think that logically this should be a great mod, I read some neg stuff about trying it.

My Z runs primo, sometimes I wish I could leave well enough alone.


#33

cpurvis

cpurvis

You've already bought the Donaldson setup, haven't you? In that case, you might as well forge ahead. Save the parts you take off in case you have to beat a hasty retreat.

If you're not a commercial mowing outfit, it's probably overkill. But what the hell? Overkill is what we do best.


#34

7394

7394

Yup, I snagged a used Donaldson set-up was on a FX691, super cheap, but looks like new (arrived today, better than the pics).

No I'm not commercial mowing outfit, just my place, & I know it's overkill. But agree "we do overkill best".

I have maybe 2 more mows left, & should be done for this season. I gotta get canister washed up internally & thorough inspection, & plot what I wanna do.


Sidenote: What I find interesting is the 2 barrel FX engines use 2 different size main jets, & they have a pilot jet which my single barrel FR does not.


Main Jet No.

FR main jet = 0 ∼ ∼ 1 000 m (0 ∼ ∼ 3 000 ft)= #124
High Altitude Main Jet then= # 122 & leanest = #120



FX main jets= 0 ∼ ∼ 1 000 m (0 ∼ ∼ 3 000 ft)
Left= #110 & R= # 114


#35

7394

7394

What the amount of negative posts saying this can't & / or shouldn't be done, makes me wanna give it a shot all the more.


#36

John R

John R

K&N filters do let the engine get more air, but they also pass more dirt into the engine.


#37

7394

7394

I agree, that's why I ruled out K&N filters early on in this thread. I'll be using Donaldson filter.


#38

B

bertsmobile1

You can blame the EPA ( again ) for the odd jets on the twin barrel carbs
Which ever cylinder fires second gets a smaller jet.
This is because the air coming into the second cylinder is slightly richer because it gets a micro second of idle circuit from the other cylinder.

All V twins exhibit this if they have a common manifold.
Even parallel twins do the same thing.
On the 50's British twin motorcycles with a single carb you could get a variety of tapered manifolds to overcome the induction bias.
So if you set the carb for the left, it would be slightly out for the right & and visa versa.
Now no one worried about this till the 10's when pencil dic#s ( to quote Bill Murry ) with no idea about the technology behind the regulations they were enforcing got results for very expensive exhaust analysers.
Just about every commercial jet pumps out around 1/2 ton or more unburned fuel on every take off where they can not engage the afterburners and that would be at just about every airport in the entire USA

And these pencil dic#s are worried about 1/10,000 lb from your mower, like it is going to make a gnats knakker of difference to world pollution.
This is h same reason why the kawasaki technicians can not tell you it will be fine because if the engine runs the tiniest bit richer, then the engine is not EPA compliant and you have committed a federal crime by tampering with an EPA compliant engine.


#39

7394

7394

I agree 100% Bert.


#40

primerbulb120

primerbulb120

I agree 100.1 percent.


#41

B

bertsmobile1

Way way way back we were talking about bypassing the fuel shut off solenoid.
Some one stepped in with the fines for "interfearing with an EPA regulated device"
They were in the order of $ 300 / day of use for a private person and $ 5000 / day of use for a company.
So neither Donaldson nor Kawasaki is going to say "yes do it" and risk fines like that despite how remote the chance of actually being prosecuted is.


#42

7394

7394

The engine mfgr said on the phone to me that same exact thing. And my Dealer shyed away also.

So for the record on this public forum, that mod would be wrong to do. And I don't wanna do anything that is wrong, right ?






And a while back one could order a mower with 'that brand' engine & pick which air filtering system ya wanted. No jetting changes either way, according to an 'insider' off the record.


#43

cpurvis

cpurvis

If the EPA will or can prosecute a mower owner for 'tampering' with the air filter system of their own mower, why have they not issued a cease and desist order against K&N for making available replacement filters for the tampering purposes?


#44

B

bertsmobile1

7394 said:
The engine mfgr said on the phone to me that same exact thing. And my Dealer shyed away also.

So for the record on this public forum, that mod would be wrong to do. And I don't wanna do anything that is wrong, right ?






And a while back one could order a mower with 'that brand' engine & pick which air filtering system ya wanted. No jetting changes either way, according to an 'insider' off the record.
Click to expand...

Yes so it is nudge nudge wink wink say no more go ahead & do it.


#45

B

bertsmobile1

cpurvis said:
If the EPA will or can prosecute a mower owner for 'tampering' with the air filter system of their own mower, why have they not issued a cease and desist order against K&N for making available replacement filters for the tampering purposes?
Click to expand...

Because K & N can claim they fit other engines which are not EPA compliant.
You will find cars are the same.
Lots of stuff that will fit on vehicles that become illegal if they are fitted.

Next time you are in a speed shop have a look at the speed parts.A great number of them carry warning _ not approved for street use , not allowed to be used in California.
Heck go to web sit that sells replacement engine and read the details about a third of them will not be allowed to be sold in a variety of states with California usually leading the list


#46

cpurvis

cpurvis

bertsmobile1 said:
Because K & N can claim they fit other engines which are not EPA compliant.
You will find cars are the same.
Lots of stuff that will fit on vehicles that become illegal if they are fitted.

Next time you are in a speed shop have a look at the speed parts.A great number of them carry warning _ not approved for street use , not allowed to be used in California.
Heck go to web sit that sells replacement engine and read the details about a third of them will not be allowed to be sold in a variety of states with California usually leading the list
Click to expand...
Yep, I have noticed a lot of "off road only" markings on things. AS IF the off road vehicles breathe different air than the on road models.


#47

7394

7394

Well my Mower is an off road vehicle.

And at least my HD FatBoy has a K&N on it with 2-1/4" Hooker (step-tuned) Long Shot Pipes.


#48

7394

7394

The K&N & Pipes I've added to my Bikes did have warning tags: off-road, or Racing use only. Doh !! :laughing:


#49

John R

John R

Any filter that claims to pass more air will also pass more dirty air.


#50

B

bertsmobile1

Not actually true John.
It is all a matter of the surface area of the filter.
You can ( and they do ) make filters the same size as the OEM ones with 2 to 4 times the surface area and they will pass more air despite being a finer mesh size.


#51

7394

7394

My conversion project (FR to FX canister)has all been mocked up, but then mow season began, & I haven't had time to finish it off.
But I will.


#52

J

Jtorres8913

7394 said:
My conversion project (FR to FX canister)has all been mocked up, but then mow season began, & I haven't had time to finish it off.
But I will.
Click to expand...
Were you able to finish this project? I'm thinking of doing the same thing but have the same questions you had. How did everything turn out?


#53

Scrubcadet10

Scrubcadet10

Jtorres8913 said:
Were you able to finish this project? I'm thinking of doing the same thing but have the same questions you had. How did everything turn out?
Click to expand...
https://www.lawnmowerforum.com/showthread.php/52096-Kawaaski-FR651V-FX-air-box-conversion


#54

7394

7394

It was finished long ago & that Z has over 300 hours on it now..


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