No foam filter

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No foam filter

Post  Mauser on Wed Apr 27, 2011 11:54 pm

Hi guys,
As I have not had a 650 before I am unsure on what power the bike should or should not have, my road bike is a ZX12R...180bhp so when I ride the 650 I was hoping the power would be impressive but she doesn't seem to have much get up and go wheelie style. She will spin the rear wheel on mud etc in 3rd or 4th without uch effort but doesn't seem to want to wheelie on tarmac ?.
She was a US imported bike with the airbox blocked off etc and the restricted carb isolator which I removed and replaced and re-jetted her back to European stock sizes, now tonight I removed the side cover and the spark mesh is there but no foam filter...question is would this cause a large loss of power ?. I have a new filter on it's way from a good friend who has a few spares.
Any thoughts guys ?.


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Re: No foam filter

Post  AURORA on Thu Apr 28, 2011 4:08 am

Did you jet the bike according to this link?

http://www.xr650rforum.com/t1068-how-to-properly-jet-your-xr650r

If you really, really want to pop a wheelie, get a pumper carb.
Though, you should easily be able to pop a wheelie on pavement with a properly jetted bike.
Any exhaust mods?

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MY $.02

Post  Bump on Thu Apr 28, 2011 4:10 am

Well, at this point I'd do a compression check for sure.

You need to run the OEM Honda air filter. Other filters will flow a tiny bit more air by having less filter surface area but that also means more dirt hitting the intake valve. You get no usable increase in power from aftermarket air filters.

If your compression is low then you almost surely need intake valves too.

The stock engine is a turd IMHO. The easy fix is to generally recreate the 1X engine. Simple to do it includes the HRC cam, Precision Concepts porting (accept no substitute), vent the side cover, rejet the OEM Honda carb (don't waste money on a pumper carb), T-4 pipe, plus the usual intake freeing up. On tarmac it will wheelie in every gear.


Last edited by Bump on Fri Apr 29, 2011 12:23 am; edited 1 time in total
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Re: No foam filter

Post  Mauser on Thu Apr 28, 2011 8:02 am

I re-jetted her back to European spec's 68s & 175 along with the carb isolator, I also run 13t~50t sprockets which again should make the front lift even easier. Exhaust is stock but the tip has been modified to about 40mm diameter outlet, not interested in spending any money on the engine, stock engine running correctly whould do me just fine, I was really wanting to know if having no foam filter @ all just the spark arrester would cause poor running ?. The bike came fully restricted which I think was a good find s in theory it shouldn't be possible to knacker a rerstricted engine...I here it's about 26% restricted with the mods fitted.
I fitted the following parts.

16211-MBN-640 CARB ISOLATOR £14.50

99101-357-1750 #175 MAIN JET £10

16012-MBN-641 MAIN NEEDLE £26.50

99105-MBN-0680 SLOW JET £11

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Re: No foam filter

Post  BuRP on Thu Apr 28, 2011 12:27 pm

Maus,

the answer to your Q is "probably".
And no, I will not try it on my bike here, to give you an empirically proven answer, as I - duh! - will not ride without a filter.
An (any!) airfilter is a restriction in the intake, and thus, because the carb is vented to normal atmospheric pressure, the pressure in the post-filter intake (carb!) is lower than this - with as a result a lower pressure sucking at the various jets, therefore you'll get a leaner mixture without a filter.
You'll have to buy a filter, and the std foam ain't bad. The UNI is at least as good filtering-wise, but it has the advantage over the std one that it has a coarser 'outer' which, in very foul conditions, will allow more airflow than the std one, as this one simply will create a layer blocking the airways. On top of this the UNI fits WAAYYY better due to it's 'rim' whcih is an absolute perfect-fit into the filterhousing - and here the std filter looses lotsa points in my book. Oh, do use some grease here, with any filter?
Soon I'll be able to report on the TwinAir filter, got some coming, and I expect them to be best - they're the inventors of this type of filter after all, with a serious reputation to loose too.
Unless you SM I'd suggest you do NOT use a K&N filter, which is oiled cotton-gauze. This type of filter only starts to properly (better!) filter once it has gathered a layer of dust, and until then it will pass quite a bit more dirt than a foam filter. Yeah, they do let more air through (the most of all types in fact), but at cost of fine dust too.

Foam filters need oil - may I recommend the best, BelRay, the blue goo? Yip, a filthy stuff to clean, but plain dishwash liquid will do the trick here.
Mind though, you also need the so-called backfire screen to support the filter. The std one is very fine, has multiple layers, and therefore it is quite a restriction - on top of the filter itself. Unless you're a clumsy twat riding wise, dropping the thing on sight of any rut hence flooding the thing and having to restart it numerous times (the airbox can catch fire, pls know it!), I'd put the way-more-open screen from XRsOnly in. It fits better (some say it fits badly but this aint true, once fit it actually stays there, and the std one falls out easily) and flows way more therefore allowing you to jet accordingly - thus a slight power-gain.

As a last but not least I'd do a compression test - cold & hot. You probably want to know if this is in spec, and I bet you dunno how long - and where? - the bike has been ridden without a filter. In a dusty environment this will cause havoc fairly quick, I'm sure you want to know this.
Let us know?


Last edited by BuRP on Thu Apr 28, 2011 8:10 pm; edited 1 time in total
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Re: No foam filter

Post  Mauser on Thu Apr 28, 2011 3:43 pm

BuRP wrote:Maus,

the answer to your Q is "probably".
And no, I will not try it on my bike here, to give you an empirically proven answer, as I - duh! - will not ride without a filter.
An (any!) airfilter is a restriction in the intake, and thus, because the carb is vented to normal atmospheric pressure, the pressure in the post-filter intake (carb!) is lower than this - with as a result a lower pressure sucking at the various jets, therefore a leaner mixture than with a filter.
You'll have to buy a filter, and the std foam ain't bad. The UNI is at least as good filtering-wise, but it has the advantage over the std one that it has a coarser 'outer' which, in very foul conditions, will allow more airflow than the std one, as this one simply will create a layer blocking the airways. On top of this the UNI fits WAAYYY better due to it's 'rim' whcih is an absolute perfect-fit into the filterhousing - and here the std filter looses lotsa points in my book. Oh, do use some grease here, with any filter?
Soon I'll be able to report on the TwinAir filter, got some coming, and I expect them to be best - they're the inventors of this type of filter after all, with a serious reputation to loose too.
Unless you SM I'd suggest you do NOT use a K&N filter, which is oiled cotton-gauze. This type of filter only starts to properly (better!) filter once it has gathered a layer of dust, and until then it will pass quite a bit more dirt than a foam filter. Yeah, they do let more air through (the most of all types in fact), but at cost of fine dust too.

Foam filters need oil - may I recommend the best, BelRay, the blue goo? Yip, a filthy stuff to clean, but plain dishwash liquid will do the trick here.
Mind though, you also need the so-called backfire screen to support the filter. The std one is very fine, has multiple layers, and therefore it is quite a restriction - on top of the filter itself. Unless you're a clumsy twat riding wise, dropping the thing on sight of any rut hence flooding the thing and having to restart it numerous times (the airbox can catch fire, pls know it!), I'd put the way-more-open screen from XRsOnly in. It fits better (some say it fits badly but this aint true, once fit it actually stays there, and the std one falls out easily) and flows way more therefore allowing you to jet accordingly - thus a slight power-gain.

As a last but not least I'd do a compression test - cold & hot. You probably want to know if this is in spec, and I bet you dunno how long - and where? - the bike has been ridden without a filter. In a dusty environment this will cause havoc fairly quick, I'm sure you want to know this.
Let us know?
Cheers Burp, your spot on with what you have said, today I made a filter whilst waiting for the new 1 to arrive, and the bike seems a lot more lively and powerful I am guessing there was no negative pressure the carb side to allow the fuel and air to be drawn into the engine....there has to be a vaccum I would think and running the bike without any filter would not generate 1.
On the same subject this would also explain when I re-jetted the bike the air mixture screw did nothing...didn't matter if it was in or out...now it does make the engine slow down as it should banana
Good find even though I should have spotted this before Embarassed I just guessed the screen was the filter and I have not bothered taking it out since having the bike, on a plus side there was very little dirt inside so i hope the last owner didn't do many miles with it missing.

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Re: No foam filter

Post  BuRP on Thu Apr 28, 2011 7:01 pm

Here's a tip for ya:
Wipe the insides of the airbox, post-filter of course (there where you can wipe easily, hence can clean it too!!!) with some filteroil and let it 'set', dry-out a bit.
When next you want to check if your engine has gobbled dirt, ie if the filter has leaked a bit, simply wipe it with some white tissue and look at that.
Simple & dirtcheap, pun intended Very Happy
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Re: No foam filter

Post  BuRP on Thu Apr 28, 2011 7:24 pm

Another tip Mauser, actually two.

Set the float level 1mm more - ie a 1mm lower petrol level! The stockers have a habit of flooding, some even do it when leaning over on the stand, and just wait till you drop it Cool It does not affect the jetting as such, and it is anyway within the spec, but you will have zero problems to come in future.
I just presume you do know how to set the level? Not upside-down but at an angle.... but download the Service Manual, find it on the net (sorry, no link) and archive it, it is - sorry for the cliche LOL - Priceless!!!

Second, a standard decorked Pig is not overly eager to wheely off the throttle. Sure, your short gearing will help no doubt, but what really is missing is a pumper, an acceleration pump. Aurora said it already, you will transform the big lazy git into an on-demand staggering mean bastid by putting a pumper on. There's 3 commonly available, the Edelbrock, the Mikuni TM40 (same as HS40), and the FRC. In Blighty I'd say stay away from the Eddie, besides that it ain't perfect by a long shot in my opinion, and also stay away from the FRC as you will have to "remodel" your tank a bit to make space..... yeah, it is regarded as the best carb, but hey, suit yourself Wink
Leaves the TM40 - utterly common, found on (AAARRGGHHH!!!!! affraid ) Harleys, and I can give you a good initial jetting to go with the Pig. Oh yeah, do buy the opened-up sidepanel from XR-Only will ya? Do that in any case, and a headerset (you quite likely got the restricted one's?) will help you gain more then also.
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Re: No foam filter

Post  BuRP on Thu Apr 28, 2011 7:36 pm

Allright, more..... Wink

You still have the spark-arrestor in???? Come on now, those things were invented for the US... US... geddit??
Choose a shoulder - and chuck it over it! Geez matey, all the above - filterchoice, opened side panel, bigger headers, uncorking, carbs, pumper - is about more INtake......... but such only works when the OUTlet cooperates!
So stuff that thing and see what you get. If still not to wish then consider a ProCircuit T4 silencer, it is - hearsay, sure - the best farter for the Pig. I got one, and only know this one, but I can tell you I've got no regrets.
But at least drill your standard (I presume) box out to 50mm diameter, and if at all possible get that arrestor out.

To "enlarge" your hole from 40 to 50 dia ain't gonna be easy, but try this: get a holesaw which consists of an adaptor-plate in which various sizes saws fit, hopefully you know the type I'm talking about. Then take a piece of sheet-metal, thinnish. Cut a piece, roll it into a cylinder-shape (like the saws) which will fit into the dia-40 groove, however it must be a bit longer than the saws!! Make some cutouts so it will 'lock' into the baseplate, then mount the dia-50 saw, and carefully insert this into the exhaust.
Your self-made dia-40 "saw" will guide the actual saw so it will cut from the same center the existing hole is cut from, so you will make a bigger but concentric hole.


Last edited by BuRP on Thu Apr 28, 2011 7:46 pm; edited 2 times in total (Reason for editing : Added the drilling-bit)
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Re: No foam filter

Post  AURORA on Thu Apr 28, 2011 7:46 pm

Post a picture of your spark plug!
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Re: No foam filter

Post  Mauser on Thu Apr 28, 2011 8:59 pm

All good stuff guys, to be honest I am not looking for any more power or expense as the bike is a chill out machine for evening rides down the lanes....30-40mph max Smile. Plug was a little sooty tonight but I had not adjusted the pilot screw the 1~3/4 turns out at that point, I will recheck next time I go for a ride. Spark arrester is opened up to about 40mm which is not to loud I have another which is as described fully open but this is too loud for where I live / ride.
Still think you need to try your bike with no filter in so you can see how bad mine was banana

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