Pod Filters ? or stick a hot poker in your eye ?

[peanut]

that is the question.

How much pain do you wish to experience !.....

I inherited my 79 Special which came with pod filters and have struggled for 2x years to get the damn bike to idle properly when hot.

I have had the carbs off and cleaned, adjusted and overhauled them at least 8x times and still I cannot get rid of the hanging idle when hot.

I have read around the net on dozens of forums until my eyes bled and nobody has yet posted a solution that solved their particular problem.

The symptoms are that the engine starts easily and idles perfectly when cold On or off the choke. Once the engine has warmed up for 4-5 minutes the idle creeps up to 2500rpm and hangs there sometimes the idle rises to 3500rpm which is practically unridable ,very difficult to change gear and lots of clutch slipping at junctions etc with the engine racing..

The reason for this is I am sure quite simple. The engine is getting too much fuel and air!
With the throttle stops backed off ,the throttle cable disconnected and the throttle valves closed and the chokes sealed the idle is still rising to 3500rpm ! it couldn't do that on just the pilot circuit alone.

My feeling theory is that something is causing the floats to rise and not come back down when the throttle valves close at idle .With the slides part way up, the vacuum in the engine will draw fuel from the needle jet and air from the venturi causing the revs to stay high with the throttle off .

Today I was randomly searching the net for a possible solution and found a post by jayel (thank you Jayel), saying that some pod filters have an internal lip which covers the air intakes at the mouth of the venturi causing erratic idle ! Bingo ! it was like a light suddenly coming on. Of course !. I remembered that I'd noticed some excess fuel lying in the pod filters last week and had taken some video of it intending to post it but I'd forgotten.

I checked the video and sure enough there was the hidden internal rubber lip and it was obvious that the lip would block the diaphram air intake at the mouth of the venturi. Have I at last found the culpret after 2x years of frustrating searching?

As soon as the rain stops I am going to rip the pod filters off and cut out the rubber lip to clear the intakes and go for a test run. Fingers crossed
http://www.xs650.com/forum/showthread.php?t=1280
http://www.kawasakimotorcycle.org/forum/mechanics-corner/55120-putting-cone-filters-82-kz550.html
http://www.xs11.com/forum/showthread.php?t=41699

 

[Brian902]

Peanut,

Around here their reference to pod filters are these ones.

They work great!

IMHO, I don't know how any bike works with those!

Good Luck

http://www.unifilter.com/

 

[fredintoon]

Hi peanut,
plan 2, you got removing them aced, now work on tossing them in the trash.
I reckon every tenth posting on this list has a variation of " - - - beware pods that block the peripheral air intakes, that are tapered, that are fluted - - - "
Install UNIpods, they don't do that and ain't like that.

 

[peanut]

first I am going to establish that that is actually the cause of the hanging idle but yes the filters have got to go !

I am considering using remote type paper k&n filters with connecting rubber or plastic hose because they might be a bit quieter than pods . I don't really want to try and source and fit the original type filters if I can avoid it.

Fred I haven't come across a single post on this forum referring to the pod restriction except the post by Jayel . Not that I suspected that the pods were a possible issue before discovering the lip today. I'm pretty sure that I have not seen a reference to it in the famous 'carb guide'
edit: obviously I couldn't have looked hard enough because apparantly there are lots of threads that I didn't find. Must have been looking with my eyes closed

 

[fredintoon]

Fred I haven't come across a single post on this forum referring to the pod restriction except the post by Jayel . Not that I suspected that the pods were a possible issue before discovering the lip today. I'm pretty sure that I have not seen a reference to it in the famous 'carb guide'

Hi peanut,
not here? I know I read it on one of the lists I monitor.
Wiggly fluted pods interfere with the air flow.
Tapered pods do that too.
Pods that block off the peripheral air passages screw things up big time.
The pods in your video hit 3 out of 3.
I was running the MikesXS pods that say XS on their ends.
They don't block the peripherals so the slow running and round town stuff was OK and as I ride like a timid old man (well, I AM a timid old man) I didn't notice the lack of top end.
But once I read about it I swapped those tapered pods for UNIpods and I can persuade myself the bike runs better now.

 

[kevski]

Hi peanut,
not here? I know I read it on one of the lists I monitor.
Wiggly fluted pods interfere with the air flow.
Tapered pods do that too.
Pods that block off the peripheral air passages screw things up big time.
The pods in your video hit 3 out of 3.
I was running the MikesXS pods that say XS on their ends.
They don't block the peripherals so the slow running and round town stuff was OK and as I ride like a timid old man (well, I AM a timid old man) I didn't notice the lack of top end.
But once I read about it I swapped those tapered pods for UNIpods and I can persuade myself the bike runs better now.

Hi Peanut, the upshot is that pods and CV's are not going to work across the whole rev range never have and never will no matter what anyone tells you, the air flow is disturbed, if you really want pods change carbs to smoothbores, or better still go back to standard air boxes as the bikes were designed with them and optimum performance in mind, also how many racing bikes do you see with pods on them.

 

[peanut]

Peanut,

Around here their reference to pod filters are these ones.

They work great!

IMHO, I don't know how any bike works with those!

Good Luck

http://www.unifilter.com/

Brian thanks for the link.
I can't find any of those in the UK but I did find these which appear to be the same Company ? it looks like UNI just wrap some foam around the pleated pods I have .?
http://www.ebay.co.uk/itm/Uni-filte...Yamaha-SR500-Honda-Mikuni-VM-TM-/231365342710

What I have read today is that pod filters are very susceptible to rain water and also changes in air flow around them like crosswinds etc They work well when they are protected from this by deflectors or covers .
They don't restrict the air flow though quite the reverse they actually increase the air flow substantially which is why you have to up both the pilot jet and main jets when fitting them .

 

[TwoManyXS1Bs]

Hey, peanut! While your engine is doing that high-idle thing, pop-off the filters and see if idle changes.

Have you seen these?

http://650rider.com/index.php?name=Forums&file=viewtopic&t=5483
http://www.xs650.com/forum/showthread.php?t=26013
http://www.xs650.com/forum/showthread.php?t=31777
http://www.xs650.com/forum/showthread.php?t=33425

 

[fredintoon]

- - - how many racing bikes do you see with pods on them.

Hi kev,
racebikes don't have pods they have horkin' great polished air intakes to get maximum power and the riders don't give a shit how long the engine lasts sucking in unfiltered air so long as the bike gets through the warm-up laps and a weekend's racing.

 

[kevski]

Fred the words are velocity stacks which have a different way of channeling the air, modern bikes are fuel injection on race tracks, road bikes need optimum performance which is why air boxes are used giving a constant air flow for the cv carbs, the race carbs with the stacks on are normally flat or round slides which can be tuned for stacks or pods.

 

[fredintoon]

Hi kev,
must admit the last racebike I looked at was a KTT Velocette with an AMAL 10 on it a half-century ago.
Doubtless things have gotten somewhat modernized since then.

 

[peanut]

Hey, peanut! While your engine is doing that high-idle thing, pop-off the filters and see if idle changes.

Have you seen these?

http://650rider.com/index.php?name=Forums&file=viewtopic&t=5483
http://www.xs650.com/forum/showthread.php?t=26013
http://www.xs650.com/forum/showthread.php?t=31777
http://www.xs650.com/forum/showthread.php?t=33425

thanks twomany I'd only come across 1x of those links . Interesting reading but none of them mentioned a hanging idle problem so I may be on the wrong track afterall but I won't know until daylight .

I think I might try your suggestion tomorrow but judging by the amount of fuel left in the pods every ride I might take a fire extinquisher with me

I've got to rectify this hanging idle its driving me insane . I can only ride the damn bike 1x mile down the road before it becomes unrideable at the moment . I'm even considering buying a new set of carbs in desperation but I really hate admitting defeat on a problem.

 

[CDNTX650]

Uni pods and only unis. They work well on cv carbs.

 

[5twins]

Yes, the evils of K&N pleated type pods, tapered pods, and the port blocking rubber lip are well documented, have been for years. I will admit, we didn't cover this in the Carb Guide, but it was written before most of this came to light. Back then, I ran real K&Ns. Never could get the bike to run quite right with them. The UNIs fixed that. All I can say is you didn't research hard enough (or actually at all). As Mulder used to say "The Truth is Out There ....".

The filters you have are the absolute worst of the worst. A cheapo K&N clone (which filters next to nothing), sharply tapered, and with the large rubber lip that blocks the air ports. Take them off, set them upright on your desk, and use them for pencil holders, that's all they're good for. Cutting the rubber lip in spots won't fix them.

Now, I know you're going to bad mouth me all over the place for these comments but look above. You've already been told all this stuff by other folks.

 

[TwoManyXS1Bs]

Here's s'more:

http://www.650rider.com/Forums/viewtopic/p=12667.html
http://www.xs650.com/forum/showthread.php?t=12024
http://www.xs650.com/forum/showthread.php?t=40673

 

[650Skull]

Yes, the evils of K&N pleated type pods, tapered pods, and the port blocking rubber lip are well documented, have been for years. I will admit, we didn't cover this in the Carb Guide, but it was written before most of this came to light. Back then, I ran real K&Ns. Never could get the bike to run quite right with them. The UNIs fixed that. All I can say is you didn't research hard enough (or actually at all). As Mulder used to say "The Truth is Out There ....".

The filters you have are the absolute worst of the worst. A cheapo K&N clone (which filters next to nothing), sharply tapered, and with the large rubber lip that blocks the air ports. Take them off, set them upright on your desk, and use them for pencil holders, that's all they're good for. Cutting the rubber lip in spots won't fix them.

Now, I know you're going to bad mouth me all over the place for these comments but look above. You've already been told all this stuff by other folks.

You have already gone through all this with peanut in December 2013.
http://www.xs650.com/forum/showthread.php?t=32499

 

[CDNTX650]

Haha. Don't do drugs kids.

 

[peanut]

Yes, the evils of K&N pleated type pods, tapered pods, and the port blocking rubber lip are well documented, have been for years. I will admit, we didn't cover this in the Carb Guide, but it was written before most of this came to light. Back then, I ran real K&Ns. Never could get the bike to run quite right with them. The UNIs fixed that. All I can say is you didn't research hard enough (or actually at all). As Mulder used to say "The Truth is Out There ....".

The filters you have are the absolute worst of the worst. A cheapo K&N clone (which filters next to nothing), sharply tapered, and with the large rubber lip that blocks the air ports. Take them off, set them upright on your desk, and use them for pencil holders, that's all they're good for. Cutting the rubber lip in spots won't fix them.

Now, I know you're going to bad mouth me all over the place for these comments but look above. You've already been told all this stuff by other folks.

ok ...you say that the perils of using the pleated pods are well documented !..I don't doubt this for a moment but as to the best of my knowledge I have never come across any reference to this until yesterday that is not particularly helpful now is it.!?

Skull has kindly pointed out that I had completely forgotten about a previous thread from a couple of years ago where you offered me some advice ..as I haven't touched a bike since that date its perhaps not surprising I had forgotten about it. I clearly have a lot to catch up on.

Now that I can see the problem of the lipped type pods myself and read all the posts about the pitfalls I naturally intend to dispose of them and replace them with something more appropriate. I have not yet decided if I will use the Ramair polyurethane pods that I ordered yesterday or ultimately search out some original stock filters and fit those . I'll wait until I have tried the Ramair before I decide.

What I would like to know 5twins is how your post specifically addresses the problem that I have requested help with ...that of a hanging idle ?

Do you think that partial blocking of the diaphram air intake holes could cause a hanging idle ?

 

[kevski]

It's the same on most forums, the way of the world I'm afraid, but on the serious side pods and CVs don't mix, its all to do with negative air pressure at the pod. Will post a link later that gives a better explanation than I can.

 

[peanut]

yes I read all about it on one of the excellent forums I posted a link to at the top of this thread. They are proper enthusiasts on there and don't suffer so much with Trolls and Flaming as we do on this forum.


Apparently one of the biggest issues is varying air pressure around the inlets caused by headwinds/crosswinds and high sided vehicles .

It amazes me that so many pod type filters get sold and fitted when they appear to have so many issues.