Author Topic: Jetting for pod filters (Read 19106 times)

racemx51 · « **on:** October 09, 2011, 09:25:10 am »

Hey guys, I put pod filters on my 73 CB 750.. Im wondering if you guys have any starting points for jetting. Im def no newbie when it comes to jetting, Ive been racing dirt bikes my whole life and back when two strokes ruled we jetted our bikes different almost every week to get peek performance...So dont be scared to get technical.. But do you guys have any starting points for jetting with pod filters. The bike already had a four into one exhaust so the only thing thats changing is the filters.. I heard two richer on the mains but what about needles and everything else? I live in the northeast so its starting to get a bit cooler now...60s or so..but during the summer is 80s and 90s where im at...
Any help?

Retro Rocket · « **Reply #1 on:** October 09, 2011, 02:28:46 pm »

Do a search for pods on a 750, have a read, then put the airbox back on and suffer none of the bull#$%* that goes with putting pods on a 750. The ONLY advantage with putting pods on the 750 for some is looks, they never run as good as the original airbox because the set up Honda uses on the 750 requires the velocity stacks that go into the airbox to run properly. It has been covered 100's of times on this forum and most of the time they screw around with trying to get an exceptable state of tune then give up and go back to what works. Now if you have a hot engine and are running different carbs then GOOD QUALITY pods like the K&N's may work, but with the stock set up, nothing runs as well as the stock airbox and velocity stacks that come with it.....

racemx51 · « **Reply #2 on:** October 09, 2011, 05:47:02 pm »

Not really, honestly I havent done that much research on this kind of stuff yet.. Ive been around bikes my whole life so I didnt really feel like I needed to read into it.. Whats your opinion?

Retro Rocket · « **Reply #3 on:** October 09, 2011, 06:43:40 pm »

Quote from: racemx51 on October 09, 2011, 05:47:02 pm

Not really, honestly I havent done that much research on this kind of stuff yet.. Ive been around bikes my whole life so I didnt really feel like I needed to read into it.. Whats your opinion?

These old Honda's were designed to use velocity stacks with the Keihin carbs. They run best with the factory stacks and airbox. I know it can be a bit confusing because there are plenty of bikes that run well with them but these old Honda's don't. King builds bobbers so the stock box doesn't fit with his style of bikes but i can tell you that the stock bike he owns runs the stock set up. He should tell people this when giving flippant advice. Like i said, there are tons of threads on here about this and even some guys that were totally convinced that pods were better have now gone back to the stock set up because of its ease of tuning and stable performance. Actually, there's one in the "what did you do to your bike today" thread....

tanman855 · « **Reply #4 on:** October 09, 2011, 09:10:47 pm »

what main Jets are you using with your exhaust and pods? I just baught the pod/jet set up from new motorcycle parts . c o m they are 115, I have a 1974 cb750.

Retro Rocket · « **Reply #5 on:** October 09, 2011, 09:23:41 pm »

Quote from: tanman855 on October 09, 2011, 09:10:47 pm

what main Jets are you using with your exhaust and pods? I just baught the pod/jet set up from new motorcycle parts . c o m I have a 1974 cb750.

Read my posts mate.... If your bike is mainly stock and uses that stock carbs you will never get it as good as the airbox and standard velocity stacks, Honda designed it that way and thats what works best. There is a member here {tintop} that has made an after market filter he calls the "antipod" it uses a modified version of the standard stacks with a single exposed filter, this works correctly because it utilizes the stock stack design.

http://forums.sohc4.net/index.php?topic=79491.0;nowap

tanman855 · « **Reply #6 on:** October 09, 2011, 09:29:22 pm »

$235 is a little steep for me(highschool student), I have a set amount of money put aside to turn this into a cafe bike (1k). And I can't get my stock airbox back on they are supper stiff. And it seems like they worked well for him.

scottly · « **Reply #7 on:** October 09, 2011, 09:38:34 pm »

Quote from: tanman855 l And it seems like they worked well for him.
[/quote

Or so he says. Of course, he also claims to have divine intervention on his side.
The airbox rubbers can be softened with wintergreen oil; lots of info on here about it.

Retro Rocket · « **Reply #8 on:** October 09, 2011, 09:40:57 pm »

The biggest problem is that most people have no idea how well these bikes run when set up well, a lot of guys here think their bikes run great when in fact they don't. Most pods are cheap crap and have no stacks built in, K&N have some with internal stacks that will help, emgo and the rest are just rubbish. Do yourself a favour and keep the airbox, there is a knack to putting them on and once mastered its relatively easy, you may want to use it after screwing round with pods for little benefit. Search the forum, you will find plenty of pod threads and funnily enough, some of the guys that swore black and blue that they wanted pods are now going back to the stock set up because it is simply the best way to get these bikes, particularly the 750, running well.. I've had 22 of these bikes and will NEVER use pods ever again..

tanman855 · « **Reply #9 on:** October 09, 2011, 09:46:50 pm »

Ok, thanks a lot guys. I'm just trying to get this thing running as good as possible, Ill try that oil to soften them up. Right now I started a thread because it isn't running correctly any advice on that too would be much apreciated

http://forums.sohc4.net/index.php?topic=96898.0

david 750f · « **Reply #10 on:** October 09, 2011, 09:56:08 pm »

+1 with what Retro says...

scottly · « **Reply #11 on:** October 09, 2011, 10:01:55 pm »

Do a search for wintergreen oil. From what I've read, it can be found in drugstores as well as online. Personally, I've never needed it, as I moved well beyond anything close to stock many years ago.

In your case, I think you would be better off sticking with the stock set-up for now, just to eliminate as many variables as possible. BTW, welcome to the forum!!!!

RustyJC · « **Reply #12 on:** October 10, 2011, 05:54:47 am »

My 1971 CB750K1 has been running K&N individual filters since 1972. Knowing what I know today, I doubt that I would do it again, but we thought that was the hot setup back in the 70s.

IIRC, with the K&Ns, I wound up with 120 main jets and the needles lifted one notch. If I remember, I'll pop a float bowl and verify the main jet sizing when I get home from work. I wound up with a pill bottle full of main jets, though, as I worked my way through them to find the best setup for the K&Ns, the Jardine 4-into-1 and the Yoshimura cam and pistons.

Just to illustrate how sensitive these carbs are with the individual K&N filters, if I do nothing more than stick my knees out into the wind at highway speed, the "scoop effect" causes the bike to go dead lean. I still may wind up going back to the original airbox one of these days - if I can find it!

Rusty

racemx51 · « **Reply #13 on:** October 11, 2011, 07:05:58 pm »

Well my plan was to try jetting it and getting it running well and if it didnt, just go back to the old airbox. Ive got two of them...So I wasnt worried if I needed to go back.. I got the pods at pretty much no money just because I know a lot of builders.. Ive got other problems to worry about right now anyways.. I fired the thing up and cylinders 2 and 3 are not firing now.. Points are, so I must have a damn wiring problem somewhere.. Guess thats my next situation..What do you guys think?

Flying J · « **Reply #14 on:** October 11, 2011, 07:24:33 pm »

haha a pods thread.

Inkscars · « **Reply #15 on:** October 11, 2011, 07:31:06 pm »

Not firing? Or not getting warm? If it's a spark issue, I'd check your coils. Don't be afraid to check your wires and ends. Some trimming may be necessary if they're not new. Now, If you're getting spark and you just threw different jets in there, You're going to have to start from square 1.
Jetting Isn't the only thing that comes into play. You change 1 thing, and it messes everything up. It's a process . Sometimes it involves taking the entire bank off a couple times to get everything right.
What kind of exhaust, what kind of filters, what climate do you live in? It all comes into play.

Psychonaut · « **Reply #16 on:** October 11, 2011, 07:38:35 pm »

Look inside the stock air box then look inside the throat of a pod.

anotherCB · « **Reply #17 on:** October 12, 2011, 06:19:29 am »

I run pods and a 4in1 (Yoshimura) on my K7, 20 larger on the mains, 2 clicks richer on the the needle, runs pretty well (a little rough around 2,000 rpm) and idles perfectly at 1,200. No other mods to engine.

racemx51 · « **Reply #18 on:** October 12, 2011, 06:08:21 pm »

I found it, just the plugs.. Tested the coil with a spark tester today and have spark on all four.. But not through the plugs.. Hadnt put new plugs in yet.. I was getting the whole bike in one piece but plugs are next so I can ride this thing around and get the testing underway..

lucky · « **Reply #19 on:** January 24, 2012, 01:49:27 am »

Quote from: anotherCB on October 12, 2011, 06:19:29 am

I run pods and a 4in1 (Yoshimura) on my K7, 20 larger on the mains, 2 clicks richer on the the needle, runs pretty well (a little rough around 2,000 rpm) and idles perfectly at 1,200. No other mods to engine.

"20 larger on the mains" What does that mean?
Can you just tell us what size the main jets are?

"2 clicks richer on the needle"
Which groove is the clip on now of the FIVE grooves on the needle? We do not know where it was to start with.

What size idle jet?

How many turns open on the mixture screw?

If you suddenly snap open the throttle does it stumble or die?

Then we will have useful information

anotherCB · « **Reply #20 on:** January 25, 2012, 05:02:32 pm »

The reason that I say "20 larger" than standard is that my carbs are different to yours. The later CB models k7 and K8 have PD carbs and I went from a 110-130. Now maybe your original main jet is 100 (just gessing) and going 20 bigger would mean 120 for you, if you want to copy me.

Same on the needle setting. From the five setting on the needle, mine is standard on the top setting (leanest possible). I moved the needle to the middle setting (2 richer than standard). I might very well be that your standard needle setting is in the middle, than you would have to go to the bottom to copy my changes.

That's why I indicated changes I made and not absolute numbers.

I didn't do anything to the idle or mixture screw.

When I snap the throttle open at 2,000 or the bike goes like hell until 9,000 (if I let her), no hesitating or bugging at all. And I am using the cheapo pod filters. Between 1,200 and 2,000 is still a rough spot, but I have nod had the time and desire to figure that out yet.

Danno · « **Reply #21 on:** January 25, 2012, 05:43:51 pm »

replace the spark plug caps and cut the wires back a quarter inch and screw the new plug caps on it will work

cb650PK · « **Reply #22 on:** January 25, 2012, 06:29:25 pm »

Quote from: anotherCB on January 25, 2012, 05:02:32 pm

The reason that I say "20 larger" than standard is that my carbs are different to yours. The later CB models k7 and K8 have PD carbs and I went from a 110-130. Now maybe your original main jet is 100 (just gessing) and going 20 bigger would mean 120 for you, if you want to copy me.

Same on the needle setting. From the five setting on the needle, mine is standard on the top setting (leanest possible). I moved the needle to the middle setting (2 richer than standard). I might very well be that your standard needle setting is in the middle, than you would have to go to the bottom to copy my changes.

That's why I indicated changes I made and not absolute numbers.

I didn't do anything to the idle or mixture screw.

When I snap the throttle open at 2,000 or the bike goes like hell until 9,000 (if I let her), no hesitating or bugging at all. And I am using the cheapo pod filters. Between 1,200 and 2,000 is still a rough spot, but I have nod had the time and desire to figure that out yet.

So when you have replaced the stock airbox with your cheep pod filters, you seem to have gained crappy running bike between idle and 2000 rpm. How is that a good trade of?

anotherCB · « **Reply #23 on:** January 25, 2012, 06:46:09 pm »

Many reasons:

1)No ugly airbox to look at
2)More power, in combination with the 4 in 1
3)Good looks for my cafe project
etc.

If I was going to leave the bike original, I would have stuck with the airbox, however that was not my intention. And as I said, I haven't even tried yet to figure out the rough spots between 1,000 and 2,000 because it is so little it doesn't really bother me that much.

cben750f0 · « **Reply #24 on:** January 25, 2012, 07:00:23 pm »

which brings me back to.....just put the airbox back on....

peace

anotherCB · « **Reply #25 on:** January 25, 2012, 08:41:56 pm »

This gets more and more like politics in the US, airbox vs. pod, republicans vs. democrats....

Why does one side always have to pursuade the other side they are right?

You want that perfectly restored classic with airbox? Good. You want that cool cafe with perfectly tuned pods? Nothing wrong with that. Oh no sorry,..... it doesn't work, how do you want to bring pro-airbox and pro-choice people together

Retro Rocket · « **Reply #26 on:** January 25, 2012, 08:48:11 pm »

Quote

You want that cool cafe with perfectly tuned pods? Nothing wrong with that.

And there in lies the problem, no such thing using the stock Honda carbs.... They were designed to run with the well engineered velocity stacks... There is no doubt the airbox will run better, sometimes 30-40 years of experiences and simple engineering principals out weigh "cool looks".... Just look at the amount of people here that shared your opinion that are now running the airbox......

anotherCB · « **Reply #27 on:** January 25, 2012, 08:59:19 pm »

As I said, politics....

If anyone is in the market for an airbox, check the for sale section in the next days

Retro Rocket · « **Reply #28 on:** January 25, 2012, 09:01:26 pm »

I totally get why some people like the look of podsw but seriously, there's no politics involved if you understand how the stock carbs work.....FACT......now there's something politicians could learn about...

{if they wanted too}

TwoTired · « **Reply #29 on:** January 25, 2012, 11:20:55 pm »

Quote from: anotherCB on January 25, 2012, 08:59:19 pm

As I said, politics....

"Politics" infers that bargaining will induce some sort of progress. Unfortunately, the laws of physics remain the same no matter what a political or popular body mandates. You can't vote for changing the speed of light and make it come true. It's a physical constant. Live with it!
Same is true for the way carbs work, on physical principles that were carefully balanced/adjusted to the stock air box characteristics; i.e.
The main jet, the throttle valve, the main air jet, the emulsion tube holes, the slide cutaway, the venturi shape, and the pilot circuit parameters were all balanced to the pressures existent with the stock air box over street operating conditions where all throttle positions are useful (as opposed to the race track where only one or two throttle positions are useful).

Is it folly, arrogance, or ignorance, that makes style mavens believe a cosmetic change cannot effect the physical balance of a well engineered machine?

I'm of the belief that the stock air box is sleek and beautiful for what it represents, and PODs are rather ugly things that make the bike look like a cheap afterthought or a freak of nature. (See pic of "attractive" external filters below.)

Does installing big boobs, big lips, and big hair on a woman really make a better woman throughout her lifetime? I suppose if "superficial" is the goal, then the answer is, yes. But, if you install big boobs on an ballet dancer, Olympic gymnast, or figure skater, her previous career is finished.

There are times when enough engine modifications may demand alterations to induction that the stock setup can't enable. But then, that's not the stock bike, is it?

scunny · « **Reply #30 on:** January 26, 2012, 02:45:15 am »

"Is it folly, arrogance, or ignorance, that makes style mavens believe a cosmetic change cannot effect the physical balance of a well engineered machine?"

been called a lot worse so thats ok. I'm running pods, under no illusion that I have improved the performance of bikey. it has been a battle to get it running to the point where I'm comfortable with it's overall running thru the rev ranges. is it perfect, well no.
if you want stock, go stock, if you don't....don't. but be prepared to do a lot of tinkering and thinking.

cben750f0 · « **Reply #31 on:** January 26, 2012, 08:40:29 pm »

not polatics, i have an wiseco 836 kitted, free flowing exhaust, was running pods, after a dyno tune, and we could never...i mean NEVER get the thing to run as good as it did with the air box, not to mention, the erratic way it ran with a strong side wind. the mid range was never right, the top end was ok, if you wanted to run 140+ mains jets, with WOT..... and did i mentions the bog we got off the line, we changed slow jets, cleaned the carbs about a dozen times, set floats high, low, factory.... tried different clip positions.... then i put the air box back on with a foam finer filter in it, LOWERed the needle a clip, and put 125 mains in and it runs a tan plug, got rid of the constant throttle hesitation at 3-4k rpm, and have a better mid range...YES pods look fuggen awesome, buti like to RIDE my bike...everyday....

cant see the polatics in that...

sorry

peace

PS yes i spelt politics wrong....twice dammit..

anotherCB · « **Reply #32 on:** January 26, 2012, 09:07:02 pm »

Man I wish I had time to reply, however have to go back to the garage to work on my "fuggen awesome" pods

Hey what about stacks? Any lovers/haters out there? The box has stacks in it so y'all must love them?

cben750f0 · « **Reply #33 on:** January 26, 2012, 09:11:13 pm »

stacks look cool, have had no experience with them, i wasnt knocking btw, cos i do love the look, just my experience...

apparently they are great, but bricks and small wild;life are the only thing they filter... someone will know though.

peace

Retro Rocket · « **Reply #34 on:** January 26, 2012, 09:25:51 pm »

Quote from: anotherCB on January 26, 2012, 09:07:02 pm

Man I wish I had time to reply, however have to go back to the garage to work on my "fuggen awesome" pods

Hey what about stacks? Any lovers/haters out there? The box has stacks in it so y'all must love them?

It all depends on how you go about filtering them. Straight velocity stacks are designed to run filter less, usually for racing, anything that gets in the way of the incoming air like brass mesh or foam socks screws up how they work by disrupting the air and causing turbulence, which makes it impossible to tune correctly.... Even MotoGP bikes run stacks into a large airbox...

Rgconner · « **Reply #35 on:** January 26, 2012, 10:21:14 pm »

Ah yes, the Lincoln Douglas debates, where Lincoln defended the use of Stacks vrs stocky filters...

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Author Topic: Jetting for pod filters (Read 19106 times)