My carb jetting for Pods

Posted: Mon Dec 09, 2013 4:08 am

Three pages to this thread and only two jet sizes posted....???? Shocked

There has to be more members out there, with good running bikes, with pod filters installed... There has to be... I think??? Confused

Posted: Mon Dec 09, 2013 6:31 am

melchiro wrote:

Three pages to this thread and only two jet sizes posted....???? Shocked

There has to be more members out there, with good running bikes, with pod filters installed... There has to be... I think??? Confused

+1

Jebby

Posted: Mon Dec 09, 2013 2:43 pm

I have not been able to take my bike out on the highway yet but I went as suggested 2.5 turns out and 80 / 120. Already 10000X better than it ever was.

Thanks!

Hawk Joined: Aug 20, 2009 Posts: 352 Location: Indiana

Jebbysan wrote:

melchiro wrote:

Three pages to this thread and only two jet sizes posted....???? Shocked

There has to be more members out there, with good running bikes, with pod filters installed... There has to be... I think??? Confused

+1

Jebby

Probably scared them all away.

Posted: Mon Dec 09, 2013 3:51 pm

coreyxh wrote:

Jebbysan wrote:

melchiro wrote:

Three pages to this thread and only two jet sizes posted....???? Shocked

There has to be more members out there, with good running bikes, with pod filters installed... There has to be... I think??? Confused

+1

Jebby

Probably scared them all away.

Ooooooh.....scary!

Jebby

Posted: Mon Dec 09, 2013 6:27 pm

ivan_the_terrible wrote:

Good, OSC. You surely know how to clean a carb,
and you routinely throw every shim away.
Now, what about "My carb jetting for Pods" ?
I am all ears. ...
Ivan

Jetting for pods? The short answer is get your money back.

The long answer is rather more complicated.

Like I've said, taking away airbox impedance drastically changes the physical characteristic of vacuum pulse, aka “signal.”

Strong signal is predicated on perfect compression and valve lift/lash, and if present you can compensate with larger jets.

However, you CANNOT compensate for weak signal no matter how large you make the jets.

80/120 is a good working setup. I keep 74.5 jets on hand but 80's are perhaps even better. Don't argue with success.

There's one variable that I've yet to see addressed in any discussion of pods but it's one that we apply as a matter of course, that is when I can't talk a customer out of it. Folks talk endlessly about increasing primary and secondary jets, but what about the slow jet? So here's a “trade secret:” 38 is the magic number.

As for shims, they have zero effect at small throttle openings so what's the point? Normal around town riding barely uses the needle jet and if we're concerned with overly lean conditions across the range...well this subject is a dead horse as far as I'm concerned.

OSC

Posted: Mon Dec 09, 2013 7:29 pm

For what it's worth my r ran like crap until I put 42slows in

Posted: Sat Dec 14, 2013 6:58 pm

Motocanada wrote:

For what it's worth my r ran like crap until I put 42slows in

Precisely!

With so many fuel/air metering "points" in the circuit (primary, secondary, slow, pilot, and air cutoff), why do we tend to concentrate on only two? Obviously the air cut isn't a variable but we can indeed re-route airflow through the carburetor interior by modifying it--although this is best reserved for extremely high-demand applications.

Personally I think that fixating on needle shimming is due at least in part to the fact that many folks believe that you can't access the slow jet except by ramming a jagged-ended piece of hardened steel wire through it---which is an open door to catastrophe.

And the fact that a lot of people don't really understand the interplay between the circuits under varying demand--which dynamics themselves change as mods that affect airflow are applied. And all of which are ultimately 100% ruled by compression.

OSC

MB-5 Joined: Sep 19, 2012 Posts: 25 Location: Pennsylvania

I run #80 and #120 as well with pods. No issues.

Posted: Thu Feb 13, 2014 5:00 pm

I did not see much chat about an 1100F set-up.I am looking for the guys who have 1123 kits on their 1100's.

2 weeks ago we re-built a 1123 engine Thanks to Steve G and Doc olds and now wondering what carbs to use and jet sizes.I have Mikunis (VM33) and they worked well on my blue 1100 stock bore w 125 main and 30 pilots.

The stock 1100 carbs in which were on the 1123 when I purchased it had #38 and #138 in them and it was running very rich as you can see from the picture of piston below.It is the piston on the right.

Do you think I should use the Mikunis or stock carbs and what size jets should I be starting with?and I am using pods.

Posted: Thu Feb 13, 2014 6:19 pm

I don't know if that's as rich as you think it is. It looks like oil on the dome to me. Bad valve seals will do that. Also having the crank breather routed to the intake tract will help that oily deposit along too. The crown and skirt isn't scorched so it looks like the top ring was still in decent shape.

The underside of the piston will give you a better idea of how the intake charge was burning, temp wise. If its rich, the burn is cooler and wont darken the bottom of the dome as much as it would if it was a leaner, hotter burn where it cooks the oil onto the bottom of the dome to a darker color.

Hawk Joined: Jul 30, 2013 Posts: 302 Location: Chicago

melchiro wrote:

Three pages to this thread and only two jet sizes posted....???? Shocked

There has to be more members out there, with good running bikes, with pod filters installed... There has to be... I think??? Confused

Mel, did you also blind the jets like it says in the original RSC mod? Or did you just drill? Or probably I'm not understanding something correctly.. I've never taken a carb apart before and am worried if I try this on my own with no experienced friend to hold my hand while I do it, I may mess something up and not be able to have a good time riding my bike anymore..

Posted: Sat Mar 01, 2014 6:11 pm

melchiro wrote:

Three pages to this thread and only two jet sizes posted....???? Shocked

There has to be more members out there, with good running bikes, with pod filters installed... There has to be... I think??? Confused

Of course I have an 1100f, 1123 kit, no idea on my cams (not stock I believe, that story is in another thread that is ongoing.......), KN filters (I hate PODS! Its like CROTCHROCKET. I can show you a crotchro.... better shut up), Supertrapp front half and collector, Vance and Hines rear pipe and canister. I have the dreaded Dyno Jet stage 3 kit. That means I am using the 155 jets. Stage 1 (which was included in the kit) is a 150 jet. I have 2 shims under the circlip.
Now I have a comment and a question. Comment: The only time the shims or clip are involved is right off idle throttle. Maybe the first 25% but I doubt it.
Now the question: I have burned exhaust valves in 3 of these motors by putting an aftermarket exhaust on and NOT re jetting. 1 Kerker, 1 Yosh, 1 Mac (dont laugh, I was finacially challenged and it sounded good on my 750C). Stock airbox, stock jets (2 750's, 1 900). Was told this was the reason by a few VERY competent professional and backyard??? mechanics. Doesn't the exhaust factor in to the amount of airflow that flows thru equation? Didn't the exhaust valves burn up because the exhaust allowed more air to flow thru the carbs which leaned the fuel air mix and caused to much heat?

PS: The reason Sonicrete hasn't added anything new is these bikes are 30 YEARS OLD! He may be a little crotchety sometimes but like Jeb said, he always answers questions. He has been a huge help to me on my F, along with a bunch of other guys on this forum. Hell, the reason he is cranky sometimes is because he is just repeating the same wisdom over and over.

Posted: Sat Mar 01, 2014 6:47 pm

The reason I haven't said anything is because the problem is the AIR not the fuel. Both have to occur at the same time and without the airbox they don't.

Posted: Sun Mar 02, 2014 4:55 am

jacksondee wrote:

.......Mel, did you also blind the jets like it says in the original RSC mod? Or did you just drill? Or probably I'm not understanding something correctly.. I've never taken a carb apart before and am worried if I try this on my own with no experienced friend to hold my hand while I do it, I may mess something up and not be able to have a good time riding my bike anymore..

NO, I did NOT blind the jets as per the RSC mod.... YES, I just drilled the Primary jet to size .80mm and the 2ndary jet to size 1.20mm, using the metric hobby drill bits...

Really, really, really, that's all I did to these carbs...That, and, I made absolutely certain, that all of the fuel passages were clear.

Is it so hard to believe?????????????? I guess so, that's why I did the video.. You're in Chicago, about 600ft elevation.. The 80/120 jet size will work for your 750.

Posted: Sun Mar 02, 2014 5:10 am

1 Kerker, 1 Yosh, 1 Mac (dont laugh, I was finacially challenged and it sounded good on my 750C.

Anyway we can get spell check on here lol? FINANCIALLY! Maybe not. Old jdblack (aka dannoman) probably would've have gotten over on even more people then. Shocked

CB1100F Joined: Feb 17, 2009 Posts: 2111 Location: Oz

Any recommended jet sizes for a stock 900 with pipe?

Hawk Joined: Jul 30, 2013 Posts: 302 Location: Chicago

melchiro wrote:

jacksondee wrote:

.......Mel, did you also blind the jets like it says in the original RSC mod? Or did you just drill? Or probably I'm not understanding something correctly.. I've never taken a carb apart before and am worried if I try this on my own with no experienced friend to hold my hand while I do it, I may mess something up and not be able to have a good time riding my bike anymore..

NO, I did NOT blind the jets as per the RSC mod.... YES, I just drilled the Primary jet to size .80mm and the 2ndary jet to size 1.20mm, using the metric hobby drill bits...

Really, really, really, that's all I did to these carbs...That, and, I made absolutely certain, that all of the fuel passages were clear.

Is it so hard to believe?????????????? I guess so, that's why I did the video.. You're in Chicago, about 600ft elevation.. The 80/120 jet size will work for your 750.

Wow, thanks man. I might just have to try it. I have the bike mostly disassembled now as I'm about to paint everything. I may as well figure out how to rip that carb out and open it up since its seems springtime isn't coming anytime soon. I'f I'm feeling spunky I'll try and photo document some of the steps.

Do you happen to remember exactly which pods you bought?

Posted: Sun Mar 02, 2014 7:50 pm

melchiro wrote:

jacksondee wrote:

.......Mel, did you also blind the jets like it says in the original RSC mod? Or did you just drill? Or probably I'm not understanding something correctly.. I've never taken a carb apart before and am worried if I try this on my own with no experienced friend to hold my hand while I do it, I may mess something up and not be able to have a good time riding my bike anymore..

NO, I did NOT blind the jets as per the RSC mod.... YES, I just drilled the Primary jet to size .80mm and the 2ndary jet to size 1.20mm, using the metric hobby drill bits...

Really, really, really, that's all I did to these carbs...That, and, I made absolutely certain, that all of the fuel passages were clear.

Is it so hard to believe?????????????? I guess so, that's why I did the video.. You're in Chicago, about 600ft elevation.. The 80/120 jet size will work for your 750.

I believe the video was fixed.... roflmao

Jebby

Hawk Joined: Jul 30, 2013 Posts: 302 Location: Chicago

Well that was a fun first experience taking the carbs out. Took quite a bit of elbow grease.

What do I do here with these two tubes? I'm assuming where my index finger is I get one of those cute little crankcase breathers that looks like a tiny oil filter?

What about the tube coming out right next to the dipstick where my thumb is?

Also the crankcase drain tube that seems to run though something mounted under the battery case and crap like that... I just scrap those now?

Hawk Joined: Jul 30, 2013 Posts: 302 Location: Chicago

Ok update:

After struggling with the RSC mod for like 8 weekends in a row, not being able to figure out why the bike wouldn't rev above 3000rpm, Mel very kindly urged me to try this jetting.

I reverted the entire RSC mod, except I left the air cut off valves plugged.

Drilled out the jets to 80 and 120.

Double checked all the passages had carb cleaner squirting through them.

The bike fired up instantly. It immediately revved as hard as I wanted it to.

I put the gas tank back on and went for my first ride since I parked the bike last winter and began disassembling it. It was an amazing feeling. I refused to give up on the RSC mod, I followed all the instructions perfectly. Just couldn't get the bike to run right. Finally after 8 weeks of struggling, I just couldn't believe that the 20 or so minutes it took to do Mel's jetting made the bike run instantly.

I'd also like to say it feels just a bit faster. This may or may not be all in my head, but it does feel a little faster.

Thanks Mel for this thread and for the friendly vibes.

Here is a youtube clip of the completed bike. Can't figure out how to embed the video into this post. Those pods sure are sexy. The airbox is the size of a freaking football, I understand the arguement for leaving it on, but I just couldn't handle it aesthetically myself..

THIS THREAD WORKS

http://youtu.be/lG0i06s2FbE

oh ps- the crankcase breather I put on there leaks oil pretty heartily. Any ideas? I can connect the tubes back to the drain box under the battery if I have too..

Posted: Wed Jun 11, 2014 2:49 am

I'm glad this worked for you. Very Happy

Posted: Wed Jun 11, 2014 1:00 pm

I don't hang out here as much as I used to--glad to see that things haven't changed much! Shocked

In 2006 I bought a clean 1100F with pods and dyna jet kit installed. It had a big flat spot from 2800-3200 rpm and the owner I bought it from had spent some serious dyno time trying to eliminate it. He could move the flat spot up and down the RPM range, but couldn't make it go away. It came with the original air box and needles so I just swapped them out and its run flawlessly ever since. Running the air box is the simplest way to get a clean running bike if you don't want spend a lot of time messing with jets, shims and such.

I've had the carbs out once since putting the air box back in and that was because I left gas in the tank too long without riding it and I got a clogged jet--we were building a house and I didn't have time to ride. It took me an hour to get the carbs out, clean them and reinstall them, its not that difficult once you figure out how to do it.

Posted: Tue Apr 21, 2015 5:03 am

melchiro wrote:

Flip78 wrote:

I have a 1980 cb750f. Stock header with a hindle can, stock cams. Would the 80/120 work with my set up or would it be too much fuel? You guys rock!

I'm assuming you will be replacing the stock airbox with pod filters.. If so, I am not sure.. But this is where buying the metric "hobby" drill bits will be put to good use. Try a 75 primary with a 110 secondary, then continue increasing the size until it runs good. With each different setup on bikes, this will take a few trial and error test runs..

But before you start this "adventure", you must make sure that your idle port are fully clean, your idle mixture screws are set and all four butterflies are in synch.

good info!
thanks Mel..

Posted: Wed Sep 09, 2015 3:17 am

Thanks to Mel! 80/120 on my stock carbs with a Carpy, Yoshi style 4into1. I personally cannot tell one iota of difference from my airbox.

Posted: Wed Sep 09, 2015 5:22 pm

FYI, as a backup I ran 75-115 with an old Kerker megaphone and K&N oval pods way back in the late '80s and early '90s and it ran perfectly.................750. Undrilled slides and no shims with OEM needles. The lower gears would pull out to ten grand smoothly all day long. The only thing I had issue with was absolute top end pull all the way out, it would only pull to around 8000+ in fifth or so. In retrospect that could have been the final gearing I was pulling at the time. I had a 42 on the back IIRC.

Put the stock airbox then back on and you should feel a bit more pep at small throttle openings say slow roll at 20 mph and suddenly gas it up just a bit but sharply. There IS a difference but many can't tell it.

Doing a slow roll at up to 6000 in low gear and suddenly 100% WFO and I could get that overweight pig of a 750 to actually pop the front wheel clean for a second without touching the clutch and roll-on only. The slides can easily be heard popping all the way up then the top-of-carb clunk and they settle back down somewhat lower at that time. You can feel the direct lift effect for just a fractional second then the motor drops power back off as the slides settle down.

Posted: Wed Dec 16, 2015 4:03 am

Stock 750 with opened up 2 into 1 exhaust and pods I ran 75 and 120 and shimmed needles with 1 or 2 washers. From what I read even stock with air box bikes will run better with 75 jets, because they were lean from the factory for emissions crap.Anyway bike ran great and only changed jets once to get there so no weeks and weeks of work to get the bike running right. Couple hours-thats it.

Hawk Joined: Jul 30, 2013 Posts: 302 Location: Chicago

About 5 years ago some of you might recognize my name because with little to no motorcycle maintenance background, I went down the RSC rabbit hole. For a year or two I was posting at least once a week needing troubleshooting help. It didn't work.

Mel pointed me to this thread. Tried it, it didn't work.

After years of being upset with the performance, or non performance, a buddy of mine made the simple suggestion to just put the damn airbox back on and be done with it.

Ordered an airbox. Put it back on. Got so frustrated with jamming the carb back in there with the airbox on after years of not having an airbox and carb removal being painless, that I decided to give one last shot to the pods.

Opened the carb up. 3 needles had 2 shims each, one needle had one shim. What the hell was I doing years ago? Changed it all back to single shim per needle.

On to the jets. Turns out I was running 80-100. I drilled the stock 68s to 80, but never drilled the stock 100s to 120. Like I just said, what the hell was I doing years ago?!

I just drilled the 100s to 120 and went for a ride.

Its over... Its all over... 5 years of carb frustration all gone now. She rides almost like a dream. Almost because there was a gurgle or two in between 3/4 and WOT, but I can live with tiny little gurgles way up there. I'm in the city, I almost never touch WOT. I don't often ride on the highway because I rip my track bike at the track, I no longer need to go that fast on my street bike with cars all around me.

80-120. Single shim. Pilot jets upped one size.

I had to remove the choke cable because she was idling at 2500. That works out just fine because the choke cable froze up earlier this summer and I was about to order a new one anyways.

I'll take the shim out if someone tells me I'll be ever happier with it that way...

Thanks Mel.

UPDATE 3.5 hrs after original post- went for another ride, longer stretch of road, better opportunity to test WOT. There is no "gurgle" as I originally perceived. She's perfect.

Posted: Tue Sep 03, 2019 2:00 am

I love it when old problems finally get solved. Nice work.

Posted: Tue Sep 03, 2019 2:14 am

WOW.... i’m Glad it all got figured out.. Yes I remember how frustrated you were back then ..

I’m glad you verified what you had, before giving up..