cb650 – pod filters
Below is the info you need to get pod filters dialed in on your 79-82 cb650.
79-80 (mechanical piston slide carbs)
- 120 main jet (stock is 92) *** try a 115-117 if you’re at high elevation
- 42 slow jet (stock is 35) *** try a 40 if you’re at high elevation. Drill out the 35 to a 40
- mixture screws set to 1.5 turns out
- float height set to stock measurement
- mac 4-1 header / exhaust (ebay)
- emgo 48mm pod filters (ebay) – (you have to slightly modify the 2 inner pods to clear the choke, i doubled up the rubber sleeve and used rubber epoxy to seal, glue them together)
- Better than pod filters are velocity stacks. Bike runs best with these. They’re a little hard to find though. You want 43-46mm. But… you’ll want to run k&n filter bags. Info HERE.
All jets bought from either:
If you’re having a hard time finding jets, you can buy a jet reaming kit and drill your stock jets out to the sizes you need.
81-82 (constant velocity slide carbs)
DynoJet makes a kit. All the info you need is on below links (the kit says 80-82, but that is a typo… it will only fit 81 and 82):
All this info for 79-82 is dependent on the fact that you’re living around sea-level, and your carbs are already running good. If you have shitty carbs, you might wanna rebuild them and get them clean as fuck before you attempt putting pods on. If you’re high up in the mountains, you want slightly smaller jet sizes than what I spec’d out.
The cycle will run a little hotter, simply because you’re going to be making a significant amount more power than stock. Makes sense that more power (more of an explosion in the combustion chamber) is going to create more heat. To offset this extra heat, I recommend adding an oil cooler. INFO FOR THAT HERE. Also, for 79-80 carbs, my set up is the tiniest bit rich, so it’s absolutely not running lean. Lean would add extra heat. My spark plugs have been a perfect light-golden brown for years now. No problems at all.
67 responses to “cb650 – pod filters”
Leave a Reply
Published - Jan 8, 2019
1980 Vintage Yamaha
“We turned YZ yellow into IT blue so you can win enduro GOLD.”
thank you once agian for the info ed this has been very useful where are you from?
we all live in center city philadelphia. where about you?
good info. now one for the 55o please.
Iam having one hell of a time trying to set up these carbs for the pods 1980 cb650 piston valve carbs my main jets were 97.5 and slows 35 now I have #120 and #45 for slows i was told the 45’s were easier to set the mixture the bike was running way to lean now its to rich Can someone tell me how to set the mixture screws do you turn them all the way in until they stop turning then turn them out i think Iam going to go crazy should I just order 42’s and start over I will tell you the bike sounds really good with the new jetting doesn’t even sound like the same bike I just dont want to blow the engine If someone can help me out that would be great. Thanks
Where did you get the seat? I need to get one for my CB650 and your’s is one of the nicer ones I’ve seen
just emailed you details…
but pretty much, I had to modify the seat pan so it’s a little slimmer and shorter, and then I had it custom upholstered at a place here in Philly called J&J auto upholstery.
i was just wondering do i have to go with the exact jet sizes for the pod mod or can i go slightly smaller?
You can go to smaller jet sizes if you’re at higher elevation where air is thinner.
I’m in Philadelphia real close to sea level.
My current set up is:
– 42 slow jet
– 120 main jet
– velocity stacks instead of pods
– mac 4-1 exhaust
… And my 650 runs awesome. Fast as shit, no flat spots in rev range. Not much difference between pods and velocity stack. With pods it ran a tiny bit rich. With v stacks it’s balannced a tiny better.
also i have the keihin pd50a mechanical slide carbs and my slow jet is pressed in how did you go about that?
I just got pods and the bike is running ALL sorts of different. Bogs when you start it,, when it starts, and then when you idle it through that it revs fine. You think jet size? Qand in my manual it said that stock jet size was 90 for the main ?
O yeah have not synced them yet and no baffle.
just emailed you. i’ll walk you through it all.
the slow jet is pushed in.
get a pair of vice-grips and pull them out.
they’ll tap back in once you’re done cleaning them.
How’s is going. You get a chance to copy the links for the correct jet sizes?
I recently bought a cb650, main jets are 90 so I regretfully assume every other orifice is stock size. The bike had a custom air box mounted but not hooked up. Instead, previous owner installed pods. I am lost as to whether I should make a 4 to 1 fitting for the air box or keep with the pods… I can’t seem to find jets for my carb, i don’t know which groove to use on the needle, and the bike runs like shit, except it runs great at idle. To get it to not run like that i have to keep it at full choke in order for it not to die on rev. This leads me to believe that it is not getting enough fuel. I took carbs off and cleaned them immaculately with B12 and ran some sea foam through it. HELP ME… Please.
Hey thanks for all the help. You mentioned 48mm pods for the slide carbs, I however have a 1892 CB650 with CV carbs. I measure about 57mm OD. Does that sound right? Im trying to find the right pods and have not had much luck.
I was wondering if you have to buy the dynojet kit for the 81 650. I just bought a bobber with pod filters and the p.o could not get it to run right. I am a gold mechanic but new to bikes
I have a 1980 CB650C that I have put pod filters on. I have tried some different jetting config’s but still not quite right. I am using the same brand pods and have ordered the jet combo’s you have tried here. The only difference will be the exhaust. I have the stock 4 on 4 exhaust and would like to keep it as they are are in excellent cond. and I like the look. Do you think I will need to drill the exhaust or any other suggested mod to the exhaust?
I have a 1979 CB650 and I cant get the slow jets out. The main jet is the screw type but the slow jet appears to be pressed in. Is there an easy way to get this puppy out?
hey, im frustrated, i have an 83 nighthawk cb650. i love the airpod look. dynojet only offers kits stage 1 which is only for riding with the airbox. ive seen on youtube some guys overpassing this. how can i?? should i restrict the pod air flow by siliconing some parts for a restricted flow? please help. i have cv carbs
This post was about 79-82 cb650.
Unfortunately I can’t help you with the 83-86 cb650.
hey enjoy reading your blog and tips. I going to go with stacks for my 82 cb650. Although I measured the carb intake to have a diameter of 56mm OD. I read you suggested 43-46 mm… your thoughts?
I have a 1980 cb650 and I am running velocity stacks, and the mac 4-1, but I was wondering if you had any idea what jets to use if I remove the muffler off of the mac exhaust or if I remove the baffle. can i still use the jets you recommended? or should I go bigger?
If you have the stock 1980 cb650 carbs, use the jets I recommend with velocity stacks and the Mac 4-1 exhaust. Don’t pull out the baffle, it’ll sound like shit. The Mac sounds awesome as-is.
Completely new to bikes and looking for help!
So I have no previous mechanics experience and no previous bike experience…so I bought a 79′ cb650 that didn’t run off a guy for $300 bucks. With the shop manual,forums and youtube I have managed to get it running! But it only idles with choke full open. Also has gas in the oil. So I removed the carbs (Keihin PD50A I believe) and am cleaning to rebuild. First I noticed whoever had it before removed the rubber components from the air cutoff valves and sealed them up. Should I be concerned or can I re jet to be a bit rich to compensate??? Also I want to convert to K&N Pod filters (maybe velocity stack after I google what that it lol) and I want to run a shortened 4 into 2 exhaust potentially with no baffles. I live in Norther BC Canada so elevation is higher than sea level for sure. I would prefer not having to buy new jets to many times as you can guess I need quite a few other parts, So do you suggest the same numbers you have posted or something else? Anyone with suggestions, tips, or just wants to help guide a new to bikes guy along the way email me at JuanCarlitoOnline@Gmail.Com
Appreciate all feedback. Thank you.
It sounds like your carbs are a little shitty. To skip all the frustration you could just buy another used set of cb650 carbs. This is probably your best and cheapest option. Or… if you have extra money to burn, you could buy a brand new pair of Keihin CR special 29mm smoothbore carbs which would make some good power and fit your bike awesome, especially with pod filters.
Ok thanks for the response. But even with new carbs or another used pair I’ll still have the same question with re jetting for pod filters and the converted exhaust. With the higher elevation and no baffle exhaust what #’s would you recommend as a starting point? I believe the elevation in the area is 1600-1800 ft depending on direction of travel.
Thanks again man, appreciate it!!
I would do everything I stated in my post but run a 117 main jet and a 40 slow jet due to air being thinner at higher altitude.
ed, I got the 120 main jets from jetsrus but they are not the same as the stock jets and will not work… they are smaller around and will not screw into the carb. where did you get your main jets from?
never mind, i was taking the whole assembly out not just the small jet part
You have no idea how much I’ve been looking for this info!
I’ve been through all kind of hell with my 79er. Two terrible mechanics and not enough experience to do this sort of things on my own. But anyways, i just have to sort out the charging problem (i think it’s the rotor’s fault)
Thanks a lot for the guide!!
Hello, I have an 81 cb 650 and i put the k and n podfilters on the bike. It also has a 4 into 2 exhaust system with baffels removed. I cannot seem to get this jetting right much like alot of the guys on here. I live near williamsport pa which is a couple hrs north of you so im assuming jets might be around the same. Ive purchased that dyno jet kit and also rebuilt the carbs. i have cleaned these carbs 3 times now but havent played with the jetting again. it only runs with the choke on spits and sputters and runs even worse as it gets warmer. Any help would be greatly appreciated.
i’m working on my -80 cb 650. installed mac 4-1, and 122 mains. pulls great on lower rpm but bogged on full theottle. so i threw stock airfilter, then it worked excellent. one option is therefore to install pods. or k&n filter in original box. anything with less restriction than stock airfilter. my q is therefore if i go with the pods, what have you done with the ventilation of the crankhouse which now is connected to stock airbox?
really nice page there!
Hello again. QUick question with the 79 cb650, if your running pods or velocity stacks what do you do wit the breather hose that comes off the valve covers and would have attached to the stock air box??
Hey, just bought a ’79 cb650 in excellent shape and trying to do the conversion to pods. I live in Boulder, CO, so I’m sure I will have to play around with your recommendations (5500 ft). About to take the carbs out, and as I am browsing the manual, it states that the slow jets are press fits and cannot be removed… How did you get around this with your bike? Were you able to remove them or did you drill them out while still in the carbs?
The slow jets do indeed pull out. Don’t listen to the manual. Use pliers and pull them out. Then when you put them back in… You’ll tap them in.
I purchased a 1980 CB650C last summer and have currently been in the process of doing a resto-mod with it. I’ll be running pods and a MAC 4 – 1 exhaust, upon looking at the Jetsrus website, did you use the Genuine Keihin main or the the OEM equivalent Keihin main set?
Also, are the prices per jet or do you get a set of 4?
Hey, thanks for the info on the slow jets, was able to swap them out no problem.
My new question is involves the engine stumbling when I hit the throttle, but once it is up to 2500rpm, it is completely fine. I initially suspected the accelerator pump, and sure enough it was not working. Fixed it (turns out there was a manufacturer defect in the diaphragm and there was no hole to allow fuel into the pumps reservoir) and tried the bike, same issue.
I have my mixture screws set to about 1.25 turns out right now, and have not had a chance to look at the spark plugs to assess the mixture.
I was wondering where you might suggest looking, and what your idle screw (not sure I have the right name, but the one on the top of the carb, right hand, engine side, turn by hand, is set at. I was doing a little reading and some people have suggested that the incorrect setting with that can lead to stumbling.
I’m going to look up the stock setting for it and try that, but was wondering if you had to play with it at all with this set-up. Bike starts fine and idles great, but at about 1200-1300 rpms.
Hey there! I have my bike set up with the suggested set up you have listed except I have a cut off exhaust, with small baffles (basically open pipes) and I have good idle, and good throttle response till about 1/2 to full throttle. Question is, with the open exhaust, would I need to go up in size for the main due to the increased airflow? Or down in size? Just trying to figure out which direction to start going!!
Thanks to anyone who takes the time to read this and answer.
This feed is great! one quick question..
Where would I find the Jets for my 81 CB650 custom Keihin carbs.. Having trouble Identifying them to be the correct jets.
I have a 1980 CB650 Custom with a CE Quieter Core exhaust, MAC 4-1 and K&N dual open air filters on it and I had to rejet the entire bike as well as tune my needles.
Don’t use those shitty Emgo filters, there are several design flaws. If you look at the inside of the rubber boots, you’ll see a lip, this actually creates back draft and doesn’t allow as much air flow as there should be.
Every circuit has to be inspected and adjusted. For reference sake, currently I have 42 slows press fit in (easy to remove gently with pliers) and I need to rejet my mains, probably going to go with 130s, maybe 135s. Also, be sure to adjust the throttle slide to the right position, many people forget to adjust that. Hope this helps someone out there.
Fitting nighthawk 650 carbs on xj 650 liveing in Denver Co. Trying to get stage two dyno kit read yours about rejetting touching base will stay in contact
Hello, and thanks for taking the time to write this article! Can you please clarify something for me?
I have the 79 with the Keihin PD50A carbs. The previous owner installed the Emgo filters and 4-to-1exhaust but never got it running properly. I believe he used incorrect jet sizes, so finding this article makes me very happy.
However, the size of air filters he installed were 42mm. Can you help me understand why you have 48mm listed? Is that why you needed to double up the rubber sleeves? Will I have any trouble using the jets you listed along with the 42mm pods?
I was just wondering if an aftermarket exhaust (Mac 4-1) will affect the readings of a compression test.
I have a ’79 CB650.
Manual says 170 +- 28, I am getting readings between 120-125 on all four cylinders.
Hoping to avoid getting back into the head…
Yes! Big thanks for this!
70 650 mac 4-1 K&N pod carbs Minnesota. Working through the carb right now, going to get it up and going try these jets and hit a dyno at some point this summer. Ill stop back when im done let every one know what I found!
You might want to add the needle height. It has to be in the highest position. I’ve done a couple CB650z’s and they all ran horrible until i put the needles in the highest positions (richest)
hey, dont know if this thread is still active but its worth a shot. great start out for the rejetting btw, but my question is, is there anything that needs to be done to the needle, like spacing and such when you rejet? i have an 80′ cb650 and ordered the jets and pods. I just would like to make sure there isnt any other odds and ends that were left out in this build that i would need to know when tuning the carbs. also, did you just put a breather filter on the ventilation port? please let me know when you can or any others, if this is still being seen. thanks!
worked a treat on my CB 650 z trike drilled both jets out so the fast jet was reading 48 and the slow jet 125 I couldn’t find 48mm pods so had to use 50mm cleaned carb to hell followed the instruction’s about float setup and mixture screw position also put an in line filter on the fuel line already had a four to one exhaust fitted on a oil cooler I picked up to help displace the heat form the increased fueling so first trial was delayed started on the button and ran well sounding awesome thanks for your thread
I have a 79 cb650. Converted the jets to 120 and 42’s. Emboldened pods. Mixture screws out 1.5. Starts and idles well. Sounds great. But only runs well with almost full choke. Any ideas? Too much air? Trying new plugs tomorrow. Thanks!
Joe have you sync the carbs first and invest in a gunson color tune if you want to get the mix ratio with out the faf of playing
I have an 81 cb 650 that i just put pod filters on and I was looking to order the jet kit listed here but apparantly they dont ship to california? is that right, and is there any way around that or another kit I can get?
The link provided for the 80-82 dynojet kit doesn’t work. I went to their website and I did find a kit, but I’m unclear if it’s bumped up jets for the pod application or stock jets. Also, does your recommendations for exhaust and everything else from the older models apply to the 80-82 as well
Just wanted to say thanks for the jet size info. I have a 1980 CB650, followed the 120/42 with pod filters and it idles great, lots of power and responsive. No issues at all.
thanks for this great info! i went with the 42/120. everything runs great, expect at cruising speed the engine seems to want to search. once i pull the choke out 1/4 it clears up. i went to a 125 main and it still does it. what is next?
Alright so I finally got my kit shipped to California, put it on as instructed though I didn’t check or adjust my float bowls. The bike will start up pretty easily but just pours gas out of the air filters. Seems to be all 4 pretty equally. So would that be my float bowls needing some major adjustment or perhaps the needle and the pin needing to be adjusted another notch?
I live in Denmark, the temperature in summer is 20 degrees.
Do you want to use 120 main jets and 42 slow jets, with pods filters on
My cb650z 1979, Keihin PD51A cab.
Gonna try to bring this thread back to life. I recently got a 1980 CB650 Custom. I’m going to run v stacks and straight pipes cut short behind the stock mufflers. I know it’s been asked before, but I didn’t find an answer. What jetting/idle mixture/needle adjustment would I use for this? I’m pretty much sea level (Florida).
got my 1980 cb650c running 🙂 it runs great other then it likes the choke out just a bit no choke it does still run just bogs a bit when revved up
I bought a 85 Nighthawk 650 over the summer that sat for 30 years. I took it to Scott at Alpha Dog Custom Cycles to clean the carbs and get it running. He insisted it had to be rejetted to account for ethanol. So he went up 5 sizes on the main and yanked the air filter snorkel off. It runs like crap and killed the fuel economy. As a test, I ran 10 galones of 92 octane ethanol free (5 tanks) on my 83 Nighthawk and it made no difference at all. Scott totally messed up my bike. And he kept my stock jets. Anybody know what the stock sizes are for the pilot and main? Thanks so much
I have been searching for the recommended size velocity stacks, but cannot find them. Would you mind telling me where you were able to purchase these?
I am having trouble confirming the exact model of my Keihin Carburetor, which is off a 1980 cb650. Looks very similar to the one that is in the pictures in this thread. What I am looking for is:
Correct Carb rebuild kit
120 main jet
45 or 42 slow jet
I want to run pod filters or velocity stacks on my 80 cb650. Currently it will run but only full throttle and fully choked with some backfiring.
Would you be able to provide links and info?
Thanks a bunch!
For anybody wondering about trying this with a 4-2 instead of 4-1 exhaust setup, this worked really well on my 1980 CB650: 4-2 exhaust, pod filters, 120 main jet, 42 pilot jet. With the stock jets I could only run on half choke and would still bog around half throttle; issue was completely solved by the bigger jets! Thanks to the author for this article!
For 83-85 Nighthawk 650 we have different carbs. If you have 4-1 with pod. Filters you will want to run a 40-42 slow jet. Stock is 35. And you will want to run a 125 main jet. I currently have 40 slow and 122 main jet with one shim on the factory needles and it’s a hair lean. Hence why I’m ordering 42 slow and 125 mains. I think that will be the perfect spot.
Hello, I’m looking to jet up to the sizes you recommended as I’m going for the same set up. Do you have the part numbers for those jet sizes ? The website link you provided is kind of confusing
What would you like to recommend. 4in2 open exhaust and stock airbox. It has stock jets and running lean I think. I am thinking about 38-40 idle and 95 – 100 main
So I’m seeing too much confusion. Lots of good information. Just hard to decipher. 1980 CB650 mechanical carbs. Open exhaust. Pods. I live in Mississippi. So you recommend 120/42 jets and then maybe sync and dial in? Just looking for clarification. This page is awesome though. Hope it’s still active.