CB360 Jetting with Pods - final answer

redwillissuperman

redwillissuperman

Keep it simple- engine, wheels, bars
Elevation: 622ft
Float height: 21mm

Stock carbs, Stock exhaust, Cheapo pods: 110 Secondary Main, 68 Primary, and 35 Slow (which is stock since the air pods are as restrictive as the stock filters except the higher float height does give it a bit extra fuel)

Stock carbs, "Race" exhaust, Good filters: 120 Secondary Main, 70 Primary, and 35 Slow

Stock carbs, "Race" exhaust, Velocity stacks: 125 Secondary Main, 72 Primary, and 35 Slow

The last setup may have benefited from some needle tuning but since this was all done on the bike from underneath.
 
21mm float height is actually LOWER than 18.5, meaning the floats shut the fuel off sooner. The smaller the number the HIGHER the fuel level in the bowls.
 
Hmm, your right! Working with the carbs on the bike has produced some mind-bending screwups (righty-tighty except when looking at the tip of the screw driver)!

I can't explain why the baseline jetting produced the best throttle response and pull through the whole rev range. I didn't hook up my heated oxygen sensor since the antiquated electrical system of the vintage Honda doesn't lend its self to that many amps.

Maybe that's why people can never gets pods to work- they are adding fuel instead of taking it away....

That low float height might explain the bump in jet size with the last mod. If I get the porch painted early enough, I'll try to change it back to 18.5 and reset.
 
The reason why guys have issues with pods is not really the jetting, that all can be reasonably fixed with plug chopping and rejetting and TIME. The issue is the carbs are designed to have a SET air flow behind them. Any major deviation in that flow less/more will cause a different pressure IN the carb and will cause the VACUUM actuated slides to RISE sooner or later in the RPM range than intended. That causes a RICH/LEAN condition that can be very hard to trouble shoot. The fix is changing the air corrector jets in the TOP of the carb. Crazy PJ is more inept at that than I am, I kept the stock boxes on my bike mainly because I didn't want to have to mess with all that. ;D

Where are you picking up your jets?
 
What do you mean by "race" exhaust? I'm running a significantly modified 360 and all I've done is gone from 110 to 115 secondaries.
 
Hey Matt I had question pop up in my head the other day, you have any idea what your air corrector jet numbers are in your carbs? I'm wondering if there is a difference in size from a CB to CJ.
 
Sonreir said:
What do you mean by "race" exhaust? I'm running a significantly modified 360 and all I've done is gone from 110 to 115 secondaries.
Click to expand...

Open headers with a short extension, no baffles or mufflers. I would assume that any of the 2-1 or 2-2 variations of a Yosh or others exhaust would have similar zero back pressure, and most probably better exhaust pulse tuning. Quick test setup though.

I really Hate "elastic band" throttle delivery or any stumbles. This setup gave me the perfect pull.

If the engine is slightly tired, the elevation higher, slower throttle opening, etc can change things. This was to give everyone a good baseline on the same bike, same day with popular choices.

Also, see the findings about the float height being down a bit. I usually like to run my float up and I make a perfect seal on the float bowl so no leaks (except after this winter where the seal popped on the one carb because I used the side stand)
 
correction.gif


This handy chart shows some jet correction for altitude and temperature.
 
frogman said:
Hey Matt I had question pop up in my head the other day, you have any idea what your air corrector jet numbers are in your carbs? I'm wondering if there is a difference in size from a CB to CJ.
Click to expand...

Sorry man, not a clue. All of the jet settings for the CJ are on page 146 of the Honda manual, but just going from memory, they look the same as the CB.
 
CB and CJ have different jetting to compensate for different exhaust systems, I think the air jets are the same though
Just changing jetting WILL NOT WORK when main jet is right (try cruising at 4~5,000rpm)
I posted the 21mm float height with pods a long time ago
 
That's what I was wondering, my bike has a stutter now at 3500-4000 BUT I have more or less stock CJ air filters/housings CB carbs w/JBM diaphragms and Mac dual taper mufflers that end right after the axle bolt. Pulls fine all the way through IF I'm WOT and going. Idles fine, but IF I'm out messing in town and the RPMS NEED to be at 3500-4000 it stutters and lurches, soon as it is out that area its fine. I was thinking maybe the CJ carbs had different Air corrector jets for the different style filters, and that is causing the slides to rise early and richen up the mixture right then. Thing is it did it with the stock diaphragms. Needle jet is currently 2 over stock (102) I have tried as high as 110 but that just made it way rich up top. Float level is 18.5mm new float needles and seats.

Ignition advance is working correctly, checked repeatedly with a strobe, both sides. That's why I figure its the carbs. Maybe move the primary jet down a couple? Say 65? Something else I'm missing?
 
redwillissuperman said:
Open headers with a short extension, no baffles or mufflers. I would assume that any of the 2-1 or 2-2 variations of a Yosh or others exhaust would have similar zero back pressure, and most probably better exhaust pulse tuning. Quick test setup though.
Click to expand...

That's why I asked. It' not uncommon to have to jet up from 110s to 120s just by shortening the exhausts. The 360 doesn't care for shorter exhaust systems and despite the extra fuel needed, I doubt it's adding any power.
 
frogman said:
That's what I was wondering, my bike has a stutter now at 3500-4000 BUT I have more or less stock CJ air filters/housings CB carbs w/JBM diaphragms and Mac dual taper mufflers that end right after the axle bolt. Pulls fine all the way through IF I'm WOT and going. Idles fine, but IF I'm out messing in town and the RPMS NEED to be at 3500-4000 it stutters and lurches, soon as it is out that area its fine. I was thinking maybe the CJ carbs had different Air corrector jets for the different style filters, and that is causing the slides to rise early and richen up the mixture right then. Thing is it did it with the stock diaphragms. Needle jet is currently 2 over stock (102) I have tried as high as 110 but that just made it way rich up top. Float level is 18.5mm new float needles and seats.

Ignition advance is working correctly, checked repeatedly with a strobe, both sides. That's why I figure its the carbs. Maybe move the primary jet down a couple? Say 65? Something else I'm missing?
Click to expand...

Try setting float at 21mm, it helps.
65 primary main jet may also help but then you will need a larger secondary main jet (not needle jet)
Main problem is, the correct jet is not available.
You can get one that fits but is 2mm too long
The 3500~5000 problem is why I've been modifying carbs for people
 
Didn't get a chance to repeat the testing with the floats set at stock height but it sounds like I won't need to. I usually run my floats in my car a bit higher to help off idle transition....but I guess I lucked out.

No issues accelerating or steady state cruise. No matter how fast I twist the throttle, no bog or flat spots :)
 
Ok, new to DTT, and FIRST bike. I have a '76 CJ360T, k&n pod filters, open exhaust, rebuilt carbs, 18.5 float height, and stock timing. I timed it, synced carbs, new plugs, and rejetted with 120 and 65. Starts and runs well except under load. It loves to accelerate, but stutters and pops (sometimes pulling away from a dead stop) while cruising--especially in 3500-5000 rpm. I am 8 feet above Sea Level. I keep fouling right plug and left plug looks good. I was thinking about changing float height to 21 and see how I fair. My time for wrenching is limited and am trying to dial it in as quickly as possible. Yes, I used the 2mm longer jets how much will that affect what is going on?
THANKS!
 
B2toad, if you read through the 360 carb information, you'll see you have various things that don't work
360's are a bit specific on what they WANT with stock carbs, they don't care what you want ;)
 
Crazypj,
I read a lot of blogs prior to settling on the jets I put in my carbs. I am confused as to your comment... Please tell me what I need to do to get my bike dialed in. As I said, first bike. I love the way I got it to look, just displeased by the current performance! I am ready and willing to send my carbs to you if you still work on other people's carbs!
Your help is GREATLY appreciated!
Thanks!
 
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