Topic: Who would be willing to help me write up a sticky?

[Scott S]

 Been working on a "So, you wanna run pods..." sticky.

 We get dozens of posts from people asking about jetting, tuning, etc., and as most of you know, there is no set answer. WAY too many variables.
 Hondaman is working on a post about the functionality of the stock system; air box, how carbs function, etc.
 
 I would very much like someone that has experience tuning for pods or stacks to chime in. Do a "blanket" write up about the process of making them function. The pros and cons of going that route.
 This is the Hi-Po forum, but the sticky would be placed in SOHC$ Bikes forum, because that's where 95% of the newbies go to ask about pods.
 I would hope someone could touch on all of the variables: state of engine tune, exhaust choice, location, altitude, etc.

 Initially, I would like the first few posts to be informative, but then it would be open to questions and replies. It would also be nice if people could add their exact combo.

 Seriously, this is something we see asked about multiple times on a weekly basis. Is there anyone here with some actual experience that would be willing to write something up for the forum? I just sent Captain and email and have touched base with BWaller about in in the past (he suggested asking here for help).
 Please reply here or PM me if you can help. Thanks!

[Scott S]

 And I should add: this would be about stocks carbs, as that's what 99.9% of the people asking questions are running.

[slikwilli420]

Ill weigh in on this. Im running stacks and sock filters on stock carbs on my race bike, and it runs fantastic with only a main jet change. I would thing the high compression and bigger valves would exacerbate any poor settings on the carbs so I think I am pretty well dialed in. The caveat is that I am running a race bike, so it likes above the top half of the now 10K RPM range, really coming alive around 6,500.

The issue with pods/stacks on the street is multi-fold from what I have gathered. First, stacks and pods are not the same beast. Pods, largely, since most seem to choose the absolute CHEAPEST ones they can find, are not made to replace the internal velocity stack arrangement from our stock air box. Stacks, to me at least, are a far better alternative and can easily be filtered to give the filtration of pods with the flow more similar to the stock air box stacks. The last piece of the puzzle is the newby them self. Anecdotally from seeing how these new riders are building their bikes (skateboard seats, $99 shocks, bullsh*t tires) I am going to assume that they are not riding the bike in the upper half of the RPM range, where the intake signal is strongest and where the bike is designed to be run. Adding pods or stacks to a bike that is intended to putter around town at 2,500-3,500 RPM in a gear too high for the speed is going to make all of it work against the intended outcome.

I was convinced pods were the way for my '76F when I first bought it in my late teens (now nearly 20 years ago) and I put them on and did all the plug chopping I could afford, changing jets up and down, needles up and down, resyncing each time. I spent many full days trying to make it work. I would settle on a good setting that felt like it pulled decently, then the next time I ran it, it was off. It didnt idle, it didnt pull off idle, it only ran OK at above 3,000 RPM. What's a guy to do, put the stock air box with K&N filter in and go. Thing ran like a scalded dog right off the bat. Im convinced that unless you are racing, the stock air box is the only real good option to make this all work with stock carbs.

[Scott S]

 Thank you for the reply. We'll probably be merging some of these topics when we get the post started. Or I may ask you to copy/paste this there.

[dkihlgren]

I translated this from a swedish site www.braigasen.se
The owner is a real carb-guy

Carburetor with fuel screw
Most common on 4-stroke carburetors (except Mikuni HSR). A fuel screw is always located downstream of the throttle and is pointed

 

Low speed jet

Start up and warm the engine. Find a comfortable idle turn using the idle screw. Set the fuel screw to 1 turn.

Slowly open the fuel screw (or mixer screw *) - one quarter turn at a time - wait a while for the engine to react. If the speed increases significantly, adjust this down using the idle screw. Continue to open the mixing screw until you notice that the rpm is starting to drop. If the rpm does not decrease even though you have reached 3-4 turns ... Change to a larger low speed jet!
If the speed instead drops as soon as you open the mixing screw more than 1 turn, then screw it in instead. If the speed does not drop even though the screw is almost closed ... Switch to smaller low speed nozzle!
With the right size of the low-speed nozzle, you should have found a rpm hump somewhere between 0.5 and 3 turns.

You have the right low speed nozzle if you find a rpm hump somewhere between 0.5 and 3 turns on the mixing screw


Needle jet

Replace the main jet with one that you drilled to 3mm. Move the throttle needle to the leanest position (clip at the top). Insert a button pin on the twist grip. Then you attach a piece of paint tape to the twist gripts fixed part and mark where you have 1/2, 3/4 and full throttle. Run on 1/4 throttle on any of the higher gears on medium rpm preferably in easy uphill. In this test, the engine will get too much fuel at a certain throttle. It is when this happens that gives us an indication of whether the needle jet needs to be replaced or not.

If you can give more than 3/4 throttle (... maybe even keep full?) The needle jet is too small. Switch to a larger one!
If the engine gets drowned already at 1/2 throttle, the needle jet is too large. Switch to a smaller one!
If the engine is drowned at 3/4 throttle, the needle jet is correct.

Needle

Finding the right throttle needle is perhaps the biggest challenge when it comes to jetting. Mikuni has manufactured thousands and thousands of size-specific needles over the years. What separates all these needles is 1) the diameter of the first straight piece 2) the length of the straight piece before taper, ie before it starts to taper and 3) the conicity, measured in degrees.
    In this situation, we are content with adjusting the needle we have. It has five positions where position 1 (top) gives the leanest mixture and where position 5 (bottom) produces the richest mixture. To test the best needle position, you can test how the engine behaves between 1/3 and 2/3 throttle at different speeds and loads. Another way is to see which needle position gives the best acceleration from about 2000 rpm up to half throttle. Both of these tests are best done in light uphill.



Main jet

Now that you have found the right low-speed and needle jet, it's time to move to the high-speed circuit. Choose a test road where you can stay on full throttle.

Give full from 1/2 throttle and see if it responds well and wants to rev. If it doesn't, try plugging the air filter to 2/3 (... or give it a little choke). If this gets better, you will mount a larger jet.
If the engine fails to turn on and you think it is doing well on full throttle then test to hold full and then turn off a little on the throttle, not much just a little. If you then feel that power increases, well, after all, the main jet is too small.
If you want to make sure that you have chosen the right main jet, you can take the help of a good friend who sits further away on the test road with a timer. When he gives the start sign, you accelerate from stationary up through the gears until you reach the point where he stands and watches you. You change the main jet and make another run. The fastest time gives you the right main jet.
Please complete with a plugchop…

[Scott S]

 Slikwilli420 and Dkihlgren, would you both be so kind as to add these posts to this thread:

http://forums.sohc4.net/index.php/topic,182280.0.html

 A simple copy and paste would be fine. I just want the original authors name by it, instead of me doing it.

[Scott S]

 Thanks guys!