Air Filters and Jetting

[ndbigfish]

I have a carburetted 99' that had a V&H exhaust set put on it and was re-jetted with Factorypro components. I think the pilot jet is #42, the main jet is #120 and needle is in the second position. It's fine and it will get 40 mpg if I drive like I borrowed it. What will happen if I install a K&N air filter to replace the stock paper element filter? I tried a Caddmann conversion and that will definitely require carburetor work. I would like better air flow without lots of work.

[blowndodge]

If you install a K&N filter you will save costs on replacement paper filters.

[macmac]

Do you know for a fact that there is just 2 jets? I suspect there is 3 which is more bike typical, but I don't know that is fact... I never owned a carbed Nomad is why.

With a right side working air intake you are going to need more fuel to match the more air the right side intake gets, no matter if the filter is K&N or paper.

If you do a left side K&N the cross over tube will still limit air flow.

Doing the Caddman kit as duel filters pretty much means the bike looks even, but the left side filter don't supply much if any meaning full air.

[ringadingh]

Just switching filters as you described probably won't change anything. It will probably breathe about the same as it did prior.

[ndbigfish]

Originally Posted by macmac

Do you know for a fact that there is just 2 jets? I suspect there is 3 which is more bike typical, but I don't know that is fact... I never owned a carbed Nomad is why.

I could only find this much information from the exhaust changeover. It sounds like an all or nothing case; switch to a right side air filter and re-jet as appropriate.

[macmac]

Originally Posted by ndbigfish

I could only find this much information from the exhaust changeover. It sounds like an all or nothing case; switch to a right side air filter and re-jet as appropriate.

Well yes sort of.. A left side only K&N is still limited to the air flow the cross over tube can do, plus that tube gets warmed up pretty good, and thew engine breaths pre-warmed air, not good.

You can leave the cross over tube and mount a filter there as stock or K&N if you want to, but if you add a K&N to the right side the left side becomes moot, or for show only.

Some people like the look of twin dog bowls and others don't, which leaves the left side a place for something else or it can be naked.

There are folks that don't want to ruin, and so remove the cross over tube, and for them the left side becomes a fake filter even if there is a filter there.

The one advatage I can see to have a folter on both sides is one day my right side filter came off riding. A car hit and dragged the paper element away i guess because i never could find it, and the same ca hit the chrome cover.

So I took off the left side cover and filter and installed them on the right side, and stuffed a rag in the cross over tube to stop any flow from that side what so ever.

In a bit more time I decided to go right side only and get naked.

I used to like tinkering in jettings, on bikes, but I have become spoiled with fuel injection and the ability it has to dial in fuel to meet certain things..

If I want fuel economy on a long ride I can dial it in and ride that way. If I want to go horse around I can dial that in too, and all it takes is a small screw driver.

In doing jetting I found some hits long ago were better than others, and I found even the best sometimes contained the wrong jets in the kit. It became a matter of seat of the pants diagnostics.

One had to know where in the rpm bands he was in order to know which jets were working and which were not. That is speaking in terms of 3 jets per carb..

IF the kawii carb has just 2 it is more simple matter to tell which is the idle speed jet and which is the main, as that way IF this is what it is, there is no mid range jet.

I don't know if there is 2 or 3... So far as I can tell the camming in a Nomad isn't like it is on sport bikes and bikes like my 1981 XS 850. My 850 hit about 6,000 rpm and gets all full of get up and go, making any cruiser look like it is standing still and that counts all the big bore kitted Harleys.

That bike is a sort of what was called standard bike, and the grand pappy to sport bikes, but it doesn't look like a sport bike.

So no Nomad I know of has that upper end wack in the pants, and all the power is created in low end grunt. The range of torque is even and there is no lift in the breathing where it almost feels like the tranny was down shifted to get more rpms fast..

If I were going to jet a Nomad I would want to know what jets there are now and what the drill sizes all are first.

Then all at the same time I would buy what ever exhaust set, and intake set the bike was going to get this time and then in a book try to figure the jetting.

Unless someone before did the same thing and documented what they did well you are are you own in the doing and the spending.

I worked on a custom cam shafted honda set up for racing and it had a custom exhaust and a custom intake so it was all unknown.

It ended up with jets from 4 different jets sets concerning the expences. It was a while ago, but one set of jets was useless, and the other sets each contained one jet that worked in its range to meet the camshaft and the rest of the set up...

I doubt this would be the case on a Nomad made for the street, but I am saying this so you don't expect to buy a set of jets and some how have everything work out as planed.

That Honda ate up more time getting the float levels set too. Just making a change in 4 carbs takes time to get each one the same.

Once you do then the 2 inner carbs become another matter again since the inner 2 run hotter than the 2 out board carbs do.

That makes a need to get the inside carbs a little richer yet.

So using the float for micro fuel management is something a Nomad can use besides jetting.

[blowndodge]

I'm pretty sure all 4 stroke carburetor motorcycle engines have an idle jet, needle jet, the needle (slides up and down inside the needle jet and main jet.

[macmac]

BD I have seen a lot of configurations, some where in a row there are 3 internal jets besides the main needle jet.. Some are screw in jets and others are pressed in and have tiny o rings.

I have no idea what type and or how many there are in a Nomad Carb. The only way I will is if someone shows up needing a fix of some sort.

I suspect 3 and hope screw in...

[tylerai]

Originally Posted by macmac

If I want fuel economy on a long ride I can dial it in and ride that way. If I want to go horse around I can dial that in too, and all it takes is a small screw driver.

Can you explain that a little further. I would like to "Dial In" a little better for my longer rides.

[macmac]

With the early version of the TFI you can mess about with pot #2 for more fuel in get up and go, and or lessen the time the fuel is called for for a somewhat more economy.

I think you can do the same things with the plug and play version as well.

When the topic is what setting is your TFI at variations tend to be wide.

Each bike varries some from anyother. Each ride rides a bit different than anyother. Fuels varry, and so does about anything.

My economy mode still gets me more power than than stock. My settings are pot 1 (1:30) pot 2 (3:30) pot 3 (1:00) pot 4 (off)

If I want to romp around in the back woods I might set pot 2 to as much as (6:30)

I am happy with pot 1 (idle) as is and can run and do run 87 octane fuel all the time.

The settings I use on pot 2 allow for No Ping ever running 87 octane, the lowest i can get.

Pot 3 is duration which can verry the time pot 2 works, and if i wanted to just go wild I could mess with the time, but dont. I am not into total hell raising.

Almost nothing is written in stone, when folks take it to be. A really good example is when folks work up mix in carbs.

A book will say the idle mix screw (on a bike it is called pilot screw) should be set at so many parts of a turn out from the seat, usually this will be 1.5 and or 1.3/4 turns, but this setting is a book setting and is ment to be a book setting for a new engine that never ran, and or a carb that was rebuilt.

So the setting is not and will not be correct for that particular engine. To find that you need either very good ears or a tach. And with the engine warmed up you 'dial' in best idle mix for fuel, and then a bit more, because all internal combustion engines tend to lean out under a starting off load.

So do injected engines. So with a TFI and a economy setting you can demand more power and not get it. That is when another adjustment is called for.

My economy settings still get plenty of romp, and I exceed the stock ecomony by a good margin. All stock this 06 Nomad got 34/36 the way I ride. With the assorted other than stock parts I got 46/48, until I added a car tire, which ate up some economy and it gets 42/46 now, still better than stock.

Others don't match my figures... But I don't know what all I did different from what they did.

My ISC are out in a card board box, the vac pod is out in the same box, the reed valves are disabled. In the doing the hose a marble might go in is just gone in the box too.

Another reason the car tire might eat up miles is it is a different diameter, but it is taller than stock still so it shoiuls have imporved things under economy.. On the other hand it has Traction Mista' and cornering is like being wired to a rail, and braking is a nightmare in Whoa!

Living in the sticks i don't use brakes much, just don't really need them and I can down shift and just drag on the brakes a little bit. Of course holding a stopped bike uses no brake material. The only time I come close to a panic stop is for Moose, Bear and Deer..


Back to TFI... I don't read the info on the papers and set the bike to what is said.

I start with just idle and pot 1 in neutral. This results in a too high idle and i must turn the air down, and re do pot 1. Once that setting seems correct i hit the road and adjust pots 2 and 3 which work as a team the way i see things.

[ndbigfish]

I spent some time reviewing the Keihin CVK40 carburetor on my 99' and it has (1) #45 pilot jet, (1) #120 main jet and (1) needle. When my V&H exhaust was put on the needle was changed to one with clips and shims (0965h7-48u7_SS). The clip is the second position and the main jet was changed to a #125. The pilot air screw was adjusted out 3 1/2 turns. The spark plugs were dropped one temperature range.

I am thinking I would like to remove the stock air filter system and replace it with an 8 1/2 inch K&N "coyote conversion" filter. I gleaned from Gadget's page that I could use the original needle with a #170 main jet and adjust the pilot air screw out 3 to 3 1/2 turns to start.

Any pointers about the spark plug temperature range? Should the pilot jet have needle in it? I could not see one in the microfiche I was looking at.

[macmac]

That seems do able to me. Understand I have never seen a Nomad kawii carb, but that info seems about right to me.

And no the pilot jet will not have anyother needle ever, except the pilot screw.

Pretty much you can leave things as they are and simply swap out the jet, and go test ride.

In order to do more you first need a symtom you don't like.

If and When that time comes then other options open up.

The float controlls the level in the float bowel. Raising that level makes engine vacuum get fuel easier, while lowering that level makes it harder.

A bigger jet does the same thing in a fuel circuit. A more tapered needle with a faster taper increases fuel. Raising a needle opens the main jet more and also places a more tapered part of the needle in it.

Plugs are not hotter or colder in as much as sparking is concerned, the difference is the thickness and length of the ceramic at the center electrode. A plug too hot will detonate fuel too soon, and a plug too cold will not burn off ash deposits.

I'ld stay with what you have and let the plug tell you what to do.