Purpose of Airbox Snorkels?

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Re: Purpose of Airbox Snorkels?

Post by navigator »

Fred wrote:
hillsy wrote:On the 1500's if you cut out the top of the filter or replace with a GMan open K&N you have to re-jet both main and pilots.
That what they may say to cover them selves from unsatisfied customers.

Re jetting is not easy its not a case of this bike uses this It just does not work like that. Do the Mod and see what you got.

You can not acheive full throttle by twisting the grip--that would be a cable operated slide. The CV carb needs full depression and that builds up from engine demand. You would need full throttle and almost full RPM I most certainly can not achieve that on any roads around here.
Therein lies your problem Freddie, you constantly tout that rejetting is not necessary. After reading this, I now know why. You never got a chance on any of your roads to reach full rpm! you put around town, and in that case never lifted the needle high enough to exceed the main jet delivery.
Here in the states we can actually get the slides lifted to the max, and jump up a size on the main jets.

Have you ever tuned a LC? Nobody makes them bikes go faster than GMan.
And I have never heard of anyone that was unsatisfied after having GMan work their carbs.

BTW, a 800 will run out of fuel delivery long before you hit anywhere near top rpm or redline.
The 1400 limits that top rpm.

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Fred
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Re: Purpose of Airbox Snorkels?

Post by Fred »

No--(using your words) I constantly tout that changing the main is not necessary. I have never said the Needle does not need adjustment I also say the idle needs increasing.

Its was a few posts back now--maybe you have forgotten.

What I say is don't just jump in with a bigger main without seeing it through. Most people seem to want to buy exhausts and air pods along with jets all in one box.

It don't work like that

I make my own jets.

Just to recap before we go completely off the rails this thread is about a removal of air snorkels and possibly a pipe swap.

This was about making street bikes ride able after pointless sunday afternoon modifications.

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Re: Purpose of Airbox Snorkels?

Post by WintrSol »

Fred wrote: You can not acheive full throttle by twisting the grip--that would be a cable operated slide. The CV carb needs full depression and that builds up from engine demand. You would need full throttle and almost full RPM I most certainly can not achieve that on any roads around here.
I've seen the pistons rise all the way when the bike was not moving, by just racking the throttle open, because air flow is a direct function of throttle and rpm, not power generated; accelerating hard in the lower gears can certainly achieve the same thing.
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Re: Purpose of Airbox Snorkels?

Post by Forge »

Actually, this thread was just about removing the snorkels that feed the airbox. While we are on that though, on my '05 S83, I have factory headers and Vance & Hines Classic 2 slip ons. I also have K&N Drop ins and a Dynojet stage 1 kit that uses the factory jets but has the adjustable needles which are set to the 3rd position per Dynojet's tech support. I have now removed the snorkels that feed into the factory air boxes so that there is a slightly larger intake hole feeding each jug.

In theory, or if someone has done it already, how much more can I open up the factory air boxes to maximize air/fuel flow through the factory headers. I do not want to over do the airbox mods, but don't mind adding an additional hole if more air/fuel flow can be achieved and utilized. I also do not want to swap jets, but I can try different needle positions as well as air/fuel screw adjustments. Like I said, I have the K&N drops ins which are capable of moving more air than the foam elements. I know that the factory headers will only allow so much volume, but I want to stay with the factory headers. I only want to enhance and maximize what the bike can do with this setup. I do not want to create a "top end only" machine, but I do like to feel her every so often on the highway.
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Re: Purpose of Airbox Snorkels?

Post by WintrSol »

If you install fresh spark plugs, then examine them after a good ride, they will give you an indication of the overall mixture, assuming you don't spend a lot of time idling. If the black on the insulator is close to the end, you may be a touch rich, and a little more air may actually be a good thing. If, however, they are already white more than 1/2 way to the bottom, you are probably lean; raising the needles one notch may be in order. Reading plugs used to be easier with leaded fuels, as there was also a shade of brown, helping discern lean vs rich. Changing the intake restrictions has a much greater effect on mixture than the exhaust, as long as that exhaust wasn't overly restrictive in the first place, which it wasn't.
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Fred
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Re: Purpose of Airbox Snorkels?

Post by Fred »

WintrSol wrote:If you install fresh spark plugs, then examine them after a good ride, they will give you an indication of the overall mixture, assuming you don't spend a lot of time idling. If the black on the insulator is close to the end, you may be a touch rich, and a little more air may actually be a good thing. If, however, they are already white more than 1/2 way to the bottom, you are probably lean; raising the needles one notch may be in order. Reading plugs used to be easier with leaded fuels, as there was also a shade of brown, helping discern lean vs rich. Changing the intake restrictions has a much greater effect on mixture than the exhaust, as long as that exhaust wasn't overly restrictive in the first place, which it wasn't.
If only it were that simple. With reversion you can have black plugs and yet the bike acts weak . With reversion it just shocks the fuel straight back through the cylinder.

Reversion is a common result of badly matched exhausts. This is why I mostly advocate leaving alone. A motor cycle is plagued by reversion not having the ability to have a long enough exhaust system to manage it.

here is a twin Kawasaki suffering quite badly



So as you can see in this case the fuel is not even getting there. Even raising the needle and adding more fuel would make no difference at that RPM.. You would be rich at 2000 rpm and weak at WOT. Most people would increase main jet to cure that with no effect at all.

Again a lot of people ride around at full throttle and would not see what is happening under the seat. If you have fuel pooling in or around your venturi or air box you have reversion. Most bikes do but its handling it. Throw this in with jetting as well and you are beginning to know what I am talking about.
I
I have said before a motor cycle engines breathing starts at the air filter and ends at the tail pipe and its ALL one package.

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Re: Purpose of Airbox Snorkels?

Post by WintrSol »

Quite right - exhaust tuning for a wide range of rpm is difficult. Changing the head pipes for shorter length or larger ID can really make an engine have problems. Slip-on mufflers without enough flow control (often open tubes that look like mufflers) can mess things up, as well. Granted, the OEM has noise restrictions to follow, but engineering the system for general ride-ability is tricky work. You have to control reversion, and tune the system for adequate scavenging over a range of frequencies; kind of like tuning a flute, there's only one perfect note, but many overtones that can help.
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