coast enrichener, among other things

[gokartmozart]

just registered about 1 hour ago , and could not get much info off another kaw forum . hope more knowledgeable people dwell here, my new kart project is a 250 ninja on an alum chassis built for clay oval racing . my question is, the vacuum hoses coming from the carbs ,one supplies vacuum to the fuel petcock ,ok so far . the other supplies the coast enrichener --- do these vacuum taps provide a pulse or a constant vacuum??? reason for asking, a fuel pump is required to overcome centrifugal force affecting fuel delivery,choices are electric or vacuum pulse. I could go either way here , but the simplest looks like the mikuni pulse type . don't want to look stupid but i'm not able to run engine right now to test vacuum, also need to pull carbs for cleaning in the ultrasonic tank

[Motofool]

Originally Posted by gokartmozart

........... do these vacuum taps provide a pulse or a constant vacuum???..........

Welcome, Randy !!!

The vacuum signal is always pulsating, in proportion to the rpm's.
Each time one of the pistons is in the admission stroke, the vacuum tubes feel a peak.

[choneofakind]

Think about it for a second. The vacuum in each carb is made by air flowing through the the venturi section of the carb. The pressure drop (or vacuum, as it's referred to) happens as air flows through a section of necking diameter followed by expansion again. Speed increases in the smaller diameter section, and pressure drops because of that. It's the same theory that allows airplanes to fly.

Now that we know why it's caused, look at how air flows. Every time a valve opens and the piston goes down, air is drawn into the head, through the carbs.



So we can assume that the vacuum will be full of pulses, since it's being created by a piston moving air in strokes.

If you have a vacuum gauge, you should be able to hook it up and read this, although the pulses will be quick and likely make reading the gauge difficult. The other way you can validate this visually is by syncing your carbs using the two bottle method. http://faq.ninja250.org/wiki/How_do_...-bottle_method Eventually, you'll see pulses of water vapor showing up in the bottles that corresponds to the speed of the engine firing.

[quarterliter]

Originally Posted by gokartmozart

just registered about 1 hour ago , and could not get much info off another kaw forum . hope more knowledgeable people dwell here, my new kart project is a 250 ninja on an alum chassis built for clay oval racing . my question is, the vacuum hoses coming from the carbs ,one supplies vacuum to the fuel petcock ,ok so far . the other supplies the coast enrichener --- do these vacuum taps provide a pulse or a constant vacuum??? reason for asking, a fuel pump is required to overcome centrifugal force affecting fuel delivery,choices are electric or vacuum pulse. I could go either way here , but the simplest looks like the mikuni pulse type . don't want to look stupid but i'm not able to run engine right now to test vacuum, also need to pull carbs for cleaning in the ultrasonic tank

I'm curious what made you pick the ninja 250 engine over a 250 motocross engine. They make more power, in a much smaller package with much less weight.

[xXecuterXx2]

Originally Posted by quarterliter

I'm curious what made you pick the ninja 250 engine over a 250 motocross engine. They make more power, in a much smaller package with much less weight.

Very true, throw a 250 2smoker in there and that kart might damn well take off into the sky.

[quarterliter]

Originally Posted by xXecuterXx2

Very true, throw a 250 2smoker in there and that kart might damn well take off into the sky.

I wasnt talking about a 2 stroke, I figured the class he wanted to run in would only allow 4 strokes. But even the 4 strokes make more power than the ninja 250.

[xXecuterXx2]

Originally Posted by quarterliter

I wasnt talking about a 2 stroke, I figured the class he wanted to run in would only allow 4 strokes. But even the 4 strokes make more power than the ninja 250.

Again, Very true. I didn't consider classification, my badddd.

[gokartmozart]

First of all, I don't like 2-smokers much , ever race behind one? ...and they sound funny. Not putting down their HP/weight ,just prefer a 4-stroke

[HoneyBadgerRy]

Originally Posted by gokartmozart

First of all, I don't like 2-smokers much , ever race behind one? ...and they sound funny. Not putting down their HP/weight ,just prefer a 4-stroke

As a die hard two stroke racer since I was a kid, I don't understand what's to not like, and I think four strokes are the ones to sound funny. Rotary and two stroke motors sound cool.

[agentbad]

Kind of like if a lawnmower and a chainsaw had children.

[HoneyBadgerRy]

To me, a single cylinder four stroke sounds like an old man farting, and a single cylinder two stroke sounds like a high tuned racing machine.

[gokartmozart]

No debate... some people like fords , some chevys. I'll stick with my 4 strokers , just like the one you're riding now.

[choneofakind]

Originally Posted by gokartmozart

some people like fords , some chevys.

But no one likes Dodge! Darn things.