Nitrous??????

[EXDUNER127]

Does anyone know anything about nos...on a stock 400ex besides pipe, filter, ect. I heard it is pretty reliable if done right and not over used, I heard it works better on a stock bike, and Im meaning for just drag racing at the dunes, what r ur guys opinions.

[wilkin250r]

Nitrous can be very reliable if done properly. Most (if not all) problems with nitrous stem from trying to get too much power out of it.

Nitrous is a gas composed of nitrogen and oxygen. When compressed and heated (like in an engine during the compression stroke) it will break down into seperate nitrogen and oxygen components. With more available oxygen, you can burn more fuel, which will result in more power.

This has limits. Burning more fuel results in higher cylinder pressures. Combine higher cylinder pressures with a higher compression piston, and you are playing with fire. Not to say that it can't be done, but it gets touchy. I don't know if it works "better" with a stock engine, but it's certainly safer with the lower compression ratio of a stock engine. However, it also safer with a forged piston rather than the cast piston that normally comes stock.

Nitrous can be safe because you can choose how much HP you want to gain. If you only want a little gain, then you're safe. If you want to triple your HP, then you could run into some very serious problems. This is where nitrous gets it's bad reputation, from stupidity. People try to gain too much.

[EXDUNER127]

Will I be able to beat piped raptors and bombard's and pred's and what is the most HP I should get out of it to stay safe...What kind of piston-stock, aftermarket????

[AndrewRRR]

If you are going into your engine I'd get a forged piston. Nitrous creates more oxygen as it breaks down (at 500 degrees F or so), and the nitrogen acts as a buffer to the increased cylinder pressures. You need to make sure your fuel system can keep up, thats the reason most people blow up things, it goes lean very quick. I'm not sure how much you can do on a stock EX motor, probably around 10hp. I think there are a few people on this forum that have put nitrous on 400ex's.
P.S.- "NOS" is a brand name (Nitrous Oxide Systems inc.), Nitrous or N2O is Nitrous Oxide.

[wilkin250r]

I've seen many different theories about how much extra HP is safe. Most engines and transmissions can tolerate 50% more HP for short bursts without severly effecting reliability. I'd reccomend, if you go much past 10HP boost, you upgrade the clutch and rod.

Forged pistons are definitely better than cast pistons, and I'd most definitly keep the compression under 11:1 if you want to run nitrous.

Nitrous does a funny thing to the powerband of your quad. It will give you more torque and boost at lower RPMs. Nitrous is fed into your engine at a constant rate, which means you get more nitrous and fuel in each stroke at lower RPMs (ie, if you get 2oz of nitrous in each stroke at 3000 RPM then you only get 1oz at 6000 RPM) Now, your engine makes more power at high RPMs, but you get less "boost". The net effect is a power curve that looks like a two-stroke.

[AndrewRRR]

Yeah it's amazing what it will do for low end torque. Just make sure you have the throttle pinned when you hit it or your cereal won't be the only "snap, crackle, pop" you hear :uhoh:

[RAPTORAZ]

Originally posted by wilkin250r
Burning more fuel results in higher cylinder pressures. Combine higher cylinder pressures with a higher compression piston, and you are playing with fire. Not to say that it can't be done, but it gets touchy. I don't know if it works "better" with a stock engine, but it's certainly safer with the lower compression ratio of a stock engine.


Compression makes no difference in nitrous performance. It's all about the fuel. If you're on the detonation limit with an engine in N/A form then as soon as you start squeez'in she'll detonate. As long as the fuel(read 110 octane race gas) you're using can suppress the detonation than high compression and nitrous work fine. My Mach I has 11:1 compression with cast pistons and she's been handling a 175HP shot of nitrous for several years now. However I do run the system a little rich and I also use 110 octane Daco race gas when on the bottle.

[ChadEXer]

All throttle, NO bottle;)

[RAPTORAZ]

Originally posted by ChadEXer
All throttle, NO bottle;)


Given identical peak horsepower figures, a boosted engine will beat a naturally aspirated engine every time. Meaning if my EX was making as much power on nitrous as your EX is naturally aspirated, mine would spank yours every time. Because a boosted engine, whether it be from a turbo/supercharger/N2O, will make more power throughout the RPM band.

[wilkin250r]

Originally posted by RAPTORAZ
Compression makes no difference in nitrous performance. It's all about the fuel. If you're on the detonation limit with an engine in N/A form then as soon as you start squeez'in she'll detonate. As long as the fuel(read 110 octane race gas) you're using can suppress the detonation than high compression and nitrous work fine.

True, you need a higher octane to run nitrous. However, not all problems with nitrous are associated with detonation. You can increase the cylinder pressures beyond the ability of the rings and gaskets to withstand, and a higher compression piston will make that more likely, even if you don't have a problem with detonation.

Just like I said, nitrous can still be used with a high compression piston, in fact it works very well. It's just a lot easier and safer to use with a lower compression because you are less likely to run into problems with detonation or increasing cylinder pressures.

Me personally, I run my nitrous a little lean. (this is not a recomendation) because I only have a 1lb bottle. In accordance with Boyle's Law, as tempurature drops, so does pressure. A lean condition is dangerous because it will overheat your engine. However, nothing happens instantaneously, so it takes a while for your engine to overheat and melt your piston. When I hit the button, the initial charge will actually cool the piston, but the extra fuel and lean condition will cause it to heat up very quickly. Since I only have a 1lb. bottle, the pressure also drops very quickly, which will result in less nitrous, same amount of fuel, causing it to run richer the longer I hold the button because my bottle pressure continues to drop.

[EXDUNER127]

Any pis of set up with nitrous, any pics of your n20 switch(button)
and where do you hide your bottle? So to run this set up safely look at my sigs. what else should I get 4 my bike be4 I install the nitrous, what recomendations now that I know that its safe to use. And how much HP (max) should I set up for?

[wilkin250r]

If you want to learn about nitrous, do a web search. You will find lots of information.

My nitrous kit came from NOS, a division of Holley. You won't find the kit on the web site, you'll need to order the catalog. Just the catalog itself has a lot of information in it, and the kit will come with complete instructions.

My activation switch was a small push button on a small metal bracket attached with a large hose clamp right next to my headlight switch. It was pretty rudimentary, only meant as a temporary solution. I can't give you pictures right now, since my quad is dismantled awaiting a complete rebuild.

One necessary item is a small fuel pump. If you get a kit from NOS, it will have one with it. The kit has a small nozzle with two lines attached to it, one for fuel and one for nitrous. You want the fuel pump going directly to the fuel solenoid and nozzle, not to your carburetor.

Nitrous is best when injected directly into the cylinder. I first tried installing mine in the airbox boot going through the carb, but I got much better performance when I moved it to the insulator boot between the carb and the air intake on the head, so I sprayed directly into the intake instead of through the carb.

I removed my toolbox and installed my bottle there.