400ex Nitrous Users

[itsallgood]

I need to get in touch with someone that is currently using nitrous on their 400. I need to ask a few questions, not the newbie questions about how much power i'm going to gain, or if I'm going to blow it up, etc.
I need to talk to someone that know's what they are doing...
PM me if your interested in helping me out a little.

[LazeR]

Just ask on here, im sure someone will be able to help you :)

[itsallgood]

I would like to post the questions on here, but someone that doesn't have any experience with it will reply with an answer that might be misleading and that's what Im trying to get away from...

[dunedragger]

So evidentially its....not all good? This is a place where all incorrect answers are corrected and correct answers are backed up.

[LazeR]

A few ppl might say something about it even though they dont know much about nitrous, but i gaurenty you will get some answers from ppl that know what there talking about.

[wilkin250r]

If somebody posts something incorrect or misleading, trust me, I'll correct them.

So with that aside, I would prefer to have the question posted here in the open so that anybody else curious about it can learn a thing or two. Also, if any incorrect information is posted, then I would like to clear up any misunderstanding out here in the open for everyone to see.

The whole point of this forum is to a place you can look for knowledge, and read up on things that intrest you, and gain from somebody else's experience. How can anybody else search and learn if the entire exhange is done through PMs?

[Demoniac]

I know someone who uses nitro, he's told me a lot about it, ask me and I might be able to help, one major thing though is that if you use it and power your engine up too much you'll blow the engine and replace it, he's done that like 5 times a year, or even more probably, he's even gotten flames on the engine and exhaust from too much nitro, he's insane :devil:

[itsallgood]

Okay, here goes then...

What kind of pressure are you running your fuel at?
What plug are you running?
What jets are you running in your fuel/nitrous lines?
What compression are you running?

What have you found to work the best for your setup?

Keep in mind this is for a NOS setup on a stock 400ex.

I will be rebuilding this winter and that's why I'm trying to get different rider setups. Right now the carb, piston, head, etc. are all stock. Except the slip-on (WB-R4)...

[Syrus]

Well im not a nitro user, but i do know a few things about it. Your going to need to replace your head gasket with a thicker aftermarket gasket, the stock wont hold for long. You will need to find the safe amout of NOS to use, to much and you'll pouch the engine in no time, if u get the right amount for each time you use it, your engine should hold up for a fair amount of time. What i mean about that, is a safe level of Nos, if you just have a trigger to hit, and spray as you go, you may spray to much, for to long, and just heat that badboy till it pops, find the same amount and it should be fine for a long period of time. It will wear your stock engine down, so putting in aftermarket rod, crank, piston etc will help her hold up. Its not safe, but play it safe anyways. Ive heard of to many stories of ppl playing with nos, never a good ending :eek2:

But nos is amazing, use it with care and you'll be just fine. Im not an expert but i hope it helps.

[itsallgood]

Thanks, that's some of the information I was looking for...(Head gasket issue)

I've talked with some people that reccommend the smaller bore, un-ported head, and stock carb for the nitrous. What's the scoop on that issue?

I'm going to tear the motor down soon and want to know what I need to replace inside the engine so I don't have to worry as much about it coming apart. I know every nitrous user says they don't plan on putting much of a shot to it, but ends up doing so. I just want it to play with, nothing to use all the time, etc. So it will be a pretty small shot. I do plan on staying with the smallest bore possible, just in case I do tear stuff up while getting it perfected. But would the port/polish really make that much difference with the nitrous?

[dunedragger]

Hey, check this out, this may be the way you want to go www.boondockers.com "And thats all I got to say about that"

[dunedragger]

O.K. one more I guess www.magnumforce.com

[1fast400ex]

i run nitrous everyweek in the summer all i do is dirt drag. my 400 has ran fine for 2 years on nitrous. no freshing up no nothing. BUT i dont lean the bike out. thats one of the biggest problems with nitrous is running lean, yes it will run like a mofo running lean, but not very long. another thing if you buy a nx kit the instructions has a sentence in it that say DONT LISTEN TO YOUR BUDDIES TELL YOU HOW THE JET FOR NITROUS READ THE DIRECTONS. this is the best advice i can give. octane rating for your fuel means alot. regular 93 will let the bike lean out at the end of the track or sooner. i run 112 octane no problems with that. weather temps changes how the bike runs with nitrous. and the pressure in the bottle as well. also you might check out atvdra almost everyone on that website is running nitrous every week too.

[NOS400]

I have ran nitrous on my 400 for about seven months, it is very tricky to get the right amount of nitrous and fuel. i have changed the jets numerous times and the 170 jet works for me. I run a K&N air filter with the nitrous needle in the back of the filter. This will keep the nitrous from blowing your engine, if you use the nitrous in consideration. I have a 14 thousandth nitrous jet. The thicker head gasket is a good idea but using your head and NOS button is the best thing to do. If you have any direct questions ask and i will do my best to answer them or find out for you.

[itsallgood]

What kind of fuel pressure are you guys running??

I'm gonna bore to the next size, thicker head gasket, mild port-polish the head, probably a better rod when I rebuild...

Do you think a different cam would be a good idea...

Btw, i'm planning on buying the Dyna Ignition system...

[wilkin250r]

Your particular setup will play a big role in your jet sizes and power output.

Nitrous Express and NOS are pretty similar, Boondockers is vastly different. What brand are you using? If you're asking about fuel pressure and jets, I'll assume you're using NX or NOS, with a separate fuel pump dedicated to your nitrous system, and a direct-injection nozzle.

Now, back to setup and jet sizes. If your nozzle is located inside your airbox, or between your airbox and carb, then the nitrous will expand from liquid to gas before it enters your engine. This is obviously going to be different from somebody with a true direct-port injection spraying liquid nitrous directly into the valves and the cylinder.

In one scenario, you have GASEOUS nitrous oxide entering the cylinder, and one scenario you have LIQUID nitrous entering the cylinder. The total volume of and amount of nitrous, fuel, and air are going to be different. They are obviously going to have different fuel requirements, but the only thing physically different in the two setups is your nozzle placement.

The length of the line between your solenoids and your nozzle can play an important factor, as it also gives time for your nitrous to convert from liquid to gas.

What's my point in all this? What works for one person may not work for you. Along with the jet size, you should also be asking about particular setup. Where is your bottle located? Where are your solenoids located? Where is your nozzle located? What type of nozzle are you using? What is your fuel pressure (you've already got that one)?

[wilkin250r]

Me personally, I'm running NOS, and it's nearly identical to this diagram I got from the NOS website.http://www.holley.com/HiOctn/TechServ/TechInfo/McNOS-ill.jpg


I'm pretty sure my fuel pump is 5psi. My particular setup is on a little 250X, so the jet size might not be useful to you. But I can tell you with 5psi, my nitrous and fuel jets are the exact same size, and I think I'm running just slightly lean.

My advise, you don't need a thicker head gasket. If anything, a thicker head gasket is actually WEAKER than a thin one. But an aftermarket head gasket designed to be stronger is good idea. The only time you would want a thicker head gasket is not for strength, but for lower compression.

A forged aluminum piston is a good idea, they are stronger than the stock cast aluminum piston.

Some people will say that high compression is a big no-no. This isn't necessarily true, nitrous and high compression work very well together, but it DOES increase the danger factor. I wouldn't go over 11:1, running full race gas. If you plan on running pump gas, I'd stick with stock compression. Even then, I would be wary, and maybe run 50/50 mix. Nitrous needs octane.

The stock Honda rod is pretty good, a heavy-duty rod isn't necessary, but again, it's not a bad idea either. Nothing wrong with a little insurance. You'll see more stress from a bigger piston and high revs than you will from nitrous. You'll probably blow your rings or head gasket before you'll break the rod.

Big bore, small bore, it doesn't make a difference, except that a bigger piston will put more stress on the rod, whether or not you use nitrous.

I wouldn't do a port and polish, or a camshaft just for nitrous, unless you're a SERIOUS drag racer. Nitrous is so easy and versatile, there's no point in customizing your engine for nitrous alone. I suggest you build your engine however you want for normal, everyday, non-nitrous use.

[itsallgood]

wilkin,

Very good info, that's what I was looking for...

Basically the image you posted is how I am going to set it up, or how I was planning on setting it up. *********. I am going to keep the lines, etc. as short as possible and sit the bottle where the stock airbox would normally be.

What location are you using?

[wilkin250r]

It's a good idea to keep all lines as short as possible, especially the lines from the solenoids to the nozzle.

Just as pictured, I have my nozzle in the boot between the carb and the head. I have my solenoids mounted to the frame directly beneath the gas tank, so the lines from them to the nozzle are only about 6 inches long. I have my fuel pump mounted to the frame near the petcock, and my bottle is located way back near my airbox, right where the stock toolbox used to be.

No, I don't have pictures. Unfortunately, I went too far with the nitrous and blew my rings, and the entire quad is disassembled waiting for a 350x conversion kit.

According to my jet size and the NOS website, I had a 20hp boost in that little 250x, and it felt like it. It brought the front wheels up in 3rd gear. But that little 250x was pretty abused and neglected when I bought it (I only paid $400) and it just couldn't handle the stress of an extra 20hp.

[itsallgood]

Where is the cheapest place you all have found to buy NOS parts.

[quadfamily]

If you are set on doing any port work then you should concentrate on the exhaust side. While injection nitrous and fuel into the engine it needs to get rid of alot more exhaust then it normally would. You may also want to polish your combustion chamber to remove sharp edges which could be areaswhere heat could possibly concentrate. Remember you're adding alot more heat into the combustion chamber. I've never run nitrous on a quad but have on several cars in the past. Same rules apply except 400EX's are air cooled and cars are liquid cooled.

[wilkin250r]

Originally posted by itsallgood
Where is the cheapest place you all have found to buy NOS parts.

I got my set on ebay for $200. I just changed a few fittings (which I could get at my local hardware store) and the electricals, which I could easily do myself. The only time I needed anything specific from NOS was various jets, which I got at my local Summit Racing shop.

So, I don't really know about cheapest prices.

[red2004 TRX450R]

If you are running NOS brand call them. They are more than happy to help you. I know they helped me a lot!!!!!

It’s a safer to keep it a little on the rich side! If it leans out too much it gets real expensive quick! And don’t go to big on the jets – (all I can do a little more – o one more will not hurt – THEM your have to rebuild) My friends car safely ran around 10.5 in the ¼ and one day he decided he wanted to brake in to the 9’s well he did once and then he sold the car because the motor locked up. One thing that I do recommend on any nos system is a low fuel pressure shut off valve!! It turns off the spray if the fuel pressure drops. When the fuel pressure drops it will get real lean and bye bye motor.

What kills nos motors is to big of a shot for your commination and lean conditions.

What u need is forged parts NO CAST – a good head gasket. And most nos motors run a wider ring gap. Call NOS – Holey and they will hook u up. Thy are the people that profected nos.

[wilkin250r]

Originally posted by red2004 TRX450R
And most nos motors run a wider ring gap.

This is something I have not heard. Why would you need a wider ring gap?

Me personally, I ran a little lean. I don't really suggest you do this, but I felt safe for two reasons.

First: Direct-port injection.

The problem with a lean condition is excess heat, usually melting the piston, or causing the piston to heat up and expand faster than the cylinder walls. If the piston gets bigger than the cylinder, it will sieze. My nitrous was directed straight into my cylinder, which means that LIQUID nitrous was entering my cylinder. This liquid nitrous has a cryogenic effect, as soon as it hits my piston, it will evaporate and remove heat from the piston, cooling it off. This will help prevent the piston from overheating.

Second: Bottle pressure.

Heat does not build up instantaneously. A few seconds of running lean will not kill your engine, it takes TIME to melt your piston. During this time that you're on the button, that little 1-pound nitrous bottle is losing pressure very fast. Less bottle pressure means less nitrous through the nozzle. You're fuel pressure isn't dropping, you're still getting the same amount of fuel. Same amount of fuel, less nitrous. Your mixture is automatically getting richer the longer you hold the button. I feel safe starting off lean, and gradually getting richer as my bottle pressure drops.

[eversoleracing]

I've ran nitrous for a quite awhile in a dirt drag set-up without any problems. I'm not sure I can answer all of your questions but I think I can help you. Here is what I have found using NOS systems:
1) I've found that the nitrous runs more consistent if you install behind the carb in the boot.
2) You should never run the same size nitrous/fuel jets, your fuel should always be somewhat larger. I generally found that a 2 size ratio for 2 strokes and 4 size ratio for 4 strokes was acceptable. Ex. 14 nos 18 fuel.
3) If you're building your engine just for nos, do your portwork, cam, etc. just build a low compression engine. NOS loves low compression.
4) To get the most from your nitrous system it is also necessary to retard the timing, and it varies depending upon how much nos you're running.
I hope this helps somewhat.

[LazeR]

This ended up being a pretty good discussion, im sure it could go further though :D I learned something from it, can it be sent to the FAQ for future reference ?

[CRE Performance]

A few tips on nitrous from an automotive drag racer of many years.....

1- Too lean is bad, overly rich is worse. It nice to be safe by being on the fat side, but if you go overly fat to stay safe, your gonna do nothing but wash the rings down decreasing cylinder life majorly. Its not good to be lean, its not best to be a little fat, its best to be stochio ( right on the money if poss).

2- Saying that, one of the best things that a nitrous user can invest in is a flowtube. Fuel pressure and bottle pressure are the two key roles that make or break you. Bottle pressure can be easily adjusted on the spot, fuel pressure on the other hand should be set while at the same conditions as when the squeeze is used. Meaning.....you put your fuel jet in the flow tube (the exact one you are gonna use, set the pressure with all things on that will be on when using it. Even bring the engine up to an adequate RPM the is close to when you are gonna use it. If you run lights when using nitrous, turn them on cause if you set the pressure with them off, then you turn them on when you run its gonna cause voltage drop slowing down the pump and turning your stochio mixture into a lean condition and a possible meltdown.

3- Other Factors....Spark plug heat range, timing, fuel quality, cam design, chamber design and compression.
Compression can be any range as long as you have the other conditons and variances correct. On an engine with lesser compression CAN handle a greater shot, but the differences between high and low can be minimal. If you are gonna run a big shot of nitrous, a nitrous ground camshaft should be a consideration and can add and utilize greater amounts of nitous for a lot more power, it may run like *** on the motor but its gains on the hose will be much greater. A combustion chamber with a nice smooth contour will inhibit greater flame travel and rid of detonation much better than one with sharp edges and squared areas. You may also contour the sharp edges on any piston eyebrows if any are present to help cure a little detonation. Fuel quality plays an important part on detonation and combustion chamber temps. Make sure you have enough octane but no more than you really need. As far as timing goes, it would be nice to retard about 3-4 degrees for every 25hp that goes through a quad engine ( on an automobile it would be roughly 2 deg for every 50hp max). I would say a sparks timing key turned backwards (if poss) would probably be a good idea if running around 30-40 hp shot or so. Spark plug heat range needs to be adjusted accordingly via viewing the plug. If you go too hot, detonation will occur and blow the plug to shreds if not blowing a head gasket or melting a piston in the aftermath. If you go too cold, you can run a risk of a misfire and this may have the same effect as one that was too hot, plus the fact that it may be too easily fouled at normal riding.

5- Make sure your engine is in good shape to start with or dont even think about nitrous. Do not overexceed your true engines capability to handle the amount of nitrous thrown at it. I.E. Dont put a 80hp shot on a stock engine.:D

Maybe this will help some;)

[CRE Performance]

Oh yeah, almost forgot the best tip of them all...........Dont be a knowitall or a dumbass and read the directions before you even start install and tuning.

[wilkin250r]

Originally posted by eversoleracing

1) I've found that the nitrous runs more consistent if you install behind the carb in the boot.
2) You should never run the same size nitrous/fuel jets, your fuel should always be somewhat larger. I generally found that a 2 size ratio for 2 strokes and 4 size ratio for 4 strokes was acceptable. Ex. 14 nos 18 fuel.


By "behind" the carb in the boot, are you saying between the carb and head intake, or between the airbox and carb in the air boot.

I have tried both, and I got terrible performance trying to spray nitrous through the carburetor. I got much better performance when I moved directly to the intake, between the carb and head, just as pictured in the diagram I posted earlier.

As for the nitrous jets, I have to completely disagree. First of all, it depends on your specific bottle and fuel pressure. The NOS website actually reccomends the exact same size jets when using certain fuel pumps and fuel pressures. Second, my experience showed something very different. My first nitrous run was done with the exact jetting you described above, a 14 NOS and 18 fuel. I hit the button, and the motor DIED. It was WAY too rich, so I increased the nitrous jet to 16, and eventually to 18, and it ran much better. Of course, I later increased both to 24, and promptly blew my rings :rolleyes: . But not before I stood the front end up in 3rd gear and could barely hold on. Boy oh boy, was that a whole lot of fun. I had perma-grin for hours after that one. :devil:

[440freak]

Anybody running nitrous in a 440 with a K&N....thinking about a new setup but not usre what i want to go with yet.

[itsallgood]

Getting closer to the install since I got my house finished...
What size fuel pump do I need to buy? Pressure wise.

[wilkin250r]

I'd say somewhere around 5psi.

What brand are you going with? Do you have a kit? Did you buy it new, or are you trying to piece something together?

Unless you have done LOTS of research, I highly suggest you buy a packaged kit. It will come with it's own fuel pump (along with all the other necessary items) and a jetting guide for that specific fuel pump.

[itsallgood]

It is a NOS system. It's a complete used kit that I bought about a month ago, and the fuel pump is bad, that's why he quit using it. So I need to replace it. I'm going to call NOS Monday hopefully and see what they recommend, and how much their's are and get the paperwork that goes with this system.

[wilkin250r]

Perfect. Before you call, I suggest you do a little bit of your own research.

Since you have most of the kit in your hands, I suggest you spend a couple hours and sit down with the kit and your quad and plan your installation. Look at your routing and lines. Since your kit is used, some of the lines may have been cut. Make sure you have everything you need.

If you are going to place an order with NOS for a fuel pump and instructions, you may as well add any needed fittings and lines in with the same order. Get a few extra jets while you're at it.