400ex doesnt run right ?

[drs2007]

i just installed a alien full exhaust system on my quad a few days ago and today is the first time i rode it. it dont seem to be runnin right ?? any help is appreciated

[hondaracer57]

did u rejet it?

[hornetgod13]

I bet you didn't rejet your carb. If you didn't than your quad is running very lean. You'll need to bump up your main jet 2 or 3 sizes and changing the pilot jet wouldn't hurt either.

[drs2007]

could you guys happen to be able to tell me wha size jets ?

[kcliff]

what kind of air filter system do you have and any engine mods, what elevation and temp where you live.

[exhorsepower]

best combonation to use is a 155 mainjet and a 42 pilotjet

[slodsm]

Originally posted by kcliff
what kind of air filter system do you have and any engine mods, what elevation and temp where you live.

Thats a really general statement and won't hold true from one motor to the next, much less since you didn't state what brand jets as they don't flow the same from one brand to the other and then lets not forget temp and elevation.


But in short, yes you need to rejet your bike.

[dariusld]

Originally posted by slodsm
Thats a really general statement and won't hold true from one motor to the next, much less since you didn't state what brand jets as they don't flow the same from one brand to the other and then lets not forget temp and elevation.


But in short, yes you need to rejet your bike.
Doesn't he have to start somewhere?:confused:

[Honda#4]

what air filter are you running? you running with or without the lid on? and elevation?

[slodsm]

That was a misquote, I meant to quote the 155 main and 42 pilot as being the "best".

Airfilter, engine mods, elevation and temp are all good questions and sure, everyone needs to start somewhere. What I was saying is when you tell someone something is best, then if they are not exactly mechanically inclined, you are doing a lot more harm than good.

It's like teaching a man to fish will feed him for life but giving him a fish will feed him then. Pointing him in the direction to start on jetting and then linking him to a good how to would be a lot better as then he will understand it for himself.


The quote just came out wrong so it screwed up the entire point I was trying to make :(

[hornetgod13]

Atleast he would have a good idea where to start. He may have to go up or down a size but, he should be close.

[slodsm]

Originally posted by hornetgod13
Atleast he would have a good idea where to start. He may have to go up or down a size but, he should be close.


Absolutely. What I was making the comment on is it was stated that it was the "best" leaving no room for improvement on either side.


I wouldn't even make a big deal out of it at all but I have small reasons. I am a mechanic for a living, I teach aviation but build hotrods and race myself in my off time. Well I can't tell you how many times some guy has tried to argue with me about a nitrous jetting, a "maximum amount of boost" or what size injector he needs because someones brothers cousins next door neighbor on the net told him it was the "best" for his car without ever even seeing it.

Wording can be taken far out of context and I have replaced many a burnt piston and warped head because someone just listened to what was supposably best without learning how to tell for himself.

[exhorsepower]

not to be a d*** but i live about a 1.5 hours away in same state and that is the best jetting that would be used around here

[dariusld]

Originally posted by slodsm
Absolutely. What I was making the comment on is it was stated that it was the "best" leaving no room for improvement on either side.


I wouldn't even make a big deal out of it at all but I have small reasons. I am a mechanic for a living, I teach aviation but build hotrods and race myself in my off time. Well I can't tell you how many times some guy has tried to argue with me about a nitrous jetting, a "maximum amount of boost" or what size injector he needs because someones brothers cousins next door neighbor on the net told him it was the "best" for his car without ever even seeing it.

Wording can be taken far out of context and I have replaced many a burnt piston and warped head because someone just listened to what was supposably best without learning how to tell for himself.
You should stop using the internet then, you get alot of that. My favorite is the 12 year old kid that read something on this site and starts spouting BS left and right, on every subject.Then everyone else is saying the same wrong info. Every forum has one.

[slodsm]

Originally posted by exhorsepower
not to be a d*** but i live about a 1.5 hours away in same state and that is the best jetting that would be used around here

So your telling me you have put his head on a flow bench and you both flow the exact same at 28 inches? He also has the same ring end gap and EXACT exhaust, filter, airbox mods, and everything else?

Not to be a d*** either, but I don't care if he lives across the street from you. What is best for you isn't best for him. Engine tuning be it one cylinder and carbed or 8 cylinders and force fed is NOT the same from one to the other even if the same guy built them on the same bench within a day of each other. If that were the case, then why even bother making more than one set of jets? Just make only 155/42 and send them in your 150 mile radius right???


Darius, I completely understand that you will get alot of that anywhere you go. 90% of the world these days is parroting information they heard someone else just as uninformed as them spout like he knew what he was talking about and so it must be correct right? The reason I make an attemp to educate on the subject is the fact that if no one does, it will only get worse. Prior to the internet, people actually had to learn how to do things, now, everyone with a modem is an expert.

[Honda#4]

Can we just get along in here and not bash people for what they say.

If you have a jetting issue just ask me then you won't get all these long threads.

[slodsm]

Now correct me if I am wrong, but the purpose of a forum is the exchanging of information to improve the knowledge of others right? What you see as bashing, I see as an education.

If all people did was just as you, how would any advancements ever be made?

[exhorsepower]

i was just trying to give him the most accurate type of jetting because i runthat same pipe on my other 400ex and were pretty much in the same elevation so i wasnt trying to bash anybody the ones trying to bash people are the ones above just running a slip-on

[slodsm]

Originally posted by exhorsepower
i was just trying to give him the most accurate type of jetting because i runthat same pipe on my other 400ex and were pretty much in the same elevation so i wasnt trying to bash anybody the ones trying to bash people are the ones above just running a slip-on

I know you weren't trying to bash but I think you misunderstood my questions with bashing. What I was trying to say is that although it is probably a lot closer to correct than what he is running, it won't be dead on just like if you have never experimented with yours, it's probably not dead on either.


All I was stating was that you can't use absolutes in mechanics, only mathematics and since the flow numbers are never the same from one to another mathematically, the mechanical portion will never be equal either. I do it for a living on cars and aircraft so it's one of my three and only three pet peeves in life.

I am actually one of the most easy to get along with people on the planet.:D

[dariusld]

Originally posted by Honda#4
just ask me :blah:

[ATVnewbie]

Lots of valid points on here and I estimate you both have validity to what your saying. I will tell you this, when I built alcohol dragster motors some motors set up the same way some did not, on an exact same motor set up. What I attribute the differences to was small differences in manufacture of the various mechanical systems which added together can change the set up from one to the other.

[Honda#4]

Ok then as long as you two both agree, it's hard to figure bashing stuff out on the net without hearing the persons voice, I'm just trying to help out the mods keeping the site clean of all the yelling and bashing and and the losers that come on this site to make retarded threads and what not.

Sorry for interrupting, please continue.

[hornetgod13]

Wow! The longest jetting thread I've seen in a while. It's a shame most of it hasn't helped out the guy that started it.
Start somewhere in the range of 152K to 158K and bump the pilot (slow) jet up to a 42K. You can buy individual keihin jets at www.jetsrus.com

[dariusld]

Originally posted by hornetgod13
Wow! It's a shame most of it hasn't helped out the guy that started it.

Why is a shame? Short boring thread (everyones heard this topic before) or long interesting one with new members involved. I vote for the long one.

[hornetgod13]

Originally posted by dariusld
Why is a shame? Short boring thread (everyones heard this topic before) or long interesting one with new members involved. I vote for the long one.

I "vote" for helping out the person that started the thread. I share my personal experiences in hopes that it can save someone some time and or frustration. Some people offer help and others sit on the sidelines and question or second guess those that offer advice.