I feel like my head is about to explode. Here's my dilema:
I live at about 3300 feet elevation. I am thinking of taking my 95 xplorer 400 up to a camp at about 9000 feet or so. Nothing too crazy, just getting me there and back basically. I understand the basic concept of jetting. Will I need to rejet for this, or can I just lower the needle one or two times.
And here's my other problem. I got the quad from a guy who lives at around 4500 foot elevation, and I can't get ahold of him to find out if its got the stock jets or something smaller. Is there any way I can check and find out? Thanks.

 

The short answer, is you probably dont need to rejet, if its just a one time thing. The motor will be running very rich and may be hard to restart. Youll also notice the proformance will drop and the exhaust may smoke.
One of two things need to be done...either more air or less fuel. So you can change the jetting leaner, or you can put holes in the air box lid and keep them covered with duct tape. As you go higher up, remove more and more tape to uncover the holes, and this leans out the mixture in all the ranges. Then as you come back down in altitude, retape the holes, to keep from running too lean.
If uncovering the holes isnt enough, then just remove the lid totally, and that should do it.
To find out the current jetting, to be sure, youll have to remove the carb and open it up, or you can just go by the drivability symptoms, and if there arent any problems, then its jetted well for your alt.
Heres a site which has the symptoms of lean and rich, and the drivability symptoms.
jetting

 

thanks, that was an informitive link. I spent last night studing up on two stroke engines, and that link helped a lot. I still have 2 questions, one being would it be better allowing more air into the box like you said, or just lowering the needle and therby reducing the fuel flow? And secondly, this is just for information. Are the threads on the main jet used for adjusting it, or simply used to hold it in place?

 

The threads on the main jet are strictly for holding it. The hole in the middle is what determines fuel flow. the needle controls 1/8 throttle to 3/4 throttle, which is where most of riding is done. Your wheeler shows to have a 200 main jet and a 30 pilot jet. If you have the stock size jetting then you might think about lowering the needle one clip only. That will more than likely get you what you want. The airbox lid is also a great idea if you dont mind it being open or if you wont be getting into water. Bubba

 

most of the guys that we ride with around here have dropped to a 180 main for all year riding wich is 2 sizes from stock and have had no problems. THIS IS FOR AROUND WHERE I LIVE yours might be diffrent but it did wake up the 400

 

Ok, all this sounds good. I won't be going through any water, but I think that I may just adjust the clip on the needle. I'd rather not drill holes in my lid for one trip, and the clip seems to be sager than running without a lid. You never know. But wouldn't I need to raise the clip to lower the needle to lean it out for elevation?

Braveops-what elevation are you at? And did you have to adjust the pilot jet too? The whole jetting idea is new to me so I'm still wrestling with it. I am still trying to get in touch with the previous owner to find out if its stock jetting or not. Does it say anywhere on the jet itself what size it is? For either main or pilot. Come to think of it, I'm begining to think that its running just a tad too rich right now. I'll have to test it and see.

BTW braveops, gorgeous area where you live. It looks a lot like where I'm at out in Cali oddly enough.

 

Im not sure which model you have, but it probably has a cv carb. One of the benifits of having a cv carb, is the ability of the carb to self adjust in the midrange. The throttle cable is connected to a butterfly, and not the slide. As the motor demands more,(by using vacumn), the carb slide rises and gives it more. So i wouldnt be too concerned about the mid range. See this page for a better discription of cv carbs carb101

You could bring a small screw driver, and adjust the mixture screw (which only controlls the mixture of the idle circuit), and isnt compensated by the cv circuits. As it runs rougher, and richer, give the screw some small moves in, which will lean the idle circuit.

If youre only going for one trip, it isnt worth the hassle of changing the main jet, id just remove the lid. If you have a clean air filter in good shape, nothing bad should happen by removeing the lid. Id be more concerned about changing the clip on the needle, ..and maybe droping a small part, or getting dirt into the carb.

Yep, the main jet and the pilot jet have stampings, which refer to the size, and some are on the side and some are on the face of the jet. See this page and it gives examples.

carb parts

Yep, raising the clip on the needle, lowers the needle into the jet, and makes it leaner.

 

Hey, I see youre in Mariposa! We should get togather and ride sometime!

 

hondabuster- thanks for the links. I'm going to pull apart the carb this weekend I hope and see what it has.

powerstroke-I'll have to get my quad working before I can actually ride it regularly but once I do I'll get in touch! Just outta curiosity, are you the one with that massive lifted white ford with the flame job across from Goldside? I've seen it at pismo and around here with quite a few toys. Always wondered what that guy did for a living.......[img]i/expressions/face-icon-small-tongue.gif[/img]

 

Nope. But im pretty sure ive seen the one youre talking about.

Yeah, let me know when you get it runnin and we can hit some trails..