I am thinking of buying an explorer 400. I hear all kinds of thangs about having to re-jet the carburetors for different altitudes and weather conditions. I want to use the Explorer mainly for trail riding in the mountains in Oregon and Idaho, but will also ride on the Oregon coast. To do this will I have to re-jet constantly? And what about riding in the winter, will that require re-jetting also? Also what all is involved with re-jetting and what will it cost? Thanks for any help you can provide.

 

Im soon going to be buying a 00 Xplorer and my dealer say's you only need to re-jet in the winter and summer months.I'll probably be putting a pipe on the 4x4 after awhile.But im wondering if the dealership informed me correctly.Can we stay all yr with the same jetting?===BILL

 

I believe the general rule of thumb is to rejet for every 1200' elev., + or -. For an increase in elev. there would be no harm done except possible plug fouling.Performance would possibly be affected with a rich mix, depending on the elev.
However, if jetted for higher elev. & riding at a lower elev. you would be running lean & could be harmful to your engine in the form of burned, scored, or blown pistons in worst case situations. 4 strokes aren't usually quite so sensitive to elev. changes unless modifications are made to air flow & breathing, in which case rejetting is usually needed with significant change in elev.
Probably the best bet, if rejetting is too much of a pain, is to jet for the lower elev. and cooler weather & simply deal with the slightly lethargic performance in upper elev. or warmer weather. It' always better to err on the side of rich than lean.

 

Hot shoe cv,my elevation will remain the same,it;s just that the colder winter weather will be around once winter arives.If im jetted for summer riding,do you thinkj my winter [same elevation] will be ok?===BILL

 

Hot_Shoe is calling it correctly.

Only small changes are needed for winter vs summer riding. This can normally be accomplished with the air screw. I once tried changing an 2 stroke ATV which was set up for running in Fla. to Michigan winter conditions. I followed the directions in the owners manual and promptly fouled a plug.

Colder weather requires a richer mixture than hot weather, but not as much as the owner's manual calls for. Small 1/8th turns on the air screw are usually all that is needed for winter driving and a little bit of 1/2 choke for about 30 seconds or less. After the usual burble and bapa bapa as it warms up it will be ready to go. One of our family members quad (2 stroke) is faster in the cold weather than it is in the warm weather. (He doesn't touch the carbureator all year and does just fine.)

Another important adjustment on the 400 is the choke. When set correctly your ATV will start instantly at any temperature. Much faster than a 4 stroke. But... if improperly set (read that too rich) the fuel inrichment circuit will constantly bleed extra fuel into the intake, lowering gas mileage and smelling rich to those following behind you.

High Elevations would make the sea level Xplorer run richer if the motor was set up for lower elevations.

Dealers who recommend changing jets in the carb are probably used to talking to snowmobile speed enthusiasts. Some snowmobilers like to run their machines as lean as possible, for maximum power and speed. When they do they reduce the manufacturers built in safety levels and risk, detonation, piston scuffing, melting, warpage, ring seizure and ultimately seizure.

Remember on a two stroke, your power will be awesome right before the engine seizes. The vast majority of seizures take place in less than 1 second. If you are lucky, you will feel the engine losing power and then shut it down before you meet
"Mr. Squeeky" But usually all that excitement is left up to the snowmobilers.

@rec.sport.snowmobiles

Polaris builds their ATVs with wider clearances than the snowmobile lineup. The ATV engines also put out less HP than snowmobile engines per CC displacement. You should be safe and free from concern.

P.S. For the longest engine life, if you can, use only non oxygenated premium fuel. It could be cheaper in the long run.

 

Read post above yours

 

By non oxygenated premium fuel do you mean regular premium unleaded fuel you get at the gas station or something special.

Thanks

 

well, if you don't wish to rejet for optimum performance you could jet one size fatter on your main, do a plug read, and if it shows a little dark then it would probably be okay for cold weather.Of course if you add a pipe it no doubt will require still another size fatter main

 

tomuchfun,
On re-reading your post I remembered your other questions. Cost? I assume you are going to do the work yourself. In that case main jets should only cost you about $5 or less. Most of this topic concerns main jets & it's very simple. In my case on a Warrior, the hardest part is just getting to the darn carburetor. After that it's a no brainer.I'd suggest picking up a shop manual if you haven't done it before. At current labor rates of $40 to $50 per hour the manual would pay for itself in about 1/2 hour. Check out the Clymer web site for manuals.

 

Thor,thank you for your advice on jetting.I will make frequent ''plug readings'' to determine if im running to lean or to rich.I might re-concider on putting a pipe on.The Sportsman was plenty fast enough for me,so this thing ought to feel like a rocket,thanks===BILL