I've only had this a couple of months and its my first atv. It has 1500 miles and runs fine, but spark plugs only last about 40-50 miles. When I pull the plug it has a light carbon build up and the electrode is burned way down. Most of the riding has been low speed, just putzing around in 2nd or 3rd gear, mostly with out 4wd engaged. The plugs are NGK cr6e which is the recommended plug.
The engine is from Suzuki. I had a couple of Suzi bikes and they would go through plugs, but not like this.

Any suggestions will be greatly appreciated.

 

id make sure the bike has the correct jets. The other owner may have had an exhaust system on it which would require him to change the jet. sounds like its getting too much gas(correct me if im wrong someone), the plug is getting too hot and burning up. you could try a cooler running plug,but you've got the plug it should have in it. ask you dealer. there is no reason that the plugs should be shot within 50 miles unless its something with the carb i would guess. my 2002 500 had 5,000 miles on it and i had only changed the plug 2 times since i owned it. once after the bike was broke-in and another time after i drowned it. try cleaning the carb. too. or just try the jet first and see how it runs. oh try turning the air mixure screw out 2 and a half turns from flush(not to tight). i think this is where you want to start,may depend on your elavation.

 

Check and see if the float height is correct, and as mudslinginfool stated check the jets. Does it have a bit of ping?

It sounds like it is running too lean and causing pre-ignition witch may erode the plug electrode.

Look at these Spark Plugs and compare yours.

If you are not running the original manufacturer plug, make certain it is cross referenced correctly.
Calls for a NGK CR6(7)(8)E, 6 being the hottest and 8 the coldest.

 

No knock or ping. The plug has a carbon build up that would indicate rich rather than lean. Plug is cr6e.

 

IF the mixture is lean the plug would run hot, as the electrode burns off the plug would not reach self cleaning temp and start to have carbon buildup.

I don't have an '03 service manual to give you the factory settings for your carb. Perhaps someone with a service manual will stop in and post them.

What octane fuel are you running? Too high could be a problem.

 

I have a service manual on disk. It says the low speed screw on the carb should be 1 7/8 turns. I will have to mess with that this week end. Checking the jets will have to wait until another major wrenching project gets done.

Gas has been 92 octane. The manual calls for 87 minimum. I started running premium when I got it since I didn't have any info on this machine and the bikes I used to ride needed it. For some weird reason, regular in El Paso is 86 octane when its 87 every where else, so mid grade might be the best choice.

 

yeah, premium gas is not needed in most atvs(usually,unless its been modified) it can actually hurt the performance using it. in other words rob power from it. El paso huh? You get some hail damage on your vehical in or around end of august/september? i was there in sept. fixing the hail damage cars.

 

Our house was right in the middle of the worst of it . My wife's 4 runner looked like the surface of the moon. Had to have the hood and roof replaced. I wasn't home for it so my pickup didn't get hurt.