well i bought another arctic cat with issues and dont know where to start so here's the prob. idles to high one day the next day it idles fine I have tore the carb apart cleaned and adjusted it to factory specs, and run about a tank and a half of gas with seafoam, but the main issue is the valves sounded like they were chattering so i adjusted them according to the manual, they werent off much but I still here the chatter, and it smokes pretty bad, I am unsure of where i need to start and thanks to any who answer...

 

First off Welcome to the forums and you didn't mention the model year of your 300 so i assuming it's the 300 Suzuki Engine ?

I've seen your post for awhile now i was waiting to see if some of the other members who know more would jump in and help you , i had an issue with my old 93' Suzuki LT4WD 300 KQ / same engine used on the AC 250 and 300's that caused the same problem with the idling of the 300 KQ , i sold it to my brother before the problem was diignosed ; it turned out to be the cables and wiring harness were bunched together so tight that the choke cable would stick when you turned the handle bars to the left or right all the way causing the choke to open and close when turning the handle bars hard right or left !

Turned out that when i replaced the choke cable whitch was alittle longer than the original one was the cause for the cable binding , i had taped the end of the new choke cable to the old one and pulled the the new cable through the plastic ties that holds the cables and wiring harness together causing the binding ; my brother fixed it by removing the plastics cutting the old plastic ties then loosing the wires and cables before putting new plastic ties and the problem was solved .

As for the smoking SeaFoam will cause engine smoke when its cleaning and burning off the exccessive carbon deposits inside the combustion chamber , SeaFoam is the best fuel treatment i've ever used for keeping the fuel system and combustion chamber clean ; however i don't reccomend using it in every tank of gas .

It's good to use to clean out the fuel system and combustion chamber , and a good preventitive messure when storing the quad when isn't going to be ridden for over a month or more in between rides , as for the valve chattering it could be the valves are out of specifications , improper carb jetting or adjustment of the air/fuel mixture screw , to high or to low octane or bad fuel causing valve chatter .

You stated that you did the valve adjustment as to the manual instructions and the chatter is still present , i would start off by changing the engine oil and filter filling the crankcase to the proper level , i assume you know where the fill level glass is between the right rear tire and fender ; fill level should come half way level of the glass then i would readjust the valve spec's making sure you're on the compression stroke when aligning the timing marks .

The manual states that you should align the " T " mark on flywheel with stationary mark on the compression stroke , then turn the crankshaft alittle past the " T " mark while watching the intake valve for movement , if there's movement of the intake valve to turn the crankshaft one complete revolution ligning the " T " mark again with stationary mark you should be able to wiggle both rocker arms a little when at TDC of compression stroke ; both valves should be in closed position on TDC ( top dead center ) of the compression stroke before adjusting valves .

One trick i've always used when adjusting valves is to remove the spark plug then sticking my finger into the spark plug hole while turning the crankshaft you will feel pressure pushing again't your finger on the compression stroke , i've found this works the best for me ; also there could be a misprint of the valve spec's in your manual i don't have the Factory O.E.M. Service And Repair Shop manual the one i have is for the 88'/89' Suzuki LT4WD 250 QuadRunner it's suppose to be the same spec's for the 300 , valve spec's in my manual are : Intake 0.03 - 0.08 mm ( 0.001 - 0.003 inch ) Exhaust 0.08 - 0.13 mm ( 0.003 - 0.005 inch ) i've always set the valve spec's in the middle range to give them ware distance between valve adjustments !

I hope this help's you out i double checked the valve spec's with my Suzuki Dealership's Technition and they confirmed them for me , however it wouldn't hurt to call your local AC Dealer to confirm that these are the correct valve spec's for your AC 300 just in case your engine is the Suzuki engine or the Kymco engine according to the year model of your AC 300 ; sorry for the long reply ! ....

williebee !..........

 

man I really thank you for all that information, some of the things I had already figured out on my own, It's a 98 model 300 I paid 1000 bucks for it
but I got a 2001 parts 250 with it also that worked out great since I had a 250 same year model, but I have pretty much figured the cam chain is stretched, I have ruled out cam chain tensioner as I have three of them now and have swapped them around with no difference, but I will look at the choke cable, I might have over looked something there, when you tear apart a carb for about the 5th time in a half a day you get a little frustrated to say the least, and all the screws were already stripped, Im looking at a cam chain on ebay for pretty cheap, dealer wants 58 bucks after tax which thats ordering it for the suzuki king quad, if I get it through arctic cat I think its 80 something, but thanks to you williebee, and swampy junior, everywhere I look on this site you guys are right there trying to help keep folks riding and offering sound advice, keep up the excellent work...