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Posted by: longlake
Moosecat;
I have a 2000 AC 300. I had a lot of trouble with it fouling plugs, stalling etc. when it was new. Took it to 3 dealers to get it fixed. Here are my carb settings.
Pilot Jet 45
Main jet 135
E-Clip set on position # 2.
I would try a combination of adjusting the e-clip with different jets. I have read lots on this forum about adjusting the valves, but that is seldom the cause of the rough idle. Just experiment and find the combination that works for you.
These bikes are notorius for this problem. They are warm blooded motors. Funny that you never hear of the Suzuki King Quad having this problem. Good luck with your bike!
Posted by: TORK
Try checking your valve clearance, even though it is low miles we have found some of them out of adjustment and won't idle correctly.
Posted by: TORK
When in doubt roll engine over until intake valves are fully open and adjust exhaust valves. Then do the same for other valves.
Posted by: TORK
Hey moosecat, sorry I couldn't get back on till now. I was telling you hoe to do valves when you don't know where timing mark is. When one set of valves are completely open then the other set is closed and can be adjusted, hope I helped rather than confused things.
Posted by: Bear4570
I'm surprised no buddy asked if you have done a compression check. I've seen problems at idle caused by a compression problem, but when you spool up the motor it doesn't have time to leak enough to cause you a problem that you will notice. By the way I really dislike diaphgam carbs, but for changing altitude like you can sometimes on a quads need them to run everywhere better.
Posted by: hondabuster
Spark plug not gapped correctly, either too wide or too close.
Air leak in the intake tract, maybe missing a gasket or split rubber.
And like tork said, check valve clearance.
Posted by: hondabuster
I dont have an ac but ill guess, there has to be some sort of way o view the timing mark. Look for a female hex head, bolt in the side of the case ,that would give you a view at the flywheel, it would be the side opposite of the clutch side. If you take the spark plug out, itll turn easier. Using the pull starter, slowly pull while watching the flywheel...you should see a "t" or other mark. When you line it up, thru the hole, check the rockers, they both should be loose. If they arent loose then, you need to spin the motor over ,360 degrees from there to the mark again. The camshaft is half speed from the crank.
I would think the shop manual should show this. Let me know how it goes.
Posted by: hondabuster
what tok was telling you, will work. Hes saying that, because hes assuming youre not seeing a timing mark. If you can see a timing mark, and youre on it, then both can be adjusted at the same time. Basicly, if you can wiggle the rocker, it means there isnt any valve spring tension on it, and its at a spot you can set the lash. Did you find the timing mark?
Posted by: hondabuster
I think youre "off right now", too. (not sure what that means) Hopefully we are helping you.
There is only the one mark on the flywheel, and either its at the top of compression stroke or top of exaust stroke. If you can wiggle both rockers,( when on the mark)then youre on the correct cycle. Unless both are adjusted too tight, then you wont be able to wiggle them at either top.
If i was you, id try restarting and running for awhile, before putting the rejet kit back in. If you put the kit back in now, and youre still having problems, you wont know if adjusting the valves helped or not.
Id run it long enough to know if the problems are gone or not. then put the jet kit in.
Posted by: hondabuster
Youll get it fixed, dont worry.
Check for spark, is the kill switch on? Pull the spark plug, put the wire back on it, ground the plug to the head and spin it over. You should see spark.
Posted by: hondabuster
Now i see what you mean by off right now...im an old fart, and needed my daughter to show me.
Posted by: hondabuster
Usually they give a range, say .005 to .009, Then i make sure the thin one easily goes in, with out forceing, and the thicker one doesnt go in. If your using the middle of the range, it should go in the gap, with out alot of force.
Posted by: hondabuster
This may bea little late, but i found an article online on adjusting valves, Not on your motor, but should be very similar.
valve adjust
Check the operation of the choke. Is it fully going off? I think you have an enrichener for a choke. Maybe your manual will show this and how to adjust it. Is the mixture screw, about 1 1/2 turns out ? Sounds like youre too rich, on the idle circuit.
let me know how it goes.
Posted by: hondabuster
moosecat, i knew youd get it. Sounds like youre a pro already.
Id try a pilot jet, thats one up(next size bigger). Some times the enrichener, is just tightened at the carb, and adjusted at the knob.Sometimes all you can do, is look at the rubber piece, that goes in the carb, for nicks or pieces missing, or worn areas. Then with it out of the carb,check that the knob actually moves it enough.Theres a separate starter jet, in the carb , that adds fuel, when the enrichener is lifted up. So going bigger on the pilot jet, does much the same thing.
Posted by: hondabuster
found some more web sites on jetting, if youre interested.
http://www.smellofdeath.com/lloydy/jetting.htm
http://www.motocross.com/motoprof/moto/mcycle/carb101/carb101.html
http://www.4strokes.com/tech/howtojet.asp
Posted by: moosecat
Do any of you guys with 300's know anything about them not idling right? I can not get it to idle steady,
I have done alot to it, arctic cat even let me swap the carb for a new one off a 04, no charge and even out of
warrantyanyway, I have put k&n filter, dyno jet kit ( had that on and off twice, not much improvement either way)
I have gone lean, rich fuel filter, cleaned carb on and off, only has 250 miles on it and I treat it great. I love my
ride and it runs great, but the idle thing is driving me crazy!
Posted by: moosecat
hey hondabuster, thanks, also got all the intake off the new 04 from the airbox to the manifold,
so, lets assume that the guys at the shop didn't check the valve clearance, like I said, I tried to check
it, I have the feeler guages bent for the intake and exaust, I have the shop manual, but, the only
thing it don't tell me is, How do I get to top dead center, and know for sure it's top dead center?
if anyone will reply to this this morning, I will try it today.
Also, the plug gap calls for .024-.028, I have tried them from .024 to .026, and I tried a $10.00
Nippendenso iridium plug.
Posted by: moosecat
So, When the rocker arm is down on the intake side, I find the tdc mark at that point, and adjust the exaust valve
side, then when the rocker arm is down on the exaust side, find the tdc mark at that point and adjust the intake valve?
I was thinking that on a cingle cylinder engine, you adjusted both valves at the same point.
thanks for the help, I am mechanically inclined, but I am new to going so deep on a quad motor.
Posted by: moosecat
Yes, I found the mark, I'm just a little unsure as to how to proceed, The Arctic cat manual does say, find the mark on
the compression stroke, then adjust valves.-Meaning both. so is that right? The intake and exaust stroke seem to be very
close to each other when I hold my finger in the plug hole, it's so close that I am unsure if I am at the right spot or not,
so your saying that if I can't move the rockers at all, that is the exaust stroke? I'm a little confused.
The rockers seem to move a little in both positions.
Posted by: moosecat
Hey, both of you guys are off right now, but I think I've got it, from what I can tell, based on the instructions
in the manual, and what you have told me, when I rotate the engine with the pull start, I watch for the mark the entire time
I rotate it, the mark only comes up once, and it looks like, everytime it comes up, the rockers, valves, and piston are always in
the same position, I used a Craftsman lazer level to line up the marks exactly, and the intake side seems to be pretty close
to spec, but the exaust side seems to be way out, it wiggles alot, so maybe thats where my idle problem is coming from,
I'm heading out to make the adjustment, and if it works, I may go ahead and re-install my jet kit per instructions, and see
if it makes a difference this time. you guys let me know what you think, And I am going to adjust the valves mid-way in spec
scale, so maybe that will be right, I don't want them too tight or too loose.
Thanks again.
Posted by: moosecat
I meant it looked like you were both signed off, well, I just finished and now it won't even
run, choke from cold start, its fouling the plug black, wasn't doing that at all before, I set them
both to spec, did't really seem to be too far off, what do I do now? I am in bad shape, I sure wouldn't have
thought it would be this bad, I'm going to take it back apart and see what it could be, but
I'm lost, if you can think of anything for me to try, please help.
Posted by: moosecat
When using the feeler gauge, should it be tight and hard to pull out, or should you just
be able to slide the chosen one in and out easily after adjusting?
Posted by: moosecat
Hey, your not an old fart, I'm 36 myself, listen, I meant I did get it to run, it just wouldn't stay
running, bad idle (worse than before), turned the plug black, kept dying, wouldnt even warm
up, so I shut er down. I think I just got them too tight, went to Auto Zone, got a new feeler
gauge, gonna set it in the middle -firm but not too tight, and lets see, thanks for all the help.
I havent given up yet, I have too learn how to do this!
Posted by: moosecat
Hey guys, just wanted to say thanks to all for all the advice, and thanks for the article, its great,
I have printed that for my manual. Listen, on Sunday night, I re-did the adjustment, set both valves in
the middle of the three settings, got it back to normal, running great, still not idling perfect, but at least its
not fouling that plug, and yes, by having the carb on and off, I have seen the choke-enrichner, but there is
nothing in the manual about how to adjust it, and I have looked at it, and can't see of any way to adjust it,
cable or otherwise, so , anybody familier with this 03 Arctic Cat 300 have any more advise on how to get
the perfect idle? I do have the idle screw set at the stock setting, 2 1/4 turns out , by the book, I think.
I have thought about going up one size on the slow jet, (idle jet), I think it is a 38, thought maybe i'd
get a 40 from Dennis Kurk, and see it that helps on idle and cold start. It takes a solid 10 min. for it
to be ready to go, man is it cold natured. the guys at the A.C. shop keep telling me the cold natured and
rough idle are from the EPA restrictions, so the only thing I can think of is the slow jet. They say they
don't know. Any way, enough of this, I'm still open for options on how to fix this idle. And thanks to
all for all the help!
Posted by: moosecat
Thanks again, Hondabuster, don't know what I'd done without you guys this
weekend, thanks for the sites, I'll check em out and try it.
The cat's running great, but bad cold natured.
