O/T valve timing on an ATV-2004, Artic Cat 400

SDE

Well-known Member
This machine sat to long and the carb. got gummed up. While trying to get it to run correctly, the engine ended up locking up. One bolt that holds the timing gear to the camshaft had sheared off. I replaced the bolt and have removed the carb and cleaned it, (twice). The problem is that everything is good while driving at slow speeds. A little faster, and the engine will not accelerate and it backfires and sputters. Is this a carb problem or is the valve timing do this? The timing gear has 38 teeth and if I am off One tooth, will it cause this problem also? It appeared to me that the index marks were half a tooth off and so I guessed as to which way it should go. One tooth is 9.47 degrees.
Thank you
Steve
 
1st.
Put another spark plug in it and make sure the gap is correct !

2nd.

The carb has "3" metering circuits.
Pilot jet: little one deep in carb next to main jet] flat blade screw driver to remove.

Pilot :is starting and off idle throttle responce. make sure you can see threw it.....

Needle: Hole range of throttle.


Main jet: Wide open throttle only.


I would guess you still have dirt in the carb.

Use Gumout carb cleaner not off brand crap it does'nt
clean as well. Pull the pilot ,main jet, and air screw. Then remove the needle and seat to make sure there isn't any dirt behind the needle seat.

The air screw "should" be set at 1 1/2 turns.

There is also fuel filters / screens in the fuel tank on the on off valve for the fuel. Pull them and make sure there clean.

NGK spark plugs "suck" they may be new and look fine but get them wet one time and there done.

If this doesn't work P.M me and we will figure it out.
 
I've got a chinese made Yamaha knockoff. Aside from the lockup, BTDT.
I think the off timing could have a little to do with it, but not everything. Never overlook the spark plug, no matter how new you think it is.
Aside from the carb itself that I finally replaced, mine was sucking air at the boot between carb and jug because the boot was cracked. Didn't see it setting still, but as you bounced around, it would flex a little and cause the screwups. Once I found it, I smeared gorilla glue all around the boot and ordered another (haven't put it on yet cause the GG is still holding).

James Rump;
What do you suggest for a plug brand? I go through NGK's like candy.

Dave
 

I try and use Autolites. We had found the 4053 was great in alot of things and 1/2 the cost and never fowled.

I have good luck with the Champions as well, the NGK are very poor quality.



Your timing isn't off. If you think of timing like a circle [0 - 45 - 90 - 180 - 360 ].

In a car if it jumps on tooth you can't turn the distr enough to get it to start with out getting into spark scatter.

The carb is dirty ... Another good test is when it is running spray starting fluid around the rubber intake and base gasket of the cylinder.
If there is a leak the rpm will go up . Sucking air "lean" burn down.....
 
Thank you everyone.
The fuel flow is ok.
The vent is not plugged.
I will try a new plug.
It does run, but not good at all.
It does not want to accelerate without the choke on.
Steve
 
(quoted from post at 18:04:39 11/03/09) It does not want to accelerate without the choke on.
Steve

When you get the carb clean, clean it again. And check that intake boot out real good.

Dave
 

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