sled firing on 2 cylinders

kirk700 srx

kirk700 srx

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labrador city n.l
I cant seem to find out why my sled is acting up again, its firing on 2 cylinders but sometimes it fires on 3 the mag side pipe gets a little warm but not the same as the center and pto. I tried changing plug, plug cap the plug is clean when I take it out, there is no carbon build up, almost like it is not getting any fuel. I have cleaned the carbs twice. There is a new stator in it last year. The pipes are clear of debris. Anyone know something else I can try?
 
kirk700 srx said:
I cant seem to find out why my sled is acting up again, its firing on 2 cylinders but sometimes it fires on 3 the mag side pipe gets a little warm but not the same as the center and pto. I tried changing plug, plug cap the plug is clean when I take it out, there is no carbon build up, almost like it is not getting any fuel. I have cleaned the carbs twice. There is a new stator in it last year. The pipes are clear of debris. Anyone know something else I can try?
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What year SRX?
 
Well, your getting fire to 2 cyl so its not stator or p/u coil. Also, the 98's fired all cylinders at once to it doesn't seem to be related to the CDI. Start at your CDI and work your way to the plug testing for Voltate as you go. Could be a bad wire or coil.
 
swap the center and mag plug wires over and see if the problem moves.if ti does you got a bad coil or coil ground,if not and your sure the carb is clean and good check compression and reeds on the mag side .the 98's fire all coils at the same time with the same two wires so if two cyls are running good its not a cdi or stator problem.
 
Check the reeds as mentioned. How does the piston wash look? When i had simular issues, my sled would run horrible, sometimes kick on 3 then back to 2... Mag side piston was clean, I mean totally spotless. I checked the reeds after checking coils, caps, changing plugs, and i was missing about half of the lower petals on my mag side reeds.
 
Ok so I changed the spark plug wires from mag to center still no change.swapped out all 3 plug caps and removed the carbs and checked the reeds, all good. I removed the breather box and it runs better. I am not sure what you mean by piston wash? the electrode on the center and pto are cardboard color but around the plugs are black with carbon and the mag is spotless.I havent check the plugs after I removed the breather box
 
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Piston wash is referring to what the top of the piston looks like. AFAIK, a properly jetted/running sled will have 85-90% of the top of the piston black, in almost a "D" shape with the flat side towards the intake, and will be clean (shiny) about .25" away from the cyclinder wall in all other spots. In my case, the cyc I was having trouble with, the piston top was TOTALLY clean, no carbon at all. If i would have been hungry, i could have eaten food of the top of the piston it was so clean...

Im sure somebody else can describe proper piston wash more clear, or maybe someone has a picture to show.

Did you check compression? Any way a headgasket could be leaking on that side?
 
Yeah checked compression 110 all the way across. Which is low but I just rebuilt the motor from the bottom up and it hasnt been running long enough to break it in. maybe I do have a leaky headgasket,but i dont smell antifreeze burning! I will pull the heads tomorrow and take a couple pics so everyone can see the piston wash. I ran the sled with the breather box off and it ran alot better,it actually seemed to run on all 3. I have another set of carbs on my mountain srx maybe ill swap them out and see if the condition goes away. The mountain is running absoultely great so I know the carbs are set up right.
 
I wouldn't pull the engine apart until I eliminated all other possible causes! If the compression is even all the way across and the other 2 cylinders are firing...low compression is not the issue, all guages read a little different so equal compression readings most times is more important then the actual reading.

I would focus on the carbs...check for blocked jets, check the choke circuit, float level, and "top hat" filters under the float needle seat.

If you put fuel in the cylinder that is not firing does it cut in?

Bob
 
kirk700 srx said:
Yeah checked compression 110 all the way across. Which is low but I just rebuilt the motor from the bottom up and it hasnt been running long enough to break it in. maybe I do have a leaky headgasket,but i dont smell antifreeze burning! I will pull the heads tomorrow and take a couple pics so everyone can see the piston wash. I ran the sled with the breather box off and it ran alot better,it actually seemed to run on all 3. I have another set of carbs on my mountain srx maybe ill swap them out and see if the condition goes away. The mountain is running absoultely great so I know the carbs are set up right.
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Not to sound like a jerk.... When you put the motor back together did you make sure that the gasket surfaces were extremely clean? Did the base gasket maybe get moved and you are not getting a proper charge into that cylinder(air leak)??? Just a thought. Bandit
 
Everything was spotless when it was put back together. I never tried priming that cylinder. Ill give it a shot tomorrow morning and let ya know how it responds. I blew the bottom rad hose off of the resevoir last night, my hose clamp snapped and I had coolant everywhere Could the sled being airlocked make the sled run this way?
 
As Sideshow says... Double check to make sure that the circuits are clean in the carbs, as this may be where your issue is.
 
I'm starting to think this is my problem .I never got time today to try a different working set of carbs but I have a babysitter for tomorrow. I will try a new set and if this is the problem I will be looking for another set of carbs. Anyone have a set of clean 98/99 carbs for sale? I have had it with the set thats on the sled now. All last winter, I had the same issues with this machine. Only work decent if it was freezing. It has stock jets and needles are set correct for <2000ft, was cleaned a hundred times.Could there be something I am overlooking on these carbs?I have had them stripped down to nothing and followed manual on re assembly
 
I don't think you need new carbs as anything that can cause the problem can be cleaned or replaced. The fact that you say it works better when its "freezing" would indicate you have an issue with too much fuel.

Need more info:

-when you cold start it does it start up on all 3?
-does it only run on 2 at idle?
-does it run ok wide open?
-have you tried a different fuel pump?[polaris tripples were nitorious for filling the engine with fuel through leaking fuel pumps]
-have you checked the float levels?
-if you have been riding it for awhile does the problem still occur or is it only on initial start and initial ride?

Bob
 
Start up runs on all 3, Sometimes blows plug. runs on 2 when gas is applied runs like a bag of $hit at WOT unless its -15 C. Changed fuel pump last year but will try again. Float levels are all set at 13mm. Sometimes it lets loose and screams like a scalled cat. Has been running better with breather box removed. I know Im leaning out ther other 2 cylinders to make the mag side run better I cant seem to figure out what is wrong with the mag side carb
 
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Do you have a primer on this sled?

If the needle + seat is worn or not seating it will allow the float bowl to overfill and flood the cylinder as the fuel pump will happily pump as much fuel into the bowl as it can.

A couple of things to check[I know you probably have looked at these]

-check/replace all the float bowl needles + seats[if one is worn you should replace them all] you can check these when carbs are removed from sled by leaving them assembled, installing a short length of fuel line on the carb inlet, turn the carbs upside down and try to blow in the line...it should resist you blowing air thru/past the needle and seat. You'll know if one is bad because it will be easier to blow air then the other two.
-check throttle valve syncronization
-check slide needles for proper clip position, wear , and proper needle + needle valve
-sticking float? [if the float can contact the bowl because it is bent it will flood]
-broken, chipped, worn out reed valves...if the reeds don't seal the cylinder will run rich.
Bob
 
You don't suppose the choke plunger on that carb is sticking or has somthing in it do you ? Or out of adjustment ? Jut a thought .
SS
 
That could very well be! are the choke plungers all the same on 33mm carbs?


SneekySnake said:
You don't suppose the choke plunger on that carb is sticking or has somthing in it do you ? Or out of adjustment ? Jut a thought .
SS
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