help, i am stumped?? flooding,bog,backfiring mag side

snowfoxsx

snowfoxsx

New member
Joined
Feb 2, 2004
Messages
139
Age
51
Location
winnipeg manitoba canada
my sled is a 97 700sx. i just rebuilt the motor, 130 psi straight accross so compresion is good, bender triples, 150 mains, 52.5 pilots, needle per setup specs. reed spacers, carbon reeds, notched stops. and new plug caps and trimmed the wires half an inch for good contact. i think the altitude is 600-1000 feet.(winnipeg manitoba)

the trouble is with the mag cylinder, it has spark, compresion and is getting gas, but does not seem to want to stay running, it seems to flood out? wet plug. the other 2 are fine, i switched plugs, and coils with that cylinder and it is the same no matter what i do. when it is running there seems to be a mist comming out of the 2 running cylinders carbs but not the mag side. it had new plugs put in (3 sets are now shot, br9es, br9eya, br9ev) i took off the reed cages and the cylinder had a lot of gas in it, i dried it out and the same thing happened. it seems to run fine on the stand, all the pipes are hot but when i go for a ride it bogs down right away and kills the mag side again?? the thing also backfires when i just touch the throttle out of one pipe(mag), the tors is bypassed so that is not it.

i am going to try another set of plugs tonight, i left a heater on it all night to dry it out i hope! i will also try swapping the reed cages to see if it is them. the carbs were apart a few times and everything seems ok, level and jets are clean but i will check again. the carbs were cleaned.

sorry for a long post but i searched the site and found a few articles but nothing really dealing with this. if anyone has any ideas please let me know!!

snowfox@mts.net #$%&* #$%&*
 

Sounds like a carb problem. Check your seat in that carb and also take the pilot jet out and blow some air thru to be sure nothing is stuck in there.
 
Im with both of them, I have cleaned carbs and taken them back off and found more #$%&* in them????? Id do that a couple times before taking that off the list. Brent
 
there is pattern here. Carbs need cleaning. Sometimes you think they are clean but you really need to clean and blow them out.
 
Doesn't sound like a fuel problem too me if the crankcase is filling up with fuel. You might be on the right track with a bad spark plug or weak spark in that cylinder for some reason. I would also check that new plug cap you put on. Is it the correct ohm cap ?
 
MrSled said:
I agree...clean the carbs really well....then go from there...what clutching are you running??
Click to expand...

89L weights, 2.4g rivit, 51/45 helix, ygy primary spring, stock secondary spring, stock gearing.

well i will clean the carbs again tonight and see what happens, double check everything and check the plug caps like i was told.
thanks you guys!!! anyone have anything else to add?? i will let you know what happens later on tonight!! :rockon: :rockon:
 
I'd go right for the carb myself, then the spark plug cap. But if you're absolutely sure everything else is perfect................why did you rebuild the engine, the only thing you could be missing is spark at the correct time. Did you check the phase on the crank?
 
sounds to me like you have a bad crank seal if you have fire and fuel but no ignition crank seal problem.to check use acetalene put near crank seal and if it picks up seal problem.ether works to.
 
had a similar situation on my 97 600. Backfire and bog when riding but good on a stand. Cleaned carbs and noticed that the float needle was sticking. The tiny little plunger on the needle was not working. When sled was bouncing around on the trail it would act up. Changed out needle and never had another prob.

Everone always says to check needle & seat, for wear but never heard of checking the plunger.
Hope you get it figured out. I'm still waiting for snow this year to even start riding.
 
plugged exhaust

Make sure the cyl in question exhaust is clear. Didn't stick rags in the stingers or pipes on the benders during rebuild?
 
Switch then reed around see if that cly flodds then you know you have a bad reed
 
thanks guys, i will try this stuff in the morning, it's been kinda cold here all week so i never bothered with it, -40 to -48 celsius with the windchill!!

i will let you all know how it goes
 
well i tried all the stuff mentioned, switched reeds, plugs, caps, coils, cleaned the carbs again(3 more times) fresh gas, lots of spark, 130 psi compresion, no rags or blockage anywere, floats are set at 13.5 mm and still no luck with that cylinder. it just loads up with gas, the pipe is cold! the inlet jet looks fine and was cleaned, if it is worn how could you tell? would this cause the trouble? my next step is to swap it with another carb and see if that is the trouble.
 
the only way to tell the inlet needles are bad is to get a new one and drop it in. I have had this happen on a exciter many years ago....
 
i cant remember whick cylinder the pulse line is for the fuel pump but if its the pto side it could be a leaky diaphram in the pump, just check and see,if it idles fine but loads up when you whack it coould be the isue, but check to see where the pulse line goes to
 
My dads 98 sx 7 was doing the same thing on the mag side last year so this year i took the carbs off cleaned them really good, and put new reed petals in and so far this year it seems to be running fine, ill find otu today for sure while actually riding it besides in the grass. but his was doign the same thign ran good untill you rode around then boom there went the plug like you said it was really wet. It ran fine as long as you had it to the bar. So ill let you know if that fixed the problem!
 
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