700 Sx Problem

L

LEFTTURN

New member
Joined
Nov 26, 2010
Messages
2
Age
59
Location
NORTH DAKOTA
I bought a 700 sx last week not running for 2 cases of beer. It has Power Inc. end dump pipes.
It will not run on all three cyliners. I bypassed the switch on the carbs and checked the switch at the throttle block with an ohm meter and it is closing.
I tried a different known to work cdi, switched tho coils around, had the flywheel off stator looked ok but dont know how to check it. There is good bright blue spark at all three spark plugs but it will only run on two. The pto side will not heat up the pipe. The center and mag side cylinders will heat up but it seems like the center one not as hot as the mag side pipe. Had the carbs off and went completely through them, clean and in good shape. Had the read cage off the pto side, looked good. Vaccum tested the fuel pump,OK, put a new filter in the tank and cleaned the tank, put in fresh gas.
When I take off the pto pipe it has gas in it. The pipes are wet at the flanges on the center and pto cylinders, the pto one is alot wetter. I had the head off and everything looked good, no scoring, can still see honing scratches. It has 125 PSI on all three cylinders after it has run a few minutes and warmed up. Could I have a broken piston skirt, or is there a seal or o-ring on the crank that could be bad? I sprayed ether on the crank seal behind the clutch ant it would not speed up the engine so I think that seal is ok. Dont know what else to check but want to get this sled going.
 
Check to make sure that the choke isn't sticking on the pipe that doesn't heat up flooding the cylinder. Did you change the plugs-Put fresh ones in? Also check as stated in above posts.
 
Our fuel quality is so poor nowadays that it plugs up carbs pumps ect very quickly on a sled[or anything else] that has sat for awhile.
To trouble shoot:
- remove the plug on the dead cylinder and put some fuel in that cylinder, replace the plug and pull it over a couple times with the ignition off
- turn ignition on and start it up
-if it runs on all 3 it is obviously a fuel issue.

When cleaning carbs ensure:
-you check your float levels
-check/clean the "top hat" fuel filters that are under the fuel bowl needle seat..they are very often missed.
When you clean the carbs

JM.02c
 
I'm not sure of which cylinder the vacuum port for the fuel pump comes off of, but I think it's the pto cylinder. Your fuel pump may be leaking fuel into that cyl. and drowning it. Pull the vacuum hose from the pump. It should be bone dry.
 
I guess when I read your post in #1, it doesnt say that you made sure the pilot circuit was open and flowing fuel not only thru the jet but it comes out the orfice in the throat of the carb when you insert the little plastic tube from carb cleaner can. the pilot jets have to be removed and cleaned and you should be able to see light thru them when you hole them up to shop ceiling, but its much important to make sure the fuel path inside the carbs is open.
 
I agree with MrViper.........sounds like dirty pilots. I just cleaned some for my brother in law on his '98 XTC 700. He had the same issue. The thing ran mint afterwards.
 
got a used stator from a salvage dealer. goes to beat ?ell now! Thanks for all the help and what a great web site!
 
It's nice when people come back and let us know what the problem ended up being. I am always curious to know.
 
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