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Hello,

I have seen some posts concerning a rough engine, but not specific to my case. Hoping for some help...

1992 Yamaha Exciter II 570

December activities: Cleaned the carbs, replaced spark plugs, new belt, cleaned sheaves...

Issue: Sled is very responsive when starting up. Runs great. Eventually, after the engine is nice and warm, the sled loses all power and idles very low. Almost to the point of dying. If I am on hard packed snow then I feather the throttle and give it a little push to get it moving, but it still runs rough. Normal idle is around 1,500 - 1,800 rpms and after warm it drops down to just barely running. I have got to believe that this is related to the no power.

Any help would be awesome.

Thanks.

Sam
 

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Hey, sounds like we're having the same problems. I got an 89' exciter 570, I think the engines are just about identical except for maybe different carbs. I've tried about everything I can think of to cure this, but haven't had any luck. If you wanna compare notes sometime, let me know I can get ya my phone number. Maybe if we put our heads togeather we can come up with something. I can at least let ya know what didn't work.
 

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Hot engine power loss

For both of you , are these liquid cooled sleds ?? First thing I would look at is to "BE SURE" you are not overheating the engine. I am only saying this due to the fact you stated , It happens after the engine is fully warmed up !

When it acts up did you happen to try to play with the choke ? Somtimes by just adding a little choke You can get them to run better. If this is the case you have a fuel delivery problem. Let us know what happens . and we will see if we can help !
 

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I don't know about the other guy, but mine is running way rich. plugs are WET. I'm getting lot's a smoke. My coolant is full and no leaks. Tried running it with the valvr to the carbs off and on, made no differance. thanks for the idea though.
 

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Dies out !

When the sled dies out, and you pull a plug you say they are all wet ! Correct ? Then I would say that you are having a loss of ignition. They would be dry if it was loss of fuel !
 

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mine I think is getting too much fuel. It's wet around the exhaust manifold. If it's ignition, culd it be my stator, and how do I check it? I've already checked my coil.
 

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Stator testing

Checking the stator is not tht easy of a job. First you need a GOOD wire diagram. Find out which wire is the feed to the coil, each one you will need to have a tester hooked to the system and monitor the supply to coils and see if it is loosing a signal. There should be a (+) power feed, and a pulsing (-). Usally the (+) is the side that dies on a bad stator !!
 

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Ok, I started looking at a clymers book, and it looks like I can take a reading at the main wire harness. Sounds a little fishy to me, but won't hurt to check. What are your thoughts. I'm guessing that pry won't be it. If it's not what next????????
 

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Did you clean out the choke bores and adjusted the plungers so they are fully seated when the choke is in the off position?
 

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I had the carbs off again last night again. Everything was spotless. Put a little more slack on the choke cables to be sure their seating. Helped a little, but not much. Last thing I did was lean it out a tiny bit. Insead of 5/8 of a turn on the idle air screw I went with a strong half turn. Ran outa time last night so didn't get to run it yet, so thats for tonight. Another thought is the Fuel pump. I heard if its not picking up good on the pulsar hose, that sometimes it can load up one cylinder. Any truth to that??? If this doesn't help I'm going to try the pump unless someone has a better idea.
 

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I just found this post and I'm having the exact same issue with my 1990 570 exciter did you folks have any luck resolving the issue?
 
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