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First of I want to say this is an awesome site! Been on it all morning.Here's the problem and I'll warn you this will be long. I was given 2 machines. One is a Yamaha excitor II(black & purple) and the other is a red machine that just says excitor. They are both 570's and I'm guessing early 90's.I put the engine from the Excitor II into the Red Excitor. I can getit to run for about 10 seconds before it starts popping out the left carb and dies. IT smells like exhast smoke after it pops. I have rebuilt the carbs,still does it. I have rebuilt the fuel pump,lines and filter,still pops.I have switched carbs from the other motor,still pops out the left carb. I have switched carbs from left to right,still pops.I have pulled the motor,pulled the flywheel,cleaned the magneto and still pops. I got desprite and pulled both cylinders of last night and they lok beautiful along with the carbs and pistons. I did notice alot of fluid in the bottem of the crank case. Oh yeah,I have also switched the coils with no change. Did a compression check and I have 125#'s even accross. What do you think of maybe the little cdi box being bad??It's about the only thing I havn't fooled with.PLEASE HELP!!
 

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Check your throttle cable switch, Exciter IIs were equipped with a throttle safety switch that was always suspect. Try to jump it with a piece of wire to by pass it.
 

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Check your throttle cable switch, Exciter IIs were equipped with a throttle safety switch that was always suspect. Try to jump it with a piece of wire to by pass it.[/b]
Thanks TD! Actually I pulled the engine out of the Exciter II and put it into the regular Exciter and I don't remember seeing that switch but I will check it out tonight.
 

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I believe it's located in the throttle assembly in the handle bars. Had a fellow I met on the trail some time ago and every once and a while his sled would spit and stall. We eventually put a jumper in the wiring harness then later his throttle cable broke. I guess it was telling us something.
 

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Your TORS doesnt sound like the problem but you can bypass it by unplugging it at the carb and plug the wires into themselves. The tors allows you to idle but not past 3000rpm.
You should not get a backfire through the carb, you said the piston is good and the rings ?
I seen a backfire melt a poo , the piston got a hole in it and lite up the oil and gas in the bottom of the airbox and I think he pissed on it to put it out. How fitting !
 

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First of I want to say this is an awesome site! Been on it all morning.Here's the problem and I'll warn you this will be long. I was given 2 machines. One is a Yamaha excitor II(black & purple) and the other is a red machine that just says excitor. They are both 570's and I'm guessing early 90's.I put the engine from the Excitor II into the Red Excitor. I can getit to run for about 10 seconds before it starts popping out the left carb and dies. IT smells like exhast smoke after it pops. I have rebuilt the carbs,still does it. I have rebuilt the fuel pump,lines and filter,still pops.I have switched carbs from the other motor,still pops out the left carb. I have switched carbs from left to right,still pops.I have pulled the motor,pulled the flywheel,cleaned the magneto and still pops. I got desprite and pulled both cylinders of last night and they lok beautiful along with the carbs and pistons. I did notice alot of fluid in the bottem of the crank case. Oh yeah,I have also switched the coils with no change. Did a compression check and I have 125#'s even accross. What do you think of maybe the little cdi box being bad??It's about the only thing I havn't fooled with.PLEASE HELP!![/b]
 

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Don't know what happened to the last attempt, but here goes again.

If it was your CDI box it will cause both cylinders to misfire - the coil fires both sides of the engine 2 times per rev. I think your problem is one of 2 things:

- Check your fuel pump - it gets its vacuum pulse through the LH side, if a diaphragm is cracked in the fuel pump it will suck fuel right into the crankcase, eventually flooding the LH side.

- Outer LH crank seal may shot - doesn't allow transfer pressure to build up in the crankcase to shoot the full charge up into the upper cylinder.

Check the fuel pump first, happened to my Exciter - easy fix, simple pump rebuild.

Hope this helps you out. Wigman
 

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Discussion Starter #8
Don't know what happened to the last attempt, but here goes again.

If it was your CDI box it will cause both cylinders to misfire - the coil fires both sides of the engine 2 times per rev. I think your problem is one of 2 things:

- Check your fuel pump - it gets its vacuum pulse through the LH side, if a diaphragm is cracked in the fuel pump it will suck fuel right into the crankcase, eventually flooding the LH side.

- Outer LH crank seal may shot - doesn't allow transfer pressure to build up in the crankcase to shoot the full charge up into the upper cylinder.

Check the fuel pump first, happened to my Exciter - easy fix, simple pump rebuild.

Hope this helps you out. Wigman[/b]
The pistons look awesome. When the machine back fires thru the left carb and dies I swear I also hear a blast or back fire comming out of the bottem left of the engine also. Would that be that crank seal failing. Whats involed in replacing it??
 

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Just an update. I completely split the case and put new seals and gaskets and it still popped and died. Was ready to give up and haul them away last night when I thought I would try one last thing. I took what I am guessing is the cdi box( a little 2" square box that was on a bracket to the air box) and went to swap with the other. When I went out to rob the one off the Enticer, I couldn't find it! I followed the wireing harness and finally found a box about 4"x6" bolted to a plate in the bottem side of the tub. I cut the wires and tried to match them to the Exciter but there was very few that matched. I matched the brown,orange, white and black. Now I really didn't expect much in my last ditch effort but I tell you I didn't even have to pull the rope all the way and the machine came to live and idled beautifully!! I couldn't beleive it. I started touching wires and got the head lamps and dash working while it was running. I did notice that when I gave it alot of gas it did bog down, thinking it is just carb adjustment but now think it may have something to do with the wires going to the carbs, which are not hooked up. Is there a way to tell or bypass them?? Just wanted to HOPEFULLY save someone eles the head ach I went thru by posting. Thanks!
 

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As somebody already mentioned in this tread, that is your TORS (Throttle override system) plug and if you don't plug it in it will idle but not run above 3000 RPM, so plug it in and you should be good to go. Or, as was also mentioned, you can jumper it to bypass the safety system. I wouldn't do that unless you think it's faulty.
 
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