Need help ASAP AGAIN!!!

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workaholic

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Jan 25, 2004
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I recently posted a problem that i was having with my PSI twin pipes for my Yamaha Exciter 570. It was running on one cylinder most of the time at idle.... I removed the pipes and put my stock back in. Put the stock 320 jets back in. The only thing i kept "modified" is the power jets in the carbs, i removed them and put a screw in the hole. Also the main jet is at the bottom of te bowl (stock) and PSI told me to remove it from the bottom (leaving the hole there, unplugged) and putting the main jet at the top of the bowl where the needle jet setter is (so the it screws upside down). Now, the problem..... At idle it still runs on 1 cylinder (always the same side) but when i give it gas it kicks in and stays on if i keep giving it gas but if i let the throttle go it goes back to 1 cylinder. If i jack up the machine and then start it it will run on both fine. but as soon as i drop it back on the ground and let it idle it goes back to one. I noticed that one of the needles (the clutch side) had 2 plastic washers underneath the adjustment clip and the "bad" side had only one. So i removed 1 from the other side and just use one on both sides. That shouldnt make a different right (besides running richer or leaner). Another thing, when i put the choke on it runs on 2 cylinders fine. I tried changing the cables sides and still the same (problem ALWAYS sticks to the same side), i just replaced the piston so the engine is fine. good compression. Could it be the powerjets? maybe the main jet needs to go back to the bottom of the bowl? I tried playing with the idle and nothing.

What do you think "reelrazor" :) you seem to know your s*i*.
 

Just stabing in the dark here.............. the common sence thing would be to make sure that carb is clean for sure....I think you have done that.

when is the last time the carbs were syncronized.

what about float level.... I thought about float level when you said that you lift the back end up and it runs on both????????????

Tod
 
the carbs have been cleaned SEVERAL time :) Also i have never plaied with the float level, but when i raise the machine the track is able to free spin, its sorta like a pressure thing or something. i am completed stumped on this problem.
 
so can it be the power jets? should i put them back in? i put the main jet back to the bottom of the bowl. I checked the float height and they are good. I havent synched the carbs though
 
engine idle

I would check your pilot jets. My guess is that the bad cylinder is plugged.
 
i checked the pilot jets and they are fine, all jets are clean and clear. It only runs on 1 cylinder at idle, once it hits 2500rpm it kicks in and runs fine but once i let it go down and idle lower than 2500 it only runs on the clutch side. What could it be?
 
i noticed that in the PSI instructions for the pipes i had it said the stock needles are 6dh7-4. My needles are 6fl82. Could that be the problem??
 
Take your carbs off again . Remove the idle mixture screw on the dead cylinder ,blow air into the hole where the screw was and see where or if it is coming out .I am not familiar with that sled but a carb is a carb and it sounds like no gas at idle .Thats where I would start . I assume that you have checked for spark at idle .
 
idle mixture screw? is that the pilot jet? I had switched the carbs sides completly and it still occured on the same side. So that means that the carb jets, hoses, ect are not plugged, most likely a bad adjustment right?

Could it be the wrong needle
 
check your wiring harness by the cdi box ive noticed they start rubbing on the motor and cause a small short that could cut out the coil or other things like your lights might be dimming etc just a problem i had with mine maybe that will help :D Richie
 
Not sure which cylinder side the pulse line from the fuel pump goes into, but see if (when the motor is off) if you take the pulse line off the case and see if the diaphram is getting extra fuel past into the crankcase. I suck lightly on the hose and stick it on my lip for a few seconds, and if it holds to my lip, the diaphram is probably ok. If you don't hold a vacuum and fuel starts to escape the fuel pump through the pulse line, it could be part of your problem. If the cylinder comes back around as soon as you touch the throttle (not waiting for a flooded cylinder to clear), maybe that's not your problem. Just something different nobody else mentioned yet. If you are running 320 mains in the standard way (not the powerjet way), I'd plug the hole where the powerjet was. It may not be affecting your low idle circuit, but I blocked mine off and ran 290s for my porting and temps where I live. (mine was an '87). Good luck, hope you get it figured out.
 
i plugged the powerjet holes when i removed the jets. So if my cylinder kicks on when i press the throttle (seems to kick on near 2500-3000rpm) that means that my pulse line is ok??? i am a little confused about the pulse line thing.
 
so i disconnect the pulse line hose from the engine case (it is on the "bad" cylinder side by the way) then suck on the hose and put it to my lip to see if it does a suction. And if it does make a suction that means that the fuel pump is ok right, and if it doesn't creat a suction and the fuel starts coming out it means that the pump is defective? If it is infact the fuel pump, would that effect the idle on that one side?
 
You switched carbs from side to side then its not the carb .Have you done a compression test ? Is there spark at idle . You have the fuel pump test right . You can check for spark at idle by disconnecting the plug wire and hooking it to an old plug that is grounded to the motorstart it and watch for spark it should be blue . If it is yellow it is to week .
 
Sounds like Fuel pump to me... I had a very similiar problem on an old Phazer. Changed the pump and it ran like a champ. Mine was running on one cylinder at idle also..
 
Is the plug on the cylinder that is not running wet or dry if you just let it run without revving it up so it does fire?

I am guessing it is dry because of your statement saying it picks up the cylinder when the choke is on, so if it is dry then that shows a definate lack of fuel and you need to check the pilot circuit, if it is wet then you need to see if you have good spark because you are getting fuel. What I do to check if the plugs are firing is just use a cheap automotive inductive timing light and you will need a battery to power it or move your car close enough. But if the plugs are so wet they can't fire the timing light thing won't work.

About the pulse line, I don't know if this is the problem because you say when the choke is on it picks up the cylinder, if it had to much fuel from the pulse line the choke would just make it worse.

When you plugged the power jet, did you leave the hoses alone? Don't remove the hoses unless your are going to also plug the holes where the fitting go.


The only problem I have had with a Exciter not running on one cylinder was a case of too much fuel, I had a broken spring in one of the choke tubes.


Also make sure your carbs are synched, it really shouldn't affect the sled at idle as long as both carb slides are seated, but if they are not both seated could be the cause of your problem if the carbs were adjusted so it would run with one slide slightly up.



The only thing that is really confusing is you say it still runs the same with the carbs switched. Are you using the same throttle cable that each carb was using originally or keeping the cables and slides on the original side but switching the carb bodies. If you are doing the latter, then that may point to a synch problem.
 
Make damn sure the choke ends are the same, the end piece that goes in the carb. Use a standard nail as a guide and sync your carbs. That will set the slides the same. Spray starting fluid around the boots and air box, if the idle comes in there is a leak. :roll: Like Wilson said, swap the carbs out and see if the dead cylinder follows the carb. If so, that makes the fix that much easier. Stick with it. You are close to the fix, sometimes I need a breather just to insure I have not overlooked something. Good luck.
 
If it still runs the same with the carbs switched you have eliminated a carb problem.. I'm tellin ya.. buy a fuel pump rebuild kit.. easy to do..
 
i change the carbs side and the problem sticks to the same side, i switched the trottle cable sides and still stuck to the same side, i switched the choke cable side to side and it stuck to the same side. So now the nest thing would be to check the pulse line right?
 
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