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Discussion Starter #1
Hi Everyone,

I'm back with the same problem. I'll try and keep it concise. The bike ran great then the pickup died on my 06 VS650 last fall. I replaced the pickup and the stator (eletrosport). I put it back together and now I have after-fire or pop corning from the number 2. It was so bad it was unridable. I chased the wires, reversed and tested the coils, retested the pickup and stator, changed the plugs, looked for air leaks, replaced the carb boots, and have cleaned, rebuilt, and balanced the carbs at least 4 times. Now it after-fires is on idle, intermittent at cruising and highway speeds. It has died coming to a stop a couple of times but started right back up. Occasionally the rpm surges up without input. It "seemed" to pop more when the bike was upright vs on the stand, but hard to tell. Float bowls? IDK anymore.

The carbs have been re-jetted for Big Air/Induction and rode fine before any problems. Everybody wants to say dirty carb, but I've cleaned it so many times. Plus, when I bought the bike in 2014 it had sat for 2.5 years. If I got it running from that, 2.5 weeks to put a stator in should not have clogged the carb that much on top of cleaning it several times since then. I have not done a vacuum test valve re-lash. It ran fine before the repair. Why would that be a problem now. I have video but no way to upload it for people to hear. Please help. I feel the season slipping away.
 

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hmmm, try swapping the wires on the pickup coil. some aftermarket coils are switched
i'll never understand why yamaha has those two wires the same color. it leads people to believe they can be switched around when they absolutely can not. i would never use an after market pick up on a 650 for the simple reason the labor to change it is to great to take a chance on installing a cheap part, plus the fact that a cheap one could strand you when you least expect it. my first one failed at 35,000 miles at the end of this season i'll be at 70,000 so i might change it this winter as part of the routine maintenance.
 

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Discussion Starter #4
I thought the same thing and reversed the wires. At first the pop corn sound stopped, but then I got monstrous back fire through carb, flame out the pipes, and it was unridable. I'm at float bowls or air fuel mix out of adjustment (can't imagine why or how) or sticking valve.

Added info. I had noticed oil leak into #2 spark bung. Did not foul plug. It would smoke and cook off as bike warmed up. Thought leak was from valve cover. Has since cleared up and stopped. Also, when disconnecting vac lines from carb boots to balance carbs, light smoke comes from #1 port but not #2. Pop corning stopped (though power drops) when line disconnected from port #2 while bike is running. I've have given this info before and am sure that this is a clue. I just don't know what it's telling me.
 

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I thought the same thing and reversed the wires. At first the pop corn sound stopped, but then I got monstrous back fire through carb, flame out the pipes, and it was unridable. I'm at float bowls or air fuel mix out of adjustment (can't imagine why or how) or sticking valve.

Added info. I had noticed oil leak into #2 spark bung. Did not foul plug. It would smoke and cook off as bike warmed up. Thought leak was from valve cover. Has since cleared up and stopped. Also, when disconnecting vac lines from carb boots to balance carbs, light smoke comes from #1 port but not #2. Pop corning stopped (though power drops) when line disconnected from port #2 while bike is running. I've have given this info before and am sure that this is a clue. I just don't know what it's telling me.
opening a vacuum line would lean out that cylinder so maybe it's too rich if doing that stopped it, a valve that got tight would cause that also. a compression test is quicker than checking valve lash if you think that where the problem is. pulling a plug is a good indicator of a rich or lean condition. the only thing you did to the bike was a pick up coil and the after market pick up's are totally unreliable, there are a lot of posts of those going bad just days after installing them. the same thing applies to stators i'll buy 100.00 used one that's slathered in epoxy rather than an aftermarket that's only coated in shellac
 

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Discussion Starter #6
Thanks again pauli466. I will do a compression test tomorrow. I put a multi-meter on the stator and pick-up and they read within spec. Actually, the factory stator is supposed to be between 3.7 and 4.6 I believe. The aftermarket read 2. IDK if that's my cheap multimeter or if less resistance is better. But I would not think that it would only affect the #2 cylinder and all three wires read the same. The pickup was within spec.
 

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Discussion Starter #7
Ok. I was not able to get a leak-down test, but I was able to do a compression test. I got 140-142 up front and 145 on the rear. I check the plugs where the AIS used to be and reinstalled the rear one. I rode it home with checking the valve lashing in mind. Today was the first day I could get back to it and I pulled the #2 exhaust (V/H short shots) off and reinstalled with copper seal gasket maker. The bike popped with the choke out but got better as pushed it in until it idled fine. I let it warm up and no problems. I pushed the bike up and the bike popped a little. So, I got off the bike and started to rock the bike upright back to kick stand and repeated. It popped every time and got worse as the bike leaned to the right. Now, I'm back to it being a carb issue. Fuel bowls? What should I be looking for? Plus the#2 plug is just showing signs of carbon. Please see the attached photos. The plug in the socket is #1.

Thanks
 

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Ok. I was not able to get a leak-down test, but I was able to do a compression test. I got 140-142 up front and 145 on the rear. I check the plugs where the AIS used to be and reinstalled the rear one. I rode it home with checking the valve lashing in mind. Today was the first day I could get back to it and I pulled the #2 exhaust (V/H short shots) off and reinstalled with copper seal gasket maker. The bike popped with the choke out but got better as pushed it in until it idled fine. I let it warm up and no problems. I pushed the bike up and the bike popped a little. So, I got off the bike and started to rock the bike upright back to kick stand and repeated. It popped every time and got worse as the bike leaned to the right. Now, I'm back to it being a carb issue. Fuel bowls? What should I be looking for? Plus the#2 plug is just showing signs of carbon. Please see the attached photos. The plug in the socket is #1.

Thanks
the thing is a plug can foul like that for two reasons, too much fuel and also a miss fire, reverse the plugs to make sure the miss doesn't switch to the front cylinder indicating it was a bad plug all along. then get some clear tubing and check your float levels. it sounds like the rear float level is high or the needle seat is leaking
 

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Discussion Starter #9
Update on this afterfire problem. I took the bike apart down to the wire harness to check my pick up connections. I replaced one that was "kind of loose" but not really. I took the carbs apart, reversed the floats to see if the problem moved with it, and bench set it. (Side note: the butterflies opened enough for about a paperclip to fit with the screw turned to fully open). I put it back together and the afterfire was better but not entirely gone. I hot set the carbs and rode the bike for about a mile and once again, afterfire at low speed up to 3rd and intermittent afterfire at speed. But it was not a bad as before. It was annoyingly drivable. I then hot set the carbs again. While the bike was running and hot I pulled vacuum lines from the carb boots. Pull the number one and the bike died. Pull number 2 and loss of power but kept running. If I plugged the number 2 port with my finger the afterfire would return. Take it off and power would drop and afterfire is gone. Some time before this problem occurred, the vacuum line to #1 split at the end so I replaced it with a similar inside diameter but thicker tubing and left the #2 alone. Today I reversed the the tubes. Now the thick vac line that was on #1 is now on #2 and the bike seems dialed in to about 95%. Afterfire on decel and little bit intermittent at speed, but barely. It's actually drivable now. I don't know what this means or what I did, but I'm putting the info out into the ether. Also, my throttle knob is turned in to almost max if not max to get proper idle. I'm still open to input. I will put some miles on it over the next few days to see if this is a permanent fix. Note: It has a hypercharger on it. The vac lines come off the carb boots to a T fitting.
 

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lock the hypercharger butterflies to an almost closed position and see how it runs, what position are the butterflies in right now with engine off, tell me that much and i can go on from there to help you out. there are tiny o rings under the main jets make sure they're in good shape there is also a gasket under the pilot jet make sure that is in good shape also if ether one of those seals are bad you'll get miss firing due to the cam overlap (both valves are open for a split second) this causes a quick pulse in the intake and exhaust and any fuel or air leaks show up as a miss or as you say a pop or skip
 

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Discussion Starter #11
Ok. So I have been riding the bike around for a bit. Very short stint test rides. Though it is more ridable than it has been it's clearly not right. It afterfires less, but it is still going on. It's bad on decel and in low or traffic gear. Open the throttle and she feels and sounds great. The throttle screw is all the way up and the bike is just at an acceptable idle. The RPMs sometimes stick when you rev it. Once I had to put it in gear to get the revs back down. When the bike is off and sitting, the hypercharger butterflies are wide open. I've held them shut and held them open while the bike was idling and revved; and the difference was negligible. It has a Stinger trap door so I don't know if that makes a difference. I will try and do a fuel bowl check once I find the proper tubing. I did not check those rings specifically, but I have done a thorough site inspection and have not found anything amiss. Plus, I don't understand how all of this can come out of whack just from a pickup/stator replacement. I will wait to hear from you before I go through the trouble of taking this carb off again for the what seems like the hundredth time.

I've been dealing with this problem since October and there is no cycle repair near me that works on bikes older than 2010 or they are dedicated to BMW or Harley. This is as close to riding that I've got so far. I've worked on plenty of cars but am new to bikes. It sat for two and half years in my bro inlaws garage. I tore it down and rebuilt it into a bobber in 3 weeks and it ran great. I replace the pick up and stator and can't get it right in 7 months. I'm getting to my wits end on this thing.
 

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Ok. So I have been riding the bike around for a bit. Very short stint test rides. Though it is more ridable than it has been it's clearly not right. It afterfires less, but it is still going on. It's bad on decel and in low or traffic gear. Open the throttle and she feels and sounds great. The throttle screw is all the way up and the bike is just at an acceptable idle. The RPMs sometimes stick when you rev it. Once I had to put it in gear to get the revs back down. When the bike is off and sitting, the hypercharger butterflies are wide open. I've held them shut and held them open while the bike was idling and revved; and the difference was negligible. It has a Stinger trap door so I don't know if that makes a difference. I will try and do a fuel bowl check once I find the proper tubing. I did not check those rings specifically, but I have done a thorough site inspection and have not found anything amiss. Plus, I don't understand how all of this can come out of whack just from a pickup/stator replacement. I will wait to hear from you before I go through the trouble of taking this carb off again for the what seems like the hundredth time.

I've been dealing with this problem since October and there is no cycle repair near me that works on bikes older than 2010 or they are dedicated to BMW or Harley. This is as close to riding that I've got so far. I've worked on plenty of cars but am new to bikes. It sat for two and half years in my bro inlaws garage. I tore it down and rebuilt it into a bobber in 3 weeks and it ran great. I replace the pick up and stator and can't get it right in 7 months. I'm getting to my wits end on this thing.
what set up for intake and exhaust are you using everything your saying points to a extremely lean condition. check the idle cutoff. (enrichening valve ) sounds like one of em is hanging up it is supposed block the pilot air jet when the throttle is closed it's a little spring loaded valve on the side of the carb you can change it or check it with out disassembling the carbs. it's called a diaphragm and spring on the parts list, its specifically for after fire, all it takes is a spec of dirt on the plunger to make it ineffective.
 

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Discussion Starter #13
I have the PMS at 3.5 turns out. Baron big air re-jet, hypercharger with trap door, and v&h short shots. Diaphragm needle set on 3rd rung if I remember correctly. When I last had the carb apart I looked at the diaphragm for tears and dirt and did not see any. This may be a dumb question, but how tight do you tighten the diaphragm needle? (that nylon slot head screw). Until it seats or a little loose?

I replaced the idle cutoff solenoid with one I had on a backup carb. I haven't swapped carbs because the backup needs a complete teardown, cleaning, and re-jetting. But at this point... Anyway, no real change. And I have the idle knob all the way in just to get a decent idle. I will exchange the springs and re-check diaphragm.
 

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I have the PMS at 3.5 turns out. Baron big air re-jet, hypercharger with trap door, and v&h short shots. Diaphragm needle set on 3rd rung if I remember correctly. When I last had the carb apart I looked at the diaphragm for tears and dirt and did not see any. This may be a dumb question, but how tight do you tighten the diaphragm needle? (that nylon slot head screw). Until it seats or a little loose?

I replaced the idle cutoff solenoid with one I had on a backup carb. I haven't swapped carbs because the backup needs a complete teardown, cleaning, and re-jetting. But at this point... Anyway, no real change. And I have the idle knob all the way in just to get a decent idle. I will exchange the springs and re-check diaphragm.
i would just seat the needle holder and stop there. there are gaskets under the pilot and main jets, sometimes they get lost when working on a carburetor and you'll never know they were there, you can try making the spring a little weaker by clipping a coil out on the air cut diaphragm to make it close quicker and easier, check the pilot air jet not the pilot fuel jet thats under the bowls. it should be right at the neck where the air box attaches
 
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