Afterfire Problems - Star Motorcycle Forums: Star Raider, V-Max, V-Star, Road-Star Forum
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post #1 of 14 (permalink) Old 04-25-2016, 09:39 PM Thread Starter
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Afterfire Problems

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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post #2 of 14 (permalink) Old 04-25-2016, 09:57 PM
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hmmm, try swapping the wires on the pickup coil. some aftermarket coils are switched

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post #3 of 14 (permalink) Old 04-26-2016, 09:16 AM
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Quote:
Originally Posted by BigBuddha76 View Post
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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Last edited by pauli466; 04-26-2016 at 09:27 AM.
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post #4 of 14 (permalink) Old 04-26-2016, 09:56 AM Thread Starter
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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.
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post #5 of 14 (permalink) Old 04-26-2016, 06:45 PM
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Originally Posted by motohead View Post
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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Last edited by pauli466; 04-26-2016 at 07:11 PM.
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post #6 of 14 (permalink) Old 04-26-2016, 09:05 PM Thread Starter
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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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post #7 of 14 (permalink) Old 04-30-2016, 07:32 PM Thread Starter
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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.

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post #8 of 14 (permalink) Old 05-01-2016, 07:10 AM
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Originally Posted by motohead View Post
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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post #9 of 14 (permalink) Old 05-28-2016, 02:46 PM Thread Starter
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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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post #10 of 14 (permalink) Old 05-28-2016, 05:04 PM
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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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Last edited by pauli466; 05-28-2016 at 05:14 PM.
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