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Discussion Starter #1
HI Guys, I really need help with this one. I thought I could fix almost any engine problem but this one is kicking my butt!
I have a 2005 650 Wee with 33,000 miles. The bike has always run great until recently. And it still does if I ride it every day but if I let it sit more than about 4 days or so, it will start right up but soon starts missing on one cylinder. After a few minutes it is idling mostly on one cylinder with the other one kicking in once in a while. If I accelerate hard, it runs on both cylinders but will still miss some as the RPMs get up around 7000 and above. As the engine warms up it starts running better and better and after 10 or 15 minutes it is running great. So for the first 5 minutes it runs worse as time goes by, then for the next 5 minutes it runs like crap, then for the next 5 minutes it starts improving and then it is fine. So of course by the time I get home it is always running fine so I can't even diagnose which cylinder is the problem.
Here is what I have done so far. I replaced both plugs, synchronized the carbs, cleaned the air filter, checked the valve clearance, and ran three tanks of gas with injector cleaner. No help. An just to make more interesting it isn't consistent. Some times it is real bad and others not so much.
Also this started after I got home from a 950 mile trip with the last 100 miles in the rain. Then I washed all the mud off. The next morning it ran like described above but I assumed it was just because it was still wet. Sure enough it cleared up as soon as the bike got good and warm but I have had this problem every since. I have had it out several times for 200+ mile rides so it should not have any residual water issues.
Any one had this problem? Any ideas? HELP!!!
Thanks,
John
 

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To me, it sounds like an injector is not putting a full stream of fuel out. When the bike is cold it needs more fuel and when hot less. You mention that you ran injector cleaner through it, what brand? SeaFoam is really hard to beat. Add in an ounce or two of Marvel Mistery oil to the tank and it does an awsome job.
I have heard that bad gas will cause this as well. Have the last couple of tanks come from the same place? Try a different station/brand.
I know that the 650's are not know for the throttle boots being loose, but I think I would also look for a vacume leak somewhere. Check all hoses and fittings.
Start with the simple stuff, then work to the harder.
 

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I would not rule out ignition wires or the coils. Heat can change resistance. As such, as the bike runs, less spark possibly to the point of no spark. Just a thought. Kind of suspected someone would have already posted something about ignition already. Good luck! BTW, I am at the other end of the Beach Line. :)
 

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Discussion Starter #4
Thanks for the responses guys. Yes I will try some SeaFoam. I have had good luck with in auto engines. It feels like a fuel issue but I can't rule out electrical. The strange thing is that I have to let it set for at least 3 or 4 days to get it to show up, I have several bikes and normally only ride the Strom for longer rides and when the wife rides with me. We went for a ride last night and the bike had been sitting 7 days and it was really bad. I am going to ride it up to the auto parts store now to get some SeaFoam and I bet it will run perfict. It is this whole setting for a 3 to 7 days thing that hurts my head. That makes me think fuel issue. I have gone through about 5 tanks of gas.
Gas has all been BP 87 octane but from several different places. It could be ignition temperature related but if so I don't see how it would run fine the next morning when it is cold. I need to turn right around and go home when it starts next time and at least figure which cylinder has the problem. It just seems to always do it when I am in a hurry to get somewhere and I know it will clear up so I just push through.
Please keep these good ideas coming!
Thanks,
John
 

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Discussion Starter #5
Follow up; still no resolution. Last weekend I put in 1/2 a can of SeaFoam and filled up the tank with gas and then put 75 miles on the bike. So yesterday (Friday) before I was in a hurry to get somewhere, I cranked it up and let it idle. Sure enough after about 2 minutes it started missing on on one cylinder and quickly got worse until it was running on one with the other kicking in once in a while. I shut it down and pulled the plug wire off the front cylinder. I started it back up and it ran on one but smoothly, no misfires. So I assume it is the front that has the problem. But then when when I reinstalled the plug wire and started it up it ran smooth for a few minutes. So I took it out on a test ride and it ran great on the highway but every time I came to a stop it would start missing again. I put on 25 miles trying to get to clear up but it never really did.
So this morning the wife and I ride to Cocoa for breakfast (over in DougP's direction) about 75 miles round trip, and the bike started and ran like new the whole trip. No misfires or ruff idle.
I am still hopeful for the SeaFoam to have an effect, just not enough miles yet, but have not come up with any new ideas. :confused:
Anyone seen this or have any other ideas?
I am thinking fuel issue and I am thinking about taking everything in the fuel system apart and cleaning it and putting it back together. I should go through all the electrical connections as well while I have it apart. But that is a lot of work for a wild guess.

P.S. DougP, are you in the Titusville or Cocoa area? I grew up on Merritt Isl. and we ride that way often.
John
 

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Discussion Starter #6
Well I may have found the problem. :) I hope so. But I won't be able to test it for a few days as it needs to set to exhibit the problem. What I found is that the last time I checked the valves and replaced the spark plug, I got the plug wire routed wrong. That is, it should go over the top of head, but had slipped around so it was coming over the side. This resulted in the plug wire being stretched tight against the head. My theory is that when the bike sits for several days without running, the plug wire absorbed enough moisture from the Florida moist air, that it will leak voltage to the head where it is tight. After running for 15 minutes or so, it got the wire hot enough to drive out any moisture and stopped leaking. I know that is a little thin but it would explain the "sit a few days" mystery. If this is it, DougP made the right call above. Ignition issue!
I will post results.
John
 

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Discussion Starter #7
Well that was NOT the problem. I thought I had it fixed as I waited 5 days and then yesterday I cranked it up and it let idle until it warmed up. It ran perfect and I thought I was good to go. Then I road it 5 miles to the gas station and when I got there it had a slight miss at idle. I filled the tank and when I started it back up it was missing bad and soon was mostly running on one cylinder at idle. As soon as I got the RPM up is smoothed right out but each time I slowed down it started missing again.:( By the time I got home it was better but still not back to normal.. I didn't get a chance to ride today (lots of rain here in Florida) but I cranked up and let idle and it ran smooth. I expect it will be cured again until I let it set a few days. I think the next step is to pull the faring and tank off and go through the wiring and connectors. Just need some time.
 

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Discussion Starter #8
Great progress today! And two points to DougP for the electrical call!
I installed a switch in the ECU front coil feed so I could kill the front cylinder with the flip of the switch. When I started it up to check my connections, it started to miss in less than a minute. I quickly hit my new switch and it went to running on one cylinder but smoothly. Switch back on, and miss again. I repeated this several times so that I was 100% sure the miss was only associated with the front cylinder. Looking at the electrical circuit, the only things in the ignition system that are separate between the front and back cylinders are the coils ( and separate outputs from the ECU). So I swapped coils (PIA!) and cranked it back up. It again started missing so I hit the switch again and this time the engine died! I repeated this several times to be sure but the problem had clearly moved to the back cylinder! It would not even run without the front cylinder. So now I know the problem is the coil. Except that when I look up the coil to order, I find that is really 4 parts, the coil, an insulator (the hard part that reaches down into the hole to the plug) and two rubber gaskets. The coil is over $50 bucks and the insulator is close to $20. I measured the coil resistance and it is right in the middle of the Good range for both primary and secondary. The insulator has a groove worn in the side of it for some reason. It doesn't look like it is enough to cause a problem but who knows. So I put the coils back in their original positions and swapped the insulators. (another PIA!) All I have to do is get it to miss again and I will be able to isolate it to the exact part.
However now it won't miss.:( So I buttoned it all up and taped the switch to the clutch cable for easy access and took it for a ride. No Joy, it is running perfict. So I guess I have to wait few days and try it again.
Yes I know I could just buy both parts and be done with it and I may do that but I want to give it one more try. I am betting the coil is good and I am basically cheap. I can't take too long though as I have another 1000 mile trip planned for one month from today and I really have to have it fixed before than.
John
 
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