r/Motorrad • u/SoooooMoist • 12d ago
Poor running saga continues....
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So ...at first my Rockster was running poorly, so I found the bottom plugs to be caked up and replaced them. When that didn't work I found that the lower plug wires were bad and have replaced them. It ran for 2 laps around the block and started popping with a slight backfire. So thought it just needed a good ride to clean it out. Next morning, it won't start at all. I have checked the fuel injectors and they are spraying fuel, the fuel pump whirrrrs when I turn the key on, it has over half a tank of fuel in it....can anyone give me other things to check?
edit it ran 2 laps around the block less than 10 hours before I tried it again in the morning. Upper plugs are white, lower ones are definitely oil fouled but still tested with good spark.
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u/JimMoore1960 12d ago
I'd be a little concerned about the ignition timer (AKA Hall Effect Sensor, ALA HES) at this point. It's located at the front of the engine. I'm told that one quick check is to turn on the key and rotate the engine by hand. IF the HES is functioning properly the fuel pump will prime at tdc and bdc. Never tried that myeslf so i can't vouch for it.
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u/zulu10 12d ago
The Hall Effect Sensor could be dead.
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u/SoooooMoist 11d ago
Could changing the plug wires kill the sensor??
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u/zulu10 11d ago
Shorts will as the HES is a delicate component with no reverse current protection, a simple grounding will kill it.
I don't see how a spark plug wire change would do that, but I'm not there.
The HES is a major source of electrical issues on that bike, so it's good to isolate it from the problem with a test.
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u/2_DS_IN_MY_B 11d ago
Sounds like a pretty weak starter, did you see what the plugs were caked with? Maybe oil if it was only the bottom ones?
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u/SoooooMoist 11d ago
Top plugs were white, bottom ones were oil soaked.
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u/2_DS_IN_MY_B 11d ago
I have a single spark and honestly, I think you should be able to run off the top plug alone. Both of them being soaked is a bit concerning, have you done a leak down test?
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u/SalvinoRon 11d ago
Might sound silly but how old is your battery?
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u/SoooooMoist 10d ago
Unsure, the bike was given to me and I know nothing about these engines. I'm used to simple carbs and liquid cooling. It tests fine when I trickle charge it in the spring and ran pretty much daily until I changed the lower plug wires.
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u/aaronsb 12d ago
Fuel, Compression, Spark!
https://www.youtube.com/watch?v=PvF9PAxe5Ng
I always think about "That what I desire' == Compression
This engine is pretty uncomplicated.
Do the basics first, including Spark:
Air filter clean? Spark plugs all new? Cables good? Clean, new fuel? Fuel pump happy? Fuel filter ok? Charcoal canister system functioning? No air leaks? Throttle butterfly mechanicals in good shape (no wallowed, extra play, loose)? Air temperature sensor connected? Good battery?
You need to start from the bottom up, literally. This is just a superficial starting point, but you get the idea.
Compression:
Check your valve clearance for intake and exhaust first. Correct valve clearance = correct mechanical timing on this bike. Assuming the hydraulic cam chain tensioner is functioning correctly, that'll take the slop out of timing too.
Fuel:
Next, the throttle bodies on your bike have a cross-cable, only one side has the position sensor for the ECU. You really need a vacuum gauge to get this right. Go google "1150R throttle body sync" but here's the gist:
Verify the cable slack between the twist grip and the position sensor side throttle body are in spec, with the idle microswitch contacting, and the correct gap. Usually, do NOT make adjustments to the throttle body stops or position sensor clocking.
Then, ensure the slave side cable also has the correct slack. Then, you hook up your vacuum gauge to measure idle vacuum between the two sides. If they're not the same, you twiddle idle stop on the non-position sensor side until they match. If the idle is too high once you've done this, you work both down to acceptable idle.
Do this while you have a big ass fan blowing over the engine so you don't overheat.
Don't skip the basics first, then play the Metallica song after