| Author |
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Jlaw68
| | Posted on Wednesday, April 15, 2009 - 09:04 pm: | 
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I'm stumped! While the bike is cold it runs great, some of the time when it warms up it runs great, but it seems for the last couple of weeks after the bike warms up it starts to surge when running above 2000 RPMs but idles fine at a stop. It jerks bad under a load or just cruising and I can watch the RPMs jump up when it surges.
I thought i might have an air leak or bad gas but the RPMs are jumping up like electrical and not down like bad gas or a leak.
Any thoughts that could shed some light on this issue would be great. |
Gunslinger
| | Posted on Thursday, April 16, 2009 - 09:50 am: |
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I had a similar problem a couple of years ago. I took it to three different mechanics and none of them could figure it out. I did my own research and determined it was the cam position sensor. Sometimes they become heat sensitive. The first clue is that the tach jumps when it misfires. The tach is electronic, so the jump is caused by irregular signals coming from the sensor.
You can do this yourself. First make sure it is not one of the other common electrical problems like a bad sidestand switch or a loose ground. The fact that it happens only after the engine heats up makes me think it is the cam position sensor. The sensor is a $79 part, and I am pretty sure it is the same as the Sportster, so any Harley dealer should have one in stock. It is a pretty easy swap, the trickiest part being that you have to remove the connector off of the old one and put it on the new one. Make sure you get the wires in the right places. Once it is in you just need to get the timing set. Give me a call if you need any help. I am in the BRAN.
I hope this helps. BTW, I spent enough time trying to fix mine, and riding it while misfiring, that the jerking cracked the trap-door in the tranny. I wound up doing a transmission re-build as well. Not cheap.
(Message edited by gunslinger on April 16, 2009) |
Jlaw68
| | Posted on Thursday, April 16, 2009 - 05:10 pm: |
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Thanks for the help. I will take a look at that tonight. what all is involved in checking the timing, and why would it be off just from the sensor going out?
BTW, how did you find out that your trap door was cracked? |
Gunslinger
| | Posted on Thursday, April 16, 2009 - 07:16 pm: |
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I found the crack in the trap door when it started jumping out of 2nd gear. The crack was at one corner at a bolt hole. It had allowed the tranny to shift just a small fraction of an inch. It was enough to cause one of the shifter forks to start grinding on the gear. I wound up replacing the 1-2 countershaft gear, the 1-2 shifter fork, the 3-4 shifter fork, and the trap door. I also changed out the stock shifter drum for the Baker unit and used the Baker billet trap door, a much more substantial unit. I doubt your problem is tranny related though.
The cam position sensor works by what is called the Hall Effect. Sparing you the physics, there is a cup on the end of one of the cam-shafts. The cup has two notches in it. As the notches pass by the sensor it signals the ignition system to fire the spark plugs. The sensor is supposed to be insensitive to heat, and I do not know why mine became so. But the manual has a section on the malfunction. As it heats up it becomes more or less sensitive and, in effect, advanced or retards your timing enough that you get misfires.
To replace the unit you will need to remove the timing cover. It is the plate in the right side of the engine case with "Cyclone" printed on it. Drill out the pop rivets and remove the decorative cover. Under it there are two Philips screws. Remove those and the cover will come off. The cam position sensor is under it. It is held by two threaded studs you will have to remove with a slotted screw driver. There is a cable coming off of it that goes through a hole and out near the drive sprocket. Find the connector and un-plug it. Once you have unplugged it you will have to take it apart, since it will not fit through the hole. There is a piece of plastic in the middle you will have to remove and the wires will come out then. Put the new cam position sensor in place by reversing the process.
The studs go through slots around the edges of the sensor. When they are loose you can rotate the sensor to adjust the timing. You will need a timing gun. Setting timing on a Cyclone is pretty easy. There is a hex plug right at the base of where the two cylinders meet. Remove it and you will be looking at the fly-wheel. Attach the leads to positive and ground and attach the pickup to the FRONT spark-plug wire (note that most timing guns will have a mark on the pickup telling you which side should be towards the spark-plug. Fair warning, it will spray a mist of oil out of the timing plug hole when you start the engine. They make clear plugs to prevent this, but I have never been able to see the timing mark through them. Fire the timing gun through the hole and look for two shallow holes drilled in the fly wheel. Move the sensor back and forth until the two marks are centered in the timing plug hole. Lock down the studs and you are done. Replace the cover. If you do not have a pop rivet tool you can thread the holes and use pan head machine screws instead. Make sure they are not too long, you don't want them hitting anything.
I hope that is clear enough. Call or e-mail if you need more detail. I would be glad to talk you through it. Like I said, I am in the BRAN. |
Jlaw68
| | Posted on Thursday, April 16, 2009 - 09:02 pm: |
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Thanks so much for the info. You explained it very well. I'll let you know how it turns out. |
Gunslinger
| | Posted on Friday, April 17, 2009 - 09:43 am: |
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Good to go. Call me if you run into any snags. |
Only1beard
| | Posted on Saturday, April 18, 2009 - 04:08 pm: |
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Just wanted to add to the things to check. The Co2 sensor may be causing this if it is shorting or has a broken wire. Just try disconnecting it. It will run in an open loop. The computer will just keep the settings the same until signal is found. If the bike runs ok you will know what the problem is. |
Gunslinger
| | Posted on Sunday, April 19, 2009 - 10:15 am: |
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I don't know what year Johnny Lawless' M2 is, but my 2000 does not have a CO2 sensor. But on the subject. There are lots of places where electrical glitches can cause the kinds of problems described here. It never hurts to give the wiring harness a once over. |
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