Pulse generator alignment question.

5 replies to this topic
  • Nummie

Posted April 02, 2007 - 01:33 PM


I am rebuilding my '84 XL600R and ran into a bit of a conundrum.
I don't know how to position the pulse generator rotor - that is the direction the tab should point in relation to the crankshaft rotation.
The camchain sprocket, drive gear, pulse generator rotor, and oil pump gear all have an extra wide aligning spline that is supposed to make the alignment straight forward (shown here from right to left respectively).
Posted Image
Posted Image

The problem is that my crankshaft does not have an extra wide alignment spline - the splines are the same all the way around the crankshaft.
This must be a crank from a different model that does not use this type of ignition.
There are no obvious timing marks on the crank.
Posted Image
Posted Image
Can anyone help me figure out how to position the pulse generator rotor?
I knoticed that the drive gear also has a bump or mark that must have something to do with it.
I am working from the official Honda shop manual and can't find any other information about setting up the pulse generator rotor position.
Even if I could just see a picture or learn where the extra wide spline is in relation to the connecting rod big end bearing.
Thanks for any help - I'm king of stuck.

Oh, and here's the thread I started for this bike rebuild project on my local dualsport site:

  • ARM-M

Posted January 06, 2008 - 11:59 PM


Did you ever find a answer to the Pulse Generator notch alignment to crankshaft. I ask because I have a 84' XR500R that I am currently in the same predicament. One thing that is different for my situation is that on the Crankshaft there is one tooth with a stamped dot on it, but the gears that slide onto the shaft have no corresponding mark of alignment.

  • scalejockey

Posted January 07, 2008 - 05:39 AM


The flywheel "f" point should be lined up when the pointer is at the coil center point. A spark happens every rotation when the pulse coil is on the crank, if it's on the cam (xr200) it happens on the power stroke.

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  • ARM-M

Posted January 10, 2008 - 10:30 AM


Thanks for the response. Only one problem, when "F" mark is ligned up with mark on Magneto cover the Pulse Generator arm will only position right before or right after direct alignment with Pulse Generator Pick-up due to the splines arangement on Crankshaft. I'm guessing right after is best since it has to send signal to controller to send spark to spark plug and that would center the Pulse Generator Arm's flat spot of splines over the Crankshaft stamped punch mark . Also I put a call out to Honda Directly and they are working on a answer for me, I will post the factory's anwer once given to me. Thanks again

  • jclaus98

Posted January 10, 2008 - 12:20 PM


Don't know if you've already figured this out or not, but I had that problem when I recently rebuilt mine. Give this a try, try to put those back on that splined shaft, you'll notice that it will only go ont he shaft when the extra wide splines on each one of the gears that go on are in just the right place. Don't force it one, just keep rotating the gear or pulse generator arond the slined shaft until it slides on, that is the correct and only place on the shaft it will go on. It doesn't look like it, but that splined shaft on the end of the flywheel is just enough wider that it wil only go on that special spot. Good luck.
P.S. The reason the pulse generator is positioned just BEFORE TDC on your flywheel is because if you were to ignite the compressed gas inside the cylinder at TDC, you'd get flames shooting out the exhaust pipes, burning up every seal associated with your exhaust valves. The pre-TDC firing allows the gas to be completely burnt by the time the piston is on its way down in the stroke, this way, when the exhaust valves open, it is completely burnt gas, and not BURNING gas.

Not sure if that's what you were asking, but hopefully, something in there has helped!

  • creeky

Posted January 10, 2008 - 03:30 PM


jclaus 98 is right, I have never seen a 600 or 650 RFVC engine that did not have the keyed pulse generator rotor. As he said, the wide splines are not obvious at first glance, but when you fiddle with the rotor, you will see what the deal is. The "F" mark on the flywheel is primarily to check ignition timing with a light.

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