Up Next, Pantah Ignition Timing Issues

Hi Eran, mmmmm something is not quite right.

Are you certain that the front cylinder is at TDC? Put a rod in through the plug hole until it touches the piston crown. Gently rotate the engine until the rod is lifted to its highest point. Check also that you are not on the exhaust stroke, also look at the marks on your cams belts. Do they seem to make sense?

You have four sets of marks on the flywheel, although it does look like you are trying to line up on the right set. At the risk of stating the obvious, you did put the woodruff key back in the slot at the end of the crank didn't you? I am sure you did.

Looking at the photo I think that your lower pick up wires might foul the cover when you try and reinstall it. Those pick up wires are a really tight fit. I would check that there is enough clearance before setting up the pick ups. It would be really annoying to get everything perfect and then find you can't get the cover on...

 

Beat me to it Andy. On my MHR, the slot on the end of the crank exactly aligns with front cylinder TDC. Based on the picture, If the crank was turned just a little clockwise, the slot would be parallel to the front head and those two dots would be aligned with the pick-ups. Eran: With my new electronic ignition, I used a chopstick, stuck in the front head for TDC evaluation; it was very obvious to me when the piston had stopped moving up. Check this 750 Pantah video; the picture of your rotor and the one in the video look identical:

 

look at this picture from the manual; see how the crank slot points directly at the front head:

 

Hi Eran

I would definitely make sure that I was exactly at TDC on the front cylinder before attempting to line up the flywheel dots. As Rick suggests, a chop stick in the plug hole will tell you when your piston is at the top of its travel. A dial gauge will be even more accurate.

The nut on the end of the crank is supposed to be torqued to 85 ft/lbs and securing the rotor so you can apply this torque is a bit awkward. In theory I guess you could have broken the woodruff key and that would have allowed the assembly to rotate slightly on the end of the crank. I suspect this is very unlikely since the key is pretty meaty and its hard to see it failing. If you have eliminated everything else you might want to check this.

Your yellow line is indeed pointing at the front cylinder, parallel with the fins, and you should aim to replicate this orientation. My pick up plate is secured pretty much in the center of the slots, allowing adjustment both forward and back. Your plate looks seems too far forward in the slot, you don't have any adjustment left.

I am sure the solution is something simple, once you have followed the steps.

 

Hi Eran: Yes, your picture depicts exactly what I mean. from your picture, the Internet and the manual, I think you are really close but simply sticking your finger over the plug hole is not accurate enough to determine TDC.

The "proper" way to determine TDC is to use a timing tool (piston lock) and a timing disc. The piston lock is a device that screws into a spark plug hole and the timing disc is attached to the end of the crank. You also need a reference pin for the timing wheel, a piece of wire attached to the motor making a pointer at the periphery of the timing disc works fine. There's a threaded rod with a rounded end that screws into the piston lock. TDC is very roughly determined by pencil/chopstick and then the piston moved down slightly in any direction and the threaded rod is screwed in until it touches the piston, stopping it from moving up. At this reference point on the timing disc is noted. The engine is then rotated all the way in the opposite direction until the piston stops moving again and again the reference point on the disc is noted. TDC is half way between the two timing disc reference points. People with older bikes that have mechanical advance will usually go to this length to determine exact TDC. You can also use a metal version of the chopstick; a part screws into the plug hole and a free metal rod moves up and down with the piston.

In your case, the manual just states to set the front piston at TDC, not how to do this. I am confident that if you stick a chopstick/pencil through your front plug hole and rotate the crank slowly, you will find that at exact front TDC, the slot on the crank will look like it does in the manual; exactly parallel to the front barrel. In this position, there should be some play in your pickup plate to allow for alignment with the rotor dots. Remove both spark plugs so that the pistons both move freely.

Note that Saltspringer's comment regarding the pickup wire possibly interfering with the engine cover is repeated in the YouTube video.

 

Note that aligning all the drive belt pulley/motor reference marks for correct valve timing is a discreet job from setting up the ignition timing. Not sure about your bike, but on mine, all the reference dots for setting up my bevel heads result in the rear head being at TDC so when I set up my Sachse ignition using front head TDC, my bevel dots would not have all been in alignment. I'm guessing that this may be the same for you although I thought the Pantah and all other Desmo motors since then had belt setup based on front cylinder TDC; I may be wrong.. Just make sure the drive belt timing is prefect and forget about it and move on to the ignition pickup plate, focusing on front cylinder actual TDC.

 

Good news Eran.