I'm attempting to get a nice DT400B running well and want to make sure I'm going in the right direction with the timing. A little background:

• Cleaned carb and put in stock-size Mikuni jets
• bike has about 115psi compression (hot)
• new stock air filter

When I first started kicking it, it would kick back badly and seemed nowhere close to running. I don't have experience with these CDI ignitions. I did check the piston TDC position compared with the mark on the flywheel and it does line up with the mark on the pickup coil at about 2.5mm btdc (2.5 was suggested as a better base setting than the stock 2.9mm). I haven't been able to get the flywheel off to make sure the woodruff key hasn't been sheared but I'm guessing with the marks aligning, I can assume the flywheel hasn't moved on the crank?Anyways I did get it to start a few times but its very difficult to start and not running great. I got a timing light on it while running and its firing at a much earlier point than when the marks on the flywheel/pickup are aligned. I'm guessing this is the auto-advance doing its thing, but is there an alternate mark I should be looking to see lined up with the mark on the flywheel?  I'd guess its about 20 or so degrees advanced - does that sound right? And is there any way to check the timing while running to ensure its set at the right place while advanced?Thanks for your help!

If it's firing before the mark, assuming the mark is 2.9 then something isn't right. At kick speed for starting it'll will be forward 'retarded ' of the mark but you'd be unlikely to catch it with the strobe while idling maybe if it'll idle just above stopping. You'll see it at kick speed plug out & strobing though. Advance on the the old system is instant & holds, doesn't alter at revs just drops off to nearer TDC for starting. Without researching I,m thinking the tab on the pulser & notch in the flywheel window are the firing point no matter where you move the stator plate, or the pulser because that firing point stays the same so it depends on crank/piston btdc as the pulser moves with the back plate if backplate if it's slotted. So two ways of altering timing but ariving at the same result. So after that essay, why is it firing before the tab in the window. Or is the tab severely bent. I'll leave it there I'm on a borrowed phone so mightve mucked it all up. Modern technology eh!!.

Just stretching that thought further, you know where it's firing in relation to the tab, so can you bend the tab to where you see the notch firing by strobe. So you know those two align. Then move the plate or pulser forward to retard it to your desired whatever, say 2.5. Or you could make a new notch in the flywheel window to match the pulse tab. Regardless thats your firing point. So move the backplate or pulser to get your timing. Ignore me if I'm making a mess, I'm away from home on a phone I don't understand & can't see what I'm typing fully. Have fun.

Can you send a video probably would help via YouTube or Imgur etc 

BILLYB,

i have had a similar problem on a dt250, i think that it is possible that the key has sheard and the marks will still line up. think of it this way, all the marks line up including the flywheel, but the crank has moved in the flywheel maybe?

in my case i had forgotten to put the woodruff key in!
cheers
les.

I've tried uploading pics of the flywheel in the location where its firing and for some reason I keep getting errors in the upload (even though the pics are only 55kb). Anyways, its firing nowhere close to where the notches align. If the notches in the flywheel and pickup coil align with the flywheel notch being around 11:00 on a clock face, its actually firing around 1:00 - 2:00 - so its way, way off and there's no way to adjust the pulsar coil anywhere nearly as far as it would need to adjust. If I upload a video, it'll show the bike consistently firing when the flywheel mark is around the 1:00 or 2:00 position.

I bought another flywheel puller in hopes of having clean threads that might not pull out of the rotor and it just arrived so I'll give it a try, to see if the woodruff key is still in place, but thinking about it I don't see how it could be out of position. The flywheel and pulsar coil marks line up very nicely when the crank is around 2.5mm btdc (I can adjust the pulsar coil to get probably anywhere from about 2.2 - 3.2 or so mm btdc. So the crank is in the right position when the marks line up - I can't see physically how the flywheel could have rotated on the crank but the marks still align around the correct btdc measurement.

The bike won't idle, but when it starts (which again, is very difficult to get it started), if I keep the revs up, it'll run and has power (I've ridden it around the yard like this and it seems pretty torquey compared to my RT3).  I also think its pinging a bit but its hard to say if that's normal 2 stroke noise or if its really pre-detonating that badly. I'll have to start my RT3 and compare it.

"I've tried uploading pics of the flywheel in the location where its firing and for some reason I keep getting errors in the upload (even though the pics are only 55kb)."

Pics need to be uploaded via a third party host, such as Imgur.

Are the magnets on those able to be removed, countersunk screws?, & could one magnet be reversed. Was just a random thought as creates havoc.

I got the flywheel off. The magnets/etc all look fine. The woodruff key was in place and flywheel mounted correctly. Can someone confirm that absolutely the bike should be firing the ignition when the flywheel mark lines up with the tab on the pulsar coil (which I've set to line up at 2.5mm btdc)? This is with an old Craftsman timing light when the bike is running above idle (it won't idle). It just seems very strange that the timing is so far advanced, I'd guess around 20 degrees. Thanks

Perhaps check you have the correct flywheel . They have identifying numbers on them , likewise the ignition base .