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Sounds like either timing is way off, or the CDI box is malfunctioning. DEET on the site could test for you. If it’s the box, you need a new used one (iffy and expensive ), if the Stator and trigger could are good, this aftermarket box will work:
There are a couple aftermarket full systems at around $4-500, or convert to a DT250 points setup.
Great bikes, but the ignition are a known weakness. Your symptoms make me lean towards a bad CDI box, but I’d have DEET test before dropping coin.
To the site!
The kickstart decompression valve only reduces compression slightly. The aftermarket cable-operated job that fits in the second spark plug hole (on bikes so equipped, and the DT400B and C weren't) releases virtually all compression and will kill the motor, not help you start it.
It's not really the high compression and high volume that causes kickback, it's timing. I'm certainly no expert, but I know that if the timing is correct, you seldom get that ankle-busting kickback. Check the timing.
When I was a new rider back in the late 1970s, my neighbor had an RT2. He sent the jug off to be bored, and it got 'lost' somewhere. He found that he could put a DT400 jug (and piston) on it and it would run. The RT2 compression release didn't fit the DT400 jug, so he had no compression release available. The exhaust pipe also did not fit - we cut the pipe and strapped it back together with soup cans and hose clamps. To start it, you needed to be wearing solid shoes and kick it firmly and cleanly all then way through to the bottom no matter what. I started it and rode it a number of times, and I was a very green new rider with my Honda 100, then my Yamaha CT green machine. Never my favorite ride, but it was a thrill!
The technique is a full stroke, unending kick, after letting the initial push in the kickstart "top out." Let the kick lever return to the top after a small movement of the kick starter (top it out). Then, you must drive your leg through the entire kick start stroke. Even if you must jump your body up to weight your leg for the kick. Until you have the technique mastered, wear a boot with solid sole so you can "in your mind" know your foot will not be hurt if it kicks back. By kicking a "full stroke" to the bottom of the kick starter's travel you get the piston into the 2nd combustion cycle which is imperative to a big bore 2 stroke starting.
I can start my '72 360 in flip flops, only because I learned the technique of a full stroke kickstart on previous bikes.
Bbd83 wrote: I guess my bruise may have healed enough to try this full commit kick through but I just feel like it just plain won't let me due to the kickback. I think a 185 dollar investment in that cdi recommendation may be a solid choice even if it doesn't 'need' it but how can I go about checking my timing? Doesn't it need to be running and I don't think the flywheel has ever been off or messed with.
First go to the tech section and download the service manual.
Link is: yamaha-enduros.com/index.php/workshop/se...ctory-service-manual
THEN, go to the ignition section in the book, and it will detail out how to check the timing. I believe it also has some resistance tests you can do to check on the functionality of the parts and pieces. The timing is pretty easy on that bike. If the timing appears to be correct, then I suspect your culprit is the CDI box as you had it running, but are getting a severe kickback. You could send just your CDI box to DEET who could verify its condition.