First time owner of modern "Thumper"

7 replies to this topic
  • ChdHpkns

Posted May 01, 2016 - 11:21 AM


Hi, my name is Chad. I'm totally new to this forum and this whole modern "Thumper" thing. I've been riding all my life. I started on a 1980 RM 80 and worked my way up to a CR 500. Mainly 2 strokes, but a few XR's in there. I just bought a 99 YZF 400. The guy says it wont start. I have not kicked it yet myself, but by hand it has tons of compression. What is the proper procedure for starting this beast??? It seems to have spark. I just want to get a heads up before I kill myself or break my leg kicking this thing. Thanks

  • Wanny14c

Posted May 01, 2016 - 03:19 PM


Hey Chad it's really simple. Push down on the kick start until you hit a ton of resistance that's TDC pull in the decomp lever push just past TDC, let off the decomp lever and kick. Good luck

  • Wanny14c

Posted May 01, 2016 - 03:21 PM


Look it up on YouTube there are a few vids on there.

  • grayracer513

Posted May 02, 2016 - 05:33 AM


. Push down on the kick start until you hit a ton of resistance that's TDC


No, it isn't TDC, it's the compression stroke, about 120 degrees before TDC.  But that is where you pull the compression release lever and move the kick starter about 1 inch farther, then let go of the comp release, reset the kick crank to the top, and kick with no throttle.  On a cold start, pull the choke knob out ad give the throttle a couple of good twists to prime the engine. 





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  • tmeyer37

Posted May 02, 2016 - 07:14 AM


 and kick with no throttle.



If you value your leg and/or knee this is an important thing to remember. When I first started out with My first WR250f I used to put my right hand on the brake master cylinder rather than on the throttle just so I didn't accidentally twist the throttle by kicking. 


Also when trying to find the sweet spot with the compression release depressed I found a little trick that worked really well, hold the compression release about 1/2 or 3/4 of the way down while slowing moving the kick starter. When you hit the right spot which is like Gray said about an inch or so past the compression stroke you will feel the compression release move like it loses resistance in the cable. Once you hit that spot rest the kick starter and give it a strong kick with no throttle. I don't know why the compression release does this but I found it to be the best way to know you are at the right spot. I have owned several manual compression release Yamaha's and this worked on everyone, 


I had to learn the kick procedure by spending a day in the garage with my brand new WR250f when I first got it back in 00, it was so corked up from the factory it was a bear to start and one I got it down in that condition it made it that much easier to start consistently once it was un-corked. 

  • Wanny14c

Posted May 03, 2016 - 06:43 AM


Sorry for the false information Gray.

  • cowboyona426

Posted May 03, 2016 - 10:07 AM


Hey Chad it's really simple. Push down on the kick start until you hit a ton of resistance that's TDC pull in the decomp lever push just past TDC, let off the decomp lever and kick. Good luck


You're missing one critical step in "the drill."  "The drill" sounds simple in theory but many struggle with it in practice.  When I first got my 00 YZ 426 anytime someone wanted to ride it I'd tell them "if you can start it, you can ride it."  That weeded out quite a few people!


Kick through until you're up against compression

Release kick start

Pull decomp lever

Push kick start 1-2" down

Release decomp lever

Release kick start

Give a good, healthy kick


All this assuming someone hasn't replaced the exhaust cam with one that has auto decomp already.

  • grayracer513

Posted May 03, 2016 - 10:53 AM


Sorry for the false information Gray.


It's a common misnomer to refer to TDC that way, and continuously perpetuated.  If everyone called it that, it wouldn't matter much but when you tell that to someone who actually knows what Top Dead Center is and how to find it, it confuses things rather severely.

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