Cold start trouble after decomp cam instal.

Hey all, as the title suggests I'm having troubles starting after installing a late model cam.

The bike is a 99 WR400f, before the cam change it was a breeze to start when cold, hot was also excellent except when lay on it's side. Now I have to kick it up to 10 times to start when cold but it's easy to start the rest of the time.

Valve clearances are perfect, but I have notice on some kicks it must get to TDC and has a reasonable amount of resistance to get past it. Do you think the timing is out? It runs quite crisp apart from the WR cough when lots of throttle is given just off idle.


i put a hot cam ad in my 99 yz400f and it changed the cold start routine...

mine was a no touch on the throttle before.. after it starts more like my 450 does now..

fuel on, choke on, 2 twists of throttle, use the kickstarter to hit the a/d pin (kinda like you used to do with the decomp lever) only don't go past it... reset the kick lever to the top and kick away... once warm, mine did not care where the kick starter was in the stroke, but cold it did... also sometimes, it would fire up better with the throttle barely open .... do not kick that bike with the throttle wide open... trust me....

that is when i dont hit the magic button instead.....

Remember that auto decompression doesn't eliminate the compression stroke. If it did, the bike wouldn't run. What it does is shorten it by about a third. When you think about it, that's what you were doing with the manual lever: hit compression, move it an inch farther, reset and kick, right? A/D simply takes you directly to the end of step two, so like Jay said, push it through to find compression, stop, reset the kick starter to the top and kick.

you taught me well gray "grasshopper son"...i still don't understand why the fuel part of my ritual changed.... but it sure did on mine was a breeze to start after i learned that... and it would bump start....and warm it was like kicking anything thinking at all..

...i still don't understand why the fuel part of my ritual changed.... but it sure did on mine anyway....
Pretty much everyone reports the same sort of change in behavior with the 400/426.

Thanks gents, I'll give the new procedure a crack, fingures crossed it works for me also!

Great work, had it started in about four kicks after not riding it for two weeks! once I get the hang of it I think one or two kicks should get the job done.


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