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jeremyd
04-08-2007, 06:04 PM
about 2 weeks ago i put a 42 pilot jet in my ex and tweaked the fuel screw when it was about 60 degrees, and it started great. this weekend i put a white bros mx4 pipe on and put a 155 main in, it was about 35 degrees this weekend. It was a whole lot harder to start and i had to keep the throttle open to keep it from dying at least until it was warmed up then it ran fine. Any ideals on what could be the problem?
GPracer2500
04-08-2007, 06:53 PM
That doesn't sound like a "problem" per se. The 400EX is cold blooded by nature (moslty because of it's air-cooling). When it's 35deg out I wouldn't necessarily expect it to just start up and idle. Some babying of the throttle until some heat builds in the engine should be expected when it's that cold.

You could likely set it up so that it will idle right off the bat when it's that cold by running an overly rich pilot circuit. But that doesn't sound like a good compromise to me.

Several quick pumps of the throttle before hitting the starter button will activate the carb's accelerator pump and send a few shots of raw fuel straight into the engine. This will help get it to fire on cold days. By doing that you're effectively priming the engine with fuel before trying to start it. I've used this method with good affect on EXs with the choke removed.
jeremyd
04-08-2007, 07:03 PM
so even wit the 42 pilot i still need to baby the throttle a little before it will idle on its own?i also had to crank the starter a few times before it started. So you dont think this will be an issue when the weather warms back up?
GPracer2500
04-08-2007, 07:14 PM
It's very likely to go away in warmer temps.
ridinrednIL
04-18-2007, 12:00 AM
I just put on the same slip on and jets and am having the same problem. Its harder to start and is definately rich even after adjusting the a/f. Should i go back to the 142 main and 38 pilot? a/f screw 2 3/4 out. Definately started easier and seemed to have more power! does this make any sense?
Eviltanker
04-18-2007, 06:46 AM
It's the nature of the beast. You will have to get used to it.

ridinrednIL, I answered your question in your post.