XR400R Fine Tuning (Cold Starting)

Hi guys,

I'm sure this has been asked and answered before but I haven't come across this specific situation it in the hours I have spent perusing threads so far... I have a small problem when cold starting my XR400. It is running the standard carburettor but I don't know what jets.

I live in Vanuatu, at sea level and the average temp is 26 degrees celcius or above so "cold" is a relative term, but when the bike is cold I have to put the choke on full, hold a little bit of throttle and then it will start first kick 95% of the time. Half choke or choke off and you could kick it for hours with no success. Once started you have to hold the throttle on manually for at least 30 - 40 seconds, or it will immediately die again. The idle speed is already set quite high (when its warm the idle feels too high), but when its still getting warm it doesn't want to idle.

Compared to problems other owners have mentioned on here I know its a small issue but its still something I'd like to fix... Is this likely a carburettor jetting issue or something else? When its warm it starts first kick, no choke, no throttle 99% of the time.

Needing to put the choke to full to start it "cold" is normal. If it started cold without full choke, that would be an indication to me that your pilot jet is too rich.

Don't be afraid to leave it on full choke while it's warming up. As it starts to warm up it will start to show indications of being too rich, then put choke to half or off, whichever the engine needs at the moment to keep going and continue to warm up.

Turning up the idle speed for warm up, then turning it back down as the bike warms up when you're riding is a pretty common technique.

For your own info and when asking for help, it would be good if you could determine your jetting at some point. And always state any engine/intake/exhaust mods too.

For now, learn how to fine tune your fuel screw, as it has the biggest effect on starting.

Hi Trailryder,

Thanks a lot for your reply - Nice to know its running "normally."

I am thinking about upgrading to an pumper carburetor in the near future. From everything on here I've read they sound like a good idea... I was going to bid on an Edelbrock on Ebay Australia last night but got home late and missed the auction end :thumbsup:.

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