Hard starting from cold

Rider in the UK with a US WR450F. 2003 model.

This has been a problem since I bought the bike.

It is very hard to start and when it does its without the choke, coughs and dies,coughs and dies, this is repeated until I can catch the revs and hold it on a fast idle to warm it up.

The choke has never been any use at all for starting and all the valve clearances are correct, the air filter clean, the cam timing correct, good plug and electrics etc.

The thing is when its warmed up its perfect at starting all day off the button under any conditions come rain or shine, even when I drowned it, I then emptied the airbox and exhaust of water, took out the plug, drained the carb, disconnected the cap and cranked it to expel the water.....and then with fuel and a new plug it started straight up :smirk:

Can anyone help with this initial starting problem, could it be the pilot circuit ??

It has a JD kit fitted (no other changes to the carb), no airbox mods, White Bros `e`series (10 discs) with tapered header, Grey wire connected to a switch to change maps, and I ride from sea level to 1500ft. this problem was also still apparent when I put the Bike back to stock. :devil::smirk::thumbsup:

What set up should the JD Kit be at and what size are the jets that dont get changed with a JD kit and what should these jet sizes be ideally ??

Please help.

Thanks in advance.


I pull my choke on when cold and slowly roll the throttle twice to allow it to prime and she should startup fine.

almost EVERYONE will say NO GAS before starting, BUT the maintainence manual says for COLD starting roll the throttle once or twice just like MM said. After I found this, it's been a much more pleasant cold starting experience.

exactly, when cold, roll, when hot, use the hot lever, once you figure it out they start great every time, well almost, :lol:

If its rely cold I will turn the idle up about a turn and a half. start. once warmed up ajust it back down.

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