Is running rough when cold typical for the WR450F?

seriously considering swapping my husky TE610 for my brother's WR450F.

he said it has always run really rough when cold, but can't find anything about this on the forums. he's had this 2006 model since new, never touched the jetting or done any mods that might affect jetting.

it runs fine once it's warmed up, but figure something doesn't sound quite right. does this just sound typical for a WR? any tips on potential problems to look out for much appreciated!

When you say running rough, what exactly are the symtoms?

If it's 100% stock (and I mean 100%) it will probably be "cold blooded" at initial startup as it's jetted very lean stock. And if some mods like pea shooter and/or intake opened up without a rejet, it will be VERY cold blooded and pop and fart until warmed up.

Like the previous poster said, can you provide some specifics?

As has been mentioned, the stock jetting is pretty darn lean. And if the exhaust has been opened up or replaced with something more free-flowing, then the bike will be very cold blooded. Maniac

thanks for the responses so far. i rode with him once few years back, i think he had to keep the throttle open a bit even with the full choke to keep it running the first minute or so. if he tried to ride it gently within the first five minutes it would just fart and hiccup and carry on a fair bit (how's that for a technical description?!) but was fine once it was fully warmed up.

i assumed it would be the usual lean setup from stock too, as he hasn't modded the bike in any way at all. but just couldnt find any posts about this on google so wasn't sure if it was just a wr thing or not. but maybe all performance bikes are like that? i've usually ridden DRZ400s etc wear the lower state of tune avoids this kind of thing....

sounds like the pilot jet could also be clogged a bit.

And maybe the fuel screw isn't open up enough. Don't compensate the fuel screw position for the proper pilot.

cool, will check all those things when i get the bike in two weeks. apparently the shop did the usual derestriction mods when he bought it and its run rough when cold ever since new, so sounds like the shop has buggered something up. possibly having the new apprentice do it all and not checking his work? :ride:

i went up one size on my pilot jet. it made a good difference in getting the bike to warm up sooner. Now that it's summer here, I only need the choke for about.... 30 secs, not longer.

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