250-500cc brakes

Just replaced my fluids and pads on my wr300 front brake and the wheel is not spinnig free. The pads touch the rotor. Is it normal??
Another thing, is dot 3 fit the bike or only dot 4? Thanks

did you push the pistons in all the way? was it hard to slip the caliper over the rotor? is it tight after trying the brakes?
DOT 4 is correct, it has the boiling point to match your equipment, you should always consult the brake system, it is usually listed on top of the master or in the owners manuall

Definatly not normal, Did you make sure the caliper was free to slide !! If you pop the front wheel out the caliper should slide left to right easily if not you will have to strip / clean lube it. If its not totaly siezed it can give a horrid lever pull like the brake need bleading and lacks bite.

It was hard to slip the rotor back in. The pistons was very hard to move. And like johnnyboy said, the lever do feel like the braks need bleeding. I did bleed them today because of that...should i check the caliper?

did you clean the caliper when you were swapping pads? this is most definitely not normal and suggests sticking pistons.

typically you only install the pad on the pistons side and use a clamp to push the pistons in then install the opposing pad install the caliper and pump the brakes at this point they should feel firm and after you release the lever they should free up the rotor to turn
if the rotor is still not free the pistons need attention

You need to remove the top off the master cylinder when pushing the pistons back into the caliper. This will keep pressure from building up inside the system...

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You can remove the pads and pump the pistons all the way out and spray some lube on them and then remove the cylinder cap and force the pistons back in place. Watch out for drip from the overflow. Brake fluid stains alot so wipe it off anything it get on.

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There is the case where the brake mounting bracket is frozen on the caliper housing ....This is a real problem and will ruin the disc or worst.

Few times on mtb and the moto do wheels roll completely free of the pads. That said a spray of half distilled water and alcohol can help clean pistons in the calipers after pads are removed and you carefully extend the pistons... Then wipe with a rag, swabs, etc.. I then will put a few drops of tri-flo on the piston for the seals and cycle pistons in and out holding one with a large flat bladed screwdriver so I can see how each piston is working. In the end slight touching is normal as long as the wheel is free. The light touching is annoying but many times a sticky seal or some dirt that loosens and remedies itself on use. As well, a sliding caliper may be more symptomatic.

Here is the thread I started on the brake sliding pins ... If the brakes are not sliding properly on the pins, you will toast something quickly ..

http://www.cafehusky.com/threads/stuck-caliper-slider-pin-front-brake.37124/

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I doubt you have this issue but best to check that the two brake component float freely as expected.

Here is a pic of the grooved slot on the brake caliper that the disc rotates in. This small slot is where the sliding pins allow the 2-piece brake apparatus to center and ride at. If that disc is not riding pretty much in the center of that slot, you have an issue with the sliding pins most likely.

If the pins and all else seem OK, you may just have too full a master cyclinder and as Ray_Ray suggested above, maybe loosen the cover and remove a small amout of fluid. The piston may not be retracting as much as it could.

I think the problem is that the piston are not coming all the way back.. also, i remove the pads and push the lever and the pistons came out one at a time... i replaced the oil to dot 4, but do i need a special tool to do that or it just like bleeding air out? Thanks

the pistons moving separately is not a surprise, it's the path of least resistance physics
to bleed them, yes like bleeding air out