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I had been facing high fuel consumption lately. To my surprise I discovered that my front wheel free rotation seems bit restrictive to my rear one even when rear wheel drags chain and two sprockets with it. (Thus, logically free motion of front wheel should be less restrictive than the rear)

Further, I rode my bike for five minutes and felt a huge difference between temperatures of rear and front rotor. Though I could touch each rotor with bare hands but front rotor was way more heat up than the rear one.

Also, I hear a light scratchy sound from a part of my front rotor while trying to rotate the wheel.

Also, I feel I require more accelerator in the first gear to pick up some speed though I rarely feel any difference in high speed (vs RPM). Like I touch 111 km/hr at a RPM of 6k on the sixth gear which is completely normal.

Also, my fuel consumption has increased. It use to be 450 kms per full tank (13 lts). Not it is 350 kms per full tank.

Bike: Honda CBR250R KMS Run: 35000 kms Major Change in Last Two Service: Clutch Plate, Front Caliper (Due to Rusting and severe resistance)

Few doubts:

  1. How much free rotation can we expect from the front wheel?
  2. Given the scenarios, Is it possible that my rotor is not completely flat? May be after a fall? How do I figure that out?
  3. Is it possible that my wheel isn't aligned? How do I figure that out?
  • ok , the scratchy sound may be cue for two things, it can either be dirt which accumulated on the calliper due to driving on muddy waters or the more probable , time to replace the entire set scratch. Recently experienced the same, changed ROTOR as well. ( Always changed ROTOR along with the pads. i made a mistake of changing only brake pads destroyed my ROTOR now after a few months forced to change both again. – Shobin P Jul 20 '15 at 11:46
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I'm a retired mechanic, I used to work on private car's and some commercial vehicles. The principal of disc brakes is the same although details might differ between car and m/cycle. Don't even attempt any brake work unless you are competent and have the right tools.
You mentioned the possibility of a distorted rotor. Can you feel anything untoward when braking - handlebar oscillation or brake lever vibration? If not, you should be OK. The wheel should spin fairly freely and come to a gentle stop. If it feels sticky or tight and comes to an abrupt stop the caliper will have to be removed. You say it's a new caliper, were any re-used exposed sliding parts cleaned and lubed with the correct grease? Can the pads slide freely where they are mounted? If not it could lead to a partial seizure and a scraping noise.

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Yes, the front wheel should spin more freely than the rear, for as you note, there is less on it to drag.

As Steve says, a non-flat rotor would result in oscillation or pulsing when braking, which should be pretty obvious on a bike. You can check it for flatness using a dial gauge (or run-out gauge).

My suspects would be a sticking caliper, or a failing flexi hose - either of these would prevent the brake from being fully released when you release the handle, causing it to drag. The heat and increased fuel consumption are both symptoms of a dragging wheel.

The other possibility would be a failing bearing increasing the rolling resistance of the wheel itself. This is easily checked by removing the caliper (or the pads if they cam be removed separately), then spinning the wheel without the brakes present - it should spin very freely.

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