Probably they have checked the rear disc & must have done improper bleeding.
So as a result some air bubbles must have entered. Dont worry it will be rectified after some time.
Keep stabbing the breaks until all these air bubbles deprecates. Dont have to do anything special. Keep applying as you normally do & it will come back to normal.
If the rear break is near to nill effect then go back to SVC ask them to re-bleed properly. They will probably say the same lame excuse that it will come to normal after sometime.
Tell them the rear break is almost useless & insist that if anything happens those guys will be screwed.

Reading about all the recent bad experiences from the owners I really have started having second thoughts about going through with getting the Bird.
Although I very much want to own a RE, but spending close to 2 lacs on a bike and getting a product with so many issues is really a let down.

have the same exact problem, I am still sitting here in ASC in Bangalore from morning 8am actually they told the same crap on Friday when my bike was 100% alright and I gave for normal 4th service but later at night on my way home the rear wheel got jammed and I somehow managed to reach home, but next day when I took my bike for ride the brake was nil, compared to previous night of wheel jam, but today I got them to fix the brake then they changed some pipe and also pumped oil for almost 1-2 hour manually(which again I am surprised for manually pumping the same) and finally they said its fine n I took the bike back home but again same problem wheel jam, but while I was waiting for a phone response from ASC they engine was cooled and now when I come back to ASC its working I am confuse whats wrong and why it is inconsistent

The problem was resolved last night, they have changed the entire rear brake pump and caliper, I was given the reason as "Piston jam inside the caliper" hence the flow of oil to rear disc was not proper, etc...... not sure if its fixed for good or will it reoccur

I guess you have an avenger too , So I'll be honest. I was riding avenger 180 for 7 years and 70,000 kms, no issues faced. It was so damn comfortable and reliable (Yes inspite of being a Bajaj)
A natural upgrade due to limitation of options (including price) for avenger is Thunderbird. I know all RE fans will bash me for saying this "MY Avenger was far far better than my 3 month old TB 500, only drawback being Power/Torque . I regret buying an RE"

Bajaj is supposed to be reliable, why do you write inspite?

Also, Bajaj is supposed to launch a cruiser in 2015, maybe you can shift back then

And what about the disc? But did they find the reason for the piston getting jammed? And these are brembo disc brakes which is a reputed brand.

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......anyhow its running fine post the changes done by ASC, covered almost 100km no issues, except for some crazy noise in rear side, its a thud sound when I jump over speedbreakers or path holes, I guess it could be shocks or something hitting against each other , not sure what is the issue, anyhow who can advice what it could be ? or anyhow experienced same in the past ?

nope they didn't change it, in fact I was pushing them to replace at least the break pad, as it was worn out faster due to jam and I had to drag it till ASC .........anyhow its running fine post the changes done by ASC, covered almost 100km no issues, except for some crazy noise in rear side, its a thud sound when I jump over speedbreakers or path holes, I guess it could be shocks or something hitting against each other , not sure what is the issue, anyhow who can advice what it could be ? or anyhow experienced same in the past ?

Naveen I have used three till date (including stock one four ).
Below in the order I have used:

1. Glasswool goldstar - Looks good. Sound bassy. Since it was having glasswool inside so you get a loud bassy sound but the sound drags after 55-60. Thump not like typical CI like but still very sweet and bassy sound

2. Short bottle having glasswool - Looks best as being of short bottle shape. Sounds exactly like goldstar but I found a little, a very little less louder than it, rest sounds very similar.

3. Short bottle Indori - This one has baffles inside and not glasswool. This silencer has that typical CI sound characteristic, some treble, little bass and a pinch of hollowness just like CI but offcourse not loud like CI for obvious reasons. This I am using right now and found best among all three, at least as far as my personal taste is considered. If you want really loud sound then this is not the silencer but if you want that typical CI sound feel then this one is the best.

PS: None of the above three silencers dropped any mileage or affectef the performance. Infact the goldie and glasswool short bottle would give a very mild increase in initial pickup.

Let me know for more queries.

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Is it free flow? If it is, then there will always be backfiring. But For Efi there shouldn't be any problems I think. Also check the bend pipe gasket at the head. Mine had a leakage got it replaced under warranty. To check for leakages apply shampoo water or foam and check for bubbles or suction.
And if ASC suggested then they themselves should be able to sought it out. Most ASC mechanics are afraid of even touching the tb500 electronics. They are either completely ignorant about it or are too scared or lazy to touch it. My personal experience. Its best to get in touch with RE service engineers. They will be able to guide you.

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Checked with two ASC, in Cuttack and in Kolkata. They say, since the silencer is free flow and length is smaller than the original, there will be back firing but it will not put pressure on engine...

BTW, as i live in Kolkata due to job, I drove the bike to Kolkata from Cuttack, Distance covered 454 Km, took 8 hours. The ride was awesome and not at all tiring.... 😆

got average of 33 kmpl ...