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  • 1 Post By KartikJ4001

Thread: Pulsar 135LS Lights Upgrade via Coil Rewinding!

  1. #1
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    Aug 2016
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    Default Pulsar 135LS Lights Upgrade via Coil Rewinding!

    Well hello there fellow XBHPians!

    I own a 2015, 21k KMS old Pulsar 135LS which has a pathetic 35/35W Headlamp which is of no use whatsoever.
    Like most of the people here, I was also searching for some mods to do to my motorcycle to fit in a brighter headlamp, but not many people own a Pulsar 135LS and I couldn't find any such related information for this bike over the internet.
    So some 10th Class Physics first. To fit in a brighter headlamp, you need more amps, which your stock stator coil cannot provide and hence you face battery discharging issues. So I read about coil rewinding and stuff over the internet and had one thing in mind, and that was to rewind my coil to produce more amps to support brighter lights.
    So yeah, this DIY thread will help you guys in rewinding your coil in order to support brighter lights.
    I relied on some popular threads such as Convert AC to DC, Let there be light etc. I went through all of the posts on Convert AC to DC thread and tried to learn everything about coil rewinding, I did learn a lot but I was still kinda confused and nervous. And then I met this absolute genius Toshar Deven! ( I shot him some long messages and he was kind enough to reply every single one of them. I cannot thank him enough, he actually went through all the pains to guide a novice like me. We soon exchanged numbers and he guided me via whatsapp. He sent me pictures, videos, long texts. Thank you very much sir! Most of the credit goes to him. Also thanks to rprathin ( for solving my queries.

    So we're gonna be rewinding our coil folks. Sit back and relax.

    1) A Digital MultiMeter to check readings(200-500 Rs)
    2) You'll need a mechanic to remove the stator coil first! It's very hard. The internal design is different from the other pulsars. The coil is placed behind the starter gears inside the rotor which is fixed and is hard to remove. Your mechanic will be able to remove it in around 10 minutes.(Labor cost 50-100rs). Oh and there's gonna be oil in there! Be prepared.
    3) Stator cover gasket.(25Rs)
    4) 19 Number Insulated copper wire - I used 19swg wire to rewind the coil after asking some seniors. I bought 0.5 KG, but that is unnecessary. About 300 Grams is more than enough.(660 per kg in my area, so around 200-220rs)
    5)Insulation Varnish Bottle(30-40Rs)
    6) Some Thicker wires
    7) Soldering iron or else you can go to any shop and get the soldering done.
    8) Insulation tape
    9) A powerful Regulator Rectifier??? (NOTE: I bought an APE RR like everyone but I faced some issues with it. Firstly, P135's lights are connected directly to the RR. The Stock RR is able to turn off the lights when the engine is off. But with the APE RR, my lights were always on, even when the engine is off. That is not that big of an issue but I faced another major issue. I was coming back from Wardha when I noticed my lights were flickering (Turning on and off post 4k rpms). I do not know the cause behind this. I tried to locate the issue but I couldn't. Hence switched back to the stock RR. The stock RR seems to be taking the load nicely for now though, I don't know what will happen in the future hence can't comment on this point.)


    1) P135's stator coil is an eight pole coil. All poles are for battery charging as it's a full DC bike.
    2) RR is situated under the tank. It's a 4pin RR.
    3) Stock coil seems to be winded with a 20-21swg wire and has approx 80 turns per pole (I counted 72 on one pole and 88 on some other)
    4) Please go through the AC to DC thread first. We don't wanna convert AC to DC but that thread is more about coil rewinding less about AC to DC.
    5) Google all the basics.
    6) Don't worry if you fail. You'll learn a lot.

    Rest everything I've mentioned below.


    1) Okay First of all, you need to remove the stator coil. Located on the left hand side behind this. Name:  side view.jpg
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    This is the stator coil. You'll notice that it has a green colored, thick insulation over the poles. Remove all the wires(De-solder) from the coil first. Make sure you understand the wiring and write it down and click some pictures.

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    2) Now carefully, you have to remove the stock windings by hand. Be careful not to damage the stock insulation. I chipped off some insulation from a couple of places and had to cover them up. If the insulation is bad, it's better you buy a new stator coil, unwind it nicely and then rewind it again. Got this tip from Toshar. In my case, the insulation was good hence I decided to use the old coil as it is. You don't wanna allow those copper wires to short to the metal pole, that's the purpose of the insulation. Count the number of turns of the stock windings while you remove the windings and also remember the place from where you have to start the winding. Please write everything down on a paper.

    Name:  bare coil.jpg
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    3) After making sure the stock insulation is good and intact, it's time to rewind. Get some good quality 19swg wire which is insulated. Wind it from the place where you have to start. The pattern is like this - Anticlockwise, Clockwise, ACW, CW... until you finish. Make sure you follow this pattern else the windings will just cancel each other. Make sure the winding is very tight. Toshar told me a very nice technique to rewind tightly, if you guys want I can request him to post it. Also, keep an MM with you all the time while you're winding and check for shorts by checking continuity. Touch the MM probes to the bare part of the copper wire and the metal, there should be no continuity. If there is, then you know you've got a short and you can quickly unwind and take the necessary actions. Keep rewinding keeping these things in mind. I managed to achieve 60-70 turns per pole (stock had 80) with the 19 swg wire. Make sure the turns are not too less or else the voltage will drop a lot at idle which will not produce enough amps. Personally, I wanted to try out around 55 turns per pole but didn't wanna take the risk. Voltage is proportional to the number of turns and current is proportional to the number of poles. More the turns, more the voltage. Less the turns, more the current. But current without voltage is useless hence you have to strike out a balance between the two. Current without voltage is no good. It took me a whole day to rewind as it was my first day. Initially, I was in a hurry and had already winded 4 poles but the winding was very bad and loose like this Toshar told me to unwind everything and then he sent me some pictures and videos via whatsapp telling me how to wind. His technique was great! Thanks man, else I would have screwed up. My windings improved after following his technique.

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    4) After the winding is complete, make sure there are no shorts again and again and make sure the winding is tight. I felt there was still room for improvement but it's okay.

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    5) Time for some insulation varnish. Dip it overnight in varnish and let the varnish do it's job. Next day, apply the varnish again and bake the rewinded coil in the sun. Make sure it's all dry.

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    6) Solder all the wires back as they were before. You can use thicker wires instead of the thinner wires by just replacing them. Check for continuity one last time before you put it back in.

    7) Now that everything is done, put your stock coil back in the bike. You are now ready to go. I installed a 55/60W headlight in my bike and it's working fine. Battery discharges at idle with lights on but starts charging at just 2k rpms. That means 6+ amps of current at just 2k rpms. I'm planning to replace the 55w headlamp to a 35W LED and use 2*15W LEDs on the crashguards. I don't think this coil can take any additional loads but will have to check that out. I'm hoping we can use a 35W HID atleast with this setup but will have to test out that as well. But for now the 55w headlamp works fine.

    Please note that I was using an APE RR earlier but I faced problems which I mentioned before hence switched back to stock RR. Stock RR is definitely pumping out at least 8 amps and looks capable but will test it out more. If anyone of you can help me out with the APE RR issues, I'll be honored. I'm planning to install a mini voltmeter near the console to check the readings.


    Here are some readings to help you guys out. Please note that I couldn't read the amps with my MM but I made some assumptions.

    1) Voltage Test-
    Remove the socket connecting the RR and put the MM probes in it.
    At Idle- 25-30 volts.
    At 5k RPMs-100+
    At 11k RPMs - 220+ volts.

    2) Amps Test-
    You'll find how to measure amps on the AC to DC thread.
    Think it was below 5/6 amps. Horn sounded weak even with the 35w light on. Very poor. 35Watt headlight =3 amps, Horn=2 amps, Other lights=1/2 amps.


    After rewinding, I immediately switched to 55w headlamp.
    1) Voltage Test-
    At Idle- 20-25 volts.
    At 5K RPMs- 70+
    At 11k RPMs-170+

    Make sure you're getting atleast 50 volts at 5k RPMs and also enough voltage at idle.

    2) Amps test-
    At idle with lights off, I got 2+ Amps. Good sign.
    With lights on, it dropped to -1 or -2 amps means discharging at idle but no worries. At 2k rpms only, I had enough amps to power that 5amp 55w light + battery charging. MM shows 14.2 volts at the battery at just 2k rpms Definitely getting 6-7+ at 2k rpms but I don't think I'm getting more than 8-9 amps as even at higher rpms, the horn doesn't sound as good as it should. (5 amps light + 2 amps horn + 2 amps other stuff)

    Will test this system further and update.

    I hope this will be helpful to atleast some people out there. Thank you very much.

    Special thanks to Toshar Deven( and also rprathin(
    Last edited by KartikJ4001; 12-05-2017 at 06:30 PM. Reason: Images
    rprathin likes this.

  2. #2
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    Default Re: Pulsar 135LS Lights Upgrade via Coil Rewinding!

    DIY Approved
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