Double Sided J-Pen

Try Violin J-pen RH (rounded) or PH (squared). I like it very much, very good control and good speed too.
Besides, you can get it light : mine is 72 grams.
It is designed to use both sides of the blade.
C-pen version is also available, but the lightest is I think around 82 grams.

Using sandpaper directly probably will be tough and it's likely to create uneven surface.  I use a sanding block.  This particular one is a Rubbermaid 54851 Sanding Block.  Use 120 or 150 grit size sandpaper.  Don't sand off more than you need.  Leaving a bit of paint behind will not hurt.

Yes, you put the sandpaper on the sanding block (or pad).  It will give you a larger flat surface (with almost even applied force/weight) when sanding the blade.  I believe you can directly put he rubber on without sanding off the paintsheet.  It's perfectly legal.  Just take off some part of corksheet or at least make it straight instead of semi-circular, so it won't interfer when you glue the rubber on.

If you will do it by yourself and you have never done it before, perhaps it is better to use finer (abrasive) sandpaperblock, perhaps 400 mesh or finer. 

You can look up the rules here.

ps: nothing is mentioned there about converting a one-sided J-pen into a double-sided Jpen being illegal.  As long as your setup adheres to the rules in section 2.04, then you are all set.

@NightyKnight
By the way the feel of Hinoki 1-ply is very different than the multi-ply ones.  You can try to bounce a ball on your bare Speed90 and Expert-H and you will know what I mean.  Usually you can tell the difference when playing it.  However the feel is a matter of personal preference.  Some people like the Hinoki feel, but some don't.

If you really want to modify a 1-ply 10mm Hinoki Jpen into a 2-sided Jpen, you can use lighter rubbers to keep the overall weight down.

All the H versions of any J-pen are designed for twiddling play.

i know someone who's playing with the SANALION and he says though it's not the best rackets he's played with, it feels a lot better holding it in his hand than a cpen blade.  he's feels there's more support on the fingers.

Although I am not leaning my finger on the cork on the backhandside, I leave it as it is, because it does not bothersome.
Your Speed 90 is 9 or 10 mm ? I have one with 9 mm thick, and I also have Cypress. After Violin, I don't like the Cypress. I still have to try again my Speed 90 with F2 (formerly it has F3).

For sure it will not be heavier than normal shake hand. Moreover, I think J-pen has less surface area compared to shake hand version, which means less rubber and less weight.

hi elpmip,

its interesting tat u are using a dbl sided J-pen setup!
it is rare to have a player favouring this kind of blade.

i'm on the verge of buying a KTS but also beri curious abt dbl sided J-pen RH blade.
emmm.... would u be kind enuf to compare both types of blade in terms of the feeling
when playing wz them? can add anything tat u feel would be helpful.

i'm a bit biased towards a Violin J-pen RH blade. i hv an Acoustic & it feels jus Great !!
also a dbl sided J-pen RH has the best of penhold !! it is light, has bigger sweet spot,
u can hook em wz ur finger, twiddle em when u need to & RPB! Best !!

thks for sharing ur experience, aeoliah. 

i used to be c-pen player converted to shakehand abt 10mths ago due to the
weak & uncomfortable penhold BH. used to lose much then, now i'm winning
a lot more by consistently smash driving pple out of balance like WLQ.  hee..hee..

my understanding of spin & strokes have deepen much since then.
as a result my penhold BH is more consistent now. i still love
penhold particularly J-pen now. so i intend to get a dbl sided one jus for kicks.
can learn RPB eh !! Yeah !! shakehand will still be my main style

interestingly, i'm quite alright with both styles w/o interfering with their respective strokes.
i find j-pen beri challenging to master !!  esp the footwork part. my gosh! its beri taxing for the body.
 tis will keep me busy for long time to come. i love Ping Pong !! hahahaha 

I've got an 80g Nittaku AP (short handle round head jpen) that I've stripped the cork off the back and RPB with it. Quite good, and the total mass is only around 145 or 150g due to the shorter face (my normal cpens are 160-170).

Hi Yuna :

Bought the Darker J Speed-90. It is a reverse J-pen meaning no cork to sand on rear side. There is no cork except on the handle.