The piston crown was originally a flat top..but I worked on it to make it an underbowl config resembling the original r15 piston thereby adding to smoothness

I would be moving to Koramangala, Bangalore in a couple of months and start living there by another 2 months or so and planning to visit Joel for Mutating some of my bikes. Does Joel work on RD350 or 650's?

superbike mods

Respected biker.i dont think he works on big bikes..however I have modified and worked on multicylinder bikes like cbr 600,Honda rune which is a 6 cylinder bike,and 8 rd 350s...so if you want any guidance on what mods to go first..just give me a call at 9840015144.i can also provide you with in depth details of the mods and ther safety factor.happy riding.cheers!!

Fascinating thread, very useful for a technical noob like me. Unfortunately the discussion did deviate a bit (the 18k thing suddenly became as disputed as Kashmir though Im not sure why) but kudos to everyone for engaging in the discussion. xbhp has been missing this. I, for one, was happy to see a scrappy debate.

As to who was right & who was wrong, we are all smart and mature enough for things like that

respected sir, i've been to Joel's garage many times and i've seen race prepared and custome tuned SBKs by Joel out there.

Ohh, so it's the Dynamic Compression that you're talking about? I was thinking it's the Static Compression . So in effect, talking on the terms of stock specification units,(since they specify only static compression which in R15's case is 10.4), the Combustion Chamber is of 15.936cc.



So, the Static CR in Harish's setup could be:

(171.548 + 15.9361702) / 15.9361702 = 11.765

(Cylinder + Cmbsn Chmbr) / Cmbsn Chmbr = Compression Ratio



But since you say you dished the top of the piston, assuming a depth of 1mm and diameter of the cavity to be 56mm, extra CC created by the dish top is:

(0.1 * 2.8 * 2.8 * 22) / 7 = 2.464cc

(Height * Radius * Radius * Pi)


So, corrected Static CR would be:

(171.548 + 2.464 + 15.9361702 + 2.464) / (15.9361702 + 2.464) = 10.4570864


Am I right? Dynamic Compression might be lower than other setups though. So what you're actually adding to Harish's setup is extra 23cc, porting for the head to breathe better, 4mm extra metal to the piston, right? Wont this heavier piston hamper high RPM performance? Especially with the lightened con-rod?
Also, please excuse if I'm wrong here, but if the bike is giving out the same amount of power per stroke, wont the piston be experiencing same amount of force per power stroke? Only difference is, the source of power. So, the con-rod will actually be subject to same amount of stress per power stroke, every-time, right? The only difference is, in Joel's setup the source of power is (higher CR + 15cc extra), and in your case it's (23cc extra).
It's just that your setup will breathe in 8cc of extra charge for every intake stroke, compared to Joel's 165cc block. So, doesn't it mean this setup MIGHT give the same power, but will have trouble with higher revs due to heavier piston, rate of acceleration might be less even though torque might be same, and there'll be a definite increase of fuel consumption over the high-CR 165cc kit? And if you're decreasing the Dynamic Compression further more, it'll be decreasing the CR of the bike to less than stock CR, with all the above calculations, right?

Agreed, the high CR setup of Joel also might have other issues, like earlier wear & tear of piston-rings, a little extra heat(but even the 174cc setup will give some extra heat due to 8 extra cc of charge burning per stroke). Is this right? So it's basically two different setups, with two different characters, both having their own advantages and issues. Can we agree on this?

P.S: All the above calculations are purely based on the assumption that the dish cavity you made on the piston top is 1mm deep, resulting in 2.5cc extra to the cylinder and combustion chamber. If the cavity is instead only 0.5mm deep, then your current corrected static CR will be:
(171.54800 + 1.23200 + 15.9361702 + 1.23200) / (15.9361702 + 1.23200) = 11.0639729

Also, what do you mean when you say "Industrial Coolant"?? Are you referring to the coolant they use in Industries for cutting tools?

Joel DOES work on two strokes. And I DID see R6 and several worn out race tires of it at his work shop. Better speak to him directly.

As much as you give respect to your customers, give the same amount of respect to your competitors too Competition is good, but discrimination and assumptions are bad, please keep it healthy.

respect??

...digislayer you don't know me well enough.i personally feel i have given enough details on the mods..anything more means i am leaving out a lot of secrets.there are no such issues with high rpm performance..you can check up with harish regarding the performance.

Let me make one thing clear not all the things given in text book work in your stated fashion.please BEAR IN MIND theory is different from practical

i have not disrespected Joel in anyway....

i have not added any metal to the piston top...i will put a detailed thread on my mods soon..the only thing holding me back is that it may lead to a lot of controversies and confusion.hope you understand.and every tuner and professional has his or her secrets to keep that's ETHICS

Is this not dependent on piston geometry? Specifically the piston pin to piston head relation?

Could not understand this part. Can you please explain a bit?

+1. Please have mutual respect.


Nice discussion going on here.

I don't see any disrespect/discrimination being shown. Lets not assume and comment on such unless there is clear indication of the same.

I am not commenting on the technical aspects as I have limited knowledge, but thats not to say, I am keenly observing the discussion trying to learn something out of it, so lets not veer off.

With all respect, I'm not assuming anything about you Shah Dupesh, I was just trying to say that it'd be better appearing if you didn't assume Joel doesn't work on big bikes When you say "Respected biker.i dont think he works on big bikes", it might actually send out a wrong message to the person(if he doesn't already know about Joel), that's all

And yes, I do agree..very strongly, that reality differs from theory. But, there're few laws of physics which never change, like "more charge burning= more heat", "higher compression gives more heat, because air heats on compression", "more mass results in more inertia, making heavier objects comparitively more difficult and lazier to move", right? Don't you agree on these laws?

I understood you didn't add metal, I also understood you actually removed the metal and made it a "dish-top" piston, like the stock piston. And yes, I do understand every tuner has his own secrets, and I wont force you to tell us those secrets of yours...if I ever ask you something that you don't wish to reveal, you can simply tell me that it's your trade-secret and I wont force you again on the same topic

I was actually referring to the Combustion Chamber size of the stock engine. In stock form, the cylinder is of 149.8cc in volume, and the setup has a CR of 10.4:1, right? When the company says it's of 149.8cc with CR of 10.4:1, they mean it's with all the stock dimensions(which includes the dish-top piston). Even though the piston is a dish-top, the volume is 149.8, right? In that case, let's say the volume of Combustion Chamber is "X" c.c.

Then,
(149.8 + X) / (X) = 10.4 / 1

Solving that Equation, we get X = (149.8 / 9.4) = 15.9361702, and that's what I mentioned

When I said "4mm extra metal" I was referring to the 4mm extra diameter that this 61mm piston has, compared to the stock 57mm piston. More diameter=more metal= heavier piston = more inertia. This is why they always try to increase the number of cylinders in the engine and keep pistons smaller in high-revving engines.(ofcourse there're many other reasons, which includes flow rate -like shahdupeshkhan said)

I'm enjoying the discussion myself over here! Just love it when there's knowledge-sharing going on somewhere :P

Please look at my above reply for shahdupeshkhan, I tried to make myself clear

+1.I too agree.I was following this thread for quite long and totally pleased with the kind of inputs being given by all the experts.
This thread is being followed by many xbhpians, and based on the conversation they will too decide what should they go for.

PS: I will feed by experience after I get my bike back from the SVC and go for a long ride.I have changed the entire head portion (new valves,cam and all the tits bits).Right now my bike is literally a new bike with a 165cc piston.
Lets see how it runs.

I got that part. This part is what I felt would not be applicable -

This is what I commented about. You assumed that the chamber volume is same as stock.

Got it now! And that is exactly the reason Joel's set up has slight vibes.

But, the lightened connecting rods may offset that here in Harish's setup and make it balanced with respect to the crank weight. Hence, I think Harish's claim of the setup being smooth as stock is possible.

write up

Sunny thanks.i wrote about the work I did and explained some technical aspects in a way,where even the most common biker will understand and appreciate.i didnt want to put up a very technical post since that would confuse most people.laws of physics no matter how basic can be bent considerably if not broken....