^^^ nicely written

Nice write up Karthik! anyone having port maps of a good street ported barrel , please post.

Thanx, Karthik. Well, it is a DT175 that I want to create out of that friend's RX135 4spd, as I don't think it will ever be possible to import one to India legally, and even then it will cost a bomb.

Meanwhile, here are the two bikes owned by my friend 2strokeworld, and I'm currently using the RX 100. The sticker mod was my creation, and the next pic shows it in close up.

Pic of Shogun # 2 is coming up.

Good write up karthik.

CC gives you Torque, and that in my opinion is more important than bhp numbers.

My one question to you, R15 being a 150cc can beat a ZMA which is 225cc, can you explain this?

An RX-Z 6-Speed being just 135cc can beat almost all the Indian make bike upto even 225cc. How?

I have never come across any relationhip between Torque & Displacement. With all due respect, could you please explain?

And yes, this is what i learnt in Mechanical Engineering papers i had in my 1st SEM engineering, & i hope this still hold good,

P = (2 x Pi x N x T) / 60

Where,
P = Power in BHP
Pi = 22/7
N = Speed in RPM
T = Torque in N-m (Newton-Meter)

We can clearly see that the Power is directly proportional to the Torque. This relation holds good even with all the DC & AC machines which powers the Locomotives & Ships.

First we need to define what you mean by beat? if your talking flat out in a straightline, then yes the R15 does that. Many reasons for this, without going into too many specifics, ZMA is a 2 valve tourer. R15 a 4 valve engine optimized for high rpms. Karizma develops max torque @6000rpm. R15 develops max torque @7500rpm. In terms of flow a 2 valve will saturate at higher rpms, it simply cannot compare to a 4valve. You will have to capitlize on the nature of a 2valve, develop it for greater torque at lower rpms and gear it tall if you want it to outdo a 4 valve in straightline performance. The R15's internals are super light. Like i said...many reasons why the r15 can do that.

really? are we talking about stock 135? coz i dont know any stock 135s that do that. The ones that do are modded...consequently more power / torque

Ah Math, my weakest subject..i hate it Funny thing though, some of the best tuners i've known are not engineers themselves. So without trying to restate in my own words, i'll take it straight from the mouth of an engineer who builds race engines, he must know what hes talking about. Puma Race Engines Technical Guide - Power and Torque 2 - Output levels for road engines, VE and improving engine design

TORQUE - A measure of the amount of energy being developed in the engine during EACH operating cycle

Power - a measure of the amount of energy being developed in the engine per minute - in other words a function of the amount of air/fuel mixture being burned per cycle multiplied by the number of cycles per minute.

So to increase torque we need to either process more air/fuel mixture per cycle or extract more energy from the air/fuel that is processed. There several ways to do that from improving mechanical efficiencies, compression, volumetric efficiencies etc.

With all that in mind, as a general rule a bigger cylinder (more CC) will process more air per cycle than a smaller one and generate more torque. If you go big bore without optimizing gas flow accordingly, all you will get which is typical of most bigbore mods you see in India is torque gained lower down with nothing much happening up top. If all your interested in is a drag race, then sure bhp numbers will help. For real world riding though, torque is what you need. Hope this answers your question on relation between displacement and torque.

Just noticed you are refering to the malaysian RXZ that comes with chambers stock. That thing already makes some 20PS@8500rpm thats more than any of the indian bikes. What sort of comparison is that? If you're trying to say you dont need CC to make power, well neither am I.

on a seperate note. There are various ways to make power from low CC. on a 2 stroke the chamber exhaust acts very much like a turbo on a 4 stroke. I will confidently challenge until someone can prove me wrong. Give me a 2 stroke and a 4 stroke with similar CC's. The 2 stroke cannot run chambers and the 4 stroke cannot run turbo. You will find the 2 stroke suddenly has no real advantage over the 4 stroke.

I said, RX-Z 6-Speed, which on Paper develops 21PS in stock trim. This is the Malay/Singapore RX i am talking about. As far as our Indian RX135s are concerned or heck even Suzuki Shogun, it has enough potential to do good enough straight-line speeds way better than the modern 150cc 4-strokes. Yes, thats 110cc vs. 150cc & 110cc winning in both pick-up as well as top-end dept.


I agree with this one & the explaination given is apt. This is the reason i dont suggest people to go for big bore, as the top end gains are very marginal or rather NIL (Ref: Your above comment in RED colour).

Anyways i really appreciate you answering my query. Thanks again.

Answered that one above.


Thats not a fault of bigbore but rather of a tuner who doesnt know how to make it work. I'll prove my point soon. Will show you a bigbore apache out accelerate a stock RD350 LT in a straightline from bottom all the way to topend....coming soon

Battling agaist a 20+ Yrs old machine!!!

Most of the LTs on road dont even do a proper 120Kmph, you can try beating them with stock RTRs. RD was a legend, but due of lack of spares & support from Yamaha India, it is what it is today.

If only Yamaha India has invested as much time & money they are doing for R15 on RD/RX series, then nobody would have dared to drag with these machines. For ex., look at the factory Shoguns & Shaolins, they are best on circuit because of TVS commitment.

Getting back to original intention of this thread, it was big-bore project for RX & not RTR. Remember we are in 2-stroke forum here. If you have any projects done on 2-strokes, then let us continue the discussion.

What your RTR can do to a stock RD, the same can be bettered by my friend's RX135. But thats about individual capabalities & it can be best judged on a drag circuit with proper timing & exit speed figures. Just asking out of curiousity, does your RTR do a sub 13secs in 0-400mts drag?

Lastly, have you ever imagined what a fully blown RD350 can do to your Big-Bore RTR ?

Good luck with your big-bore project.

I'm talking good state of tune LT that does a true 140kph

Wrong mate, R15's rule the track now and by miles, best you catch up on the scene.

You dragged yourself into it. My original comment was simply on torque, nothing 2stroke or 4stroke specific. The same big-bore rules apply nevertheless

Right said about individual capabilities. You obviously havent heard of the Ten10 Racing Group B R15. Will smoke even the TVS factory shaolins in straightline and corners..forget your friends bike. My apache is a daily ride which will do a 14 sec quarter. Your friend rides his 13sec RX to work? Lets not get into a mine is bigger than yours contest, thats for kids

I have no need to imagine. Been there done that, read up on my site if you haven't http://killerdude.web.officelive.com/Mybikes.aspx.

And lastly to clarify again. refer to my earlier post. 2 stroke no chambers, 4 stroke no turbo, same CC's / number of cylinders. Thats a fair comparison if you want to make one.

Since when did R15 start racing with RD/RXs??? Which official event permits 4-Ts & 2-Ts to be raced simultaneosuly???


My friend doesn't need to. He does so in drag race only, not in B'lore traffic. I assume you do 14secs even in B'lore traffic for 0-400mts !!!

Btw, i dont need to hear about any racing teams, thats not my job, i am a 2-stroke enthusiast & everybody here in xbhp 2-stroke forum knows that.

About your R15, its very unfortunate that drags can't happen with 2-stroke. If it did, your perception will change for RX135 & its capabalities.

Once again wishing you all the very best for your big-bore RTR & hoping that someday it will eventually beat a 175cc Bajaj Auto 2-Stroke RE.

Hmmm, wont let it go will you? just have to dig yourself into a deeper hole. The Indian National Road Racing championship is the event if you havent heard of it, the premier road racing event in the country. When 2 strokes were being phased out in 2009 both Group C 2 strokes and Group B 4strokes ran together on the same grid. The 4 strokes dissapeared in the distance and they werent anywhere close to the way they are performing now (i think Joel has a video..we should post it). So lets not even go there


Posted a harsh response to that..but its evident you're still learning...i'll let it go