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Originally posted by Joel
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I'll clarify your doubt in open. Makes it clear for the others reading this too.
More CC (cubic capacity) with a large bore is not the only way to make more engine horsepower. You will gain more low end torque, but you significantly loose at top. Because you are still using a cylinder head which was originally designed for a 135cc LC motor. Inlet valve size is 19.5mm and exhaust is 17mm. Not sufficient for a 62mm block to flow at high revs. My 165cc race bike, makes more power (on the dyno too)than a Ninja 250 can even with mild engine works, being 85cc lower. Why?
A stock R15 makes approx 14.2bhp at the rear wheel on the dyno with STP correction factors and ambient conditions. My bigbore 165cc kit gives the engine a good 2.5bhp+ boost without any work. No exhaust, no intake, no cam, no ECU change, no AFR change, no nothing. So please do the math. What are we at now?
Coming to the Dyno part of the story. Most of the dynos used to depict the horsepower values abroad have no reference to SAE correction factors and mostly are defined to simply overstate values to the consumer. Also most are non-branded basic roller dynos and are well under or over real calibration values. Dynojet, Dynapack etc are the reputed and well recognised ones.
Now, coming to the T135 and R15 comparision.
The LC135 and R15 use the cylinder head in stock form. Same valves and same part numbers. The LC135 uses a 54mm piston and the R15 57mm. Technically you are already pushing the flow numbers. As per my flow analysis, 60mm is the limit to what a stock valve can flow. Even cams cant push things too far. Then it has to be taken to next levels of cylinder head development. Now you should realise why I do NOT recommend my custom 176cc block for a stock engine. Thats my test mule for my upgrades and my engine runs nothing stock. Hence makes that much power at top and all rev points.
Now, an engine which is starving from gas flow (read - overbore) will also tend to vibrate a lot. Too many pumping losses and retarded combustion efficiency is what you are then gifted with. Ofcourse you will feel the low-end torque has risen, yes coz you are NOT reaching the max combustion efficiency at low revs.
The LC135 has the same radiator size as the R15. FYI.
Coming to your bigvalve head story.
Thats the black art. Every indo/thai aftermarket company promotes a bigvalve head. What flow and performance you can get out of that head, leaves a lot to be really derived in real world conditions. Its a combination that everybody thinks is making power, but a dyno will prove you wrong. When you are playing with gas-flow, you simply cant agree that bigger and higher is better. Thats where engine development and racing experience comes to play. Making a bigvalve engine bullet proof and super reliable, YET making awesome power is something you always desire. But making it work is a Bittch!
Nobody selling his product will say, he is selling anything inferior. Its always left to the consumer to decide what he needs and what is genuine. Social networking is indeed a common way of selling imports. Every brand vouches for its product, nothing wrong.
There is always a feeling with us humans that the other side of the land is always greener!
.
FYI, I have attained the highest specific output ever derived out of the LC yamaha SOHC engine by anybody till date with whatever hardware, or CC in the world! I'm now at 200bhp/ltr and gunning for more!. Which means for every 100cc, I'm making around 20% power of the CC. I sure know something about these engines my friend
.
Last bit. I would not guarantee/custom tune any maps to anyone who is using a kit prescribed by themselves from elsewhere. Reliability and performance will depend on the hardware and I do not wish to get blamed that my ECU is at fault and caused the catastrophic engine damage. I will however assure with my tune-up combinations only. ECU tuning is very time consuming and an expensive affair. If something needs to be done as a special case, I will attend it personally but risk is thyselves.
More CC (cubic capacity) with a large bore is not the only way to make more engine horsepower. You will gain more low end torque, but you significantly loose at top. Because you are still using a cylinder head which was originally designed for a 135cc LC motor. Inlet valve size is 19.5mm and exhaust is 17mm. Not sufficient for a 62mm block to flow at high revs. My 165cc race bike, makes more power (on the dyno too)than a Ninja 250 can even with mild engine works, being 85cc lower. Why?
A stock R15 makes approx 14.2bhp at the rear wheel on the dyno with STP correction factors and ambient conditions. My bigbore 165cc kit gives the engine a good 2.5bhp+ boost without any work. No exhaust, no intake, no cam, no ECU change, no AFR change, no nothing. So please do the math. What are we at now?
Coming to the Dyno part of the story. Most of the dynos used to depict the horsepower values abroad have no reference to SAE correction factors and mostly are defined to simply overstate values to the consumer. Also most are non-branded basic roller dynos and are well under or over real calibration values. Dynojet, Dynapack etc are the reputed and well recognised ones.
Now, coming to the T135 and R15 comparision.
The LC135 and R15 use the cylinder head in stock form. Same valves and same part numbers. The LC135 uses a 54mm piston and the R15 57mm. Technically you are already pushing the flow numbers. As per my flow analysis, 60mm is the limit to what a stock valve can flow. Even cams cant push things too far. Then it has to be taken to next levels of cylinder head development. Now you should realise why I do NOT recommend my custom 176cc block for a stock engine. Thats my test mule for my upgrades and my engine runs nothing stock. Hence makes that much power at top and all rev points.
Now, an engine which is starving from gas flow (read - overbore) will also tend to vibrate a lot. Too many pumping losses and retarded combustion efficiency is what you are then gifted with. Ofcourse you will feel the low-end torque has risen, yes coz you are NOT reaching the max combustion efficiency at low revs.
The LC135 has the same radiator size as the R15. FYI.
Coming to your bigvalve head story.
Thats the black art. Every indo/thai aftermarket company promotes a bigvalve head. What flow and performance you can get out of that head, leaves a lot to be really derived in real world conditions. Its a combination that everybody thinks is making power, but a dyno will prove you wrong. When you are playing with gas-flow, you simply cant agree that bigger and higher is better. Thats where engine development and racing experience comes to play. Making a bigvalve engine bullet proof and super reliable, YET making awesome power is something you always desire. But making it work is a Bittch!
Nobody selling his product will say, he is selling anything inferior. Its always left to the consumer to decide what he needs and what is genuine. Social networking is indeed a common way of selling imports. Every brand vouches for its product, nothing wrong.
There is always a feeling with us humans that the other side of the land is always greener!
.FYI, I have attained the highest specific output ever derived out of the LC yamaha SOHC engine by anybody till date with whatever hardware, or CC in the world! I'm now at 200bhp/ltr and gunning for more!. Which means for every 100cc, I'm making around 20% power of the CC. I sure know something about these engines my friend
. Last bit. I would not guarantee/custom tune any maps to anyone who is using a kit prescribed by themselves from elsewhere. Reliability and performance will depend on the hardware and I do not wish to get blamed that my ECU is at fault and caused the catastrophic engine damage. I will however assure with my tune-up combinations only. ECU tuning is very time consuming and an expensive affair. If something needs to be done as a special case, I will attend it personally but risk is thyselves.
Thanks for the really highly detailed answer.
Helps all of us here.
Joel you rock.
, what about my set up? Will there be something 'special' for guys like me 
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