Help Topic Approved

thanks ken da for the approval..no replies as yet??

what will KRP do exactly??? please elaborate.

the porting job..when i asked them if they could port the bike, they replied in affirmative and quoted the money and time..now since porting takes some expertise and specific tools, i thought they would get it done from karol bagh..so i am in search of the place that carries out the machining jobs of pistons and cylinder heads in karol bagh..

u cant find any1 better than joel to do porting for 4strokes...recently i got my uni pimped by him..u vl be surprised by the way it makes power...insane..try contacting him if u want proper performance...

pradeep

thanks pradeep da..but the problem is joel is in bangalore n myself in delhi...so i needed somebody in delhi only..

I'm wondering what is "head porting"? Is it same as enlarging the intake & exhaust ports & changing the valves? Can someone throw some light here pls?

yup but not exactly enlarging the ports but making them smoother..it's even not necessary to change the valves

For four strokes, head porting involves the enlarging of port taper and most often the smoothening of rough edges in and around the ports that obstruct flow. Idea is to get maximum flow from a given port and sometimes, ports need to be made smaller to improve the rate of flow. A classic example is the LB500s port which is way too large for a good flow number Valve jobs are different. It may begin with a three/five angle job to enlarging the valves.

Shubanker,

It is better to get a good job on the ports done even if it means shipping your head to Bangalore. Most people try meddling with the stock head and end up messing it beyond repair. A friend of mine is in trouble after his LB500s head was fiddled around with by a "top" bullet mech in Bombay. Now, he is waiting for a new head from RE which is proving to be difficult to get.

Cheers,

Jay

Thanks guys, yes now I recall reading this sometimes back; the fine polishing causes improved performance & you're right valve changes are not required too. Appreciate it.

A thought to all those who talk about porting and the so called polishing.

All our Indian 4-strokes have a side draft port design. "Porting and polishing" is the wrong term used and that does not give any gain in performance. Polishing the ports will weaken the velocity of the charge and a smooth surface will attract the molecules. The port size effectively reduces(at dynamic conditions) and hence you loose out on the overall performance. Since in India nobody has a clue of what porting means, I must tell you that its not a job of some roadside fellow or some uneducated machinist who has no clue of gas flow and its related dynamics in a cylinder port. A lot of engineers and top tuners globally have invested serious time and effort and money through flow bench analysis and modelling to obtain the best port deisgn. And if it was this easy as getting a neat job done from a guy in Delhi, I'll recommend they all make a visit to India and save all the trouble of developing .
Although even the best port will not make any radical change in performance in a puny small capacity engine, with other related mods it will indeed transform. It all depends on what you intend to do with the engine.

Having said that, polishing and merely hogging a port is not the right approach to making power and unless you have really understood what the engine demands, leave it stock. I have seen a few so called "Delhi" port jobs and I am in such pity of those poor owners. YOu can get a so called port job done for 1000rs. Isnt that a steal?

The very concept of porting in india is to simple enlarge the hole and then assume that it will go fast. Its somehow works on a 2-stroke engine(coz you get more area and duration and hence some bump in power). But that wont work on a 4-stroke. And all these guys have not invested even a fraction of their lifetime to understand what a 4-stroke engine demands to get better performance. I have one Karizma head which came from a friend who did the ports at Delhi. He would always complain that the bike was slower than stock and then when I looked inside, I discovered the magic. The ports were so perfectly goofed up. I could post the pics later.

Joel - Thanks for the explanation & as everyone tell me here, I too admit you're the best for 4 stroke, hmmm, let me say, peformance tuning.

Now, I'm very sure to have read this somewhere that the opening & closing areas of the valves are polished, mark it only polished to smooth which is called porting & I too agree no one can simply enlarge the size of the intake & exhaust ports due to the complications involved.

So could you educate me on what the real idea of 4 stroke porting means or is it a wrong terminology to be called so? If so, what's the right terminology & how's it being done? TIA.

Porting of cylinder heads is a really big subject. You need to do a lot of research on the same to understand the whole affair. Ports can define your power peak, torque peak, power delivery, volumetric efficiency and a lot of factors. It contributes the most to the listed factors. Porting needs expertise and lots of understanding of engines. Its a mix of metal art and engine analysis expertise.
Polishing of intake ports is a debated subject since flow analysis show drop in cfm, while the old school of thought say the opposite. However polishing of ports stand correct for the exhaust port, since the gases need to be expelled asap without any surface restrictions.
Polishing of intake ports is only done in special cases while the port design is very radical. Not on our conventional side draft ports. Like I said its a debated affair since most go by logic (they feel, smooth is better for flow) and others by actual flow test results.
Here is an example to prove the theory of polishing.
Take a sheet of a polished surface or glass and slightly tilt the surface and let water drip down from the high point. You will find traces of water left on the glass.

Now take a textured, or rough sheet (non-absorbing) sheet and drop water.There will be zero traces of water.
This is exactly what happens inside a polished intake port.
I have only quoted the theoretical facts and not MY methods.

cant comment on actual porting but yea, bigger might not be better (acc to fluids mech i have learned)

Larger can help if the quantity of fluid is more, for the same fluid coming in, it MAY act the opposite, letting out the fluid slowly (giving less quantity/time)?

Pls correct if wrong
Just trying to apply what i have concluded (never read it anywhere)
I am trying to apply Physics i have learned, may be wrong


Joel loved the example of the rough and polished thing!
reason behind it being surface tension (yet another complicated thing :P)