Advance Porting and Exhaust Port Degree Help.....Yamaha RXZ

[malvechaitanya]

Friend I have a RXZ 135 4speed 1997
I have done the following upgrades...
*Alloys and Front Disc
*Proton Expansion for RX135
*K&N Airfilter Rc1060
*Proton Fiber reeds
*head shave
*Upjetting
*Upgrade to 5speed gearbox
*Upgrade Clutch Bell to 74 teeth from old 71 teeth
*Sproketing

Now have fitted an a fully polished 5 speed block (porting as per stock 5 speed block) standard piston(ART)

But the problem is the power band starts from 6.5k rpm and ends at 8.5k rpm....A very narrow powerband...
I expect powerband from 6.5k to 10k rpm...As I have to beat my friends Pulsar 220....Rather I need a proper port Degree of exhaust port ,degree the 4 transfer port and the direct or boost port.

Im doing the bike myself...
If u have done any research regarding the port timings please help me out with it...

Now the standard 4speed ports are 3-4 mm small than the 5 speed ports....And I have 5speed block....Is and further porting required for the 5 speed block....If so please provide the proper calculations.....Thanks and regards...

[ananthkamath]

Two-stroke porting and exhaust is not a thing that can be discussed in one thread. You have to delve deep into it to even understand what's going on. Your approach of using mm and port timing is too simplistic: this is NOT a 4-stroke engine and things are not that simple!!

An excellent and highly technical online forum called Macdizzy used to exist when I was into this, but now it has vanished.

Its not much, but its a start. Get the following books and read them cover to cover:

The Two-Stroke Tuners Handbook - Gordon Jennings (google it for a pdf, i'm not going to post the link here and read this book for an understanding of how things need to be done)

Design & Simulation of Two-Stroke Engines - Dr. Gordon P. Blair (this is a highly technical book and an excellent investment if you are obsessed with two-stroke performance; i was blown away when i read it; however, its quite expensive!!)

You will get a few ideas on what needs to be done after you read this. And yeah, throw away that proton chamber. Its no good for your goals.

[Ajaybiz]

Try our own indian 2 stroke forum may be you'll get some answers, as porting is not joke needs qualified tuners.
Looks like you are having issue with carb and jetting, get them rectified and get digital CDI(must for performance 2 stroke bikes).

[malvechaitanya]

I Think the Ports are not matching with the Exhaust....A Mechanic told me that the Proton Exhaust Is Designed for rally ??? Now Whats that...He even told me U need to do Heavy Porting to support the Proton Silencer....And After doing so City Driving will become difficult.....Even the Engine Life & Mileage will drop Drastically....

What Is A Rally Bike ??? What are the essential mods needed for the same...

[speedcrazy]

Hey there

I think your problem does not lie with your port setup, but rather with your expansion design if you are looking for an even power band. 10K on stock barrels, ignition and carbs is a tough task.

Proton chambers are designed for stock bikes and are very aggressive in a narrow power band. To give you an example, when we were racing RD's I have tried one on a stock bike, however found it was quite detrimental to the power band and peak power. Shortly afterwards found a similar dimension Proton Expansion being used for a stock Samurai!!! Obviously the calculations will be off somewhere.

I assume the "Proton" reeds you are talking about are the set that come with the exhaust should be "Boysen". How many petals, what material and how thick are the petals?

PM me your e-mail address, I'll send over a few pdf articles and calculators for expansion design, which will give you an idea of how small parameters can change engine characteristics drastically.

I would suggest you work with a reputable tuner with some experience near where you are, you will learn a lot more practically than pouring over books.

While 2 strokes are relatively simple in construction, tuning them to run quick, reliably can be a frustrating, time consuming and expensive affair if you don't know what you’re doing.

Cheers and Good luck with your Pulsar vendetta, remember that your bike has the potential to slay much bigger fish :-)

Robin

[invincible7]

Rally bikes are of many variants.. if we are talking about endurance races like the raide the himalayas.. the bikes need to be made specific to withstand the roads at that levels and be able to perform on those kind of terrains. If we are talking about motocross races, the bikes are made to perform depending on the track the race is planned on. so the bike will range from bottom end performances to mid ranges depending onthe kind of turns in the tracks. Generally moto bikes lasts for a single of mostly 2 races, so the kind of engine building is drastic to make power. However i dont think you would need that kind of machine which you have to build after completing few thousand kms. To get power from the machine is hell lot tricky given the importance to its reliability.
Since i also own an RX and in the process of making it fast. This is what i have done on my bike to give you an insight.
Custom porting (Stage II)
Custom Chambers
RXG Stock Carbs - You can choose a flat side carb for more power delivery with proper upjetting.
Stock Rims 18" - You can choose alumunium rims for making the bike lighter
Reed Valves - you can upgrade from choosing between Fibre to carbon fibre reeds
Head Shaving - to increase the compression.
Custom CDI.
Filters - UNI's

Doing this would give you enough power to enjoy the ride while keeping the mind and eyes open because if any one of them is not working one would end up crashing somewhere for sure. And yes there are more things which can be added to make it more faster.

[malvechaitanya]

Originally Posted by speedcrazy

Hey there

I think your problem does not lie with your port setup, but rather with your expansion design if you are looking for an even power band. 10K on stock barrels, ignition and carbs is a tough task.

Proton chambers are designed for stock bikes and are very aggressive in a narrow power band. To give you an example, when we were racing RD's I have tried one on a stock bike, however found it was quite detrimental to the power band and peak power. Shortly afterwards found a similar dimension Proton Expansion being used for a stock Samurai!!! Obviously the calculations will be off somewhere.

I assume the "Proton" reeds you are talking about are the set that come with the exhaust should be "Boysen". How many petals, what material and how thick are the petals?

PM me your e-mail address, I'll send over a few pdf articles and calculators for expansion design, which will give you an idea of how small parameters can change engine characteristics drastically.

I would suggest you work with a reputable tuner with some experience near where you are, you will learn a lot more practically than pouring over books.

While 2 strokes are relatively simple in construction, tuning them to run quick, reliably can be a frustrating, time consuming and expensive affair if you don't know what you’re doing.

Cheers and Good luck with your Pulsar vendetta, remember that your bike has the potential to slay much bigger fish :-)

Robin

Thanks Friend for your precious reply....
Indeed I had a practical experience at a professional mechanic....Related to porting and polishing....literally a lot of people just do polish the ports and call it as porting....I have worked on 4 Transfer ports and Exhaust Ports and the boost port(Even auxillary ports which are unpresent in stock rx)...But the mec. is not providing the exact degree calculations and so I still dont have the exact degree Calculations (degree from ATDC)....My bike is doing better than a 5speed machine but I want A Power Band from 7000-10,000/11,000 rpm range....First of all I had ported my 4speed block same to 5speed block then noticed the powerband from 3000-6000rpm then rpm died at 7000rpm on tacho meter...now lifted the ports 3mm exhaust n 2mm boost port and 2mm transfers and noticed that bike had tremendous power from 4500rpm-7500rpm and dies at 8200rpm....For now the piston is dead...And reboring it with a rajdoot 170cc piston....And Even further porting the block will make the ports swing 7000rpm-10,000rpm but im rather FEARED that the exhaust will die and not support that great rpm range....

And ya those proton reed valve are fiber reeds and are as same size of stock reeds only difference is there are 2 plates each side....The first plate is as size of stock plate with hole and the second (small) one covering the holes

This is the pic of my Proton Expansion Chamber