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Porting the 2-stroke


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Normally after ported cylinder block ..the tuner need to tune the fuel supply (main jet, pilot jet)..then u have to put on a free flow exchaust..for 2 stroke porting..the pilot jet have to set to more (load) it means..u will not get smooth ride during lower rpm like 2/3 k...n ur bike became high rev bike...the power will only boosted up once u reach certain rpm thus clutch have play a important part over here...just like some turbo car...when rpm increase to 3k then u only feel the power that boosted up!

 

Enjoy ur porting....but my advice is better get a set of original block ..then "kan kan cheong" .....just like me, ported myself...DIY

 

Just my 2cents sharing...:cheeky:

small little red devil:bouncefire:

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  • 1 year later...
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I wonder how many of those talking here back in 2003 is still alive n walking straight....!!??

 

 

yes 4 yrs already.

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  • 5 months later...
  • 4 months later...
Guest deganduss

Don't play with the port unless u gat $$, time & place to test the bike.

If want to learn start with single cylinder, 2-stroke, air cool small capacity engine.

Good luck

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can sp piston be ported? will it improve the peformance? i ported my bloc and carb....but my top end is still the same xia...abit boring..lol

 

If u ported the bloc u must port the piston also the exhaust to make it no block from inside of it.so many to do not only port the bloc.

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  • 1 month later...
Currently i own an SP. Yesterday went to JB and enquired on porting. Most of them charge in the range of 140-200 rm.

 

Should i go ahead with porting or should i not? whats the aftermath of porting?

 

Thanks alot.

 

Lol,I was just thinking about that too.Wish to enquire whether porting will bring the engine life down to half?Plus,do I always need to premix 2t and petrol after I ported?

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  • 4 weeks later...

porting will definitely quicken wear and tear... but.. iam also interested to know porting for SP 150.. not the diy way but thru shop way..

BAJAJ Pulsar 180(apr06)-(nov07)

HONDA NSR 150 sp(nov07)-(mar09)

HONDA specIII(mar09)-(dec10)

HONDA wave125(dec10)-(nov12)

YAMAHA rxz135(nov12)-

top speed: TBC

mileage: miles away

Quote: not the fastest bike but the faster rider...

**if iam wrong please correct me, iam only new to this**

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  • 3 months later...

for 2t bike, you can make 1mm chamfer at the piston skirt to improve the lubricant. ive done and the effect i get it make my bike cooler (usually sunny day&traffic reach 80'c now ard 70-75'c)

 

next thing i do is make sure all port dont have protruding shape that will disturbed the flow. result my bike run much more quieter at 6000rpm & above 8500rpm, the gear sound are louder than exhaust

 

next i shorten the cylinder height by 1mm to increase the compression, but make sure the gap between piston & piston head is not less than 1mm (less than that its quite uncomfortable to ride on street) make sure to take RON98 to avoid detonation. before assembling make sure on BDC (bottom dead centre) piston is not blocking the exhaust port, if blocking occur trim the top piston edge accordingly to prevent blocking (usually only about 0.5mm) result more pull, reach cruising speed much easier (110km/h) didn't feel the rpm drop on up slope road. my bike is mito it might have different measurement value on different bike :thumb:

Save 2-Strokes. :thumb:

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2 stroke porting is a messy job, if u cut too much u will losing power instead of gaining.

Rule of thumb is to start removing material bit by bit and have it tested.

 

Simple method is to cut down the head height which commonly done by any workshop which also known as "potong blok". By machining the top portion of the block, it automatically increase the exhaust port duration as piston has to cover a larger area (in height) but remember to check BDC to ensure the exhaust port edge is aligned with the piston dome. Appropriate shim need to be places between crankcase and head to equalize the missing height. For sure u again have to retunning your carb and exhaust too.

Motorbike manufacturer didn't give any detail for your bike porting duration but some did. Good example Cagiva mito

 

Details in manual:

Transfer port duration - 130 deg

Exhaust port duration - 170 deg (PV close), 192 deg (PV open)

 

Those bikes equipped with PV (power valve) u will not complaining that much as at 192 deg u can easily rev that bike to 12000rpm.

Those which are not will normally select to fall in between. If u cut too much u will loss power at low rev (below 6000) as the bike totally not really responding and eat up fuel too.

 

Easy way is to cut/ trim front edge of the piston along the exhaust port (same width) as if u screw up, u just need to get a new piston as it is cheaper compare if u cut the block as it is not reversible.

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One disadvantage of ported block 2 stroke bike,Need to rev or drag either 3rd or 4th to achieve better top end.Example my RXZ,Ride normally from 1st till 5th gear normal speed no suddern urge but still can go 110 without stress,But wanna gain 140 have to drop 1 gear drag till 6-7k rpm change to 5th gear then woila,Sometime overspeed.

Klass 2,3,4 i shiny Professional'noye litsenziya

 

1993:Class 2B-Yamaha RXK/RXZ/TZR125RR/SDR200/WR200-Aprilia RS125R-Kawasaki KRR150ZX(Former)

2000:Class 3-Honda Civic 1.6esi(Former)Proton Exora 1.6Turbo(Current)

2004:Bus Driver Vocational License

2009:Class 4

2011:Class 2A-Aprilia RS250-Honda CB400SF PB1-KTM250EXC(Former)Yamaha XJR400R(Current)

2013:Class 2-Suzuki B-King 1300(Former)

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Normally after ported cylinder block ..the tuner need to tune the fuel supply (main jet, pilot jet)..then u have to put on a free flow exchaust..for 2 stroke porting..the pilot jet have to set to more (load) it means..u will not get smooth ride during lower rpm like 2/3 k...n ur bike became high rev bike...the power will only boosted up once u reach certain rpm thus clutch have play a important part over here...just like some turbo car...when rpm increase to 3k then u only feel the power that boosted up!

 

Enjoy ur porting....but my advice is better get a set of original block ..then "kan kan cheong" .....just like me, ported myself...DIY

 

Just my 2cents sharing...:cheeky:

 

wah you actually know how to port? you damm zai. :thumb:

2009 - Honda NSR SP 150.

 

2010 - No bike. :(

 

2011 - No bike. :'(

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  • 4 months later...

have my bike done porting b4 and my piston nearly got jam because i saw the piston got wears off at 1 side when i sent my bike for block overhaul...........it can be quite dangerous when u gets a piston jam during ur riding on the road ..... ur engine needs to do modifications to endure the high speed and heat after porting too

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