Porting!

[kesman20]

new design. ok?
very good performance 1/8 mile 10 seg

ImageShack - Image Hosting :: p1030729x.jpg

 

[KVracing]

There! Now I have read this whole fucking topic! hehe xD You will really learn a lot of porting by reading this topic. And thanks to Mack for gd input! But about the "homework" link, I think this motoman from mototuneusa has ritierd, I think it's a old website..

I read about porting at wikipedia, and exept from a lot of words, it really was gd, so chekk it out; en.wikipedia.org/wiki/Porting_(engine)

Peace to us tuners xP

 

[robbo23]

hey guys could someone put some pics up to help me with the porting process.cheers

 

[KVracing]

Lol, there is like 16 pages of gd info and a lot of pics xD

Stupid quesion..

 

[sean01]

good to see alot of ppl giving it a go.

but i see alot of ppl are polishing the hell out of there intake ports.....

ppl stop polishing your intake ports, your doin nothing more than destroying your port work...
use no less than 120grit paper, ideally 60-80grit should be used.

the rough port walls are used to atomize the fuel...

 

[no_crf50_here]

last weeks effort It's going onto Michael's motard

 

[50 nut]

Dude that head wont last long before you drop a valve, you have taken all the meat away from valve allowing it to float under big revs meaning it will be tears....

 

[coolmodee01]

yeah

pete doesn't build donks to last long

just to go fast for a bit

 

[no_crf50_here]

Dafunk has his head the same way for months with out issue in his 140cc motard and still going strong. so time will tell.

I feel my motors last ages considering how i ride

I have more dyno time on thrus & friday, so might try that head on friday

 

[dafunk]

my head is similar not the same .true it hasnt had problems yet .the 125 has been similar for a long time with no problems , but it has much smaller valves.
but yeah some of the valve guide is gone. i dont think there will be a problem .
will be great to see dyno results.

 

[mrbrnz]

i've done my head the same way, time will tell.

 

[no_crf50_here]

This is the head i got from Akuna the other day and is currently fitted to my bike
Exhaust

Intake

Valve sizes only 1mm bigger but seems to make a nice little difference over the stock YX head (Intake 28mm exhaust 24mm) Left Stock YX on right

 

[sean01]

i did a yx150 last week. did the same on the guide boss's as that left the standard size valves tho.i polished up the exhaust port a little more tho...didnt have time to take pics as it was for a bike that was getting a new engine for the hri rd 6.

ported it Wednesday and engine was built and running thursday night..
195cc....man its got some stink...
shame we were having carb troubles on race day....

 

[Cactus Jack]

Here's a few pics of flow tested port jobs ...

http://tinyurl.com/INTAKE-PORT-1

http://tinyurl.com/INTAKE-PORT-2

http://tinyurl.com/EXHAUST-PORT

http://tinyurl.com/COMBUSTION-CHAMBER-EXHAUST

 

[sean01]

is that your own port work?

seems they have been semi polished on the intake and chamber...was there a reason for that? methanol?

 

[Cactus Jack]

No it's not my own work ... but he knows exactly what he's doing since he's a professional head porter ...

http://tinyurl.com/HEAD-ON-FLOW-BENCH

http://tinyurl.com/HEAD-ON-FLOW-BENCH-2

I do my heads pretty similar ... I learnt to how to do them gradually in stages using stop watch testing of the engine in an actual bike ... no imaginary power gains ... IF fuel was falling out and clinging to the port walls as some people claim ... they'd be brown stained or coated with carbon ... instead there's only a very small stained patch on the valve throat ... right behind the valve stem ...

http://tinyurl.com/XR75-STOCK-VS-PORTED

http://tinyurl.com/XR75-PORTED-INTAKE

http://tinyurl.com/XR75-COMBUSTION-CHAMBERS

 

[sean01]

very nice work.
i remember the dayz of the xr75...not many getting around my neck of the woods anymore...tho i do know of 1 that is highly modified...xr100 head...and some cdi ignition from some other engine.. not sure on the engine size, but on a flat track it keeps up with cr85's (hard to believe i know)and the kid riding it is the heaviest kid there...
lol to look at it its hard to see the xr75 there..

 

[sean01]

heres my latest port job from this arvo on a zongshen 140.... it had terrible short turns in it...

140 zongshen port work pictures by ozconsoles - Photobucket

 

[themountain]

looking good...intake is almost square...nicely done....did you work on the valve seats also??

 

[sean01]

nah no valve seat work, head is only about 5hrs old i think...but the ports/inserts are taken out nearly to the valve seat

just re-lapped them in before assembly