Planet Minis

x6rs

im going to port my head on my lifan 140cc engine, thinking about using plastic to change the shape of the intake port, heard about a plastic called jb weld that holds up to 300 degrees celsius, is this a good plastic or do you recommend some other plastic weld material? also i wonder if anyone has any good pics of a succesfully plastic ported head. theres one guy in sweden who port heads using plastic, one of his bike left 19.6 bhp.. tried that bike this weekend and damn! thats a monster but he wont send me pictures

motox2k

have a read of this Mini Dirt Bikes & Pit Bikes Forum : MiniRiders.com.au - Porting! pictures do not work but it will help you.

I have just ported a head and I cannot belive the difference it has made, myself and a friend have the same bikes and in his words "its like going from a 250f to a 450f".

I can post some pictures later as its out of my bike at the moment.

x6rs

would be really nice of you if you could send some pictures! i already ported 3 heads but without using plastic, but now i want to squeese the last hp´s out of mine...

motox2k

i have not used plastic, i undertstand that you only use this if you have made them too large and need to reduce.

any way, all i have done is match the inlet and exhaust port to the manifold.

inlet


exhaust

x6rs

the guys who get maximum horsepower use plastic to change the angle of the port to get a better angle to the valve, the guy who got 19.6 hp on the wheel didnt make the intake bigger than 27mm but changed the angle... is there anyone in usa that has as much power in his chinese engine???

on the heads i ported i carved out material around the valve to make it look like a sharkfin, then it splits the air and go around the valve instead of straight over it, this has made a huge different in power.. we have tried on taking away more material, but the biggest gains we got from just changing the shape.

motox2k

read this then, should give the infor you require, this has not been tested on single valve inlets.

Homework

x6rs

awesome!

Z50King

ehh i like my ideas too

motox2k

care to share your ideas?

mrsrixon

has anyone on here tried that type of port job described in homework? i would like to know before i get my head ported.

x6rs

the 19.6 hp engine is not a dream, i know that guy that made it, and hes got a movie and papers to confirm it, he even has án engine that makes even more hp, but he hasnt dyno tested it yet..

x6rs

by the way it was a jialing engine with big bore(140) kit, japanese high comp piston,rotorkit and lifan head, the lifan 140 engine managed to make 18 hp

50mAfIa

ive ported a bunch of stock 50 heads, a few trail bikes heads, and some ct 70 and stock 110. i dont open the intake any bigger just knock out the guide, rough it some and polish the exhaust port, my heads have mademore power, u can really feel the diff.

x6rs

im loooking for pics of some heads that have been plastic ported, i want to make as many hp as i can without flow testing....and as wide powerband as possible..

x6rs

im even thinking about putting a 3valve head on my 140 lifan if its possible??

smartt yamaha127

If you are, I have a Brand new 3 valve head Im not using. Complete with everything.

x6rs

ok, im still just thinking about it, gotta check if its possible first, the 3valve head should generate more power when ported than a 2 valve... only problem is that i live in sweden, but it depends on the price of the head...

Kurlon

Says the math. 2 19mm intake valves should flow equivalent to a single 29mm intake, with better low lift flow.

x6rs

i heard there was a problem ith the 3 valve heads, that they crack between the intake valves... so maybe its safer to go with my 2 valve???

Kurlon

Heh, haven't had the opportunity to test. Someone else has though, just waiting for them to test things out...