Mods to 138cc oil cooled lifan?

[mjc85]

Purchasing a new bike pretty soon with a 138cc oil cooled lifan, what engine mods would you recommend? I don't mind spending some dough

One mod i want to do is a Inner Rotor kit, maybe a cam (what one ? and where from), what other work would you recommend ?

I just want this bike to haul ass and keep up with the three 80cc 2 strokes i ride with if possible. I would buy an 80cc 2 stroke myself but i prefer the power delivery of a 4 stroke and it suits the type of riding we do perfectly, i tend to keep up with the 2 strokes on my Orion through all the corners (the guys i ride with are a bit soft) and up the mountains but they smoke me down the straights.

Mitch

 

[noidea]

Porting
Increase compression (high compression piston)
Inner rotor
Cam
Clean up the muffler a little (bit restrictive if your not worried about noise)
And finally jet your bike to suit the mods you do and the fuel you use (higher octane if you going high compression)

Thats a list of what your aiming to do with any engine for max performance.

You may wish to focus on handling aswell, put some better fork oil in and maybe spring spacers if your a big bloke.


with these mods your bike will flog a factory 80cc 2 strk any day.

have fun with it!

 

[mjc85]

Ok, i am pretty technically minded and know nearly everything about pit bikes but i know almost nothing about the inside workings of a 4 stroke motor. I have learnt everything i know from owning an Orion and having to troubleshoot so many problems. Would i be able to change cam, do porting and install a higher compression piston myself with some help from the forum?

Also what sort of cost could i expect to do these mods noidea? And what cam and where could i purchase it?

The bike i am purchasing has all Billet parts, billet hubs, CNC wheels, and fast ace suspension front and rear. So i'm aiming for the bike to go as good as it looks if not better =) And to smoke those damn whippersnippers

 

[crazzy #1]

iner rotar kit your looking at 500 but worth it... cam, another good option but as noidea said porting and also polishing would be good

 

[crazzy #1]

oh, btw 138cc pitro/dhz out of the box would flog kx,yz,rm,cr 80 out of the box... if u know what i mean

 

[pugs5l]

if you want to keep up with the jap 2 strokers buy one.it will work out much cheaper in the end,and handle alot better.a half decent rider on say a yz80 will always smoke a mini

 

[crazzy #1]

depends, got a kx 80... was a straight though... he would kill me in track as he is a pritty good rider

 

[mjc85]

oh, btw 138cc pitro/dhz out of the box would flog kx,yz,rm,cr 80 out of the box... if u know what i mean

Bike i'm buying much better quality than DHZ and Pitpro, built in same factory but its the top of the range bike they make. Wholesale price is $950USD whereas those DHZ and Pitpro are about $280USD.

As for a piston, what one should i buy and where from ?

 

[thrill seeker]

sounds like a pretty good bike your getting with lots of billet parts. Can you tell us who it's from?

 

[crazzy #1]

mjc85 wouldnt happen to have a pic of your mistery bike? and that fairly cheap... something im going to look into when im out of school IMPORTING

 

[wezza]

oh, btw 138cc pitro/dhz out of the box would flog kx,yz,rm,cr 80 out of the box... if u know what i mean

Thats a load of shit, most of those 2 stroke 80s are making around 20bhp compared to 8-9 max for DHZ/Pitpro or any standard china pitty. One of my mates has a stock 85 rm80 and that thing is about 50 metres in front of my BSE 125 by the time I hit fourth.

 

[roost]

Ok, i am pretty technically minded and know nearly everything about pit bikes but i know almost nothing about the inside workings of a 4 stroke motor. I have learnt everything i know from owning an Orion and having to troubleshoot so many problems. Would i be able to change cam, do porting and install a higher compression piston myself with some help from the forum?

Also what sort of cost could i expect to do these mods noidea? And what cam and where could i purchase it?

The bike i am purchasing has all Billet parts, billet hubs, CNC wheels, and fast ace suspension front and rear. So i'm aiming for the bike to go as good as it looks if not better =) And to smoke those damn whippersnippers

inner rotor $280, cam regrind $125,lightened oil slinger $50, piston $80, boreing $44 ,gaskets $40, porting $200, carby $120(not a mikuni go with keihin a little more expensive but worth it) grand total $939 prices are aprox. With this setup it will rev like a 2 stroke and haul ass, throttle responce will be amazing, i have this set up now as i have removed my stroker kit so i can use this motor as my race motor. And yes theres nothing better than the sound of a totally decked four stroke

 

[noidea]

was waiting for your reply roost.

As for the porting job, im sure you could do as good as any by yourself. If you have a read thru the porting thread i started filled with alot of macks wisdom you will get there. Im very happy with my two porting jobs just wish the engine would run now!!!

Yea you could do the porting, change cam and change piston.

Boreing, oil slinger, inner rotor and cam grind i suspect would have to be outsourced.

 

[mjc85]

So what sort of power figures approximately would the motor be putting out with the $939 of mods ? Double standard?

 

[roost]

So what sort of power figures approximately would the motor be putting out with the $939 of mods ? Double standard?

about 15hp+, if tuned propally compared to the 9.5hp standard. It does not sound like much but give it a go you will be battling to hold on to it, if that is not enough you can stroke it, balance everything and go for the magic number of 20hp but buy all your safty gear as a 20hp pit bike will bite

 

[cranga]

about 15hp+, if tuned propally compared to the 9.5hp standard. It does not sound like much but give it a go you will be battling to hold on to it, if that is not enough you can stroke it, balance everything and go for the magic number of 20hp but buy all your safty gear as a 20hp pit bike will bite

DREWL gimme gimme gimme

 

[mjc85]

about 15hp+, if tuned propally compared to the 9.5hp standard. It does not sound like much but give it a go you will be battling to hold on to it, if that is not enough you can stroke it, balance everything and go for the magic number of 20hp but buy all your safty gear as a 20hp pit bike will bite

Ok, well where do you guys recommend i buy all the parts i need and where should i get the work done ? Would prefer to get it done on Sunshine Coast or Brisbane but could get it to the Gold Coast

$289 for an inner rotor kit sounds cheap Roost, where is this price from? And the keihin carby you recommended is that a 28mm one ?

Cheers
Mitch

 

[crazzy #1]

the kx80 is 98... so maybe that explains it

 

[Bones]

sounds like your going to have one mean beast on your hands there. let us know how you go with it

jump onto www.faster-minis.com and they have some pretty trick bits you may be able to use.

Cheers, Tony.

edit: only just found out this joint is in Oregon, pretty fkn far to order parts but yeah.

 

[mjc85]

sounds like your going to have one mean beast on your hands there. let us know how you go with it

jump onto www.faster-minis.com and they have some pretty trick bits you may be able to use.

Cheers, Tony.

edit: only just found out this joint is in Oregon, pretty fkn far to order parts but yeah.

Yeh mate i hope so, i want to eventually race as well but i duno if there is anywhere to do it 'round here. I'm in Noosa, QLD