china bike 122cc dohc 4 valve project

[tormentandglory]

Hi everyone Just thought I'd tell people about my mini project I've been working on. I'm building a twin cam china bike engine.
The japanese kits are badly overpriced, I'm tired of burning cash on kitaco and takegawa engine parts. I've built a lot of mini engines in the past 10 years or so and I thought I'd have a go at building a china bike that was a bit more special.
I've started with a mojo 110cc three valve engine. It now has a gpz400 piston which makes it 122cc. I'm using zxr250 valves, cams and all associated hardware. For the actual head, I'm using the original 3 valve thing, but i've cut the back off it, welded the ports and chamber up totally, and re-machined my own chamber and ports. The camshafts and buckets will be supported in a billet alloy cambox, which bolts to the back of the head (unlike the takegawa one-piece design).
I've uploaded a few pics of the progress so far. Its been slow going, and there's so much work to do! Getting access to the machines at work is tough sometimes as well. I'm hoping it will be running in a few months.
I'll post updates as I get further into the build.

[MasterSpoon]

wow
that looks like there is alot of work going into that and hopefully it all pays off

[tormentandglory]

There is an obscene amount of work in it and I'm not even a 1/3 of the way there yet. And I don't know if its gonna work, I have no drawings. I'm just working out of my head.

[themountain]

SWEEET...keep up the good work !! Anxious to see how its running....what size does have the valves?? what cam do you use??Will it be for dirt or street??

[tormentandglory]

it'll be for dirt. i'm using the zxr250 cams, the valves are 19.5 and 16.5mm. I'm putting it in an xr50 :-)

[tubes380]

thats some crazy stuff, do you mind if i ask why you have put in the extra couple of holes in the chamber? the ones between the two sides if that makes any sense, sorry i am lost for a better explanation.

[arkark]

100% cool man ,, keep up the good work ,, you have 2 make a video when you get it going ,, plz

[tormentandglory]

Originally Posted by tubes380

thats some crazy stuff, do you mind if i ask why you have put in the extra couple of holes in the chamber? the ones between the two sides if that makes any sense, sorry i am lost for a better explanation.

Not quite sure what u mean tubes, but the hole in the middle will be the spark plug hole, and theres a bit of a blemish next to it where the welding isn't quite perfect.

[epod]

Wow, I can't wait to see how you make the timing chain operate the 2 cams.
Good luck. Ride on MSO

[Cactus Jack]

Originally Posted by tormentandglory

Not quite sure what u mean tubes, but the hole in the middle will be the spark plug hole, and theres a bit of a blemish next to it where the welding isn't quite perfect.

He's talking about the two reliefs at the ends of what appears to be a flame trough .... You've done a stack of work there mate ...... it's good to see someone having a go at engineering their own parts ......

You're spot on about the Jap parts being grossly over priced for what they are ....... and you're obviously a skilled tradesman who's fully in the know so you can see it whereas a lot of others can't .....