help with cam/head/valve

[diff333]

Hey guys. I have a orion 2007 125cc with engine number DJ154FMI.
Ok, got the bike with a bent inlet valve. Ordered new valves and timing chain according to the engine number. Firstly the new chain was a link longer so I first used the old chain to check everything. Thats where things went well weird. I put the timing in spot on (I am a mechanic so I know what I'm doing) turned the crank by hand to check and on the seventh revolution off the crank the inlet valve hits the piston! So obviously the ratio between crank and cam gears are out. So i found out from the previous owner that he changed heads. Problem is now i have 3 heads,One of them must be the 110cc cos the valves are much smaller, 4 cams and only 2 cam gears. Problem is the only gear that fits on the original head,according to the previous owner, is a 28 teeth wich means the chain i got will be far too long the other gear is a 32. i also have a 34 gear that doesnt fit on any off the cams but it seems to be the right size for the length of the chain i got from the agents. Can anyone make heads or tails out of this. I've tried finding a manual for that specific engine number but nothing. and the agents here in SA are not helpful at all!

 

[sean01]

well firstly i would be finding out what crank gear is on it.. double the teeth count on tht and thats what cam gear you need to run...

i would be reverting it back to the original head if you can change cam gears as some have 2 bolt holes and some have 3

 

[diff333]

Thanx Sean. I counted the crank gear as 14 teeth so that means it will be the 28 which luckily fits the cam in the original head, which i'll be putting back. Hopefully this a.....e didn't change the cams as well. He changed the head cos the one bolt on the intake manifold was stripped! Now this means i will have to shorten the chain? The one that was in when i got the motor, with the 32 cam gear is a 86(43 links) and the new one from the agents is 45 links. Any way to calculate the correct length or will i have to do it by trial and error?

 

[sean01]

chances are that the chain in the engine when you got it was the original one.. if the valve in the original head was only bent a little i doubt you would need a new chain..

 

[diff333]

They did split the chain and did a poor job of it. I dont know if they added or removed links tho. I'm sure i'll get it figured out the weekend. Thanx for the info

 

[The_GDFP]

If you have 14/28 sprockets, a 69mm tall head should require an 84 pin chain. If it uses an 81mm tall jug, 88 pins. If it's the 78mm tall "normal" mid-block, it really shouldn't have 14/28 sprockets.