How do i reset the timing on a 2007 ttr-125E?

SOURCE: Yamaha FZ 400 engine timing

hi,normal way to set up fz is as follows,remove left hand engine cover and you will find cdi picups with a backing plate and interrupter tongue,remove all the spark plugs(dont get the leads mixed up),turn the motor by hand up to top dead centre on no1 piston,the tdc mark the plate will line up with the cdi pickup,no1 piston will now be at tdc,both sets of valves ex and intake should be closed and the tappets slightly rocking,if thay are not and any of the valves on no1 piston are open or tight,look to the end of the camshaft (where the cam fits into the bearing surface)and there will be a horizontal mark on each camshaft,release the cam chain tensioner,slip the camchain off the sprockets and rotate the camshaft untill the marks on the camshaft are exactly parrellel to the rocker box mating surface,fefit the cam chain and check alignment then retension the adjuster and check the marks again,if you have it right the marks should still be exactly parellel with the rocker box and the piston should still be sitting at tdc,if it is out by 1 tooth do it again untill it all three marks are exactly right,failing to do this WILL result in a valve sailing through the top of a piston,then it becomes a bigger job again,after you have got them adjusted correctly ,turn the motor over by hand to check that nothing is binding,if you are satisfied that everything is right,then use the starter and you should have compression,hope this helps

SOURCE: i had to replace my timing chain

you need to find a thing called tdc top dead centre. if you look on you tube you will find loads of videos to explan it. tdc means where your piston is at its highest and your valves are shut.

SOURCE: replacing timing chain on ttr 90

There should be a timing mark on the magneto, rotate crank until line is visible thru inspection hole. This will position engine at Top Dead Centre. Have head complete with gaskets, valves, springs and camshft in place and position with camshaft chain in ready position, (you have to hold chain thru camchain opening) Place head on and bolt tight (no need to torque down yet) and pull camchain tight on opposite side to tensioner (fully loosened) and feed over camchain sprocket, take up tension with tensioner screw/bolt. This will have engine TDC with valves closed (as if to fire) rotate engine by hand and ensure tracking of camchain and tension is steady on chain. Valves should actuate in time. Have a close look on camchaim sprocket and a mark of some sort should show against corresponding mark on camshaft journal cuos.


http://www.yamahaownershandbook.com.au/index.php

Need the Manual: Down load from the link above, enter model, make year and download for free. (It's in four languages however) The relevent detail is in chapter 4-8 to 4-13. I think, Cheers.