timing issues

Well, if i align the cam lobes as it's pictured on the 450cam conversion, the dots on the other side are not even near being aligned, if i align by the dots, the lobes don't align. also, i don't know if it's 14 pins or 12 pins, between the 2 dots..

i now have it aligned by the dots (lobes look wrong) and she starts and runs, but it feels very underpowered so i know it's probably wrong..

can someone point me in the right direction on this? every topic seems to say a different thing... some say 14 pins and align per dots, some say 12, some say dots are not fullproof so do it by the lobes.. i'm tired of taking it apart and putting it back together.. what's the 100% fullproof way to set your timing right?

Refer to this post:


To arrive at timing that looks like that, do this: (understand that the original cams had an E and an I mark, and a punch mark at 12:00 o'clock. The 450 cam has a punch mark for the E, and another at 12:00)

> Roll the engine into position with the tensioner in place; TDC with the cam 12:00 marks up. Remove or back off the tensioner.

> Leaving the exhaust cam in place, set the timing on the intake cam exactly the way it's described in the manual, with the I lined up as well as possible with the surface of the head. It is important that there be no slack in the run of chain which goes from the crank to the exhaust cam, or the one between the two cams. To get that, turn the engine backward a very few degrees by turning the cams backward, then, while holding pressure in against the tensioner guide, turn the crank back forward to the TDC mark and check the intake. Correct it as necessary.

> Remove the exhaust cam, and reposition it until there are 14 pins between the 12:00 marks on the two cams.

> Recheck the timing with the tensioner in place.

The reason that you need to do it this way is because the 450 cam has marks on it for a different cylinder head with different spacing between the cams. In ordinary circumstances, you would not use the two 12:00 marks at all. But since there is nothing on the 450 cam that can be used to set the timing relative to the crank, you must first establish that the intake cam is timed correctly, and then set up the 450 exhaust to be in the correct relationship to the intake, which in turn tells you that it's properly timed to the crank itself.

The difference of opinion as to how many pins there should be in between the two stems from all the different timing modifications done to the '02 and earlier models to change a WR to YZ timing and vice-versa. Don't be confused. In the 450 cam swap, 14 is the only correct number.

hello grayracer,

i may have explained myself poorly, my cams are stock early YZ! so i'm guessing the correct answer is all that but with 12 instead of 14, right? so that the 12oclock dot points up


ok i tried 12 and it seems ok..

No, in the case that they are both stock cams, you line up the E on the exhaust cam with the head, and then the I on the intake also with the head, and ignore the 12:00 marks and don't count chain pins at all.

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