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RSRBOB, Technician
Category: Motorcycle
Satisfied Customers: 1078
Experience:  Former Factory Service Rep, Dlr Line Tech, Service Manager, General Manager, Store Owner
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how do you set the timing on a ttr90 2001 yamaha i have the

Resolved Question:

how do you set the timing on a ttr90 2001 yamaha i have the manual but it does not say
Submitted: 8 years ago.
Category: Motorcycle
Expert:  RSRBOB replied 8 years ago.
Hi Doug,
Are you trying to set the cam timing or ignition timing? If you could specify which timing you are trying to set, I can help you.
Customer: replied 8 years ago.
Customer: replied 8 years ago.
Expert:  RSRBOB replied 8 years ago.
Customer: replied 8 years ago.


Expert:  RSRBOB replied 8 years ago.
Well Doug, the ignition is all electronic, so once its bolted up, the timing is set. There are only two variables in the timing, and the one that would be most common to cause spark at the incorrect time would be a sheared flywheel key. This allows the flywheel to move on the crank which changes the timing in relation to piston travel.
Now, you can check the ignition timing with a timing light. The same timing light used in automotive service can be used on your motorcycle.
On the left side of the engine crank case cover there is a small plug with a straight slot in it. That is the timing cover plug. You will need to take that out. Connect the timing light to the spark plug high tension lead, and start the bike. Point the light at the hole you uncovered and look for the "firing range" on the edge of the magneto rotor. It has two lines that are perpendicular to the circumference and one line between those other two lines connecting them together. Sort of like this: I----I but the dashes would be a solid line. That range has to be next to the pointer on the case cover. If you can see the range by the pointer. The timing is good. It is not adjustable.
Now, is there a problem like the bike won't start that you suspected the timing was off?
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Customer: replied 8 years ago.
Expert:  RSRBOB replied 8 years ago.
Customer: replied 8 years ago.
Customer: replied 8 years ago.
Expert:  RSRBOB replied 8 years ago.
Ok, so what you really need to do is set the cam timing, so the valves open and close at the correct time so they don't hit the piston again.
Ok, I will walk you through this.
First, take the spark plug out, if it isnt already.
You will need to either back the tension off the cam chain tensioner by turning the screw inside the end cap in until it stops. You can then slide the screwdriver off to one side and pin the tensioner in place so you can get the cam gear on. If you can't hold the tensioner like that, you can remove it for now and install it later.
Position the cam in the head with the cam lobes pointing away from the top of the head, and imagining a line from the center of the cam shaft through the center of the crankshaft bisecting the angle formed by the cam lobes. Sort of like an upside down V, where what would normally be the top of the V is more or less pointing down towards the crank and not up towards the top of the head.
Turn the crank, while holding the cam chain semi tight so it doesn't bunch up on the gear on the crank, so that the "I" mark is aligned with the pointer in that same window we had talked about earlier. That places the piston at top dead center, or TDC for short.
Now place the chain on the cam sprocket, which should NOT be bolted to the cam at this time. If it is, remove it. We will bolt it on in a little bit.
When you put the chain on the sprocket, you want to position the sprocket to the one line on it points towards the arrow pointer on the cylinder head at the top of the opening for the cam sprocket. Ultimately, everything is going to be in a straight line from that pointer on the head above the cam sprocket opening to the line on the cam sprocket, the center of the cam shaft and the center of the crankshaft.
Place the cam sprocket on the cam shaft, and turn the camshaft so the bolt holes line up with the cam sprocket. You may need to pull the sprocket away from the cam to be able to move it, but it should rotate freely. You will not need to compress any valve springs to do this. As long as that V (cam lobes) is pointing down, you are good.
If the "I" mark on the cam sprocket does not align with the stationary pointer on the cylinder head, take the sprocket off the cam and jump the chain over the gear teeth the appropriate number and direction to get it to align. While you are doing this, the tension on the cam chain should be on the bottom.
Once you get it aligned, install the cam gear bolts. Use blue lock tite and torgue them to 14 ft lbs.
Do not turn the crank through until you install the cam chain tensioner, it will jump timing.
Now, install or release the cam chain tensioner. You should hear it snap and should see the tension being taken up in the chain.
Now, SLOWLY rotate the engine counter clockwise by turning the nut on the end of the crank, behind the large plug on that same left crankcase cover.
Roll it through 2 or 3 complete times. If you ever feel any resistance, STOP. You dont want to bend another vavlve.
After you have rolled it through 2 or 3 times, come back to TDC compression. Compression would be after the intake valve goes down and comes back up and stops moving, then look for the "I" mark on the magnetor rotor to align with the indicator on the crankcase cover. Line that up on the rotor, then check for the "I" mark on the cam gear to line up with the stationary pointer on the head. If it lines up, you are good to go. If it is off a tooth or two, release the tensioner, take the gear off the cam and move it accordingly, then re-check it for accuracy.
That should fix you up!
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