TDC markings on crank , iv got 4 lines ???


7 replies to this topic
  • painkilla

Posted April 18, 2006 - 06:06 PM

#1

need some help/advice here guys

Im doing the valves on 2003 650r , however on my flywheel or crank thing iv got 4 lines like this : I I IF IT , now i thought i had to line up the IT with the little sight notch in order to get TDC , however this isnt working for me
in this position i cant even slide a 0.1mm feeler gauge,in fact no size will slide in , so after about 2hrs of cursing i decided to rotate crank so that I I notches line up with the sight notch , and guess what it worked,in this position the rockers had a bit of slight play up and done ,so iv adjusted my valves to 0.15mm(0.006in) Intake and 0.203 (0.08in) EX

Im using the 2001 manual , and off-road.com as a guide(there test bike is a 2001 as well , why is my bike different ? has there been changes to the marking on the crank since then ,

any info would be appreciated ,
cheers

  • qadsan

Posted April 18, 2006 - 06:30 PM

#2

TDC should be at the 'T'. The 'F' is where spark occurs. I don't know why your bike would be different. You can roughly determine where TDC is by placing a long enough wooden dowl in the spark plug hole and making sure it's at it's highest point on the compression stroke. Just don't break the dowl off inside the cylinder. If you happen to have access to a piston stop and degree wheel, then you can accurately find TDC and know for certain what's going on.

You simply find your approximate TDC and then screw in your piston stop about half way down in place of the spark plug. Turn the flywheel in one direction until the piston lightly touches the piston stop and make a note of your reading on the degree wheel (or flywheel) in reference to a fixed point. Then rotate the flywheel the other direction until it lightly touches the piston stop again and make another note of this reading on the degree wheel or flywheel in reference to that same fixed point. The TRUE TDC of your engine will be 'exactly' in the middle of these two readings.

  • don87xr600

Posted April 18, 2006 - 06:32 PM

#3

The IT mark is only correct half the time. You were on the compression power stroke. Spin it again you are on the correct intake exhaust stroke.

  • Max Power

Posted April 18, 2006 - 06:47 PM

#4

The IT mark is only correct half the time. You were on the compression power stroke. Spin it again you are on the correct intake exhaust stroke.



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  • HawkGT

Posted April 18, 2006 - 07:36 PM

#5

don87xr600 is correct. The "T" mark only gets you to TDC on the compression stroke half the time. It gets you to TDC all the time but there are two different TDCs, one is on the compression stroke, one is on the exhaust stroke. The compression stroke is the one you want for valve checks.

The "T" mark identifies TDC. The "F" mark identifies the initial spark advance (1300rpm or less). The pair of "hash marks" identify the full spark advance (over 1300rpm). If you look through the hole with a timing light while the engine is running: below 1300rpm the light should show you the "F" mark. Above 1300rpm the light should blink somewhere in-between the pair of "hash marks".

Sometimes you can be at TDC on the compression stroke and still have no play in the rockers. If this happens then the auto-decompression system has been activated--you can't adjust the lash when it's activated. Spin the crank around two or more times to deactivate the auto-decompress and then continue. On my bike, sometimes the auto decompress doesn't seem to what to deactivate. I think maybe you've got to spin it over at a certain speed or something to deactivate it.

  • painkilla

Posted April 18, 2006 - 07:52 PM

#6

hey thanks guys

i learnt something there, its pretty interesting what u all said .

cheers

  • Max Power

Posted April 18, 2006 - 07:53 PM

#7

Posted Image

  • creeky

Posted April 19, 2006 - 03:59 AM

#8

To make sure that the engine is on the compression stroke and the auto decompressor is not activated, operate the kick starter slowly until you feel compression,(this might take 2 or 3 revolutions of the engine) then slowly rotate the engine with a wrench on the flywheel bolt until the "T" mark is lined up. Now you are ready to adjust the valves.





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