# how do u find tdc???



## countryboy61283 (Mar 20, 2010)

I been reading threw the service Manuel and say for example when it says turn your crank shaft till you read tf on the notch does that mean your at tdc? Cause right below it, it says caution make sure your at tdc before doing such n such


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## KMKjr (Jan 9, 2009)

Put a screwdriver or something in your spark plug hole and when the #1 piston is at the top, that's TDC.


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## MeanGreenMan (May 24, 2010)

KMKjr said:


> Put a screwdriver or something in your spark plug hole and when the #1 piston is at the top, that's TDC.


Yes, that's how you would check for any TDC. And you must remember that there are 2 types of TDC for 4 strokes.
If you want the compression TDC for checking/adjusting valve clearance, not the exhaust TDC, you must rely on the TF (for FRONT cyl) and TR (for REAR cyl) mark on the rotor. If you set the valve clearance on exhaust TDC, typically the clearance is way too much and engine makes lots of noise.


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## KMKjr (Jan 9, 2009)

MeanGreenMan said:


> Yes, that's how you would check for any TDC. And you must remembe there are 2 types of TDC for 4 strokes.
> If you want the compression TDC for checking/adjusting valve clearance, not the exhaust TDC, you must rely on the TF (for FRONT cyl) and TR (for REAR cyl) mark on the rotor. If you set the valve clearance on exhaust TDC, typically the clearance is way too much and engine makes lots of noise.


Sorry, car/truck knowledge, not much quad...lol


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## NMKawierider (Apr 11, 2009)

KMKjr said:


> Sorry, car/truck knowledge, not much quad...lol


Its about the same. On most any 4-stroke engine, the TDC on exhaust stroke may have some valve overlap which means the rockers are still on the cam ramps. Not where you want to be to set valves.


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## countryboy61283 (Mar 20, 2010)

I'm rebuilding my motor my self so I'm still confused in the whole tdc thing and making sure timing is on


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## dookie (Mar 24, 2011)

U'll notice on the exhaust tdc the valves are tight and on comp tdc the vales will have a tad bit of play. Thats how mine were.


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## kdixer (Apr 14, 2010)

TDC is when the piston is as far up in the cylinder as it can go. Only one cylinder will be at TDC at a time.


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## hp488 (Sep 23, 2009)

If you are confused pull the plugs out and use one of your fingers stick it over the plug hole and turn it over with a wrench and when you are on the compression stroke it will push air past your finger then you know that you are on the the right stroke. That will get you close to your marks then you can use a screwdriver to find the very top, which should be on your marks. Repeat for other cylinder.


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## jrfonte (Mar 9, 2010)

Tdc is when the piston is at the very top of the compression stroke. There are 4 strokes to a 4 stroke engine. Intake stroke : the piston moves down into the engine the intake valve opens (exhaust valve is closed) allowing air and fuel mix to be drawn into the cylinder. Compression stroke : as the piston moves up towards the head the intake valve closes then the air fuel mix is compressed as the piston reaches its Max travel (Tdc) and the spark plug fires. Power stroke: after the plug fires the piston is pushed down away from the head from the combustion from the air fuel being ignited under pressure. Exhaust stroke: as the piston reaches the bottom of its travel on the power stroke the exhaust valve opens and the piston travels back up towards the top of the head and pushes the spent air fuel mix out of the cylinder. As it reaches the top of its travel this is again Tdc but its Tdc on the exhaust stroke. Then the cycle repeats itself starting over from the beginning.

The easiest way to determine wheather your on Tdc on The compression stroke ( which is where you set your valve lash at) or Tdc on the exhaust stroke is to watch the valves move as you turn the engine over by hand. When the intake valve opens while rotating the engine by hand( the direction it normally turns when running) and then closes again watch your screwdriver or dowel rod that you put in The plug hole ( as a previous post by someone else stated) when the rod starts moving back out of the hole and stops moving that is Tdc on the compression stroke. If it starts to move back down you went to far. Your marks on the flywheel, crankshaft,magneto or whatever that shows tdc for timing should be lined up or very close to where they need to be.


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## MeanGreenMan (May 24, 2010)

dookie said:


> U'll notice on the exhaust tdc the valves are tight and on comp tdc the vales will have a tad bit of play. Thats how mine were.


+1.
That's how exactly it is on ALL the 4-stroke engines that I have checked so far.
That's why if you (incorrectly) use the Exh TDC to set valves, it will be too loose.


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## dman66 (Feb 20, 2011)

*TDC*

When I first bought my brute 750, the engine was very hard to start - cranking forever with working the thumb throttle til she started. I new something was wrong.... I wound up checking the valve clearances - well there was no clearance on compression or exhaust strokes - SCREWED??? So I rotated the engine a couple of times carefully watching the cams on each head to see the cam lobe positions - the Kawi manual is'nt clear on where the cam lobes should be , but the lobes should be facing downward towards the engine,and not up position - I started with the front cylinder first lining up the marks " TF " with the little notch on the cover.Then check/adjust valves - exhaust is towards the header pipe,and intake is towards the carbs. Once done,rotate the engine ccw 180 degrees to line up the marks " TR " - check/adjust vales. Then rotate engine a couple of times and recheck everything you just completed - Better to double check your work.


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## countryboy61283 (Mar 20, 2010)

What's it mean when it says in the manual when install rocker case make sure your at tdc at the end if compression stroke?


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## NMKawierider (Apr 11, 2009)

countryboy61283 said:


> What's it mean when it says in the manual when install rocker case make sure your at tdc at the end if compression stroke?


TDC stands for Top Dead Center. There are two TDCs - One is the exhaust stroke...rather at its end, the other is the compression stroke...the end as well. This is the point where the piston is straight up. TDC on the compression stroke is where you set your valves.


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## Stogi (Feb 24, 2010)

TDC is when both cam lobes are pointing down and the piston is at the top of the stroke. I use a piece of coat hanger stuck in the plug hole to feel when it's there. For us that run a * key the marks on the flywheel are no good. They tell you to put the rocker cover on so the cam doesn't jump a tooth, only after the cam is timed right though.


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