TDC accuracy

I fell stupid asking this for some reason. But here goes..
I noticed on the front of my motor (04FE550) there is a screw (plug) that covers a hole where a screw could be inserted to hold the crank in place at TDC?.
The question is:
Can you pull the plug and insert a screw long enough to hold the crank in place and adjust the valves by this? Or, is this a general holding device?
Thanks,
John

Said screw hole is indeed for locating and locking TDC.
Dale

Thanks Dale!
Is there such a screw available on an 02 400?

jmumme said:

Thanks Dale!
Is there such a screw available on an 02 400?

Click to expand...

Not as OEM.

just for anyone thinking the scribed mark on the flywheel is 'true and honest' forget it! it was 6mm (1/4") out on mine. check using the 'dead stop' method and scribe new lines.

regards

Taffy

Dead Stop? Is that when the piston stops due the broken dial indicator in the spark plug hole? :lol: :lol:
Sorry, I was giddy there for a second. Taffy can you please elaborate on the Dead Stop procedure?
Thanks!

i use a 'wassels' protractor for whatever bike i work on and get the original out, stick it under the photocopier and reduce and reduce until it's the size of the flywheel, cut it out, sellotape it to a bit of card board box, cut the centre out so that it looks like a quiot and i can get a socket on the flywheel nut still.

with the alternator cover off, next i put a long bolt in the top alternator cover screw hole. on the bolt i'll place 2 nuts each side of a 'teardrop' that i've drilled to slip on the bolt.

the 'arrow' points at the cardboard protractor that now sits on the flywheel using blue-tac. pinch the two nuts up to keep it honest. i place the protractor on with the "zero degrees" on the flywheel mark for TDC. lock it all tight so the 'arrow' skims above the cardboard.

using something that will literally stop the piston next so what you do is up to you-but i have....

a tall tube is screwed into the plug hole. there is a pinch screw in a drilled and tapped hole from the side up near the top of the tube. it's there to stop a steel rod at the right place. about 12mm showing is nice...

so the pinch screw stays above the rocker cover as i thread it in the plug hole. i have a steel rod in the middle that can slip up and down. it slips through into the cylinder head by about 12mm and stops the piston if i lock it in with the pinch screw from the side.

turn the engine gently one way and see where the piston stops and then go the other and see where it stops.

if the protractor is in the right place it'll say 28 degrees (for example) one way and swing to 28 degrees BTDC the other. you adjust the protractor until either way it says the same degrees-ok?
if you then look behind the protractor-and it's in line with the flywheel mark....

then i was fibbing and telling whoppers!

regards

Taffy

hI jmumme,
To find Top Dead Centre by the positive stop method I first remove the flywheel and attach a motion pro brand metal degree wheel between two nuts and flat washers on the (now exposed) threaded part of the crankshaft.Make up a pointer by looping a piece of lock wire around a convenient cover screw and tighten it so the wire will not move on the screw.Bend the other end of the wire so it lays close to the degree wheel.Slowly turn the crankshaft until all the valves are in the closed position,then rotate the crankshaft anticlockwise a bit . Break the centre out of a old spark plug that fits your bike,then tap a wooden dowel in the hole,leaving enough of the dowel extending into the combustion chamber that it will stop the piston before it can reach top dead centre.Next turn the crankshaft clockwise slowly until you feel the piston touch the wooden dowel.Write down the number in degrees that the wire is pointing at,eg sample 50degrees btdc,next turn the crankshaft in the opposite direction slowly until you feel the piston again touch the wooden dowel,eg sample 30 degrees atdc.Add the two results together eg 50+30=80 divide by 2=40,set the degree wheel to the pointer at 40 degrees by turning the degree wheel,careful not to let the crankshaft move even one degree.Remove the sparkplug complete with dowel.Turn the crankshaft until the wire pointer is on the 0 degree mark.That is true top dead centre.Keep in mind that the piston is at 0 degrees once when the exhaust valves are open(four stroke engine)and again when all valves are closed (compression)and to set valve clearance the valves must off course be closed.It is a good idea to check and record your valve timing when you have your degree wheel set up,measure in degrees the points when your valves open and close.This is useful info if you ever have to replace your camchain,cam or even replace the cylinder head.Also by carefully recording the valve openings/closing, the amount of slack or rock in the camchain can also be measured and wear detected by simply rechecking your numbers anytime you wish by reinstalling the degree wheel and checking your numbers. Hope this makes sense to everyone ....nsman

what?


:twisted: :twisted: :twisted: :twisted:

liked mine better


tart!!!!!

regards

Taffy (babe)

liked yours better too

Thank you both for your feedback.. I'll give it a try!

John

Hi John.
For the record and regarding simple valve lash inspection / adjustment:
One need not be all too concerned with precisely locating TDC. Simply insure you are on the compression stroke and roughly locate TDC using most any method including that of a plastic soda straw dropped into the spark plug hole.

A single precautionary Note:
Insure that you have not settled onto the auto de-comp lobe. (ie To error just past TDC is quite safe)

Best Regards,
Dale

Ps
Avoiding the auto de-comp lobe is what the locating screw on late model engines is all about.

Mouch Gracious Senor's . All such excellent advice.. Have a great weekend! ccasion5:
John

LINEAWEAVER said:

Hi John.
For the record and regarding simple valve lash inspection / adjustment:
One need not be all too concerned with precisely locating TDC. Simply insure you are on the compression stroke and roughly locate TDC using most any method including that of a plastic soda straw dropped into the spark plug hole.

A single precautionary Note:
Insure that you have not settled onto the auto de-comp lobe. (ie To error just past TDC is quite safe)

Best Regards,
Dale

Ps
Avoiding the auto de-comp lobe is what the locating screw on late model engines is all about.

Click to expand...

Maybe This Is Why Dads Bike Wont Start,Used A Screw Driver To Find TDC And Made Sure That The Valves Werent Rocking And Adjusted It That Way.
If It Doesnt Start On The Tow Rope I'll Recheck Them