position of the piston relating to cam lobes
01-03-2009, 06:34 AM
#1
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Squid
Thread Starter
Join Date: Oct 2008
Posts: 64
position of the piston relating to cam lobes
I am wraping up the valve job. Three questions:
1. If I look into the spark plug hole, the piston should be up when the FT is alligned on the fly wheel, correct?
2. If I Irotate the engine by hand; when I see the cam lobes of the front cyl., exhaust and intake facing down on the lifters the piston should not be up, correct?
3. Do the cam shafts spin once around exactly and the piston make one full up and down cycle each time the flywheel is turned 360 degrees?
Thank you.
Darren
1. If I look into the spark plug hole, the piston should be up when the FT is alligned on the fly wheel, correct?
2. If I Irotate the engine by hand; when I see the cam lobes of the front cyl., exhaust and intake facing down on the lifters the piston should not be up, correct?
3. Do the cam shafts spin once around exactly and the piston make one full up and down cycle each time the flywheel is turned 360 degrees?
Thank you.
Darren
01-03-2009, 07:00 AM
#2
Senior Member
SuperBike
Join Date: Mar 2007
Location: Williamsburg, VA
Posts: 2,455
It's early for me and I'm not thinking right, but I'll try to explain this as best as I can.
You have to think about the 4 different strokes of the motor.
Suck, squeeze, bang, blow.
There is a slight pause of the piston at the top of it's travel. This is where it should be when the ft is aligned. But on which stroke? That's the important question. The FT will actually line up twice during one sequence. Once on compression and once on exhaust. On the compression the cam lobes should all be up and no pressure should be on the valves. The exhaust valve will be closing and the intake barely starting to open on the other one.
This may not exactly answer your question. If you have not already done so please try and find the manual online or paper. If you can't find it PM me your email and I will try and send you a digital copy.
You have to think about the 4 different strokes of the motor.
Suck, squeeze, bang, blow.
There is a slight pause of the piston at the top of it's travel. This is where it should be when the ft is aligned. But on which stroke? That's the important question. The FT will actually line up twice during one sequence. Once on compression and once on exhaust. On the compression the cam lobes should all be up and no pressure should be on the valves. The exhaust valve will be closing and the intake barely starting to open on the other one.
This may not exactly answer your question. If you have not already done so please try and find the manual online or paper. If you can't find it PM me your email and I will try and send you a digital copy.
01-03-2009, 10:47 AM
#5
Senior Member
SuperBike
Join Date: Jul 2005
Location: MN
Posts: 1,548
yes, you can have it all lined up perfectly (valve timing wise) and be one TDC off from correct. The timing to the rear cyclinder is important - that is where the direction the cam lobes are facing is important - they face one way on the compression stroke and another way on the exhaust stroke. Get the manual, be sure rear and front are workign together - easier now than re-doing it.
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