timing problemds

[newton]

i've got honda shop manaul on cd but it does't say which way the cam gear goes on the cam are the lobes up or down when the marks on the cam gear and head are lined up it's on a 200 bigred if it's wrong way seems like it put it 180 out

[Daddio]

I don't think it matters. I think that you'll find that as long as the marks are lined up it will work. These things fire on every stroke so it isn't as important as on a multi cylinder engine. I could be wrong but I'm pretty sure it will work either way.
I thought I was wrong once but I was mistaken.:D

[SWIGIN]

I don't think it matters. I think that you'll find that as long as the marks are lined up it will work. These things fire on every stroke so it isn't as important as on a multi cylinder engine. I could be wrong but I'm pretty sure it will work either way.
I thought I was wrong once but I was mistaken.:D

they do not fire every stroke...its a 4 stroke


the lobes should be down when the mark is up on the gear....this is the only way to time it and have the marks line up

[Dirtcrasher]

At the firing mark, the lobes need to be opposite the rocker arms, or in other words - on the compression stroke.

Most people don't know that one crank revolution is equal to 2 cam shaft revolutions and lots of times the cam is 180 degrees out from where it needs to be.

EDIT - thanks daddio, maybe next time you can help someone bend a valve? Please don't post engine help unless you have it down...........

[newton]

At the firing mark, the lobes need to be opposite the rocker arms, or in other words - on the compression stroke.

Most people don't know that one crank revolution is equal to 2 cam shaft revolutions and lots of times the cam is 180 degrees out from where it needs to be.

EDIT - thanks daddio, maybe next time you can help someone bend a valve? Please don't post engine help unless you have it down...........

got a manual on cd but it does't show that

[Daddio]

Thanks for the heads up dirtcrasher but I knew that on a 4stroke it takes 2 revolutions of the crank to get one revolution of the cam long before you were even born. By the way 2 revolutions of the crank to one revolution of the cam???If you read what I said again maybe you will understand what I meant. His engine will be 180 degrees out every other revolution and if the marks are lined up correctly it won't bend a valve. If on the other hand the marks are not lined up correctly it will probably bend a valve no matter whether the lobes are up or down.
Thanks again for your vote of confidence.

[Dirtcrasher]

got a manual on cd but it does't show that

Probably because at one point they show how to assemble the cam sprocket onto the cam. Then the sprocket has a line or a notch or a dimple that is referenced during cam chain/crank timing.

But, if you know how the 4 strokes work, you can cam/crank time any four stroke just by looking at what the parts are doing.

Most of the ignitions don't seem to get adjusted very much. Some models have a pulse generator that has elongated holes but most are factory set. Not that they couldn't stand tweaking.....

[Daddio]

I thought that the cam sprocket would only go on the cam one way do to the offset of the line up pins.Or am I wrong on that to?
Also back in my day we didn't have any fancy CDI units with their fancy pulse generators that run off of the cam gear that only fire on the power stroke,we had points that ran off of an eccentric on the flywheel and they fired on every revolution whether we wanted them to or not and WE LOVED IT!

[Dirtcrasher]

What I meant was if the sprocket only goes on the camshaft one way, then any line or notch or indicator on the cam sprocket aligns the lobes with the crank for the compression stroke. At that point the "T" on the crank shows in the timing hole.

I don't have your manual so I don't know how yours is set up. Some sprockets can be installed off by 180 degress and some are fixed.

I seriously don't pay any attention to any of that because sometimes you are working with different models that are set up different.

If you know the strokes - intake, compression, power and exhaust - you know that the cam needs to be in a position where it is not opening any valves. So, if it's overhead cam then the lobes need to be 180 degrees away from the rocker arms at TDC on piston 1 compression stroke.

Some people don't want to look that deep into it, and would prefer to match up notches and lines.

If you know how it works and what it needs to do, you'll be a better mechanic.

[McDerry]

If its 180 out it will still start as the pickup is mounted on the cam.