Jump to content
Sign in to follow this  

Cam timing!!! Which mark to use???

Recommended Posts

Since i haven't gotten an answer in the other thread i guess i will try it here. If there are 2 marks on the flywheel, which mark gets lined up with the arrow on the case

Share this post


Link to post
Share on other sites
Since i haven't gotten an answer in the other thread i guess i will try it here. If there are 2 marks on the flywheel, which mark gets lined up with the arrow on the case

you can use either side of the motor , i like to use the left side ignition ( since the cam is on that side its easier )

the double marks you get to first are the ignition fire marks ,( been this way on motorcycles for over 40 years) the single line is the tdc mark,----you cant go wrong,-----you can slowly kick the motor over and get it on tdc by feel ,-------i really do not see why everybody has so much trouble lining this up,----it is only correct one way,

or you can check your self by using both sides of the motor and seeing that the dot on the rt side primary drive gear is aligned up with the arrow at the same time the single line mark is lined up with the notch on the left hand side.

there is only one tdc ( you can even do it with the cam lobes facing forward if you want-----you cant get it wrong -----its easy to see when you missed it by one tooth )

once you get used to what the motor feels like at tdc you can put the chain on the cam without even looking at either side of the motor for a mark,

its easy ----just play with it for awhile and it will start making sense to you :thumbsup:

Share this post


Link to post
Share on other sites

there is only one tdc ( you can even do it with the cam lobes facing forward if you want-----you cant get it wrong -----its easy to see when you missed it by one tooth )

:

is that what the second marker on the cam chainwheel is for, that you can also check the timing with lobes facing forward? :thumbsup:

I hope so cause i always mount it randomly (never had problems though)

Share this post


Link to post
Share on other sites

the 2 marks on the cam is to level it out. You just make sure the lobes are pointing backwards.

Share this post


Link to post
Share on other sites
Originally Posted by kelstr

its easy ----just play with it for awhile and it will start making sense to you

I did now I have 2 kids! :thumbsup:

theDogger

Share this post


Link to post
Share on other sites

You guys are funny. Just line up the marks on the right side, put the cam to where the lobes face rearward with the sprocket bolts lined up vertically and hook it up.

Share this post


Link to post
Share on other sites
You guys are funny. Just line up the marks on the right side, put the cam to where the lobes face rearward with the sprocket bolts lined up vertically and hook it up.

That's what I do normally when taking the cam on and off. With the head removed, is motor at TDC every time the piston is at the top of the stroke with the (right side) marks lined up? I guess another why to ask the question is, does the plug fire every time the piston is at the top of the stroke?

Share this post


Link to post
Share on other sites

I never check the bottom end to see if it's a TDC. I pull the cover and turn the motor over until the cam is facing back with the sprocket bolts lined up vertically. That's TDC on the compression stroke. It does fire every time the piston is at TDC. If you are just reshimming, just zip tie the chain to the sprocket before you remove the sprocket from the cam. That way there's no way to get it off a tooth as long as you bungee the chain and sprocket up to keep it on the crank gear.

Share this post


Link to post
Share on other sites
I never check the bottom end to see if it's a TDC. I pull the cover and turn the motor over until the cam is facing back with the sprocket bolts lined up vertically. That's TDC on the compression stroke. It does fire every time the piston is at TDC. If you are just reshimming, just zip tie the chain to the sprocket before you remove the sprocket from the cam. That way there's no way to get it off a tooth as long as you bungee the chain and sprocket up to keep it on the crank gear.

You say it fires every time the piston is at TDC. With the head, cam and timing chain assembled, TDC is every 2nd time the piston is at the top of the stroke. When putting the motor back together, is it possible to get the timing off by 1 stroke even though the marks are lined up? In the manual, it just says to line the marks up on the right side of the engine and make sure the piston is at TDC on the compression stroke. It makes it sound like it's possible to assemble the head and cam with the piston at the top of the stroke but not the compression stroke.

Share this post


Link to post
Share on other sites
You say it fires every time the piston is at TDC. With the head, cam and timing chain assembled, TDC is every 2nd time the piston is at the top of the stroke. When putting the motor back together, is it possible to get the timing off by 1 stroke even though the marks are lined up? In the manual, it just says to line the marks up on the right side of the engine and make sure the piston is at TDC on the compression stroke. It makes it sound like it's possible to assemble the head and cam with the piston at the top of the stroke but not the compression stroke.

Top Dead Centewr occurs twice for every power stroke for a 4 stroke. There is TDC on the compression stroke and TDC on the exhaust stroke. It fires on both. The piston and ignition don't know which TDC the piston is, only the cam determines this. If the piston is at TDC then where the cam is determines whether it's the compression stroke or exhaust stroke. Word?

Share this post


Link to post
Share on other sites

That's what I wanted to hear. I realize that I made that more painful then it had to be. Thanks.

The zip tie on the chain is genius - am I the last person to find out about that?

Share this post


Link to post
Share on other sites
I did now I have 2 kids! :ride:

theDogger

oh my god,-----i did the same thing :cry: -----i should not have ever done that ,

they are finally grown and gone THANK GOD !!!!

boy thats a happy day ----- :thumbsup::ride:

Share this post


Link to post
Share on other sites
Top Dead Centewr occurs twice for every power stroke for a 4 stroke. There is TDC on the compression stroke and TDC on the exhaust stroke. It fires on both. The piston and ignition don't know which TDC the piston is, only the cam determines this. If the piston is at TDC then where the cam is determines whether it's the compression stroke or exhaust stroke. Word?

I beg to differ slightly on this comment. It only fires on the Compression stroke :thumbsup:

Share this post


Link to post
Share on other sites
I beg to differ slightly on this comment. It only fires on the Compression stroke :thumbsup:

Wrong. It fires on both. The crank turns twice for every revolution of the cam. The flywheel turns with the crank so it fires at the top of the stroke twice per 4 strokes.

Share this post


Link to post
Share on other sites

okay, so the 450x has 3 lines. One with a t on it for tdc and two before it. They are about 1cm apart from each other. Just timed the bike. The dot on the right side is useless. The bike pulls wheelies in 3rd at 1/4 throttle

Share this post


Link to post
Share on other sites
I beg to differ slightly on this comment. It only fires on the Compression stroke :thumbsup:

the ign. fires twice , its called a wasted spark , combustion does not occur because the valves are on overlap and there is no compression

Share this post


Link to post
Share on other sites
I beg to differ slightly on this comment. It only fires on the Compression stroke :thumbsup:

this is the root of all misinformation. the flywheel is connected directly to the crank. The crank spins 360=the flywheel spins 360. the flywheel/magneto/ or stator triggers the spark. it Sparks once every 360 degrees. Just like a 2 stroke but the second spark is just for shits a giggles.

Now a car has a distributor that makes one complete rotation per 2 rotations of the cranks

Share this post


Link to post
Share on other sites

If all this is right then why did my HC II let my :thumbsup: exhaust valves get into the piston? Don't you have to degree the cam in? I thought these cams were just a bolt in,align and go.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×