Cam timing video


Littleeagle28
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Cam timing video

Post by Littleeagle28 »

followed the shop manual to set valve timing and followed forums where possible, does a video exist of how to do this correctly that anyone knows of or have done themselves. Would be a great help to me me as pictures ( or videos) paint a thousand words for me.

Many thanks.

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Re: Cam timing video

Post by herdygerdy »

Hi there Little Eagle 28,

Sorry I do not have any video, but this pic will help avoid any issues. NOTE, because this pic was taken from the front of the engine, cyl. no. 6 is on the left and cyl. no. 1 is on the right.

Image

The key thing to get absolutely right is that when both the intake and exhaust cam lobes for cylinder No. 6 are FACING each other as in the pic (ie; both lobes are facing towards the spark plug), then both the intake and exhaust cam lobes for cylinder no. 1 must, I repeat MUST, be facing AWAY from the spark plug (ie; 180 degrees opposite to cylinder No. 6 cam lobes).

If you are unfortunate (hamfisted?) enough to get it wrong - as I was more than 20 years ago - you end up with two cylinders firing on the combustion stroke simultaneously, instead of one. The resulting vibration is worse than a 650 single with all the engine mounts only finger tight.

To try and illustrate this in words, instead of the compression strokes on the cylinders during two rotations of the crankshaft happily going like this (bang, bang, bang, bang, bang, bang) six times, instead they go like this (BANG!, BANG!, BANG!) only three times. Quelle horreur!

Worst of all for your valve train, you will then have four valves opening and closing together instead of two. This doubles the load, not to mention shock, on the cam chains and sprockets and it is this that causes (usually) the long 'A' cam chain to break, with large side order of bent valves thrown in for free. DAMHIK. And this, "Laydeez and Genimin", is what is colloquially known among us sad CBX addicts as "The 30 km Rebuild".

Hope this helps.

Cheers...Tony
Last edited by herdygerdy on Fri Jan 29, 2016 5:03 pm, edited 3 times in total.

Larry Zimmer
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Re: Cam timing video

Post by Larry Zimmer »

Given the number of occasions for cam timing issues that occur in the forum, your photo should help much! Thanks, Tony.
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Re: Cam timing video

Post by tevan »

A picture is worth a thousand words!

Littleeagle28
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Re: Cam timing video

Post by Littleeagle28 »

herdygerdy wrote:Hi there Little Eagle 28,

Sorry I do not have any video, but this pic will help avoid any issues. NOTE, because this pic was taken from the front of the engine, cyl. no. 6 is on the left and cyl. no. 1 is on the right.

Image

The key thing to get absolutely right is that when both the intake and exhaust cam lobes for cylinder No. 6 are FACING each other as in the pic (ie; both lobes are facing towards the spark plug), then both the intake and exhaust cam lobes for cylinder no. 1 must, I repeat MUST, be facing AWAY from the spark plug (ie; 180 degrees opposite to cylinder No. 6 cam lobes).

If you are unfortunate (hamfisted?) enough to get it wrong - as I was more than 20 years ago - you end up with two cylinders firing on the combustion stroke simultaneously, instead of one. The resulting vibration is worse than a 650 single with all the engine mounts only finger tight.

Also, and worst of all for your valve train, you will then have four valves opening and closing together instead of two. This doubles the load, not to mention shock, on the cam chains and sprockets and it is this that causes (usually) the long 'A' cam chain to break, with large side order of bent valves thrown in for free. DAMHIK.

Hope this helps.

Cheers...Tony
Many thanks Tony, I have managed to assemble as per your photo, but I think I may still be a little off,as It will not fire at all (even with easy start).

I shot in some air through the No. 6 spark plug hole from a compressor, and I could feel the air comming out the exhaust at No. 6 exhaust as set up as per your photo.

Do you know of a way of aligning the cams spot on?

Many thanks
Arnie

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Re: Cam timing video

Post by Jeff Bennetts »

Littleeagle28 wrote:


Do you know of a way of aligning the cams spot on?
A few things to take into consideration, the cam chains are abnormally long and a bit little sloppy by now in a 35 yr old bike, you have four cams wobbeling around in the head, then you have a second chain driving the ignition so you can only be so precise. Some people take the trouble to slot the cam gears but I'm not sure it will do you much good unless you have a fairly low mileage or rebuilt motor and everything is tight.

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Re: Cam timing video

Post by wyly »

:text-thankyouyellow: :text-goodpost: , bookmarked this page for future reference
CBX a work in progress, still improving...GS1150EFE completed and awaiting modifications.....RD350, remnants in boxes scattered throughout the garage

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herdygerdy
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Re: Cam timing video

Post by herdygerdy »

Hi there Little Eagle,

My observations from the FSM, Camshaft installation is described on pages 6-21 through to 6-23.

Cams are installed in the following order.

First - Exhaust cam for cyls 4-6
Second - Inlet cam for cyls 4-6
Third - Exhaust cam for cyls 1-3
Last - Inlet cam for cyls 1-3.

When installing the first camshaft, (the exhaust cam for cylinders 4-6), it is vitally important to:

a) have the crankshaft 'T' mark aligned with the FRONT crankcase mating surface line before starting; and

b) "walk" the sprocket around the chain to ensure the two cam sprocket punch marks (180 degrees from each other) are aligned as close as possible with the head cover mating surface.

But...as mentioned earlier, because the cam chains are most likely a little worn, and therefore longer, (or the head/cylinders may have been decked which also changes the total height in relation to the cam chain length), you may only be able to get the two punch marks aligned with the head cover mating surface as near as possible. One sprocket position will get you very close, any others will be too far. Take your time on this and you will know which is the closest position.

Once the inlet and exhaust cams are correctly in place for cylinders 4-6 and the punch marks align as close as possible with the top of the head cover mating surface , then when installing the two remaining cams (for cyls 1-3), there are ONLY two options. It is only possible to get it absolutely right, as per my pic, where the cam lobes are for cyls 1 and 6 are 180 degrees away from each other;

OR

completely 180 degrees wrong where you would see cam lobes for cylinders 1 and 6 in EXACTLY the same position and facing the same way.

Once the cams are installed, check out my instructions on another post in this forum on adjusting the cam chains.

Not withstanding all the above, if you are confident the cams are installed properly AND you have measured and adjusted the valve clearance shims (good idea to set them to the wider end of the allowable range), then you should be good to go.

If it still does not start, then perhaps you have a fueling or electrical issue. And that Little League, is a whole 'nother bunch of fox holes to explore.

Keep us posted and good luck. Rest assured, we WILL prevail!

Cheers...Tony

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Re: Cam timing video

Post by daves79x »

If you are getting air passing out the exhaust valves with the cams as shown, then either your valves aren't seated from some mechanical problem, or they are shimmed way too tight. Check all your valve clearances to make sure some valves aren't being held open.

Dave

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Re: Cam timing video

Post by Littleeagle28 »

Got a Whole household sick at the moment, so maybe next weekend will investigate.

Thanks for all info so far

Arnie

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Re: Cam timing video

Post by Littleeagle28 »

Got to look at the bike again today, almost no compression on 1 and 6 cylinders. I THINK I've put the cams together properly as per the book, and the posts here, so how can I now check what the problem is and what I must have cocked up?

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Re: Cam timing video

Post by Littleeagle28 »

Have checked valve clearance and noticed most of the shims have no clearance at all, but are tight on to the cam, except maybe 4 or 5 cams. What could have caused this after the rebuild?

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Re: Cam timing video

Post by daves79x »

So you just installed the cams/shims the way they were before the rebuild? Cutting/lapping of valves and seats will almost always require total re-shimming from what was there before. I install each cam with loose shims in the head on the bench and check for rough clearances (wide). Once installed I tighten them up to .004-.005 inch - no less. You need to start from scratch and re-shim every valve. Be prepared to loosen a cam or two if you have zero clearance and the bucket won't spin.

Dave

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Re: Cam timing video

Post by Littleeagle28 »

daves79x wrote:So you just installed the cams/shims the way they were before the rebuild? Cutting/lapping of valves and seats will almost always require total re-shimming from what was there before. I install each cam with loose shims in the head on the bench and check for rough clearances (wide). Once installed I tighten them up to .004-.005 inch - no less. You need to start from scratch and re-shim every valve. Be prepared to loosen a cam or two if you have zero clearance and the bucket won't spin.

Dave
Thanks Dave.
Will do.

When you say once installed then tighten up to .004-005 inch, how do you mean tighten up?
Arnie

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Re: Cam timing video

Post by daves79x »

I mean tighten up the clearances to .004-.005. In your case, you'll be loosening them up a LOT to get to that clearance. You do know that this is the reason for no compression? Many valves are being held open during the compression cycle and not allowing the combustion chamber to pressurize. Good thing many were bad as if just one or two, the bike would have run, and likely burned several valves.

Dave

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