cam shafts wrong direction, 25 mile fix?

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Achim Grabbe
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cam shafts wrong direction, 25 mile fix?

Post by Achim Grabbe »

Hi all, I remember that topic but didn't find anything via the board search. If you mount the left cam shafts the wrong direction and run the engine, you get a total of about 25 miles before _what exactly_ happens? Wrong direction means: crank T-mark is aligned and the cam buckets from #6 showing to the plug, #1 also. Right direction: #6 buckets showing to the plug and #1 are showing away from the plug.
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Post by alimey4u2 »

Before the cam drive chain frags.....

The valve actions of opening & closing valves are "balanced", the valve springs working in conjunction with each other, requiring a relatively light cam chain to add rotation...
Last edited by alimey4u2 on Fri Aug 08, 2008 4:38 pm, edited 1 time in total.
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Don #6141

Re: cam shafts wrong direction, 25 mile fix?

Post by Don #6141 »

Achim Grabbe wrote:If you mount the left cam shafts the wrong direction and run the engine, you get a total of about 25 miles before _what exactly_ happens?
The cam chain breaks . . . . and if the engine is spinning, it's pretty disastrous. I bought a bike (cheap) after just such a case with 16 bent valves, 15 cracked guides and one bent rod

It runs pretty poorly (because it's now a big three instead of a six) so you get plenty of warning to shut it off . . . .

Don

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Post by alimey4u2 »

Basically, if the cam lobes on number 1 cylinder are pointing in ( towards the plug,) the cam lobes on the number 6 cylinder should be pointing out & vice versa

Correct me if I'm wrong guys....
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Post by Achim Grabbe »

Been there, done... I had my cylinders rebored and honed (sp?) for first oversize pistons, got it mounted and started it. A very strange noise appeared and I recalled: I did mount the cam lobes #1 and #6 facing each to the plug. I then just got the cover off, fixed it and started again, very much better now. Made a little ride and all seems to be fine.
Thanks guys, I just wanted to know what would have happened, when...
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Post by alimey4u2 »

Glad you caught it in time Achim..... :thumupp:
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Post by daves79x »

Can you tell us exactly why you installed the cams incorrectly the first time? The VERY early '79 Honda shop manuals showed the cams installed incorrectly, and this is why most of the incorrect installations happened. Do you happen to have an incorrect manual? Just wondering as this topic has been discussed many times here and elsewhere.

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Post by Achim Grabbe »

It was just: "I think they have to be mounted this direction", nothing special. I know that it has been discussed before but didn't find it here. And sometimes if one thinks to know it all it happens nonetheless... I am pretty fit in knowing the CBX engine, theoretically. Maybe that's the reason? I did not use the procedure from my manual (not the original Honda manual) but made a note in it for the next time.
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Post by daves79x »

Achim:
I'm very happy for you that you didn't run the engine until the chain broke. It is very nasty and VERY expensive to fix. The CBX engine is really very easy to work on but I tell everyone to get a shop manual and follow the directions EXACTLY for whatever they are doing, as these engines usually won't forgive mistakes such as this. You could be easily looking at $1000 or more to fix a head from a broken camchain.

For everyone, the engine Don refers to that's now in the Katrina bike had a broken camchain and 16 bent valves and 15 cracked guides. Also 1 bent rod. I'm assuming it let go at pretty high rpm. If you were to take that engine to a shop and pay for all parts and labor to repair ready to reinstall, you would have close to $2000 in it. Good used engines are less than that. We had close to $500 in parts alone to fix Don's and that was with a head I donated and no cost for labor.

As the carpenters say over here "measure twice - cut once"

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Post by alimey4u2 »

It was on another board where a Gentleman (onecool59) had a problem of an unusual noise at idle. After much input from several well wishers, we diagnosed the problem as cams 180 degrees out. Luckily no damage was done & I think George (cbxtacy) now has that bike....
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Post by cbxtacy »

If you set the cams 180 out, and try to turn the engine over by hand, as the valves are opening it is extremely difficult to turn the wrench. When the valves start closing the wrench is practically ripped out of your hand. And that's with no spark plugs in the engine. It makes it real easy to see why setting the cams 180 out will give you accellerated cam chain wear.
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Post by alimey4u2 »

Excellent tip George.... :thumupp:
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Post by Achim Grabbe »

Strange, before final assembly I usually turn over the engine by hand/wrench, to make sure nothing is fallen into the open plug holes. I have found nothing that would have made me think ?! It was just the strange noise at first start that had made me scratching my head.
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Re: cam shafts wrong direction, 25 mile fix?

Post by Mike Nixon »

Achim Grabbe wrote:Hi all, I remember that topic but didn't find anything via the board search. If you mount the left cam shafts the wrong direction and run the engine, you get a total of about 25 miles before _what exactly_ happens? Wrong direction means: crank T-mark is aligned and the cam buckets from #6 showing to the plug, #1 also. Right direction: #6 buckets showing to the plug and #1 are showing away from the plug.
Achim
The engine's firing order changes. Instead of outward, inward, middle (1-5-3-6-2-4) it becomes more linear, which stresses the camchain, an already borderline part. Watch out for the K&L replacements (including those sold by CBX vendors), as their pins are smaller diameter than stock so the chains are even less strong.

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Post by EMS »

daves79x wrote: you would have close to $2000 in it. Good used engines are less than that.
Thanks to the "price pimping" that has been going on in the last year or so, I doubt you can find one for less than $2,000.- now. :roll:

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