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Swapped cams and trouble arose!

Old 09-21-2011, 07:36 PM
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Swapped cams and trouble arose!

So to follow with the exciting title, I picked up a set of stock cams and decided to swap exhaust cams with the intake cams because the exhaust cams are similar to the Moriwaki cams....


So the swap went very easily outside of the crank bolt cover, it was botched and took an hour to get off....

Followed the manual to the period, and everything lined up perfectly, I hand tightened my manual ccts and the cams were perfectly in line... 20 minutes later, I hit the starter and there is a loud rattling coming from the engine.

It sounds like the chain, but when I tightened it again, it felt as though I had never tightened it to begin with and when I started the engine, I was able to turn it in, I'd say a full 540 degrees before it started to get finger tight again.

It seemed to be almost a full I'd say half a cm further on the adjustment bolt than prior to the swap. It seems out of place to me, but there again, this is my first time in this engine.
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Old 09-21-2011, 07:53 PM
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Odd. Seems like you had slack on the wrong end of the cam chain when you tightened. I'm not sure how this is communicated in the manual, but when you installed it, did you pull it tight over the cam away from the CCT, then over the closer one so that all of the slack was on the CCT side? Just a guess...
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Old 09-21-2011, 08:44 PM
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I'm with 7moore7. Whenever I install cams I set it with all the slack on the CCT side to start with. Gotta kinda think about which way the crank will be pulling on the chain. Then I give them engine a few revolutions with a ratchet while still fiddling with the CCT and checking slack, just to make sure it is uniform throughout.

Also, what exactly is hand tight? Whatever it is, it's unreliable. I like to just feel between the cam gears. With no load on the cam lobes I like about 1/4" deflection in the chain, with a fair amount of force applied. This may be a tad on the tight side, but that's just fine with me.

And I think the swapping cams thing to resemble Mori is a myth. Very little about them is the similar. I'm pretty sure I stumbled across some false information on some old-*** thread once or twice while researching this myself. Something about the exhaust cams having quite a bit more duration than it actually does. All of my personal measurements match what the manual says. 245 degrees intake and exhaust IIRC. All measurements taken on 1998 cams btw. The only advantage to be had is that the stock exhaust cam has slightly more lift than a stock intake cam.

And did you degree them? I don't think it's enough of a difference to have caused any of your current issues, unless you didn't tighten the bolts, but I don't believe you can simply swap cams and keep the timing in spec. I can't say for sure though. I slotted the gears before they ever went back in. So I guess I didn't check to see if it was 100% necessary. Again... I don't know for sure that the timing needs adjustment after a swap, just a hunch.

Last edited by mboe794; 09-21-2011 at 08:53 PM.
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Old 09-21-2011, 09:33 PM
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See that's what I suspected before I was in the engine and made a mental note of such.

I had all the slack on the CCT side and when I tightened them, I rotated the engine around about 10 full revolutions and rechecked tension and cam lobe position. It was I'd say about 98% on the money; and I did NOT degree the cams, that is more for a future project when I've got a little more time.

Everything was set properly, and there was zero noise while rotating the engine. I even did a 3" pull clockwise and pulled a little slack out there and re-checked and re-tightened.

When I hit the starter it scared the crap out of me and I shut it off after about I'd say 20-30 revolutions. I then set my idle a little higher, double checked the CCT and then started it up again and when I did, it felt like the tensioner bolt just went completely slack and I screwed about a full turn and a half because it caught resistance and I think the noise went away a little bit but it was far from a normal noise.

I didn't get the front one as my wits were at there end and it was no longer beneficial for me to stay there working on it. So maybe all the noise is from the front? I can't seem to get the top of my bolt so I'm gonna take the airbox off, tighten, run again and check.


It wasn't a cam contact noise either, it just sounded like a realllllllllllllllllllllly lose chain, but I thought it wouldn't be that lose and what scared me more was the fact that it went way passed where it was originally before I installed the cam.


And Mboe, I'm pretty sure we saw the same info, it was on the british firestorm forum, but by my measurements it's not quite there in the same term as Moriwaki but I think it is a greater degree than the intake. But I did anything but extensive testing on the cam. But who knows, I just wanted to get my hands dirty It is not necessary to degree cams during installation except in super high performance, low clearance engines, I think.

Every other valve job I've done I haven't degreed them and all of my other jobs have turned out perfectly.
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Old 09-21-2011, 09:35 PM
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Does it have compression still? Have you tried again since you re-tightened the cam chain tensinor? Did it run when you cranked it over?
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Old 09-21-2011, 09:38 PM
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Originally Posted by bass4dude View Post
I had all the slack on the CCT side and when I tightened them, I rotated the engine around about 10 full revolutions and rechecked tension and cam lobe position. It was I'd say about 98% on the money; and I did NOT degree the cams, that is more for a future project when I've got a little more time.

So let me get this striaght. It's possible to install exh. cams in the intake position without degreeing the cams, and not have anything hit? And run?
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Old 09-21-2011, 10:05 PM
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Originally Posted by msethhunter View Post
So let me get this striaght. It's possible to install exh. cams in the intake position without degreeing the cams, and not have anything hit? And run?
I don't think so.. And thus his problem.
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Old 09-21-2011, 10:08 PM
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Originally Posted by lazn View Post
I don't think so.. And thus his problem.

Thats what I'm thinking as well. I fear he may be removing cyl. heads, and replacing 4 intake valves in the near future.

Does it still have compression when it cranks? Spin it over with a wrench, and see if you get resistance from compression. If you don't check your intake valve clearance. I'm willing to bet you could stick a cigarette through the clearance now.
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Old 09-22-2011, 04:22 AM
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I'm thinking what these two people above me are..the new profile of the cam are interfering with the slack in the chain. anybody have the int/exh oem cam specs?
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Old 09-22-2011, 09:01 AM
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Originally Posted by nothing View Post
I'm thinking what these two people above me are..the new profile of the cam are interfering with the slack in the chain. anybody have the int/exh oem cam specs?

What we are refering to is the cam timing events are off, causing the valves to open and close at the wrong times, which may have caused piston to valve interference.
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Old 09-22-2011, 09:06 AM
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It didn't sound like a collision noise.

I very well might be wrong but the engine starts right up and there is otherwise no problem.

I'm gonna swap the cams back and see what's going on but the difference in lift is not that great. Nor is the degree of timing, it's less than the specs of any afm cam and it states that it does not require degreeing of cams when installing afm cams. Hence, why I didn't degree it.
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Old 09-22-2011, 09:42 AM
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Originally Posted by bass4dude View Post
It didn't sound like a collision noise.

I very well might be wrong but the engine starts right up and there is otherwise no problem.

I'm gonna swap the cams back and see what's going on but the difference in lift is not that great. Nor is the degree of timing, it's less than the specs of any afm cam and it states that it does not require degreeing of cams when installing afm cams. Hence, why I didn't degree it.

Alright then. If it runs, there likely isn't and damage yet. What I would do is check you cam chain tension again. What I would be concerned about is the timing events of the cam. You could be close, but a few degrees makes a HUGE difference in performance. If you have gone through all the trouble of putting the exhaust cams in the intake spots, you might as well take the time to degree them in. You've come this far, why not just go all the way. You're so close to being done.


One thing I have been thinking about doing is getting an extra set of cams for my bike and doing the cam swap like what you have done on the cheap. I want to put the exhaust cams in the intake slots, and send the other cams out to be re-ground to the Mori specs. I just wish I could find some thinner headgaskets for the damn thing to bump up the compression. I have noticed that I am starting to use a little bit of oil, so it might be time for new pistons/rings soon anyways. When I do tear into this thing though, it's going to come out as a completely different bike. It will likely be down for a while, and run and look like a totally different bike when it's done. USD's on the front, higher compression with ported heads, a different tail, and full fairings most likely from either an RC51 or a ZX6 (circa 2k vintage).
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Old 09-22-2011, 09:43 AM
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Well... Since you have swapped places on them, did you set them "according to manual" as you where looking at the markings, or "backwards"...
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Old 09-22-2011, 09:45 AM
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Originally Posted by Tweety View Post
Well... Since you have swapped places on them, did you set them "according to manual" as you where looking at the markings, or "backwards"...
I did it to the lobe positions, so they're the right way around.

The markings were perfect and set on perfectly on the cams and the timing marks were fine.
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Old 09-22-2011, 11:25 AM
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Leak down test?
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Old 09-22-2011, 12:09 PM
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Originally Posted by msethhunter View Post
What we are refering to is the cam timing events are off, causing the valves to open and close at the wrong times, which may have caused piston to valve interference.
Exactly, like the exh. lobes may be wider and both the cams in the head are pushing on the valves to closely together (too small lsa) causing tension in the chain between the cams, and then when the engine is on compression stroke or power stroke the slack is elsewhere along the chain..
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Old 09-22-2011, 02:09 PM
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Originally Posted by nothing View Post
Exactly, like the exh. lobes may be wider and both the cams in the head are pushing on the valves to closely together (too small lsa) causing tension in the chain between the cams, and then when the engine is on compression stroke or power stroke the slack is elsewhere along the chain..

Ahhh. I understand your previous post now. I see what your getting at. Like the way the cam timing is now, is allwoing slack in the wrong spots. Got it.

Sorry if my posts might seem to ramble. I have a salivary gland stone that's been messing with me real bad over the last few days. I'm on some heavy pain meds right now(tylenol with codine), so my thoughts aren't very clear. The damn thing is the size of my pinkie finger tip!

Sorry to thread jack. You can have it back now OP.
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Old 09-22-2011, 09:19 PM
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Well, if someone can come up with an explanation for this, you get a big gold star in my book.



As of right now, just having worked on the bike an hour ago, I reset the cams with the stock IN cams and once again, per manual.

However, now when I start it up there is a slight ticking.

A little further diagnosis shows that I've got excessive valve lash on my front intake valve. SO! It doesn't appear that I've done any permanent damage, but I won't know till I get my new shim, but if someone can explain to me how that could have happened, like I said, you'll be a golden star =)

Compression test tomorrow, no leak down tests yet, but I'd say perhaps on the weekend, but we shall see!!
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Old 09-22-2011, 09:55 PM
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Originally Posted by bass4dude View Post
Well, if someone can come up with an explanation for this, you get a big gold star in my book.



As of right now, just having worked on the bike an hour ago, I reset the cams with the stock IN cams and once again, per manual.

However, now when I start it up there is a slight ticking.

A little further diagnosis shows that I've got excessive valve lash on my front intake valve. SO! It doesn't appear that I've done any permanent damage, but I won't know till I get my new shim, but if someone can explain to me how that could have happened, like I said, you'll be a golden star =)

Compression test tomorrow, no leak down tests yet, but I'd say perhaps on the weekend, but we shall see!!
Excessive lash as in .001? or much more? One or both valves?
If both, and if more than a few .001, you likely had interference of with valve to piston contact. When that happens the valve no longer seats, and you get excessive clearance.
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Old 09-23-2011, 03:34 PM
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F/ 155psi (problem cylinder), R/ 158psi.

Plugs are a nice tan.

Leakdown 3% on both cylinders (fairly good considering the almost 40k it has on it).

I didn't get the valve cover off today, but I think I narrowly avoided certain doom.
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