Cam Chain Tensioner - again
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Cam Chain Tensioner - again - 8/27/2005 10:56:22 AM
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DRam
Posts: 392
Joined: 7/21/2005
Status: offline
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Greetings. After reading all the posts about cam chain tensioners and cam chain rattles I have a question. Everyone says that their cam chain rattles on startup, then quiets down as the engine warms up. Mine does the opposite - it's fairly quiet on startup, but becomes noisier as the engine warms up. The local Honda mechanic listened to it and said it was cam chain noise. The noise is intermitent. Some rides there is no noise, others it is noisy for a while, then goes away. Other times it is there the entire ride. It occurs from 1500 - 2500 rpm, suggesting is related to a specific vibration frequency. On throttle or off makes no difference. I removed and cleaned the CCT, after which the noise disappeared for a few hundred miles, then reappeared. It isn't as loud as before, but is there. Exploration with a stethascope shows the noise loudest at the cam cover with the probe placed at the cam gear/chain area. My question: is it possible that the noise I'm hearing is not related to the CCT? True, it disappeared for a short time after cleaning the CCT, but perhaps in removing and replacing the cams and all related items something else was adjusted differently. One post indicated that with a Honda CCT kit you get the upper chain guide. Is this an item that wears rapidly? Mine looked good, as did the others, but maybe it's wear one cannot see.
Thanks for any advice you can give.
DRam
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RE: Cam Chain Tensioner - again - 8/27/2005 12:50:38 PM
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slowpoke
Posts: 518
Joined: 8/6/2005
From: Denver, Colorado
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I've never taken one apart, but does the CCT operate off oil pressure or spring pressure? The oil pressure is highest at start up when the oil is thick and at high RPM's. The spring could be replaced or shimmed. The Honda manual shows the CCT attached to a slider. The slider could wear, the chain could stretch, and the cam chain guide under the cylinder head could wear. How loose was the chain? Could you pull it away from the teeth on the cam sprocket?
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RE: Cam Chain Tensioner - again - 8/27/2005 3:25:36 PM
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DRam
Posts: 392
Joined: 7/21/2005
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Slowpoke: It apprently operates off of spring pressure, I could find no way oil pressure would feed to it. There is a cylinder / piston arrangement that apparently pulls oil in as the chain is tightened, then prevents the tensioner from backing out. The tensioner is rivited together, I could see no way of shimming the spring without drilling out the rivits. I could not pull the chain away from the sprockets & it did seem tighter after working the CCT over. I hadn't though about it, but perhaps the oil thins out enough that it can release the CCT piston when everything is hot. Thanks for the thoughts.
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RE: Cam Chain Tensioner - again - 8/27/2005 7:29:09 PM
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MarkR
Posts: 854
Joined: 8/20/2005
From: Gold Coast, Australia
Status: online
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Mine is noisy when cold or hot but seams to get a little quieter when under higher revs
I haven’t cleaned it yet as I don’t have a manual, will let you know how it goes.
I also suffer from breakdown over 7,000 rpm but I expect I have crappy plugs or tuning issues as the shop I brought it from gave it a BS services.
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RE: Cam Chain Tensioner - again - 8/27/2005 9:36:30 PM
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DRam
Posts: 392
Joined: 7/21/2005
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This is great - a site where people can talk to other who ride the same bikes. Very nice. Hope you find a simple cause to your high-rpm problems.
DRam
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RE: Cam Chain Tensioner - again - 8/28/2005 10:04:03 PM
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ozrider
Posts: 14
Joined: 8/1/2005
Status: offline
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Hi guys, I am a new owner of a second hand 89 model cbr (i think they did not release this bike in the US like in uk and australia etc.)
this is the biggest issue I face with my bike is this lousy cam chain rattle. I havent as yet taken it apart to fix it but my mechanic mentioned that there is a spring only cam chain tensioner (off a vfr i think) that can replace our oil dampened version. If anyone knows more about this it would be great. I will call my mechanic and find out what exactly it is. Hopefully he will be forthcoming.
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RE: Cam Chain Tensioner - again - 9/2/2005 3:05:05 AM
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MarkR
Posts: 854
Joined: 8/20/2005
From: Gold Coast, Australia
Status: online
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Took the bike for a ride today, I think the cam has got a little quieter now, but still nosy at low revs.
Hot/Cold doesn’t seam any different but I really feeling the power drop under 3,000 RPM.
The bike also runs rough under 3,000 RPM, I’m thinking plugs and carbie tune/balance.
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RE: Cam Chain Tensioner - again - 9/4/2005 9:15:23 PM
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DRam
Posts: 392
Joined: 7/21/2005
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Same here - quieter after fiddling with the CCT, but still rattling. I think it's going to get a new CCT and chain this winter. The CBR1000F isn't known for making a lot of power below 3000 rpm. It come on a little stronger over that, but doesn't really start making power until 6000 or so. At least, that's how mine runs. It should run smoothly below 3000 though. You're most likely on the right track looking at the carbs, plugs and wires. It's amazing what a difference synching the carbs can make.
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RE: Cam Chain Tensioner - again - 9/4/2005 9:39:07 PM
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slowpoke
Posts: 518
Joined: 8/6/2005
From: Denver, Colorado
Status: offline
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As the cam chain stretches and the CCT doesn't take up the slack, the valve timing retards. That means the engine runs better at higher revs, but worse at lower revs. I'm not sure if a new chain and/or a new CCT will cure it. Advancing the cam timing using slotted cam sprockets could bring back the power down low. Has anyone used slotted cam sprockets?
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RE: Cam Chain Tensioner - again - 9/5/2005 1:36:22 AM
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MarkR
Posts: 854
Joined: 8/20/2005
From: Gold Coast, Australia
Status: online
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I wonder if change the baffle and increasing the back pressure will smooth things out a bit, maybe?
I've been told that a new Cam Chain will cost about AU$140 and 2.5 hours labour
I was going to balance the Carbs myself, but I properly should get a mechanic to do everything
I was told about AU$250 for mercury gauges, I did find a couple of sites that showed you how to build your own, one with oil, another was a dry method, if anyone is interested.
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RE: Cam Chain Tensioner - again - 9/5/2005 9:04:55 PM
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Rx7man
Posts: 279
Joined: 8/21/2005
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hey, for synching carbs, I found a pretty good way of doing it.. take anordinary engine vacuum guage and a length of that red silicone vacuum tubing, and plug it onto the vacuum port... you can do this with the bike running
then you'll notice the guage flutters like mad (a liquid filled guage may work nicely) but you can just squeeze the tubing a tiny bit at a time until it steadies but still reacts... take an initial reading on #2, then do #1, adjust, go back to number 2, take a second reading... go to #3, and then #4. i did mine, they were nearly within spec of +-1"Hg... they're bang on now (my reading was around 7 in HG, but it doesn't matter what it is as long as they're all the same)
as for cam chain tensioner, i'm intersted in what your findings are with the rattling, mine is a little cluttery when it's cold, particularly under 3000
I really cant complain about the power under 3000, I mena it's not a vtwin, and it's not a big block, but it really has no issues with low arpm
and for the hig RPM bad running... definitely check the plugs and wires... you may also want to check your fuel supply (filter, pump, and shut off valves)
of course we're interested in sites that will save us money by making our own tools :)
_____________________________
Do not do as I do, I decline all liability and responsability for those who copy or attempt to copy what I have done
Mechanics... Start what they finish
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RE: Cam Chain Tensioner - again - 9/8/2005 12:22:43 AM
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DRam
Posts: 392
Joined: 7/21/2005
Status: offline
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"As the cam chain stretches and the CCT doesn't take up the slack, the valve timing retards. That means the engine runs better at higher revs, but worse at lower revs. I'm not sure if a new chain and/or a new CCT will cure it. Advancing the cam timing using slotted cam sprockets could bring back the power down low. Has anyone used slotted cam sprockets?"
Ah, good point. How many degrees of retardation do you think it would it take to make a noticable difference? When I worked my CCT over and put things back together the engine ran noticably different - much smoother idle, where before it had a lumpy, hot-cam type of idle. Unfortunately I didn't check to see if the cams were timed correctly, and wonder if they had been advanced a tooth or two.
Interestingly enough I just synched the carbs today. Got them spot on at idle, then ran the engine up to 5000 rpm. By then carbs one and four were pulling considerably more vacuum than two and three. Is that normal? What might cause it if it isn't? Plugs? Wires? Valves?
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