CBR 1000F "Hurricane" 1987-1996 CBR 1000F

Henry's new 1000F CCT

  #1  
Old 06-10-2012, 06:44 PM
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Post Henry's new 1000F CCT

Guys/Gals,
I know this subject always touches a nerve.
Here's a new take on the subject. A new idea based on a new theory of why the original design didn't quite work.

Like any 1000F owner I've been more than a little pissed off with the embarrassing rattle that the otherwise stupendous engine's cam chains emit when cold. The result is a line of thinking and some considerable research which has culminated in a modification to the original Honda design which I think you're going to like. It's also possible for most owners with a reasonable level of mechanical skill to replicate. I have no intention of keeping what seems like a good idea to myself. This, after all, is what this forum is for. Sharing!!!

A few fore runners who have tried a manual or semi manual approach to modifying the 1Kf CCT have tried to go for a manual tensioning approach. Admirable in effort but I have always felt that the original design was kind to the cam chain, unlike most manual tensioning methods. Temperature change for a start demands some degree of tolerance. Manual tensioning methods are inherently intolerant. After all, a chain is a chain and even cam chains have tight spots.

So here's what I've come up with. A new approach apparently.....

Here's a picture of the final design prior to first installation. I had to make a few changes to the screw holding the spring after installation but that I figured that would be the case. There's only one way to tell if it's right. Fit it.

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The following pictures are the components and the assembly. I hope you can work out what's going on....

This is the lever which attaches to the top chain guide arm. It consists of a 6mm bright steel bar which has been threaded to connect to the fork clevis end and has two areas ground out to match the diameter of the pins that hold the chain guide to the tensioner body. The bending and shaping of the bar took some time but were quite logical and hold it firmly in place.

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Here you can better see the hollows ground into the shaft which match the guide pin holes.



This is the small arm where my new tensioning device does it's work. I can't believe Honda never thought of this. There's a lot of play between the two arms and much potential for even the best fitting assemblies to get worse (loud) even after a few thousandths of a mm of wear. I think the noise is not coming from the chain but from the chain guide vibrating the top parallel arm. Solution..... give it some tension too.

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So this is what it ended up looking like prior to first install

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This is the bracket/top plate I formed to hold the spring

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Inside the body of the CCT you can see how the Clevis joints fit neatly in there. I had to file it down to fit with a degree of clearance.

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And here's the final installation. It took a while to get everything settled down and tightened up but the effect was worth it when I fired her up. No rattling. Just the sound of engine. Pure CBR from cold!

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Tomorrow I ride.
I'll keep you posted as to how this little mod pans out but given that I'm averaging 10000 miles every 5 months I think I'll be able to report whether this little contraption works over a fairly short space of time.

Comments on a postcard please!

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  #2  
Old 06-10-2012, 07:14 PM
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Nice work Henry, seems an elegant fix for the problem.

Cheers, SB
 
  #3  
Old 06-10-2012, 07:17 PM
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fookin slick - Henry me old son - always knew you were good with shaft work

ME ..... planning on taking it one step more on your design

bring it (bolt) on up through the cam bridge bracket - spring up to that point -
butterfly the cam bracket or fender washer to retain a longer reach spring - and
locking nut setup on the valve cover - one inside one outside with rubber grommet to
seal the deal - making for remote adjustments as time wears on and as cam chain
stretches.

Nice job man - real nice
 
  #4  
Old 06-10-2012, 08:57 PM
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Henry, you are a genius! Keep us up to date.

DRam
 
  #5  
Old 06-11-2012, 12:56 AM
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Outstanding Henry !!!!!
I will be studying your design before fitting it, but it looks genius !!
My chain seems to "buzz" intermittently when cold, and this I think is the answer.

Sprock - sounds like a good mod too.
Always better to be able to adjust without removing the tappet cover, although not sure how necessary it will be....time will tell.
 
  #6  
Old 06-11-2012, 02:59 AM
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OK, so when does it go into production?
 
  #7  
Old 06-11-2012, 07:01 AM
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That depends on demand TK. I'm quite sure the design could be developed enough to merit a small production run. I don't think you'd ever need to buy another one if you upgraded.
 
  #8  
Old 06-11-2012, 07:26 AM
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As a quick update....
my first ride out this morning was an absolute joy.
Given that the very same CCT was rumbling and grumbling before the mod, the first 15 seconds of riding from cold immediately put a massive grin across my face. All I could hear was the sound of the exhaust and for the first time since owning the beast I felt that it was running as it should.
I took the first section of motorway quite easy just to see if there were any untoward noises but she just felt turbine smooth. in fact there is a slight improvement in reducing engine vibration at higher speeds. I need a bit more riding time to properly assess this.

Sprock,
I don't think you're ever going to need to adjust the modified tensioner through the rocker cover. This solution is designed to set and forget. Give your brain a rest.

I'll explain more about the thinking and theory behind the modification when I've got time and of course keep you all updated with its performance. So far, so very very good.
Yipeeeeeeeeeeeee!!!!!!!!!!!!!!!!!!
 
  #9  
Old 06-11-2012, 06:10 PM
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Hey Henry,

Would you do a small production run or perform a retrofit on a customer CCT?
 
  #10  
Old 06-11-2012, 06:17 PM
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I'd be in on that !!

Though would be happy to have the fabrication posted and fit it myself.

Cheers, SB
 

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