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The Honda CA95 / Benly 150 Restoration The little brother to the CA160 in our family of Hondas

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  #1  
Unread 10-26-2013, 04:52 PM
tjejenskille tjejenskille is offline
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Default RH cylinder tachometer cover leak

So just getting peoples' opinions on this. My '63 Honda CA95 has the tachometer-type RH cylinder cover. Nothing in there, just the cover and the screws holding it in.

For some unknown reason, when I reassembled the engine, it had a constant leak from the bottom-most corner that would run along the cooling fin to right above the exhaust header. Put new gaskets in, tried putting thin layers of liquid gasket on the fiber gasket, 1 side then liquid gasket on both sides, and still leaked.

Then I took a razor and scraped any and all gunk off the mating surfaces, leaked still, then dremel-sanded both surfaces in frustration. Anyways, now I have it fairly well stopped with red RTV silicone caked in the edges. Not pretty, and I'm thinking if I ever sold this bike, what the world would I say to the next owner about it?

Not sure if anyone else has had this issue? Could the tachometer cylinder side cover just be so worn down it wouldn't seal no matter what? Occasionally I still get a small oily residue on the cooling fin above the exhaust header from a leak at the tachometer but it's rare. Is it ok to purchase just a regular RH side cylinder cover without the tachometer piece there and see if that stops the leak?

This is one of the few riddles left to me about this bike, other than that, running fairly well.
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  #2  
Unread 10-27-2013, 05:37 AM
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Larzfromarz Larzfromarz is offline
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If the tach drive isn't there ditch the cover and install a non tach drive cover.
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  #3  
Unread 10-28-2013, 01:45 PM
grubsie grubsie is offline
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The problem is most likely the gasket. If you take the tach cover off and look closely, you will see a hole just below the hole that the camshaft goes in. This is the drain hole to allow the oil gathered in the tach cover to go back into the head. There should also be the same size hole in the cylinder head just below the camshaft that lines up with the hole in the tach cover. Most of the gasket kits out there do not have this hole opened in the gasket. If there is no hole in the cylinder head just below the camshaft, you need to drill a hole in the cylinder head. You can do it in place by using a lot of grease and going slowly to catch the drill filings. Change the grease several times while drilling. In your current situation, oil is being pumped into the tach cover with no place to relieve the pressure.
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  #4  
Unread 10-28-2013, 06:31 PM
Sam Green Sam Green is offline
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Sorry to contradict my learned friend Larry but the cover from the later model can't be used as the tach drive gearbox has the bearing for the camshaft built on to it. The camshaft runs in the gearbox, not in the head as it does in the later models.
Like Grubsie says, check that the oil return holes are both clear.
The only other reason for leaks (other than bad surfaces) is if a tach gearbox has been modified to work with a later head. This can be done but the later head still needs to have a hole drilled to allow the oil to return to the head.
If there is no oil return hole, pressure will build up in the gearbox and chances are, it will seep by the gasket.
Pictures of the inside of the tack gearbox and the mating surface of the head would help to determine if you have a modified tach cover on a late head, it can't be determined from the outside.

Sam.
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  #5  
Unread 10-29-2013, 04:53 AM
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Larzfromarz Larzfromarz is offline
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Please do Sam as I don't have this model to learn from or reference. I'll always bow to your knowledge regarding the Benly powerplant. Grubsie's solution sounds correct as well and is a good description of the what sounds like the real trouble.
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  #6  
Unread 10-29-2013, 06:04 AM
Sam Green Sam Green is offline
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Yes Larry, if he posts some pictures of what he has it will make it easier to figure if he has bad surfaces of mismatched parts.

Sam.
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  #7  
Unread 10-30-2013, 05:12 PM
tjejenskille tjejenskille is offline
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I'd like to insert images, I just can never figure out how to attach it to a URL off my desktop. I suppose that's something I can google.

I remember cleaning out that hole on the engine itself, but never thought about it on the gasket itself. I'm kind of excited to try it this weekend.
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  #8  
Unread 10-30-2013, 07:50 PM
Sam Green Sam Green is offline
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Don't worry to much about the gasket, the oil return hole is inside it not on it.
If you still can't post pics, just tell us about it.
When you look at the inner part of the tach gearbox, does it have what looks like a bushing that fits into the large hole in the head?
If so, does the large hole have a slot cut through it at the bottom of the hole?
If yes to both these questions, can you see a hole under the bush?
The hole should/will line up with the slot.

Sam.
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  #9  
Unread 10-31-2013, 12:49 PM
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Larzfromarz Larzfromarz is offline
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Talking

Posting pictures here is not too difficult-
Below the "Quick Reply" box is tab or button called "Go Advanced", click that.
A new "Reply to thread" window will appear, scroll down below that window and find the "Manage Attachments" button, click that.
A new window called "Manage Attachments" will appear with the choice to "Upload File from your computer" or "Upload File from from URL". If the file is on your computer like I do my picture files, then choose "Upload File from your computer" and "Browse".

Click the "Browse" button and you can look to the location on your computer where you have stored the picture. You can upload up to five pictures of the appropriate file size as seen in the chart below. Likely it will be a jpeg which is a standard file format for pictures. Check the "properties" of your picture (right click on your picture and then the bottom of the pull down menu) to see if the file size is compatible.

If you are trying to upload from a url ( a picture from the Interweb) just copy from the browser address line and paste the url into the "Upload file from url" empty box.

Once all files are of the proper size (you can resize pictures in the Windows Paint program) simply click the "Upload" button. If the files are accepted you will see the file name appear in a new box called "Current uploads" found in the same window. You may then dismiss or close the Uploads window and if you use the "preview" button from the posting window you can see if you photos have been successfully uploaded.

Last edited by Larzfromarz; 10-31-2013 at 12:55 PM.
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  #10  
Unread 11-02-2013, 11:54 AM
tjejenskille tjejenskille is offline
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Thanks for the information.

Just thought you guys would like to know, at least so far, it looks like the tachy leak has been fixed!

I took off the cover, cleaned both mating surfaces, then cut just a little notch where the holes meet, and it seems to have fixed it! Man! All this time it was due to crappy design by whoever the heck manufactures these gaskets. I wouldn't be surprised if it was somewhere in Asia...
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