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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 10-05-2007, 11:06 PM
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I sat down in the morning ready to install the new valves in the nice clean cylinder head. But when I looked closer I realized I still needed to clean out the carbon inside the valve ports that. Ahhhhhh, better fill up on coffee and warm up the cordless Dremel tool for some more dirty work. <_< I scraped out the gummy carbon gunk out and used a couple different attachments in order to do a quick grind to remove the majority. Nasty stuff and there was a lot of it. Now that I could see the casting it was pretty easy to tell that it was pretty rough around the edges inside there. I threw in an aggressive HSS steel grinding bit into the Dremel and turned the power to full tilt. Wow what a difference. I'll have much more air finding it's way into the combustion chamber now and it should flow a little easier with the rough bits removed. Take a look!



I used a very sharp pic to remove carbon from the tiny crevices and the threads in the spark plug threads. The result is the above portion of the picture. The below is after about 20 minutes with some precision grinding bits in the Dremel tool. I have at this point done a little lapping of the valves. Basically to lap in the valves you make sure you have cleaned up the Honda valve seats and apply a little compound in between the valve surfaces. Grab a valve suction stick and do the valve lapping dance. After a few minutes you'll have some nice surfaced valves that are ready to hold some serious compression.



While assembling any parts with a friction surface I always use synthetic grease. Nothing works better to make sure that there is no damage to anything while the engine is working to lubricate itself during that crucial first startup. Make sure a light film on the stems before you insert them into the Benly 150 valve guides. And here we are with all the new valves lapped in and the fun part is now over. Get pumped up for a very stressful session of installing the valve "keepers" or valve "keys" into the valve spring retaining cups.

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Unread 10-06-2007, 10:19 PM
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Installing the valves into the Honda Benly 150 head is a bit tricky. They are so far down into the casting that it's a challenge to get tools down on the springs. Here is how this works:
  • Each valve must be firmly against its seat with a clamp
  • The valve spring retainer must be pushed down on the spring past the indent on the stems end
  • The "keepers" or "keys" as I will call them, must be pushed into place one at a time
The first valve took me 20 minutes to figure out the process with the right tools that I had on hand. This was no easy task as I neglected to go through the hassle of finding a valve spring compressor that would actually fit this little cylinder head. I used a clamp to hold the valve in place just as shown below.

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Unread 10-06-2007, 11:16 PM
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Now here is the tricky part. If you don't have a spring compressing tool that can get into the valve spring area then you need to grab a wrench or fork of some type. It needs to be strong enough to hold down the springs while you tap in the valve keys. A 7/16" wrench is a good size. The Craftsman brand has sharp edges which don't slip from the valve spring retainers as easily as other brands in my tools. I have a tool that inserts them quickly that I use on Lexus engines but the tools' diameter is just a bit too large to fit in the hole to press the spring as far as it needs to go. I was very sad that it wouldn't fit as it makes this process a snap. Oh well. Finding the proper tool designed to do this would take so long that improvising on my own methods is the best choice.



The ONLY way I could find to get a good enough grip on the cylinder head is to hold it in your lap while you work to push the spring retainer down with your wrench. Obviously this takes a good amount of force so put on a thick glove or wrap a rag around the wrench so it doesn't dig into your palm too much.

The exacto knife is what I use to push down on the valve stem keys. I tried using steel picks, sharp punches and screwdrivers and they were all attracted to the keys magnetically. While you are pushing down on the springs with one hand and trying to move the key down in place with the other hand it is VERY annoying when they stick to your tool and you can't get it in place. I was not happy. But then I found that my exacto knife with aluminum handle wouldn't cause the keys to be attracted. This was the only tool I could find that the key wouldn't stick to and it worked perfectly. The sharp pointed blade was strong enough to push the keys into place and the very sharp point was able to push the indent in the key just fine. To clarify I made sure to take a close shot of exactly what I was dealing with.



It took me 20 minutes to get the first one into place. With this method they will only go in one at a time. Each valve requires 2 to hold it in so it took 4 minutes for the #2 keeper/key to go in. Then after this practice I was able to get the other ones in place quickly one after the other.
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Unread 10-06-2007, 11:34 PM
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Afterthoughts and the last tips I have for people getting ready to change out their valves on their small Honda motorcycle engines:

The process I have described is similar for many other motorcycles engines. If you could find someone to help you out with this process you will have a much easier time of it. With the springs requiring so much pressure to push down to expose the keyway for the key, there was no way I could take a picture. But you get the idea. With the tools I have shown I can now do this process very fast. It just took a long time to find the right ones that would even fit in the restricted area. :blink:

I recently had finished doing the valves on a Lexus 1UZ-FE V8 engine. These engines have 4 valves per cylinder which makes for 32 valves total! Now if you want to talk about a lot of work! The first cylinder worth of valves was fun but when you realize that it has to be done 7 more times you want to shoot yourself.

Installing 4 valves with hand tools wasn't that bad at all and it had to be done! With how much carbon buildup that was inside the ports and all over the old valves, the newly cleaned head, slightly ported valve ways and new valves make for a much happier running engine. I can't wait to see how much power will come about after all these changes and the larger pistons. In all the Hondas I have rebuilt in the past new piston rings provide the greatest results. Fuel economy goes way up when you replace the piston rings.

Once I had finished and adjusted the rockers I was delighted to put the caps back over these areas and kiss them goodbye for a very long time. Mission complete, but I will be on the lookout for whatever special tool Honda recommends to pop these things in and out! :P

Good luck and good night.

OH and to continue reading about putting the cylinder and head back together click here --> Assembline Honda CA95 Engine
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  #5  
Unread 11-26-2009, 03:14 PM
Sofblend Sofblend is offline
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Default Installing Valves and Benly Valve Springs

Love your pics and info Smithers. The valves in my engine each have dual springs which should be replaced but the only ones for sale that I find show only the large outer spring. Does anyone know where I can purchase the correct (8) springs?
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