Compression and Carbs


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dan1995
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Post by dan1995 »

well larry , you "helped" more than i ....at least you drank more beer :lol: :lol: :lol:
Dan 1995

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Coast to coast and border to border on a CBX
My goal was to ride farther and faster than my wife could bitch....
I needed a faster bike....
So I got a BUSA!!!!!

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alimey4u2
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Post by alimey4u2 »

That's a moot point Dan...... :lol: :lol:

Joking aside, it was Prestons attention to detail that really impressed me. I can be "anal" at times at perfectionism, but Preston was right there with me....... :lol: :lol:

Nice Guy too....... 8)

HondaJohn
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Compression and Carbs continued with other stuff...

Post by HondaJohn »

Well, the drinking beer part is very, very important so you probably deserve more of the credit than you realize.

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Post by EMS »

Preston has many talents. Have you ever seen him giving a how-to-deal-with-your-husband's-motorcycle-addiction speeches to ladies?



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Larry Zimmer
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Compression, etc.

Post by Larry Zimmer »

Thought there might be some stuff here to make it worth another look-see.
Larry Zimmer
cbxlarry@sbcglobal.net

HondaJohn
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1981 Compression Follow Up

Post by HondaJohn »

Well, it has been awhile since I posted my question about compression on my 81 CBX. Since adjusting the valves, doing carbs etc.. etc.. and putting about 300 miles on it, the compession is now between 135-146psi. Adjusting the valves brought them way up. Had two that were too tight so this explained that low compression. I have a 79 with an 80 motor, 16k miles, and it has compression of 131-141psi. I am currently baffled by the ebayer that claims his silver 79 now on ebay, has 175 psi in all 6 cylinders. Has anyone ever had this kind of compression on a stock CBX? 175psi in each?? I am re-learning a lot about these bikes and have collected four of them 79, 80, 81 and 82. The 80 and 81 came from the original owners and are 100% original/stock.
79, 80, 81, 82 CBX's, 87 Hurr 1000F, 83CB1100F, 87 VFR700, 01 Blackbird
40 yrs of Hondas and still baffled....

EMS
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Post by EMS »

The method on how you check compression and what instrument you use may have a lot to do with the number you end up with. The run-of-the-mill meters may vary quite a bit. The manual spec says 171PSI +/- 14 PSI
But even that is a conversion from the old metric spec of 12 +/- 1 kg/sqcm and does not quite jive , if you use the correct factors. I have two PSI gauges that are off by at least 10% from each other. If you squirt some oil in the cyclinders and check your compression, you may get a higher reading.

HondaJohn
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175 psi compression

Post by HondaJohn »

You are correct about different methods of checking compression. I check it with all plugs removed, throttle fully open, engine slightly warm (for obvious reasons), air fiter in, air box lid installed, cranking until gauge needle stops/peaks. Regardless of how the compression is checked, I have never heard of or witnessed a compression of 175 psi and this is the original question. I don't care what method you use, I dont "think" you will ever get 175 psi - in all cylinders??? Not happening!! Unless you have a gauge that is stuck on 175psi....
79, 80, 81, 82 CBX's, 87 Hurr 1000F, 83CB1100F, 87 VFR700, 01 Blackbird
40 yrs of Hondas and still baffled....

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alimey4u2
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Post by alimey4u2 »

"Just" did a compression test with a warm engine that needs to be blown out a bit...156-165psi were my readings...
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