{"id":28551,"date":"2024-12-28T00:01:03","date_gmt":"2024-12-28T08:01:03","guid":{"rendered":"https:\/\/exhaustnotes.us\/blog\/?p=28551"},"modified":"2024-11-30T08:43:32","modified_gmt":"2024-11-30T16:43:32","slug":"exnotes-product-review-yonligonju-compression-tester","status":"publish","type":"post","link":"https:\/\/exhaustnotes.us\/blog\/index.php\/2024\/12\/28\/exnotes-product-review-yonligonju-compression-tester\/","title":{"rendered":"ExNotes Product Review: Yonligonju Compression Tester"},"content":{"rendered":"
By Joe Gresh<\/h6>\n

If you’ve been keeping up with us here at ExhaustNotes you’ll know I had a lot of trouble getting Zed, my 1975 Kawasaki Z1 900, running correctly.<\/p>\n

In between rebuilding the carbs and tinkering with most everything I could think of it dawned on me that maybe the engine was just tired. After all, it wouldn’t be unusual for a 50-year-old, air-cooled engine to wear out after 46,000 miles.<\/p>\n

I used to have a nice compression tester that was at least 40 years old. In the big move west I can’t seem to find it. Maybe it got tossed after one of the many floods that inundated our house in the Florida Keys. I forget the brand but it had a flex hose and several adaptors for different size spark plugs.<\/p>\n

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I don’t need a pro-level compression tester as I’m not in the mechanical business anymore. This cheap, cheerful Yonligonju<\/a> (say it three times fast!) Chinese kit on Amazon looked like the goods for less than 20 dollars.<\/p>\n

The Yonligonju<\/a> comes with a nice, blow molded plastic case that keeps all the little bits in order.<\/p>\n

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It amazes me how China can build such a nice kit for so little money. Including the quick release flex hose, this kit comes with adaptors to fit 5 different spark plug sizes.<\/p>\n

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In addition, the set came with two of the rubber bung type connectors. To use these, you just hold the compression tester tightly in the spark plug hole. It speeds things up on a multi cylinder engine. This works well enough if you’ve got enough hands for the job.<\/p>\n

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My Yonligonju<\/a> worked well, showing 80-ish psi on all four Kawasaki cylinders. This isn’t great compression but the cylinder pressures were nearly even and Zed might have done better if the engine wasn’t cold. My Kawasaki manual claims 85 psi as the lower limit and Zed may get there warm. What do you want after 46,000 miles?<\/p>\n

Besides compression, what you’re looking for with a compression tester is one cylinder being much lower than the others. This indicates a problem in the cylinder. The actual psi number is less important. Unless they are all really low…<\/p>\n

Anyway, the Yonligonju<\/a> gauge proved compression wasn’t the reason my Kawasaki was fouling plugs. See the latest Zed update for the full story.<\/p>\n

The compression gauge held the reading without bleeding off for the few minutes it took me to look at it. There’s a pressure release valve on the side of the gauge that also worked as it should.<\/p>\n

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This isn’t a kit that will see a lot of usage.\u00a0 If you’re like me, a home-shop tinkerer, the thing will do the job for not much money. Hell, just taking your bike to a motorcycle shop once to test the compression would cost five times what the tool cost.<\/p>\n

I think people rebuild old motorcycle engines more than is needed. Two-strokes especially get the piston, ring and bore because it’s so easy to do. Most likely the bike would have run fine the way it was.<\/p>\n

For classic bikes that don’t see everyday use it’s enough that the engine runs well. There’s no need for a ton of compression with today’s crappy fuel anyway. I’m guessing the Yonligonju<\/a> will last a while sitting in my toolbox waiting for another engine to test.<\/p>\n

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