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Honda: INNOVA125i(2010); CBR250R(2013)
1,075 Posts
Discussion Starter · #1 · (Edited)
[Compression test on other Models - LINK To My YouTobe Playlist]

1. The purpose of the test is to check the condition of one or more these upper engine areas:
(1). The valve area:
  • Damaged valve seat,
  • Build-Up of carbon deposits,
  • Valves coming out of adjustment.
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(2). Engine head wall area: Rectangle Product Font Parallel Slope

  • Build-Up of carbon deposits.
(3). The connection area between the engine head and the cylinder:
  • A damaged engine head gasket,
  • A problem with the sealing surfaces.
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(4). Piston/Rings/Cylinder area:
  • Worn piston,
  • Worn rings,
  • Worn cylinder wall.
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(5). Major general damage to upper engine:
  • A hole in the piston,
  • A crack in the cylinder,
  • A crack in the engine head,
  • A broken connecting rod,
  • Worn or broken valve or valve mechanism.
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2. How did I become the owner of a compression tester:
"Cylinder Compression" has a romantic sound, something that is associated in the imagination with professional mechanics, something that is of a great interest, kind of, in the tests before buying a second-hand motorcycle... Then I saw that tool costs ONLY 17USD, so I decided, out of great curiosity, to buy one.
This week the tool arrived and it looks really nice: A dial gauge, A tube, some adapters, and some other adapters馃槉
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Just please don't ask me what's so exciting about a dial and some tubes, it's not a rational thing.... if I thought it was a quality tool kit I would have ordered it with his dedicated box, but with the box it cost 25% more....

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Maybe it was not a good idea to purchase the God tool without a box? And maybe and after all it was a good idea, because as part of the worship of the "divine" tool, and for the fun, I built a dedicated cardboard temple for him...
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Honda: INNOVA125i(2010); CBR250R(2013)
1,075 Posts
Discussion Starter · #2 · (Edited)
3. A few more words about the tool and the adapters:
Regarding the pressure gauge
, it should be in the range of 300PSI, because:
  • The target value for measurement is 188PSI,
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  • and it is possible, in the case of Carbon Deposit on the piston and the sidewalls of the engine head and on the valves, then the pressure may also reach till 220PSI (The carbon deposit reduces the volume of the compression chamber, therefore it is caused over pressure).
Regarding the adapters, the ONLY necessary adapter is the one that fits the threads of our plug: M10x1.0. And a universal adapter is also possible (a metal tube with rubber at the end. when the conical rubber part can pressed into the plug hole).
Regarding the model of the kit, I was looking to buy only the M10 adapter, but I did not find such a kit. I found a kit that sold with two adapters M18, and M14.
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And I also saw that the price of the kit based on the two adapter is not really different from the price of a full set like the one I bought.

4. Cylinder Compression Tester - D.I.Y:
Those who want to make a compression tester for themselves need a:
  • Pressure gauge that measures a range of 300PSI,
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  • Hose that hold pressure (hydraulic hose), 350mm long,
  • Two Clamping rings for the hose,
  • M10x1.0 screw adapter for the threads plug + O-Ring I.D. 7mm x2.3,
    OR a universal adapter with conical rubber that can pressed into the hole of the plug.
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5. CBR250R Has Two Big Issue,
(I chose to have fun with a compression test, but since CBR250R 2013 as a single cylinder engine, this test has no special value for us).

The first thing, in engines with one cylinder there is no meaning to a comparative test between different cylinders compression in the same engine, as happens in multi-cylinder engines.
The second thing (which flowing from the first), when our single cylinder "fakes" at work it is easy to feel it even without a compression measurement, and it is easy to ask questions that will direct us to understanding the problem even without a compression test, for example:
  • Are there any noises characteristic to valves? You can always do a valve clearance check and rule out that problem, if You found that the clearance is in spec, or you can fix it by adjusting the valve clearance (adjusting by shims P.3-11 to P.3-13).
  • Is there smoke coming out of the exhaust? Smoke could indicate an oil leak from the valve seals, or from the piston rings. The valve seals are easy relatively to change without opening the engine, then you can see if the problem is solved. If so, great. If not, then the problem is in the piston, piston-rings, or cylinder, and maybe all three together. Either way this requires opening the top engine, and if the top engine is opened anyway it is already acceptable to renew all the three.
  • Is there a decrease in engine power, such that it is not accompanied by noises or visible signs? Then we can: Check fuel consumption first? The ignition system? The fuel system? The air intake system? and Valve adjustment?
  • A cylinder that loses compression strongly always be followed by smoke from the exhaust, and as the problem worsens, the smoke gets thicker. Clear signs will also appear on the plug, such as: a plug that wet from oil. Below a compression value of 100PSI it is most likely that the engine will no longer get started at all.

And after all this, the Honda's service book leaves us the option to do a compression test (P. 8-6), not that a professional mechanic might be required for this, because in single cylinder engines if there is a problem it pops up above the surface, and you see and feel it even without the need to confirm the diagnosis by a compression test, BUT...
  • The test itself is relatively simple job,
  • It is an inexpensive test that does not require expensive equipment,
  • The test is there for the case that it is required (It's a common test at check-list before buying a second-hand bike),
  • Or for the curious like me. Just for fun (My engine does not raise any suspicion on losing compression).:coffee:馃馃槆

Honda: INNOVA125i(2010); CBR250R(2013)
1,075 Posts
Discussion Starter · #3 · (Edited)
6. Preliminary requirements for performing the Cylinder Compression Test.
There are all the usually things such as: Previous knowledge in motorcycle mechanics, previous experience, appropriate tools, maintaining safety at work, etc...because this post is not intended to encourage the do this type of mechanics job, and therefore it does not pretend to cover all the important topics to complete successfully that kind of mechanics job.
WORNING: Performing mechanical work on the motorcycle without a qualified and licensed mechanic is very dangerous and may cause major damage to the motorcycle, and cause severe bodily harm including death.

For the purpose of the Cylinder Compression Test and during the test, we are required to rotate the engine at a speed of 490 rpm. The goal should be achieved by turning on the starter motor. If the starter is not able to give the required performance to drive the engine at 490 rpm, this will damage the reliability of the compression test and cause it to wrong results. To ensure that during the test the starter manages to turn the engine at the required rpm spec, for this purpose we will precede to compression test four questions:
  1. Does the starter rotate normally?
  2. Is the battery OK? We will check the voltage in a static mode, it should be above 12.7 volts. And we check voltage in dynamic mode when the starter is turned on, It should be over 10 volts.
  3. Is the charging system OK? When the engine is running, check the voltage on the battery terminals and it should be around 13.9 volts at idle.
  4. Does the RPM gauge on the tachometer show the requested value? Approximately 490 RPM...MMM... It turns out that the tachometer only works after the engine is started. It does not measure the rotation speed of the crankshaft without completing the starting process.

7. Test Procedure
(1). Preparations First
  • Remove the MIDDLE COWL (HONAD'S Manual Service P. 2-7)
    [ Three Bolt + Three Snap Fit Clips + two wires]x2, Right side AND Left side.
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  • Unhook The Rubber (heat shield) (HONAD'S Manual Service P. 3-8)
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  • Release The Radiator from his BOLT
    (HONAD'S Manual Service P. 3-8)
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More will coming soon...

Honda: INNOVA125i(2010); CBR250R(2013)
1,075 Posts
Discussion Starter · #5 · (Edited)
Helps to keep charger on battery during this procedure.
Looking forward to your test! (y)
Anyone taking bets on results?
My charger gives, 0.5 and up to 3 amps (A charger stronger than that destroys my battery), the starter consumes dozens of amps (100Ah CCA?), therefore connecting my charger while starting It has a negligible contribution (and maybe damage the charger?).
The battery should be allowed to recover for 10 minutes between the tests, and in those ten minutes I can help it to recover with the charger, and maybe I will do so. Thanks.

Danno what's your bet?

Honda: INNOVA125i(2010); CBR250R(2013)
1,075 Posts
Discussion Starter · #6 · (Edited)
Even better to borrow large auto-battery to provide consistent power.
Connecting an unsuitable battery to a motorcycle should perhaps only be done in emergency situations, let's say like roadside repairs. A car battery provides a current that almost 10 times more than a motorcycle battery, so in certain situations it can cause damage to the motorcycle. I don't have a car battery for this use, but even if I did I wouldn't do it. It is possible, but also not recommended.

P.S. My battery is new and strong, if it is not enough to give the appropriate 490rpm for the test...mmm...then the measurement will be lower. I don't currently have a way to measure the RPM. Maybe it's possible to calculate RPM by counting beats and measuring their time from the video I will shot? I will try to check it.

570 Posts
It is forbidden to connect a charger during cranking. This will DAMAGE the charger.
It is forbidden to connect an auto-battery with a higher current to the motorcycle battery, this will DAMAGE the motorcycle battery.
You need to take electronics class. So many things completely wrong here that I can write 2-yrs worth of university classes...

Why? Because so many things you say have no experience behind it. That's topic for different discussion.

My bet is you will get less than desired 188psi with your test. Because you've got no experience with this. Then I will explain why.

Honda: INNOVA125i(2010); CBR250R(2013)
1,075 Posts
Discussion Starter · #8 · (Edited)
My bet is you will get less than desired 188psi with your test. Because you've got no experience with this. Then I will explain why.
Yes, if you have explanations I would love to hear them, you can explain now, and you can explain later. Everything is fine, All is good.
Right now my expectations are: Because my engine works, and it works great, I assume that I will get a figure that is not far from 188psi.

Honda: INNOVA125i(2010); CBR250R(2013)
1,075 Posts
Discussion Starter · #9 · (Edited)
so many things you say have no experience behind it.
Danno, every year mechanics face before a new models which they no experience with, but the mechanics has accumulated experience and knowledge that help them to successfully deal with the innovations. For me, the work of testing the compression It's new but it is not a mechanical challenge, it is purely an emotional experience. This is not an inspection that is currently necessary for my good engine, for me It's a matter of curiosity and fun to play with, etc. it is what it is.

Honda: INNOVA125i(2010); CBR250R(2013)
1,075 Posts
Discussion Starter · #10 · (Edited)

7.Test Procedure
(1). Preparations First

  • Release The Radiator from the two FRAME-BOSS

    (HONAD'S Manual Service P. 3-8)
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In the Honda technical book (P. 8-6), and at most technical manuals you will find instructions to perform the compression test when the engine is warm. The purpose of that requirement is to let the engine run until it reaches his working temperature.
Advantage: When the engine is working the metals expand from the heat, so the metals are taking their true place, and therefore it is considered more accurate test. The expansion of the metals at a normal system creates a better seal between the cylinder, the rings, and the piston (Heating the engine has no effect on the quality of the seal on the other sealing areas: The engine head gasket, AND The valve seats).
  • Warming up the engine significantly takes more time, especially when it is performed in cold weather.
  • Execution the test on a hot engine, and a boiling exhaust, requires much more attention and CAUTION: When screwing the plug in and out, you have to be careful not to destroy the threads on the head engine that are made of aluminum. And great care is required NOT to get severe burns from the heat.
  • When the engine is in good general condition, and if the cold test results are good, the Hot Test is an unnecessary test.
In section 5 I explained that in principle this whole test is quite unnecessary for us, the owners of motorcycles with a single cylinder engine. If you have already decided to perform the test but for no real reason (like I'm going to do), because the engine is in very good condition, in that case it will be enough to do the cold test (But I intend to do the hot test as well for research and for fun).
The advantages of the cold test are:
  • It is faster to perform,
  • There is NO danger like performing a test on a hot engine and a boiling exhaust.
  • The main advantage: The cold test is including the the hot test, because an engine that seal compression when it is cold, sealed when it's hot.
    The opposite will NOT true, an engine that may not seal in a cold state, may well seal in a hot state. A sealed HOT engine is a normal good engine.
COLD TEST Disadvantages:
It is no coincidence that the manufacturers guides us to perform a hot compression test even today, when there is a significant improvement in the quality of the metals, compared to what was accepted decades ago, because there is no point in announcing a compression problem earlier than necessary if in a hot state the problem has not yet appeared. Every engine reaches the end of his life, and there is no point to going into an expensive repair on an engine that is running properly at working temperature.

(3). The TEST
Important note:
BEFORE removing the PLUG, the Pipe in which the plug is located must be cleaned with air pressure to prevent dirt from entering the engine head after the plug is removed.
  • Disconnect the spurk plug CAP
    + Remove the PLUG
    (HONAD'S Manual Service P. 3-8, 3-9)
Important warning: You must reconnect the plug to the CAP, and short its body to the ground in a good, strong, and stable electrical contact, away from the engine plug hole:
  • to prevent DAMAGE to the ignition system,​
  • :eek:馃挜馃敟and to prevent the possibility of a FIRE馃敟馃挜:eek:.
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  • Disconnect the fuel pump connector.
  • Connect the compression adapter to the hole of the plug.
  • Turn the main switch to the on position, and the kill switch to the on position.
  • Turn the throttle handle to full throttle.
  • Press the starter button, and hold it until the compression gauge stops, OR no longer than seven seconds.
  • Record the compression value in the gauge.
  • Press the pressure release valve button to reset the gauge.
  • Between measurements let the battery to recover for about five to ten minutes.
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Honda: INNOVA125i(2010); CBR250R(2013)
1,075 Posts
Discussion Starter · #11 · (Edited)
8. The generic instruction booklet that comes with the Chinese tool, I read it, in my opinion it is written very well. I am attaching it below for your reference (two photos):
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9. More Ref: Haynes Service & Repair Manual Book No' 5919,
P. 2A*5 Section 3 (P. 2B*7, Section3)
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Honda: INNOVA125i(2010); CBR250R(2013)
1,075 Posts
Discussion Starter · #12 ·
My bet is you will get less than desired 188psi with your test. Because you've got no experience with this. Then I will explain why.
My engine from 2013 odometer at 68,500Km.
So...COLD test 85psi
Testing with a hot engine maybe next week.
How should I remove a hot plug from a hot engine? Hmmm...
Only 85psi doesn't make sense?
85psi is a dead engine. I have a life engine.

Honda: INNOVA125i(2010); CBR250R(2013)
1,075 Posts
Discussion Starter · #13 ·
Report from today:
  • The motorcycle has been standing for a month and a half, and the first start was very difficult. It required a large number of attempts, and at the end one longer attempt. Once the engine came back to life it ran fine. Between the failed starting I took a breaks of 5-10 minutes to let the battery recover, and it was also necessary to charge it.
  • After about 7 minutes all 3 lines are already on, after 15 minutes the fan still hasn't started working, but I didn't want to go up in rpm, so I stopped the engine at this point.
  • Yes, it is possible to screw a plug out despite the heat, you have to be really careful. In the first stage I used leather gloves that insulate heat, but it's hard to feel what you're doing that way, so later I gave them up.
  • Then the compression gauge clock decided it was on strike. It took me at least an hour to manipulate this problem. I disassembled his valve, lubricated it with engine oil (the fuel vapors from yesterday's test caused it to get stuck, Chinese time:ROFLMAO::coffee:)... and then the engine had already cooled down. Nevertheless I took a measurement with a warm engine(not hot) and it came out 90psi.
  • When I screwed the tube out it turned out that the adapter remained screwed inside the engine head...I closed the tube to the adapter with blue Loctite. I left the Loctite to dry, tomorrow there another a day.
  • So I still need a compression test with a hot engine, and if the compression will still low, then also a compression test with oil... and only then there will be conclusions.
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Honda: INNOVA125i(2010); CBR250R(2013)
1,075 Posts
Discussion Starter · #14 · (Edited)
The second day went much easier.
With a warm engine I measured 97psi.
with oil.
Just before writing the conclusions, here are some background information:
  • My odometer at 70,100Km (Model 2013).
  • My engine runs smoothly and beautifully (The test was performed only out of general curiosity).
  • My plug looks good:
    Gas Plant Electric blue Metal Macro photography

  • My best fuel consumption in long-distance riding that was recently measured is 39kpl.
  • There are no signs of smoke from the exhaust.
  • The oil level remains constant.
  • The engine does not heat up.
  • The engine run up nicely to the maximum rpm in each of the first to four gears, I did not check about the fifth and sixth gears (I ride at a maximum speed of 115 km/h).

  1. The Rings, the Piston, and the Cylinder are good (Because the test with oil came out the same as the test without oil)
  2. The compression leak is from the valves.
    In my opinion, the reason is divided between two factors:
    ---Natural wear.
    ---**But MOSTLY The valve adjustment which I performed is close to the minimum gap range (The length of time the valves are opening are longer).

    **At the moment I don't intend to test the thesis regarding the valves adjustment because the engine runs smoothly and beautifully, and because valves adjusting is a complicated operation (relatively).
Summary of the emotional experience:
It was interesting, and the results surprised me: Under 100psi.
According to the literature I read les then 100psi it's a finished engine. And my engine is very much alive.
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Honda: INNOVA125i(2010); CBR250R(2013)
1,075 Posts
Discussion Starter · #15 · (Edited)
I asked John from Partzilla (Start at 12:55):
1. The compression test is mainly intended for comparative between different cylinders in the same engine, and less for measuring a single cylinder engine.
2. It happens that the cheap devices sold in the market are not accurate, not that this explains the low measurement I measured, but it does not make sense that an engine works normally with half of the compression. I try to check if my measuring device is accurate.
3. It is also worth going back and checking the valve adjustment.
4. If the compression is really low, then there must be a more serious problem in the engine that needs a closer inspection.

I will see if there is a cheap way to check the AliExpress compression gauge calibration. Regarding checking valve adjustment? Right now the engine is working fine so why to touch it? But I intend to find time for it and check that too, to remove doubt. But first I need to see if the problem is with the compression gauge.
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Honda: INNOVA125i(2010); CBR250R(2013)
1,075 Posts
Discussion Starter · #16 · (Edited)
Great John Talley did it again!
"How accurate yours gauge is?" [J.T.]
My answer: I checked, there is a deviation of ~1.75 bar (25.4 PSI):whistle::coffee:馃(Maybe more, because there is a problem with the needle, it gets stuck at About 5.5bar...)
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1.75 from 5.5 is 32 x 100 = +32%
Therefore, a measurement of 95 PSI (Hot) with the correction factor of +32% and I get a value close to 125 PSI, still a low value but not a deadly low one, and this is before valve adjustment correction.

I wanted to have a fun, I had fun, I shared it...that's what a compression test is all about.
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Honda: INNOVA125i(2010); CBR250R(2013)
1,075 Posts
Discussion Starter · #17 · (Edited)
Another update:
Well, the manufacturer's instructions are to start the engine with the starter. And the manufacturer also gives a reference of 490 rpm. I did the test with a battery that is strong, and actually quite new. So there was no particular reason to suspect that it would give a rpm value far from Honda's specifications.

The motorcycle's tachometer will NOT read rpm while starting.

BUT...Regarding the video attached above,
the data are these:
Between time 0:06 and time 0:10, with an accuracy of about 4 hundredths of a second (because my camera shoots 30 frames per second) I measured 4.03sec. At that time I measured 14 rotation cycles of the crankshaft. In the video there are 15 cycles that recorded. The first cycle, at the moment of the first start, is slower than the other cycles, so I did not include it in the calculation.
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The calculation:
I will divide 60 seconds by 4.03 seconds and get 14.89.
Multiply 14 cycles by 14.89 and get 208 cycles per minute.
In 208rpm, I got 85psi (Cold engine)

My conclusions:

Since there is a relationship, even if not linear, between the compression pressure and the rpm (As the RPM increases, so does the compression pressure), therefore a result of 85psi at 208rpm, which is less than half rpm than the recommended 490rpm, And if we add to this information the information about the 30% deviation at the gauge... well this case it would not be excessive to guess that my engine meets the specifications of 188psi.

So now you also know
what this DEMON looks like in reality!

CBR250R 2013 Compression Test
Behind the scenes

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