0 compression?!

Hey guys, rather confused so there are a couple questions here I think...

Background is a Kawasaki Z250, bought non starting and still non starting. I have rebuilt the carb (CV32, but have not removed/changed the float valve seat - not sure how, that's another question) and then realised I really should check the compression of the engine...the tester set arrived today and I tried to test for compression by removing the spark plug, opening the throttle and hitting the starter button.

Usually, I do get sparks from the spark plug, but for the compression test, I got a 0 reading. Nothing moved at all.

So first question relating to this thread is, are there any reasons why this might be? I checked the starter relay and it is good. I didn't have time to check the starter motor, but I'm under the impression that seeing as I am usually getting sparks from the spark plug, this is not the issue. Am I correct?

Secondly, this is the second time that I have been getting sparks from key hole, which heats up my key and produces a burnt smell. Dumb question, but is there a problem with my electronics? I have not noticed this before. With this key hole sparking issue, I have also noticed that my signals are not working anymore. My battery is reading at 12.52V when plugged into the bike, and I have been trying to give it a bit of a charger every month or so.

I guess thirdly, I am wondering what else should I be looking into to get the bike started? The reason I rebuilt the carb was that I wasn't getting any fuel through them when I tried starting the bike. Now that I have rebuilt and rejetted for pods (have not put in a new diaphragm or been able to remove the float valve seat as mentioned above), I am thinking that may be due to either of those reasons.

Any advice would be greatly appreciated.

Thanks.

Yes, there is a problem if your lock cylinder is sparking at you.

As for the compression question:

Spark, Fuel, and Compression are unrelated, but all required for a gas engine to run. When you press the starter button, does the engine turn? If it does not spin, you will not build compression. If it does spin, but you still are not building compression, then there is another problem. You are obviously new to engines(just an observation, not a slam) so start by making sure you are using the tool properly. Is it screwed into the plug bung properly and sealing well? Is the pressure release valve held open?

Next, have you checked your valves for proper gaps? If the valves are not closing, you will not build compression. If the valve lash is correct and the cams are timed properly, move to the next likely problem. If it was a leaky head gasket or VERY worn rings, I would still expect to see some compression, though it would be low. If the engine is spinning, the tool is sealing properly, and the cams and valves are all set right, but you are still seeing 0 compression, it may be time to pull the head. You may have bent valves, a hole in the piston, et cetera. I'm unfamiliar with this bike, but I am assuming it is a 4-stroke. If not, oops...

As for spark: if the engine is not spinning, you probably won't be seeing spark... But start with the compression part first.

i know there a lot of really helpful people on this forum.. maybe i can help you help yourself with someone elses help

check this guys page

http://dansmc.com/troubleshooting2.htm



Ok, it turns over, but does it have any compression ? Take out the spark plug(s) and ground the plug wire leads to the engine. This is to prevent burning out parts of the ignition system. Screw in a compression tester gauge. Open the throttles wide open and crank the engine. If you don't have the throttles wide open, you will get a low reading. You are going to need at least 100 PSI (pounds per square inch). Depending on the compression ratio, you could have 150 to 170 PSI or even higher. I have seen engines run on as little as 65 PSI (an outboard) and I have had them NOT run on as high as 90 PSI (a chain saw with a pinched ring.) A down and dirty way of testing is to put your thumb over the spark plug hole and turn the engine over. No matter how hard you push your thumb down, the compression pressure should blow your thumb off. If you can hold the pressure with your thumb, there's not enough compression to start the engine.

If you have a four stroke engine, it's always worth while to check the valve clearance to see if one of the valves is tight and leaking compression. See the Valve Clearance Page. To figure out whether it's the rings or the valves try this. Lock the crank with a wrench, with the piston at TDC (Top-Dead-Center) and run some compressed air in through the spark plug hole. Make sure you have a good hold on the crankshaft wrench or the engine will spin, throwing the wrench off ! Now listen. If you hear air coming out at the carb or air cleaner, the intake valve is leaking. If at the exhaust pipe, it's the exhaust valve. If at the engine breather, it's the rings.

While the spark plugs are out, and we are cranking the engine over a lot, do it just a bit more. Do it till the engine oil light (if it has one) goes out, or until you feel that enough oil has been pumped to all parts of the engine. If you use the kick starter, kick it maybe, 30 times or so. If you use the electric starter, crank the starter no more than 10 to 15 seconds. Then let it sit and cool off for a minute. Motorcycle electric starters are very fragile and very expensive. If you crank away for a minute or two, the starter could be burned out.

So we find we have compression, what next ? Check for spark. I like to use a new spark plug with the ground electrode bent straight out and a clip soldered in the side. Connect your tester to the big thick spark plug lead and crank the engine. You should see a nice big fat blue spark. If you don't, disconnect the engine kill button. If there still is no spark, you will need to determine if the engine has points or electronic ignition. Most (but not all !) bikes built before 1980 have points ignition. Most bikes built after 1980 (but not all !) have some sort of electronic ignition system. If in doubt, pull one of the crank end covers (Usually 2-3 screws) and look ! If you have a battery and coil points system see the points page If you have a points magneto system see the Magneto page. If you have an electronic ignition system see the electronic ignition page.

also

sorry to be a copypasta but this might help you and others

You can have the hottest cam, perfect ignition timing, clean carburetor, and fresh gas, but without good compression... that engine is not going to run. The first thing I do, when a non running bike comes in, is to run a compression test. If the engine does not have at least 100 PSI (Pounds per Square Inch) in each cylinder, I won't work on it, except to rebuild it. It would be a waste of the customers money if I "Tried" to make it run.

100 PSI is the minimum. It should be 125 to 150, and some engines have as high as 170 PSI or more. Yes, an engine can run with lower compression, but it will run very poorly. I've seen old, big, multi-cylinder outboards run with as little as 65 PSI and some lawnmowers run even less. However, for motorcycle engines 100 PSI is really on deaths doorway. Use your time to rebuild the engine, not to get another five or ten hours of life (maybe !) out of it.

The drill is simple. Remove all the spark plugs, ground all the spark plug wires or turn off the ignition, if possible. Screw or push the end of the gauge into the spark plug hole, open the throttle wide, and kick away. I like to kick (or turn the engine over with the electric starter) about four to five times and then check the gauge. Remember the reading, release the pressure on the gauge, by pushing the little releases, and do it again. If the reading changes, do it till you get several readings that are all the same. That would be the correct pressure.

When you remove the spark plug, it might be a good idea to loosen the plug a bit and then blow out and around the plug with compressed air. This is to blow out any bits of dirt that might fall into the engine through the spark plug hole, as you remove the plug. This is an especially good idea on dirt bike engines with deep, forward facing, spark plug holes.

Technically, You should do this when the engine is hot, but I don't like burning my fingers, so I always do it when the engine is cold. A hot engine would probably read a few pounds more, but a cold reading will tell you what you need to know. Run the test on each cylinder. All the cylinders on an engine should be within ten pounds of each other. In other words, a four cylinder engine reading 145 PSI, 150 PSI, 147 PSI, and 155 PSI would be considered good. If it had 135 PSI, 150 PSI, 150 PSI and 155 PSI, it would not be considered good. Something is starting to go wrong with that first cylinder. OK, you have a cylinder that reads low. Is it valves or rings, leaking that compression ? A quick, down and dirty test is this. Squirt some oil, maybe a teaspoon's worth, into the cylinder through the spark plug hole. Now run the test again. The oil will hold compression for several turns of the engine. If your retest with oil gives higher compression, you will know the rings are worn. If there is no change in compression, it's the valves that are leaking. If you think it's the valves, it's always a good idea to check the valve tappet clearance. If the valves are tight, they could be leaking compression. If the valves are tight, reset them to the proper clearance and test again. if your compression comes back don't thank your luck, thank Jesus ! He just saved you an engine rebuild.

This test is one of the most important tests you can make. Time and time again, I see people work for hours trying to get an engine to run or to run good. I ask "Did you run a compression test ?" they say "Oh, it has compression" I ask again, "Did you do an actual test ? What was the PSI ?" They say "It feels like it does !" So they run a test, and guess what ? No, or little, compression. Don't waste you time on a dead engine. Run a compression test first thing.

If you have an engine with Constant Velocity carbs the test is still done the same, with the throttles wide open. You might think they would read different, but they don't seem to.

Sometimes the spark plug holes are kind of weird in the size department and you will have to use an adapter on the end of the compression tester gauge. You can get a lot of different types of adapters, but sometimes you may need a special adapter that no one sells. You can try to use the push type of tester. It has a rubber tip that fits into the spark plug hole and is held there by hand pressure. Sometimes, due to the position of the spark plug, that will not work. If you can't buy the right adapter you can make one out of an old spark plug.

To make one, simply take a spark plug that fits the engine you want to test and remove the part of the metal base that is crimped over the ceramic portion of the spark plug. You can do this with a hack saw, and the crimped part will come loose like a ring. Now you can knock the ceramic part of the plug out with a drift from the nose end of the plug. This leaves you with just the metal portion of the plug. Now you can cut threads inside the end with a tap, like the one above, or weld it up with metal and redrill it to the right hole size if the plug is too big to tap as is.

If you don't have a compression gauge handy, all is not lost. A down and dirty way to do it is to simply press your thumb over the spark plug hole and hold it there tight. Now have someone kick the engine over. No matter how hard you push your thumb, the compression pressure should blow it off the hole smartly. If it won't, you don't have enough compression to start the engine.

I had 0 compression on the YZ50 I picked up. Figured my gauge went bad as it was one I have had for hmmm about 30 years now. As I was messing with the carb, I noticed the head/jug move. Snugged the head bolts, still no compression. Figured it would take less than 10 minutes to have it down to the case so I tore it apart. No gaskets or rings. Found the problem!

You did remove the schrader valve from the compression adapter?

If the tester is Harbor Freight, return it for a refund. They are notoriously unreliable.

If it reads zero because the motor isn't turning over, let's address that issue

Ignition key hot- dead short somewhere in the system. Check your wiring.

Fuel: Does fuel flow through that float valve? Simple check is to remove the float bowl and turn on the gas and see if it dribbles out of the float valve - Tip: use the PRIME position if your tap is vacuum operated.

Hey guys,

Thanks for the replies.

Tommy - I am definitely new, so new that I'll have to ask a really stupid question - how do I know if my engine is turning when I hit the starter button? I know that the engine isn't seized (so in my understanding, it does turn - pushed the bike around in all gears) and there are sounds coming from starter motor and I get spark.

The z250 is a four stroke

Milky - the copy and paste was good. I had read the second part from Dan Mc, not the first and I will definitely look into some of those things mentioned.

Really? - I'd been trying to avoid opening up the engine as you can probably tell I have very little experience with most things at the moment. But if its unavoidable I am happy to do it. I just don't want to make things worse at the moment.

PJ - am I suppose to remove the shrader valve? I didn't do this.

teazer - I didn't get the compression set from HF, but I did it on some online store. They were the cheaper than ebay and anything else I could see. And again I'm not actually sure if the motor is turning when I hit the starter button, but I do know that it turns from the "pushing" test.

For the carb, I know that fuel does go into the float bowl, but I haven't done the check you speak of. Is the purpose of the float needle valve to supply the fuel into the float bowl? The problem is/was that the fuel wasn't moving beyond the float bowl as per my inspections, but now after my meddling, it has stopped filling up to the correct levels.

Thanks for all the input so far.

Schrader valve is supposed to hold compression but if you remove it you will see if needle moves.

When you hit the starter button,
Does the bike at least sound like its trying to run, is there anythign coming out of the exhaust?
I'm thinking your starter clutch is fried of similar and your starter isn't turning your engine.

It should sound like your car when you turn the key before it starts, lug lug lug lug, etc.

if you don't have a kick start you could do compression test as if bump starting. Put in tester, put bike in 2nd gear, pull clutch, push bike and get it moving, jump on and let clutch out and it will turn motor over if starter clutch is bad, that will give you the readings. Make sure if carb is on to have WOT.

And again I'm not actually sure if the motor is turning when I hit the starter button, but I do know that it turns from the "pushing" test.

Click to expand...

This is the first thing you need to know. You're not checking compression if the engine isn't turning over. You're just looking at a gauge. When you turn on the key, and hit the button, describe in detail what happens. You should hear the engine spinning. Not just the starter motor, but the engine. If you don't, you have a separate problem, and need to solve that before you can check compression. Do you have a buddy that knows bikes? You need some help. Nothing wrong with being new, we all started somewhere, but if you don't know if an engine is spinning or not, you're really not equipped to rebuild carbs, diagnose electrical problems or deal with low compression. No offense, not calling you dumb, but you are obviously very new to this and a little guidance will save you tons of time. The forum can help, but nothing can replace a little one on one with an experienced friend.

Hey guys,

Thanks for the replies. Based on what the majority is saying, I have a feeling that my engine was turning over before, when I originally did the compression test. I can't be 100% sure cos I don't actually remember, but I remember it sounding different from how it sounds now, which is just the click of the starter relay...

Seeing as I use to get a spark, and it sounded like the below video, I think that's the case.



So it looks like the issue has compounded to include electrical gremlins - not sure why the starter motor "stopped" working, I had a check of the connections between the starter relay and motor, after which it tried to work, but stopped within a second.

So, just building up a mental list of things I should so I can once again try doing the compression test, I should:

1. Check what's gone wrong between the starter relay and starter motor - involves seeing if electricity is reaching the starter motor, and if so, then taking it apart to see if something inside has failed

2. Once this is ok, check for leaks in the engine - involves tear down of sorts, to check valves etc

Does that sound about right?

After that I will have to go through the electronics to make sure nothing else will short/fail.

The bump starting sounds great, except I dare not do it with the TFCC tears in both my wrists. I may try to see if a friend is willing to do it for me, but I don't want to further damage them

Hey guys,

So I got compression, but not much - 30 psi.



Looks like the 0 reading, and probably the sparks from the key hole were due to two very stupid mistakes.

1. I neglected to put the bike into neutral.
2. I hadn't properly "grounded" the spark plug wire...I had removed the spark plug from the wire and just had rubber connector lying on the engine - I was confused as to how this was grounding it but didn't take that thought any further...

Feel a bit stupid about all that, and now worried about the state of my CDI...especially since it was new...

Thanks for all the input. I'll now be going through the other checks and tests to see why the compression reading is so low.

Sounds like you have a long way to go. Nothing wrong with that; we all start with zero knowledge of these things. I remember when I was a kid I used to be completely baffled about how my dad could tell what engine configuration a car had by the sound. I also remember the first time I ever really dug into an engine. My dad was rebuilding a small block Chevy and had me doing most of the disassembly and watching and learning about what went where and did what. At some point we were in the house looking up parts on the computer and he told me "go grab the camshaft, I need to take some measurements"...
So I go out to the shed, all 100 pounds of me, and I proceed to muscle the crankshaft, which I swear weighed almost as much as I did, all the way back to the house. I walk in, so proud of myself, and he says "I asked for the cam...that's the crank..." man, was I embarrassed. I doubt he even remembers that, but I sure do.

Now, my recommendation, and this is based off of how I learn so maybe you are completely different, would be to get the shop manual fo your bike, read a few books on how internal combustion engines work and how to troubleshoot and fix them, and dig in. All I.C.E.s work basically the same. A 700hp 454 works the same as your z250. After you learn the basics of how they work, how the power is transmitted to the back wheel, how the electricity flows to operate the starter, the ignition, et cetera, then tear the bike apart.

Pull the tank and seat off, pull the wheels off, pull the engine out of the frame, pull the wiring, et cetera. Strip it down, then assess what you have, what is bad, what you want and need, and what you can throw away. Start checking parts. Pull the head, check the cam and valves, all that good stuff. Overkill? Sure, but you'll be learning the machine and you'll havea new appreciation for what it does for you and what you should do for it. You'll know how it works and what parts do what, so once it is back together if it ever gives you problems you'll have the right foundation of knowledge ad experience to figure out what is wrong and how to fix it. It'll truly be YOUR bike, not just an appliance. You'll have a greater appreciation for your ancient, outdated, underpowered and over weight steed than any yuppie has for his shiny new R1 or Road King.

And once you've torn it apart, learned the inner workings of YOUR machine, and put it all back together, you'll be one of the guys your friends come to for wisdom, rather than the guy who has to worry about asking "dumb" questions. And you'll be helping to carry on the torch of the gearhead. Dig in, get your hands dirty, feel the satisfaction of a job well done.

Sure, this may delay you getting your bike on the road a little bit, but I think it will be worth it in the end. Hell, I've got a GL1100 that I tore down over the winter, and I'm dying to throw it back together to ride, but I want to make damn sure I don't have to redo it next winter because I half-assed it or cheaped out and am not satisfied with the results.

Plus I don't want to get stranded 1,000 miles from home.

Thanks Tommy,

Yeh that was the plan to start, but then I started getting annoyed and wanted to get it on the road so I could learn to ride properly. I guess now I don't have much of a choice - not tearing down for the fun of it but it seems the only way to go now.

Still annoyed at such a stupid mistake. The CDI is new as well, and it didn't come cheap. Wondering how damaged it is...

Sham,

Don't beat yourself up. We all make mistakes. It comes with being human. CDI is either fine or dead. Rare for them to be slightly damaged or partly functional. As a rule, they either work or don't.

If you need some inspiration, there's always Chopper Reed http://www.youtube.com/watch?v=1EY7lYRneHc

Now back to Compression. 30 psi is incredibly low. It is possible that it's correct, but more than likely that cheap gauge is reading low. Unfortunately that bike appears not to have a kickstarter, so it's not possible to kick it over and get a sense of how good or bad the compression is.

It would be nice to know what the compression pressure really is. Do you know anyone in Sydney that might lend you a gauge or come over to test it for you?

If the compression is really low, the probable causes are:

- Rust or debris on valves stopping them from closing properly
- Stuck rings

Less likely:
- Hole in the piston
- badly worn bore or broken rings

It's pretty easy to remove the head on that bike and to inspect, clean and repair it. You'll need a gasket set and a valve spring compressor and that is best borrowed. No point in buying a ton of tools for a first bike unless you can afford them and plan on doing more projects.

You can always put it on an airline and see if readings increase?

Hey teazer,

Thanks - good to know the CDI should be ok then, as I can still get sparks.
I'm leaning towards doing the rebuild now - it seems to make sense that a lack of compression would be behind the reason for fuel not getting "sucked" through the carbs...
I'm looking for gasket sets online now, the problem being that the C model, which is mine, is in fact a D model in America, which means the labeling of these gasket sets confuse me a bit.

I'm looking at either:
K14046-237 (http://www.ebay.com.au/itm/290600929717?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649#ht_500wt_813)

K14046-142 (http://www.ebay.com.au/itm/370568717275?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649#ht_1118wt_1032)

I realise one is top end and the other is a complete set but yeh. Is there a means of determining this, as it seems different from finding individual part numbers from microfiche. I sent off an email to z1 this morning hoping for some help from them.

Don't really know anyone in Sydney interested in taking bikes apart, so unless I take it to the mechanic, I won't get much help there. Valve compression sets seem to be able to bought on the cheap <30 and might be an easier way to go...

PJ,

Not sure what you mean by airline - I'm picturing a plane?

Thanks guys.

sham said:

PJ,

Not sure what you mean by airline - I'm picturing a plane?

Thanks guys.

Click to expand...

Try picturing a compressor with a rubber hose (line) coming out of it ;D