Need Help with non starter bike

[struckjm]

https://youtu.be/DnSeZaGf9Mw

That's what it sounds like.

[struckjm]

Since I bought it (non-running) in June, I have replaced:

Oil & filter

Sparks

Battery

Fuel tank petcock and fuel lines

airbox (factory) and filter (K&N replacement)


There's fuel to carbs, there's spark at plugs. I don't know what to do next. I took carbs off and gave them the once over, but was hesitant to rebuild them.

[Meukowi]

compression? fuel&vacuum lines in correct places? timing might be wrong aswell..  cant be too big problem here..

[SK Racing]

Have you verified that there is spark? The GS500 has 3 switches that can prevent the engine from running.

• Clutch lever switch
• Side stand switch (when in gear)
• Kill switch on handlebar

[struckjm]

Yes, there is spark.

Starter fluid in airbox doesn't give it life.

The fuel tank petcock is new, as are the fuel lines to the frame petcock. There's gas in the carbs.

I don't know how to assess compression or vacuum. Need help!

[Sporty]

https://youtu.be/DnSeZaGf9Mw

That's what it sounds like.

Sound like very low or no compression, BUT I'm listening on a phone.

If it has spark and compression, it should fire on starting fluid.

Pull out a plug and see if it's wet with gas.

If you don't have a compression tester, hold a thumb over the plug hole and bump the stater.
It should push your finger away forcefully.
You can also do this with bike on the center stand, trans in fourth gear and rotate the rear wheel.

[struckjm]

Can you recommend a compression tester? I am starting to feel like this may be the issue, a lack of compression or a total block of gas from carb in to engine.

[Sporty]

All you need is a basic tester that has a 12mm adapter threads.

The tester needs to have the schrader valve in the end (tire valve core)

Avoid the harbor freight, Pittsburg  and similar testers for $20 in a plastic box that read very low on a motorcycle (if you want any accuracy)

This Innova or Actron will be fine.






The OTC brand for about double the price are nicer and come in a good box, but you don't need to spend more for a tool you use infrequently.

[Sporty]

Can you recommend a compression tester? I am starting to feel like this may be the issue, a lack of compression or a total block of gas from carb in to engine.

Even if the carb jets were plugged solid, it should fire on starting fluid.

Back to basics,
Air, fuel, compression and spark

Remember the four strokes... Suck, Squeeze, Bang, Blow. (Intake, Compression, ignition/power, exhaust)
It has to pull the air/fuel mixture in, then compress it for the spark to light it off.

If the valve timing events are off (or not happening) because of a cam chain failure.
If the cylinders are extremely worn or stuck piston rings,
There is no suck and no squeeze...

Now, if you find that you have compression... then you have see if the spark is happening at the correct time. (Ignition timing)

[struckjm]

Sound like very low or no compression, BUT I'm listening on a phone.

If it has spark and compression, it should fire on starting fluid.

Pull out a plug and see if it's wet with gas.

If you don't have a compression tester, hold a thumb over the plug hole and bump the stater.
It should push your finger away forcefully.
You can also do this with bike on the center stand, trans in fourth gear and rotate the rear wheel.

The plugs are dry. " bump the stater." do you mean press the starter button?

If the plugs are dry, there's spark, and nothing happens, is it reasonable to test the carburetor by simply placing gas in the spark plug hole and seeing if it combusts?
I'm starting to think there's either no compression or no fuel is getting in to the cylinders.

[Sporty]

Sound like very low or no compression, BUT I'm listening on a phone.

If it has spark and compression, it should fire on starting fluid.

Pull out a plug and see if it's wet with gas.

If you don't have a compression tester, hold a thumb over the plug hole and bump the stater.
It should push your finger away forcefully.
You can also do this with bike on the center stand, trans in fourth gear and rotate the rear wheel.

The plugs are dry. " bump the stater." do you mean press the starter button?

If the plugs are dry, there's spark, and nothing happens, is it reasonable to test the carburetor by simply placing gas in the spark plug hole and seeing if it combusts?
I'm starting to think there's either no compression or no fuel is getting in to the cylinders.

Yes, bump or "jog" the starter button, not hold it down. Just something to try in absence of a compression tester.

You can also put your hand or a small piece of plywood over the carb intake and see if there is a good "pull"

Just be careful of hands and fingers.


The staring fluid should make it run if the engine is mechanically ok and has spark in time.
Yes, You could try a little squirt of gas instead of the starting fluid.

[struckjm]

I've blown the aerosol starter fluid into the airbox and then tried to start it with no difference.

[Meukowi]

did you have wide open throttle while you did it? just pour few drops of gas in sparkplug hole and start, its a guaranteed test for testing engine.. it bypasses the carb.. if it wont even try to start then theres some larger problem

[struckjm]

Can you recommend a compression tester? I am starting to feel like this may be the issue, a lack of compression or a total block of gas from carb in to engine.

Even if the carb jets were plugged solid, it should fire on starting fluid.

Back to basics,
Air, fuel, compression and spark

Remember the four strokes... Suck, Squeeze, Bang, Blow. (Intake, Compression, ignition/power, exhaust)
It has to pull the air/fuel mixture in, then compress it for the spark to light it off.

If the valve timing events are off (or not happening) because of a cam chain failure.
If the cylinders are extremely worn or stuck piston rings,
There is no suck and no squeeze...

Now, if you find that you have compression... then you have see if the spark is happening at the correct time. (Ignition timing)

Compression gauge reads 0.0 PSI. Is that correct? I can feel pulses of air coming from plug hole or even exhaust pipe. The gauge is digital and it never reacts to the test on either cylinder. Just flat-lined.

So let's say it is right... then what? Rings, valves, other stuff... what kind of a head ache and or expense I am in for then?

[struckjm]

So I am beginning to think that the cylinder has no compression.

I bought a digital gauge, and it reads 0.0 PSI. I hope it works right. If it does, there's literally NO compression at all.

I am no mechanical wizard, but I am willing to try and fix this myself.

Where do I start? What's the easiest or most likely culprit? I have been told cam timing and valve clearance on Reddit.

Are there any good Youtube videos out there for the GS500, or even the 450 (which I understand was basically the same engine) that go in depth over valve clearance checks, or cam timing checks?

[Sporty]

So I am beginning to think that the cylinder has no compression.

I bought a digital gauge, and it reads 0.0 PSI. I hope it works right. If it does, there's literally NO compression at all.

I am no mechanical wizard, but I am willing to try and fix this myself.

Where do I start? What's the easiest or most likely culprit? I have been told cam timing and valve clearance on Reddit.

Are there any good Youtube videos out there for the GS500, or even the 450 (which I understand was basically the same engine) that go in depth over valve clearance checks, or cam timing checks?

If you're worried about the compression tester working, try it on another engine.


In your video, it sounded as if it was turning over fast with little to no resistance. That's what led me to think low or now compression.

I would remove the valve cover and see if the camshaft chain is intact and the cams are moving. Then worry about timing checks and valve clearance.

If you have a source of compressed air, you could also put air into the cylinder through the spark plug hole. That would find out if you have bent valves or very bad pistons/ cylinders. If you want to try it, I can give some more details.

This should help:

http://forum.gs500.pl/ftp/Studi/Suzuki_GS_500_E_F_1989-2009_Service_Manual.pdf

[struckjm]

Thanks.

I found the Valve Clearance Check/Adjustment video from BaltimoreGS on Youtube, and it's not nearly as complicated as I feared.

In the video, I also got the impression I could assess the cam chain, cams and timing once the valve cover is off. Just be rotating the engine through a couple of turns.

Is it possible for a valve to be out of spec (too open or too closed) because of sitting a long time and getting stuck in position? If so, what's the fix for that?

[Sporty]

Thanks.

I found the Valve Clearance Check/Adjustment video from BaltimoreGS on Youtube, and it's not nearly as complicated as I feared.

In the video, I also got the impression I could assess the cam chain, cams and timing once the valve cover is off. Just be rotating the engine through a couple of turns.

Is it possible for a valve to be out of spec (too open or too closed) because of sitting a long time and getting stuck in position? If so, what's the fix for that?

Yes, take the valve/cam cover off, rotate the engine and see if everything is moving,... if so check cam timing.

Valves can stick open.. doesn't happen a lot, but they can from corrosion, or bad fuel residue or serious overheating, lack of lubrication. (The last two usually have plenty of collateral damage)

Sticking closed, not really, not on an OHC engine, there is a lot of force from the cam to open the valve... just a fairly light spring to close it.

Pumping air into the cylinder will find a stuck open, bent or burnt valve.

If you have a stuck open valve that isn't bent or burnt, you might be able to remove the cams, the lifter bucket, get some penetrating oil in there and work the valve.  Otherwise you pull the head off and bring it to an automotive machinist for repair.

What I don't know is how tight the valve to piston clearance is on the GS500. Some engines will bend valves when the cam chain break or a valve is stuck open (interference engines)
Other engines are ok (non-interference)

[struckjm]

Parts came (feeler gauges, and new gaskets for breather and head) so I tore the top off today.

The cams look fine, the chain is correct, the timing appears to be correct. IE, all the marks (RT, chain marks etc) line up where they are supposed to when they are supposed to.

I was hoping I would see valves open and close visually, but that doesn't seem to be the case.

Valve clearances are less than .04mm, ie below spec. But I don't know by how much... Range is .03 to .08, and my .04 gauge is the smallest I have, and it won't insert at all, meaning actual clearances I assume are .03mm or less, the latter being more likely.

So is it simply valve clearance? Buy a few new shims and Voila? That doesn't seem right, but I definitely don't know really either. I also don't get how low/no clearance would result in 0.0PSI compression.

If it is as simple as shims, does a clearance of 0.00mm imply that if I went .05 or .1mm down on shim, I should be in the right place after? like if the current 2.50 = 0.00 clearance, than a 2.40 should give 1.0mm of clearance?

[SK Racing]

It's likely someone stuck shims in there that are too big and the valves are not closing. That would result in zero compression.

Only by removing the shims will you know what sizes they are. And only by temporarily installing thinner shims will you be able to measure the gaps. From there on you'll be able to calculate what sizes of shims are needed.