Removed downpipes looking for Oil loss clues - photos!

[Mick_J]

Does it really matter if the compression tester is calibrated, as long as all cylinders are the same or one shows up different is all you kneed to know.

[vonny232]

Does it really matter if the compression tester is calibrated, as long as all cylinders are the same or one shows up different is all you kneed to know.

Yes, I think it does (going by what Andre said).

The engine mechanic suggested all 4 cylinders may be worn (given the reported 130PSI per cylinder). As a result, he does NOT recommend an engine overhaul.

If however, it turns out the compression is actually good for all 4 cylinders, then perhaps an engine overhaul would be less risky.

[Andre]

Does it really matter if the compression tester is calibrated, as long as all cylinders are the same or one shows up different is all you kneed to know.

Yes, I think it does (going by what Andre said).

The engine mechanic suggested all 4 cylinders may be worn (given the reported 130PSI per cylinder). As a result, he does NOT recommend an engine overhaul.

If however, it turns out the compression is actually good for all 4 cylinders, then perhaps an engine overhaul would be less risky.

Does it really matter to have an accurate and calibrated compression tester as well as doing the test correctly? I think so. It is one thing if the tool is measuring the real pressure and another thing is when it is a totally bogus piece of junk. Have seen reported comparison of 2 tools where one showed even pressures while the other showed one cylinder clearly having much lower pressure than the others.

There is the approach of one mechanic who said that he hadn't done a compression check in 30 years. If he sees a problem he just tears the engines apart and then sees clearly what needs to be done. If you don't have to worry about your or others wallet than that is a fine way of doing things!

I wouldn't base a decison on a test result that I don't trust. 2 Compression chambers look squeeky clean while 2 show oil and carbon chunks. It is clear that there is a problem on #2+3. Maybe it is "only" the oil rings. As T24 said this won't affect the compression. If it's just the oil rings then using thicker oil won't do much good. Still expensive to replace these rings.

You can just keep riding as is. Millions do keep (d)riding their vehicles in similar situations. Fine with me. With an oil-burner they wouldn't do that for long nowadays in Germany as emission testing will get to them within 2 years. 

Unfortunately, if you can't do the work yourself, it can get expensive. A used replacement engine might be the ticket but it is expensive (the engine itself and the labor). A rebuild even more. When you replace the engine, the old one can be opened up by yourself (?!). If it turns out that it needs only "inexpensive" things like new valve stem seals or oil rings, then you have a spare engine or can sell it and recover some of the costs.

If however, it turns out the compression is actually good for all 4 cylinders, then perhaps an engine overhaul would be less risky.

Yes.... perhaps.

Question, can you buy "calibrated" compression testers?

Sure you can. For the right money.  Unfortunately I haven't seen any on the usual suspect Internet sites that state their accuracy. Didn't look that hard though. Also hard to determine how easy they can be calibrated (they all can in the end). Calibration is not a "do-it-once" deal. Depends on "requirements" how often it needs to be done. For compression check it needs to be in the ball park. Size of the park and frequency of the plays are up to you as the owner. For calibration you need a reference too.

There are places that will do the calibration for your  $$.

A professional workshop who has pride in their work will have a reasonable accurate and calibrated compression tester. Likely the best option for most.

For myself I will get a pressure transducer for use with my oscilloscope. These all state their accuracy and are easier to calibrate. Can do much more with that combo than just compression check. Probably can buy a good replacement engine with a setup like that. It's a hobby - so money is well spent.

[Eric GSX1400K3]

If you were keeping the bike long term, and if not confident to attempt your own rebuild, getting a reputable indy or workshop to diagnose and repair would be my course of action. You may very well end up with a sweet runnning unit.

If not, then ride the bike as is and perhaps sell it in the short or medium term.

These engines are relatively bullet proof, but everything  has a limit, so the carbon build up in #2 and #3 will start to affect valves and seats, rings and pistons eventually, making repair / replacement inevitable and more costly.

Entirely your call.

[vonny232]

Cheers for the feedback guys.

@Andre - I work in electronics so use Scopes all the time. Didnt know you could use a pressure transducer to measure bike compression. Do you have any info on this?

In the meantime, I have a friend who will lend me his standard compression gauge. He reckons its accurate but cant be 100% sure.

@Eric GSX1400K3 Knowing myself, I will keep the bike long term. I suppose taking the decision to rebuild the engine depends on how confident I am that just cylinders 2&3 are leaky, and the other two are Ok. This depends on a reliable compression test and I will look into this.
As I said before, I will likely look for a spare engine over the summer, and any plan to overhaul the existing engine will happen once its been replaced.

A couple more questions:
1) I read elsewhere that cheaper quality Oil is more likely to break down over time. Is it right to think using a very high quality (and likely expensive) Oil would last longer than cheaper stuff? I read some folk put fully synthetic 10w-40 Oil into the bike without any problems? Perhaps even a slightly thicker 15w40 might have less tendency to leak past the rings?

2) As Eric said, the carbon deposits inside 2&3 will eventually take its toll on the rings and valve seats. What can I do to buy some time here so I get at least another summer season out of the bike? Is there anything I can do to try and remove/burn off the carbon deposits without removing the head? Is there any kind of liquid I can pour into the cylinder to "dissolve" or "loosen" the deposits so they are expelled out the the exhaust portals?
Ideas such as running some "washing" diesel Oil for a few hundred miles, or flush the system with some "sea foam"? Any views?

[grog]

Just ride it mate, stick 600 ml in every 2k. Thats a lot of riding, so many nice corners to enjoy.

[Andre]

Andre - I work in electronics so use Scopes all the time. Didnt know you could use a pressure transducer to measure bike compression. Do you have any info on this?

Lots of infos available on these. Just search online "oscilloscope pressure transducer"

An example that explains some: https://www.youtube.com/watch?v=_mJdxrhx45Q

Instead of buying an expensive one, DIY options abound.

You might also look up "relative compression testing". An oscilloscope with an Amp-probe allows you to do that.

There is just a ton of stuff that can be tested with an oscilloscope.

No need to buy an automotive oscilloscope. A regular scope is just not as comfortable. Take a look at https://www.picoauto.com/library/automotive-guided-tests for many applications.

[Andre]

1) I read elsewhere that cheaper quality Oil is more likely to break down over time. Is it right to think using a very high quality (and likely expensive) Oil would last longer than cheaper stuff? I read some folk put fully synthetic 10w-40 Oil into the bike without any problems? Perhaps even a slightly thicker 15w40 might have less tendency to leak past the rings?

The VI improvers break down quickly in the gearbox. With a "cheap" oil I noticed gear changing became less smooth after about 2k km. The full synthetic oil I use does not show this "behavior". Full synthetic oil does have a much higher VI inherently and does not need much, if any, improvers (depending on the viscosity range).

However, in your case the oil may not stay in the engine long enough to crunch the VI Improvers to pieces sufficiently to warrant an expensive oil!

The operator manual allows for a 15W-50 oil. A thicker oil will have less tendency to leak for sure.

[Andre]

In the meantime, I have a friend who will lend me his standard compression gauge. He reckons its accurate but cant be 100% sure.

It's good to get a comparison with another gauge.

[vonny232]

Thanks Folks.

To be clear, the manual allows for 15w50 Oil (NOT 15w40)? As I saw on another thread people talking about 15w40 when discussing types of Oil.

I live in Ireland and other than a plan to drive to Scotland this year, I dont have plans for any long treks (especially to very hot countries) so I suspect a thicker Oil will be Ok provided others have used it before.

I see Motul do a 5100 semi and 7100 fully synth...

Oh, and ill check out those pressure transducers

[seth]

From the Suzuki factory service manual

[Andre]

"FUEL AND OIL RECOMMENDATION" from Service Manual page 1-5:

Just noticed that even a 20W-50 is allowed (Also note the environmental temperatures)

[KiwiCol]

2 pictures, 1 says 95 octane & the other 91 octane.    Why can't (didn't) they get their 'spec' agreed before printing . 

[Andre]

2 pictures, 1 says 95 octane & the other 91 octane.    Why can't (didn't) they get their 'spec' agreed before printing . 

These may be both "correct" They mention the method used for the 91 octane value (Research Octane). This is missing for the 95 octane. Could be that the "Technical Writer(s)" goofed up. Not the first time I might say

In the US they use (RON+MON)/2

Examples:

(RON 91, MON 82,5): 86,8
(RON 95, MON 85): 90
(RON 98, MON 88): 93

I'd go by the value which has the method mentioned with it. Also the table (without the method mentioned) shows US volume numbers even though the 14 was never sold on the American continent. Someone was sloppy

[seth]

@KiwiCol
The picture is from a UK Suzuki workshop manual from 2002 .
The supplement from 2003 says the same