Gesa

[Dwayne]

So, I did a compression check on the '97 GS500 'Gesa'. Got her running and allowed her to warm up. Upon start up there was a light hint of greyish - white smoke that persisted while she idled. And a smell of unburned fuel which I assume indicates running rich (she has a Delkevic exhaust system).

Once she was well warmed I shut her down and pulled the plugs. First thing I noticed was that her right side was far warmer than the left side. Right side plug was darker and a bit wet. Left side plug was grey and dry.

Installed the compression gauge on the right cylinder first, twisted the throttle to wide open and hit the starter. Got a reading of 105. Me thinks that is way to low. Did a repeat, again 105.

Did the left cylinder and got a 105 reading. Repeat test yielded 105 again. So both cylinders are reading identical but likely low from what I've been able to determine.

Buttoned everything up and started her again. Rode around the parking lot of the store beside my place. Throttle response was extremely sluggish. Defintely not normal.

I've only had her 24 hours and am doing my best to comb this forum for likely problems but would appreciate the help of those who know this model better than I.

So... gurus of the GS500... please present thoughts and issues where I might focus attention. Your collective help and guidance will be appreciated. And a free cyber cookie goes to the individul who nails the problem.

[The Buddha]

Try checking valves to make sure they're closing when they should. Then try putting oil in the chamber to see if its rings. Diagnose before you tear it apart, save you lots of grief cos some problems only show when its running.
Cool.
Buddha.

[Dwayne]

What do you recommend for the amount of oil? Teaspoon?

[gsJack]

Both cylinders too low but equal check valve timing first.

[Dwayne]

gsJack... thanks for this advice. Makes the most sense with both giving the same reading. Btw... what is the optimal compression range reading? Haven't been able to ascertain in my online searches.

[gsJack]

Compression check on my 02 GS at 100k miles:

                  #1 cyl             #2 cyl
Cold             135 psi          135 psi
Hot              140 psi          140 psi                           
Oil added
to cylinder    155 psi          160 psi           
                   170 psi          190 psi
                   200 psi          190 psi

Suzuki Spec:



Added one squirt of oil for each check with oil until they topped out.

[Dwayne]

gsJack... excellent. Thanks.

I had just found a video on YouTube put out by BaltimoreGS where the specs were given.

[iamhiding]

silly question but its easily overlooked, were you holding throttle wide open when testing?   thats what i forgot to do the first time anyway  haha you'll get low but equal readings if you dont.

[Dwayne]

Yes. Had it wide open.

[Dwayne]

Warmed the bike to operating temp this morning to do wet compression test. Added about 1cc oil for the test. Readings on both cylinders were 110. Correct me if I'm wrong but this indicates a valve issue? This may account for the light grey smoke and the left cylinder staying much cooler. Also checked spark and both are positive, though the right plug seemed weaker and less visibly intense.

Thoughts?

[gsJack]

Have you checked cam timing yet as shown by diagram in my post above?

[Dwayne]

No chance as of yet. Wife unit had some honey-doos for me today. I had just enough spare time to do the wet test and swap out the clubman bars it came with before I had to do what makes her happy.

---

The bar swap. For the moment I'm using the brackets that came with the clubmans until a pair of factory style top clamps arrive that I ordered off of ebay which will lower the bars a bit more. At the moment the banjo bolt coming off the MC is touching the cluster bracket which is offsetting the bar about 1/4" to the right. Lower position will correct this issue. Yanked off the factory mirrors as well. Something else to sell.

[Big Rich]

I'm going to +1 Buddha's comment above: unless your valves are in spec, you can be chasing your tail. And while you're doing the valve clearances, you'll be able to check your camshaft timing as Jack mentioned too.

[iamhiding]

just checking  didnt actually notice when i first read the post, my bad 

Yes. Had it wide open.

yeah with that in mind i'm with everyone else on the matter and hey at least its only a 4 valve twin, that means half the work right 

really looking forward to seeing more progress

[mr72]

Correct me if I'm wrong but this indicates a valve issue? This may account for the light grey smoke and the left cylinder staying much cooler.

I'd bet with a combination of smoke (oil burning) and low compression the same on both cylinders your problem is rings.

If there was no smoke then I'd say valve timing would be high on my list to check.

Could be valve timing and rings. But if it's smoking, that oil is most likely getting into the combustion chambers past the rings. It could be a bad head gasket or cracked head etc...

Other issues like valve clearances, carbon build up on the valves, bent or burnt valves, etc., would not produce the same low compression reading on both cylinders. Probably would be low on both but different readings (mine with bent valves and carbon buildup was 80 and 120 psi).

And please don't take this the wrong way, but are you confident your compression tester will register more than 110 psi? Can you verify it is giving the right reading? I know if I got such a consistent result on what might be a worn out engine I would suspect the tool is failing. Seems quite odd to get exactly the same low reading on both cylinders.

Your cool cylinder is probably either carb imbalance or some other carb problem... clogged pilot jet, float valve sticking, vacuum leak, etc.

I wouldn't worry about the ignition. You have bigger problems to check on first.