GS550ES Running Quality Questions

[ryonker]

Did you check the compression with a hot engine? And with the throttle wide open?

Service manual says to warm up engine to operating temps. Shut off, then do the compression check. Also, throttle should be held wide open.

A major cause of low numbers (other than the above) is also your valve clearances. When clearances are off, compression will drop.

Good Luck!

[strawboss]

Did you check the compression with a hot engine? And with the throttle wide open?

Service manual says to warm up engine to operating temps. Shut off, then do the compression check. Also, throttle should be held wide open.

A major cause of low numbers (other than the above) is also your valve clearances. When clearances are off, compression will drop.

Good Luck!

ryonker,

The engine was cold, but I did hold the throttle open. I checked the valve lash on cylinder one, to make sure it wasn't holding the valves open, and the valve lash was good. I can believe the engine being hot or cold could make a few pounds difference, but not the drastic amounts I am seeing on my engine. I think I may have some badly worn rings. The engine doesn't use any oil, but the compression ring must be worn.

Thanks for the info.

Ryan

[chef1366]

Drop a little oil into the cylinder and see if the compression numbers rise.

[ryonker]

Where in Wisconsin do you live?

Rick

[strawboss]

Updaet

Chef & Rick,

Sorry for the delay. Been working on my car a little - too many projects going on. After Saturday morning when I made my reply I started thinking about the WOT while doing the compression test. I started doubting myself about holding the throttle open when I played things back in my mind. I know that WOT is the usual procedure for a compression test, but I wasn't 100% sure I actually did - more focused on pressing the start button and not frying myself with spark plug voltage!!! So I proceded to adjust the valves since I had the valve cover off already. I found a couple a little tight around 0.002" and a few about 0.006". The weren't terriible, but I set them all between 0.003-0.005". I forgot what a tedious pain that is!! ;-)

After I reinstalled the head cover I re-did my compression test with my Mac compression gauge and the engine warmed up. I got 125 psi on 1, 2, and 3, and 130 on 4. I repeated the test a couple of times and got the close to the same readings. These are a little low according to the OE spec, but are above the 115 psi minimum in my Clymer.

So, thanks for the heads up and making me think about my procedure! The bike still ran the same this morning. It starts up and idles great. It cruises good, but doesn't like to take a lot of throttle while running higher speeds around 50-60 MPH (approx 5k RPM in 6th gear). Lowering the needles seemed to help, and if you don't crack it WOT you can get it to accelerate decent, but you have to modulate the throttle just right or you will feel a decrease and stumble when you twist too far. I think I should mark my throttle from closed to open in 1/4 throttle increments so I can determine if this is consistent or always happens a the same spot. I would think if it is always at 3/4 or more throttle, the bike needs a smaller main. However I know the 1 needles needs to be replaced for sure and one other needle is not too far from it. I changed a needle or two on Polaris quads and once they wear through the gold coating the machines just run fat at "normal" throttle positions -foul plugs and run like crap. So I guess I should get that DynoJet kit ordered since I can't find stock or other replacement needles. Plus I will get mains to play with.

While I was working on my bike I checked the resistance of the coils. Primary was 4 ohms on both and secondary was 34.5 and 34.7 ohms. I did the relay mod so the coils are getting a good strong 12+ voltage signal. Valves are set, intakes are good, intake o-rings are new (thanks Robert Barr!) I checked the plug caps and wires for arcing one night in the garage with the lights off - didn't see any. My plug caps are original yet, but they look OK. Suzuki is crazy at 14 bucks each for replacements. Anybody know the part number for replacement NGK caps?? Petcock is working properly. Float height is 1 mm higher than stock at 21.5 mm (fuel level lower). Diaphragms look good. No exhaust leaks. Air filter is clean and sealing properly (now). Not sure what else to do other than start jetting.

I should probably do a plug chop at WOT sometime. I need to get some new plugs so that I get a good reading. I just am hesitant to change stuff from stock since the bike is all stock yet: airbox, exhaust, air filter, etc.

Any advice is appreciated. This community is great and I am glad that I found it!!

Rick, I live outside of Lomira, WI which is south of Fond du Lac and North of Milwaukee just off Hwy 41.

Later,

Ryan

[chef1366]

Sounds like the igniter is bad.

[strawboss]

Yup, this thought has crossed my mind, but there is no way to test the igniter according to my manual either. New ones from Suzuki are $300 or $400 bucks. I watched ebay for a while, but haven't found nothing yet. Anybody have one laying around I could buy for a nice price or try out?

[strawboss]

Finally Running Good!!

Hello All,

I haven't been on here in a while, but I thought I would post some updates. I have been tinkering with my bike since the last post. I tried a different igniter with no luck - still ran the same. Then I bought a Dynojet kit and messed with that. Couldn't get it to run good all over the place. It was either rich down low and really rich mid range or lean down low and OK mid range. I ended up getting a set of carbs from a guy off Craigslist with 15k miles on them. I put his needle jets and the stock jet needles in my original carbs and it runs good. I messed with the new needle jets and the dynojet needles too. It ran better with just the needle jet change, but couldn't get it to run good all over the RPM/load range. I did go down two sizes on the main and added a 8 in^2 area hole to the airbox (with an outerwear screen) also - the engine must be getting a little tired. I put in a new Uni filter also. Now it runs good and fuel mileage is about 43-44 mpg again.

I bought a Dr. Mom's Otoscope that was real nice too. You can look into the needle jets easily and see the marking inside of them from being worn. I didn't think this was a big deal until you realize the P-2 to P-3 diameter change is 0.005 mm with is about 0.0004 inch. Therefore if you can see the marking from the needle contact it is probably worn enough to affect the jetting. The otoscope also worked well when looking at the air bleeds and part numbers stamped into the jets as well. Works great for reading spark plugs too - way down inside the plug!! I highly recommend this tool for about $25 from Amazon. Also, I looked all over for new OEM needle jets and jet needles, but no luck. I even emailed the guys from motorcylcecarbs.com also looking for some needle jets and he said I was pretty much SOL. Had to find NOS, salvage, or good used ones. I have been watching ebay for a while, but haven't found any NOS parts yet.

Well, I hope someone finds this post useful!! I have 33k on my bike now and hope to get to 50k without too many more problems! Also, I bought some Berryman's ChemDip for cleaning carbs and it works awesome. Much faster and makes the parts cleaner than the old Yamaha carb cleaner I have been using for years!! Got to run.... Good riding!!!

Ryan

[chef1366]

Glad you got it sorted.

[strawboss]

Thanks Chef!!