Engine won't rev over 2k rpm

[mallen82]

Ok, first I want to say this is my first post.  I searched on the site for an answer to my question but I guess I don't know how to word it properly if the answer is already out there.  If it is I definitely appreciate you pointing me in the right direction.

Soooooo, that being said, I just bought my first GS500.  It's a '94 that's been sitting in storage for about 1.5-2 years.  We pulled it out a few weeks ago to start it.  Gas tank has been dry but we used the same oil that's been in the engine.  Oil change is next on the list.  When we turn it on it idles extremely rough right around 1.5k rpm, which seems a little high from what I read here.  It won't run without full choke, and when the throttle it opened it doesn't go above 2k rpm, just getting louder with the occasional backfire.  I did put the lower petcock in prime position when first starting to make sure there was enough fuel running to the carbs.  The next step is to mix some seafoam into the tank or pour it directly into the carbs.

Any ideas what I might be looking at?  Anyone have any experience using the seafoam?

[Big Rich]

Skip the Seafoam- a bike that has been sitting that long needs proper cleaning/maintenance. Pull the carbs off and clean them out, along with the tank and petcocks.

[mister]

Ok, first things first...

Start Up Procedure

1 - put choke on full
2 - put petcock to prime (not normally needed, but do so in this case)
3 - press starter
4 - leave choke on full

There is more after this, but to just get it going do the above.

Now, you will also want to check your spark plugs. Bad spark plugs will cause all kinds of issues. So don't chase anything else down until you have changed the spark plugs.

There is a good chance, you'll need to clean the carbs and change the valve clearances. But you need to start with good spark and some kind of fuel flow first, right?

From here, *I* would make any initial changes to the idle screw first - It may or may not be bronze colored on yours mine looks like white nylon/plastic



So... change plugs, put on prime, start with full choke and leave on full, make idle screw adjustments to see if anything changes.

Changing the oil and making sure enough fluid in the battery should also be done.

Let us know when you have done these, and what the results are - take photos of your plugs and put them up too.

Michael

[adidasguy]

Also check the air filter. A bike sitting that long could have an air filter full of spiders.
Also be sire the carb boots to the engine have not rotted and are is getting sucked in.

[mallen82]

Thanks guys.  The air filter looks pretty good.  I replaced the fuel lines and found I have a bigger problem before I get to that....a pinhole leak in the tank.  I'm taking that to get welded along the seam first (tank's been emptied and dry for 3 days now).  I checked the air intake on the carbs and they look dam clean.  I was hoping to get it running without having to pull them and rebuild but looks like that might not be an option.  It's my first bike in over 14 years s I wanna make sure I treat her right.  I'll let you know how it turns out over this week.

This place seems like an amazing community so far from all the posts I've been reading, thanks a ton in advance for this and any future help you guys give me!

[numus]

Do you guys recommend running something like SeaFoam at all? I have read sometimes it isn't good for the engine and also read that people swear by it...

[mike__R]

Do you guys recommend running something like SeaFoam at all? I have read sometimes it isn't good for the engine and also read that people swear by it...

I've never had a problem with it, and I use it every winter to stabalize the fuel when the bikes aren't being ridden for several months.  I have heard of folks with problems but in most cases I have found out they used more than the recommended amount.

[mallen82]

So the welding shops near me don't wanna run a weld down the seam....whatever, so we're going to use some tank sealant on the inside after it's sat for a week or so drying out from having gas in it.

I decided to go the carb rebuilding route instead of the seafoam just to be on the safe side.  Plus it'll give me a chance to get to know my new baby a little more.  So my next question, I've searched for carb rebuild kits and think I'm going with the one from carb kit capital:

http://www.carbkitscapital.com/carb_kit_list_model.php?make=Suzuki&model=GS500

I saw this recommended on a few other threads and just want to see if anyone's used it or not.  Seems like there's not many parts to the kit.  (It's almost to the bottom of the page, you can't view just that one kit)  I'm going to give them a call as well to make sure I have everything I need since it's so cheap anyways.

I know I'll love that bike more in the end doing all this work myself on it but MAN I just wanna ride that thing....

[Big Rich]

Drain the tank as best you can, then put some Dry Gas (or whatever the stuff is called to remove water) in the tank. I mean, a couple bottle full. Shake it all around and pour it out. That should get the majority of fluids out. You can hook up a blow dryer set to low/no heat to help air out the tank.

Or a radiator shop should be able to dry it out and seal it too.

[numus]

Think i am going to seal mine when i go to paint it... just looked inside it and it is rust city...

[mallen82]

Ok, so I finally had time to try and work on this thing now that it's getting too cold to ride in my current gear.....

I rebuilt the carbs and tested it out but same thing, huge stutter while it tries to start, but if I play around with the idle air screw I can get it to fully start but it just sputters.  I did the recommended settings for the screw and that didn't work well, also tried a number of different levels of turn to no avail.

I also bought a brand new battery.

I checked the float height this morning.  The left carb looked ok, no problems with the height, right at the gasket level.  When I tried the right carb no fuel would come out.  I've never worked on a bike before this and just noticed that the prime fuel line (or whatever it's called, the secondary line) only goes to the left carb.  I see an inlet on the right carb but nothing goes into it.  Is that the right setup?

I did change the spark plugs out.  They were solid blackfrom halfway down the threads down.  When I put the new ones in today and tried to start the right cylinder popped and then blew out a puff of smoke.  I checked the spark plug to see what's going on and it's threads are covered in oil.

[mallen82]

This is the old spark plug.  I'm thinking I have an oil leak or something because I took the new one out again an it was soaked in oil which I'm guessing is what caused the pop and smoke form the cylinder.

[Big Rich]

I dunno about the oil- I'm on my phone and can't really tell, but that plug looks dry. For peace of mind you can usually "rent" a compression tester from an auto parts store. Just make sure it comes with the proper spark plug hole adapter.

While I can't help with the routing to the right carb, it sounds like you have some sort of blockage or something. Make sure you are getting a strong spark on the right plug, then be prepared to pull the carbs off and clean then.them

[mallen82]

That plug is the old one taken out after trying to start a few times.  I'm guessing the oil burned off of it.  There is definitely a leak in the left cylinder, the new plug got soaked with the new oil I put in immediately after trying to start, nothing on the right as far as I can tell.  The hose routing is correct after checking some diagrams.

I was going to start with the shim clearances first.  Anyone have any ideas what else the leak could be?  I'm thinking it has to be either the shims, head gasket, or the piston rings.  Any other options that I should check up front that I could be missing before I have to take it to a mechanic?

[bigfatcat]

This is the old spark plug.  I'm thinking I have an oil leak or something because I took the new one out again an it was soaked in oil which I'm guessing is what caused the pop and smoke form the cylinder.

Are u sure that's oil ?  Looks like soot to me, as in incomplete combustion, either because very rich, or plug is firing only intermittently, or both.

[piresito]

It doesn't look like oil to me too, it seems like too rich mixture.
My ride had that problem too, won't rev over 3K after being in storage. Just needed a good carb clean, sync and ready to go! Check if the choke is working properly.
Have you checked valves?

[scratch]

Looks more like someone has been leaving the choke on too long.