5000 rpm "wall" .....

[bonanzadave]

Look to see that the the larger passageway at the air-intake side of the carb to the underside of the diaphragms is not blocked.

and on the other side of the coin make sure its not too big. Some owners like to drill holes in their airboxes thinking more air - more HP. Same thing with the airbox cover. Make sure its sealed tight.

[Nessism]

The problem with having other people work on your bike is you don't learn, you spend a lot of money, and there is always something else to do so it costs you more money, again and again. Best to suck it up and start learning how to do things for yourself. For example, you need to perform a valve adjustment otherwise the engine WILL be damaged. This is not optional. This little running challenge is just the beginning...

Hitting a rev limiter like you say is likely the igniter. Could be the carbs too of course. If it were my bike I'd go though the carbs completely and verify everything is clean. The rebuild tutorial is linked in my signature. Don't forget to replace all the carb and the intake boot O-rings too. If that doesn't fix the bike then I'd start hunting an igniter or bite the bullet and get a Dyna S. You can always sell it to someone here if it turns out your original ignition system is fine.

Sorry for the tough love but you bought a 30 year old bike that needs work. What did you expect?

[AJ]

and on the other side of the coin make sure its not too big. Some owners like to drill holes in their airboxes thinking more air - more HP. Same thing with the airbox cover. Make sure its sealed tight.

Agree with Dave. These are very balanced circuits and small modifications often have unintended consequences.

But just for clarity, I was talking about the oval port at the top of the horizontal main air passage tube in the aluminum carb body. Don't think Dave was confused, but want to make sure the OP was not.

[AJ]

The problem with having other people work on your bike is you don't learn, you spend a lot of money, and there is always something else to do with costs you more money. Best to suck it up and start learning how to do things for yourself. For example, you need to perform a valve adjustment otherwise the engine can get seriously damaged. This is not optional.

Hitting a rev limiter like you say is likely the ignitor. Could be the carbs too of course. If it were my bike I'd go though the carbs completely and verify everything is clean. The rebuild tutorial is linked in my signature. Don't forget to replace all the carb and the intake boot O-rings too. If that doesn't fix the bike then I'd start hunting an ignitor or bite the bullet and get a Dyna S. You can always sell it to someone here if it turns out your original ignition system is fine.

Sorry for the tough love but you bought a 30 year old bike that needs work. What did you expect?

Could not have said it better.

It took me four tries to get the carbs working on my 1982 GS1100e and I finally broke down and tore them all the way down like Ed recommended. And I worked for several years as a Honda/Suzuki mechanic. FWIW, mine was doing something very similar ("rev limit" at 4-5000 rpm). For awhile, I was almost convinced it was the ignition igniter. One look at the price of those convinced me to give the carbs one more try. Without shortcuts! LOL!

Patience. You will get this fixed.

[Lupo]

Same problem

I just inherited an '80 GS650E with exactly the same problem. The only thing different is when it's in Neutral I can rev it up as high as I like. In gear, 4000 tops and it poops out. Very curious to see how things play out with yours...

[FLHGSRay]

Do the carbs and valve adjustment. And don't sorta do the carbs. Take them off and soak them and make ABSOLUTELY SURE that all the passages are clear. I'm sure that many here that had to do their carbs multiple times will admit to not doing a complete job the first few times, then broke down and did it right. You've got to tear them completely apart and soak them and clear all the passages and then replace all the o-rings with the right pieces, not just some junk off ebay. If it's still pouring fuel out the carb, you've got a float valve not doing it's job. Could be it's just got a piece of gunk in it. The floats and float valves are the only thing I didn't replace on mine, but I've done this a hundred times and understood the chance I was taking. It worked out ok. My carbs worked great the first time. Don't get scared off by the valve adjustment, follow the directions religiously and you'll be fine. You may only have to buy 1 or 2 shims. You can check the cam timing while you're doing it, and eliminate that from your list of possible causes. Then I'd forget trying to decide whether ignitor is bad and spring for the Dynatek EI and new plugs. The best $150 you'll spend.

[firstGSrider]

HOw did you get the engine so clean? Mine looks like yours did and it looks like you got the cooling fins nice and clean. You use something in particular?

[Nessism]

For all you newbie guys...please check the link in my signature about common newbie mistakes. Incomplete carb cleaning is at the top. Also, the "ceiling" issue is often caused by the jetting being too lean (such as trying to run the bike without the airbox or filter). There is tons of info in the archives and stored by basscliff, so you guys need to dig in and do some maintenance.

[jaywelchy]

Lots of great posts ..

So to clear some things up..

The carbs no longer leak fuel .. the pilot jet was too large, and was gushing fuel in at idle .. and only idle, causing the fuel to pour out. I replaced with factory size pilot jets, and thats cured.

I agree on the "complete" carb clean .. I know I went through the carbs rather lightly, and the bike shop synced and played with floats .. no parts replaced.

The bike will rev out fine in neutral .. but thats a no load situation, and tells me nothing. The "wall" is under power, and under load.

I have O rings ordered and on the way ... I have factory 92.5 main jets on the way (in case originals were drilled out ... )

The plan is to gather the O rings, jets, and needles IF I can find them, and print out the tutorial on CV rebuilds from Basscliff's site. Then to rebuild like it should have been done the first time. ( I am guilty .. have gone through lots of carbs "lightly" with wonderful results. Not these!)

I am not discouraged, but rather interested .. in the bike, and the work that needs to be done.

Valve adjust will be on order also.

As far as brutal honesty .. I crave it! Bring on the thoughts and honest opinions

I am excited to get this little bike running well ... should be a fun ride.

And again, this is my first exposure to the old GS bikes ... and once I bought and paid for this 550, I did a ton of research on parts availability, which introduced me to the history and the GS 1000 ... which I really, really wish I had. Love the Cooley bike, but the Red with white #34 race replica ... THATS the bike I want to build!!

One project at a time ...... still scouting for the bigger GS ...

Jason

[Nessism]

Pilot jets, regardless of how large, can not make fuel pour out of the carbs. You have a stuck float needle and/or a petcock dumping fuel down the vacuum line.

Good luck and glad you have turned the corner and are getting serious.

[bietau85]

Pilot jets, regardless of how large, can not make fuel pour out of the carbs. You have a stuck float needle and/or a petcock dumping fuel down the vacuum line.

Good luck and glad you have turned the corner and are getting serious.

yea what he said,lol... I was scratching my head at this thinking why would a pilot overflow fuel...

[jaywelchy]

Hmm .. maybe I need to be more detailed. The pilot jets (idle circuit, yes?) were a few sizes larger than stock. Bike fouled plugs quickly at idle when I bought it, AND when it sat and idled, raw fuel would drip out rapidly, almost pour, where the airbox boot and carbs come togethor. Obviously there were no clamps on the boot/back of carb joint, and the extra fuel was not being drawn in at idle...hence the leak.

I hope this makes sense, and if not will be good for a quick chuckle! Ha!

Jason

[Nessism]

Hmm .. maybe I need to be more detailed. The pilot jets (idle circuit, yes?) were a few sizes larger than stock. Bike fouled plugs quickly at idle when I bought it, AND when it sat and idled, raw fuel would drip out rapidly, almost pour, where the airbox boot and carbs come togethor. Obviously there were no clamps on the boot/back of carb joint, and the extra fuel was not being drawn in at idle...hence the leak.

I hope this makes sense, and if not will be good for a quick chuckle! Ha!

Jason

Your leak theory is wrong. The floats are letting too much fuel into the float bowl so it's over flowing. Or the petcock has failed and fuel is flowing down the vacuum line. The pilot jets have nothing to do with it.

[TheCafeKid]

Hmm .. maybe I need to be more detailed. The pilot jets (idle circuit, yes?) were a few sizes larger than stock. Bike fouled plugs quickly at idle when I bought it, AND when it sat and idled, raw fuel would drip out rapidly, almost pour, where the airbox boot and carbs come togethor. Obviously there were no clamps on the boot/back of carb joint, and the extra fuel was not being drawn in at idle...hence the leak.

I hope this makes sense, and if not will be good for a quick chuckle! Ha!

Jason

It doesn't make sense cause that's not how they work brother.

Fuel is metered into the float bowls of the carbs by a float valve. It works much like your toilet tank does. Gravity and air pressure, combined with vacuum draw of the motor allow fuel to pass from the tank into the float bowls. When the fuel reaches a certain level, the float valve closes and the fuel flow essentially stops, or slows at least. Just like your toilet. The pilot jets in your carbs are actually fed through the main jet, and emulsion tube. (were you to open them, there would be, or should be, a rubber cap covering the actuall pilot jet. If not, you'll want to remedy that)

Now, even if the jet was massively too large, it may foul the plugs, but the float valves "should" prevent overflow of gasoline. If you've got that much gas leaking, you've got either shot float valve needles, leaking Oring around the valve seat (which since you said they've never been replaced, is likely) or a bad petcock, or all three. The performs equipt from the factory are designed only to flow when the motor is turning over, unless they're on the "prime" position (it flows freely then). If the petcock is bad, it may flow gas all the time. Try as they might, even float valves in perfect shape cannot hold back the pressure from a tank full of gas. They'll give up, and the gas will over flow into your crankcase. Which is bad as gas will wash the cylinder walls and crank bearings of oil, leaving metal on metal contact. I'm sure you know that isn't good.

I'd suggest, as has been already, tearing the carbs down, replacing the Orings after properly cleaning them, and replacing your 30 year old petcock with new. (rebuilds fail more than they succeed and are a waste of money...buy new a d don't worry about it for another 20 years)

The carb rebuild tutorial by Nessism and many others is quite comprehensive and thorough, and while daunting at first, they're quite easy to rebuild. Just be organized and thorough. Once you've done it, you'll be amazed at how easy it will be to get the bike to perform as it should.

There are no shortcuts brother. They end up being the long way around. And motorbikes are a lot like airplanes. When something fails, it's generally painful, and possibly fatal. If ya need some help, shoot me a PM, I'll pass ya my number and can talk you through as much as I can. Anything to help.

And to answer your question:
I absolutely LOVE my ZRX. Its everything I love about GSes, but better brakes, suspension and rubber. Oh, and a wee bit more power helps Like a good friends brother used to tell him: you don't need 100+ horsepower to have fun on a bike......but it helps.

[BigD_83]

Do you have access to a decent compressor?

So far my first tear down, clean, and rebuild per the tutorial (without compressed air) is holding up ok, but I would have felt better with the higher psi that my new compressor is putting out.

I found cleaning the carbs on my 650GD that canned air worked ok, and carb cleaner was slightly better, but I just wanted more oomph in the stream to really clean out the small passages in the carbs.