No power at low end, then lots???

[Anonymous]

My bike has a hard time getting power when I first open the throttle. Giving it throttle seems to be working opposite to what it should do, if I give it power it starts to die down. I have to give it throttle really slowly for it to actually get more power or it will stall out. Once it gets past the low end then I have no problems and lots of power? What could this be?!

I have synchronized the carbs (3 times!!), I have fidgeted with the idle, I recently rebuilt and cleaned the carbs (I did not see holes in the diaphragms or CV boots). For synchronizing the carbs I am using for the first time the nifty mercury gauge not the "floaty balls" but I think I am using it correctly?.

Any ideas why giving throttle seems to be choking my bike!!!!! I have to waddle my bike forward at every light until it gets rolling a little then I have ALL THE POWER IN THE UNIVERSE!!!! Throw ideas at me and I will look into all?.

1980 GS550L: stock 4 "round top" carbs, stock airbox/filter, after market 4 to 1 exhaust.

[AOD]

hmmn...with a 4-1 on a stock setup they reccomend you rejet. how do your spark plugs look? lean, rich, okay?

my problem on a 550 i sold was putting pod filters on a stock carb setup...even after i rejetted it. the problem was too much air in the idle-air screw...i had to close them down a bit.

with your carbs, the CV carb, i think you have an adjustment screw for the low end fuel when it is running off the pilot circuit. once you are on the throttle, and it picks up, like you say, you are running off the needle, then the main jet. i would take a look at the pilot mixture screws, and if that doesn't work, you may have a clogged pilot circuit.

~AOD

[KW]

Maybe an air leak around the carb to head inlet rubbers, or knackered 'O' rings between inlet/head?

[Dark Jedi]

Also check timing. Maybe the advance timing is set right, but the low end timing is wrong?

[Pete's GS]

It sounds like our low-speed jetting is off. Since everything is stock except for the aftermarket exhaust I think the jetting is okay (I have the same set-up) but the low-speed jets are clogged and dirty. Try running some Techron and some premium in it. That should do it since it sounds like your choke is fine. You could also spray some carb cleaner into your airbox with the filter out while the engine idles and rev it a little. I hear Gunk makes a good one. If that doesn't do it, then I'm afraid it's time to throw a party and PULL YOUR CARBS and clean them according to the method on this site. It works. Pulling the carbs is such fun on these bikes where there's about 1 mm of room to jiggle the carbs on and off. Makes you almost want to throw away your airbox and put on K&Ns except your bike will run worse. But I think this so-called "Italian tune" of using the Techron and premium should be all you need. Good luck.

[Anonymous]

Problem solved!! Thank you all!!!

Problem solved, here are the three things I found out, may this help others.

1) There is nothing more satisfying than actually finding the solution to a problem.
2) When I set up my profile for this forum, I accidentally used the same signature line as some one else (I thought it was a little know saying regional to Providence, RI -I have since deleted it)

3) The problem was the vacuum line to the petcock?. Here is why. My nifty mercury gauge connects to 4 threaded holes in boots on the engine side of the carburetors. The vacuum line to the petcock is a 5th hole. When I took off the gas tank and connected the 4 hoses for the gauge, I left that 5 hole open?.. As some of you suggested I did have a leak somewhere, but it was not a small leak it was a 10mm hole sucking in air as I tried to synch my carbs!!!! I did manage to synch the carbs, but that open hole was throwing off the entire thing?.

It all makes sense now doesn?t it. I synched the carbs with that open 5th hole. Then I put the bike together again. When I stuck the gas tank back on, I reconnected the petcock vacuum line -plugging up that 5th hole. Then when I tried to fire her up, it was all messed up!!!

I synched the carbs back up, but this time I left the petcock hose in the carb and plugged up the other side?.. I can't remember the last time she ran this good?.

Hope this helps