No Mid Range Throttle

[Guest]

Hey guys, my 81 650 sat for 6 months and now she runs like dirt. At first I only had idle to 1/4 throttle with the choke all the way out. I put sea foam in the tank and ran it for a bit around the parking lot, which eventually yielded 2/3 to full throttle as well, but no 1/4 to 2/3 throttle. From 3000 to 5000 RPM, the engine just wants to die.

What exactly would be your order of attack? I'd love to not pull the rack...it's such a pain. I know I have to though...which jet is it that controls mid throttle?

[cowboyup3371]

Did you put stabil in the fuel before parking it? If not, I would recommend cleaning the carbs properly

[hjfisk]

Pull the carbs and give them a good cleaning

[tkent02]

First I'd give the Sea foam time to work. Can't hurt, might help. If it gets a little better every day, in time it will be running pretty good?

I only say this because pulling the carbs on a 650 is a bitch. The correct fix is what these guys are saying.

[tom203]

Yes, worth a try with seafoam. Double dose it, making sure it gets to carbs ;just park it (on centerstand) and run at low speed (might have to crank idle stop screw up) a bit. Stick a fan in front so no cylinder gets too hot. shutoff, offer sacrifices and let it cool down. maybe you'll get lucky and seafoam will find the pilot circuit passages. Don't go far, if it works, your idle will shoot up as carbs kick in. Good luck,

[GSX1000E]

Berryman's sells a fuel cleaner that REALLY WORKS and it is only about $7.50 a can at NAPA auto parts stores. "Total Fuel System Cleaner". Pour the entire can into your tank and DO NOT SPILL IT on anything!
Run the bike and continue to top off the tank with fresh gasoline as the miles pass, it WILL clean the gremlins out of your fuel system.

[ssanderson1]

I gave it another go today...no improvement. I may just pull the stupid rack tomorrow and clean them out. Such a pain.

[850 Combat]

Draining the carbs before parking it helps. So does pulling off the vacuum line from the petcock, plugging it, and running it until it won't run any more.

For next time...

[ssanderson1]

Pulled the rack this morning. Tell you what...if you thought it was hard getting the rack out in 80 deg weather in sunny southern california, try getting it out in 25 deg weather in oklahoma! All the rubber was cold and hard. Took a while.

I'll get to cleaning them out in a bit. Hopefully that solves the problem.

[ssanderson1]

3 out of the 4 pilot jets were plugged to high heaven with a nasty green goo. My best guess for where that came from is the oil that was put on the air filter a few years ago...? I don't remember it being green, but I can't imagine what else would be able to get into the pilot jets that's green.

Any Ideas?

I've done my best at clearing the pilot jet holes with a wire bristle and carb cleaner. They're soaking in more cleaner now. I'll probably give them another 10-15 minutes, spray them out real good, and try to get the rack back in.

[tom203]

Personally, since carbs are off, and you got some kind of green goop (which likely got sucked up into tiny idle circuit passages ),. I'd opt for the full monty carb clean and be sure, not just hopeful. No sense having to do it again .

[ssanderson1]

While the carbs were off, I used carb cleaner and a wire bristle to clean out all of the small passages.

Got the carbs back on...which is a bigger pain than taking them off!

Started right up! I was feeling optimistic....until it was still running like crap! I gained mid-range throttle as long as the choke was out. If I tried to push the choke in, it wouldn't take any throttle at all. It will idle, but won't take any throttle.

I had a thought to reach back and make sure the exhaust was coming out of the pipes equally. Wouldn't you know the left pipe was producing 1/2 the amount the right one was!
Then I reached down and felt each header pipe coming out of the head. #1 was dead cold and the others were nice and hot.

I'll check the plug and switch it out tonight or tomorrow. Anything else I should think of?

[850 Combat]

You did have the air box and filters all reinstalled, right? If not, put them back on and try it.

The jets are not the only thing that clogs. There is a little passage between the bell mouth, the pilot jet emulsion tube, and the fuel screw. as a minimum, you need to make sure that it is open to all three openings.

[ssanderson1]

You did have the air box and filters all reinstalled, right? If not, put them back on and try it.

The jets are not the only thing that clogs. There is a little passage between the bell mouth, the pilot jet emulsion tube, and the fuel screw. as a minimum, you need to make sure that it is open to all three openings.

I never removed the air box and filters...they haven't been off in 2 years probably.

However, I changed out the #1 spark plug....no change.

After idling for several minutes, pipe #1 was cold, #2 was warm, #3/4 were HOT.

To check for spark, do I have to take all 4 plugs out or just the one I'm interested in?

If I'm getting spark, looks like I'll be pulling/cleaning the carbs again.

Any other suggestions?

[tkent02]

You can check for spark on one at a time or all four. Usually it's done singly.

Strip and dip, or go ultrasonic. A perfectly running GS is a beautiful thing.