Problem with cylinder #2 (82 GS550)

[Sluggo]

Newbie to forum. I am working on a friends 1982 GS550 that he picked up for $300 (41k miles). He bought it from a guy who had let is sit "for a while" and it just "needs the carbs cleaned". ^o

I've owned 25+ bikes in the last 20 years and have wrenched on all of them. Surprisingly, I've never touched a GS. (I'm partial to Moto Guzzi's, they are simple to work on).

The problem:
After cleaning the carbs. Bike bogs down at 4,500 rpm under load. Bike starts and revs fine to redline. Idles a bit lumpy at 1,000 rpm. Ride it around the block, it bogs at 4500 rpm in ALL gears. Shot water from the kids squirt gun on headers and cylinder 2 is not hot.

The good:
1) Tank clean & gas good
2)All cylinders have 120+ compression.
3) Spark seems good to all cylinders

The bad
1) GS airbox is a pain in the a$$!! (not much room to work with there)
2) Petcock is near impossible to turn, but seems to work in PRI and RUN.

What I have done.
1) cleaned carbs (TWICE)
2) flipped plugs from cyl 1 & 2 to see I had fouled one. (Nope)
3) flipped plug wires from 2 & 3 to see if I had a bad coil (nope)

I ran into the guy who sold it two him & he was surprised I got it running. It hasn't run in years.

I'm going to pull the carbs one last time & check the float height on #2 again and clean it a third time. Any other ideas? Would the vacuum line give me any problems if the fuel cock is messed up?

 

[mike_of_bbg]

probably a bad petcock sending fuel down carb #2 and fouling it out. Time to replace; check for signs of fuel in the petcock vacuum line.

 

[Sluggo]

Wow that was fast.

I'm going to block off the vacuum line, put it on prime and see if it makes a difference.

 

[Guest]

Welcome to GSResources. If you wanna make that thing run right you're in the right place. You've got a ton of info coming your way.

Once you learn how these bikes work you'll kick yourself in the butt at how simple they are.

Yes the airbox is a PITA on many of these bikes but if it isn't in good working order the bike wont run for sh!t. These bikes are pretty thouchy to air leaks and the like. Bad intake O-rings can goof things up too.
In other words if everything isn't working as it should you'll end up chasing your tail trying to sort it out.

The last one I had that wouldn't run on a single cylinder(650E) ended up being a carb issue just after a fresh proper cleaning. Never did figure out exactly what the problem was. I disassembled that particular carb and bench fed fuel into it and it seemed fine. Put everything back together and it ran like a top.

Hang around, you'll have your friends bike running great in no time.

 

[Sluggo]

Ok. Fuel cock is definately an issue. Quickly put some duct tape over the ends of the vacuum line & #2 cylinder is back to life. Bike isn't perfect, but it is definately a starting point.

Suggestions on where to pick up a new petcock?

I'm not a big fan of our local Suzuki - Honda dealer. I'm all about supporting local business, but they act like it is an inconvenience to deal with older bikes & they will end up ordering a part that typically takes longer to get and costs more than most online sources.

 

[mike_of_bbg]

Loosening the front of the rear fender might buy you a quarter of an inch or so more clearance to slide the airbox back for carb removal. I hope that when you say you cleaned the carbs twice you did it (at least the second time) the way we normally recommend: full disassembly with 24-hour dip of the metal parts in Berryman's or similar and re-assembly with new o-rings from cycleorings.com and original brass (not from carb rebuild kits).

You should go post in the GS Owners forum and introduce yourself.

http://www.z1enterprises.com/Petcock-vacuum-Suzuki-1715.aspx

 

[Sluggo]

I broke the carbs apart the first time, but didn't do the o-rings or brass. I'll order the o-rings just to be smart, as for the brass. I'll leave that up to him. So far, everything has come out of my pocket.

I personally would go with a complete gasket kit for the entire bike. I recently rebuild a 1972 Moto Guzzi Eldorado with a Dnepr sidecar, and a 1974 Moto Guzzi Eldorado police bike. It is easier (and eventually cheaper) to just get all the gaskets & o-rings for old bikes than to piece them together & pay shipping. IMHO

My next big project is a 1976 BMW R90 cafe racer. I also have a 2004 CBR F4i that I just need to find the time to put back together after the previous owner bent the frame stunting it. Motor is in, just need to hook everything up.

 

[BigD_83]

Ok. Fuel cock is definately an issue. Quickly put some duct tape over the ends of the vacuum line & #2 cylinder is back to life. Bike isn't perfect, but it is definately a starting point.

Suggestions on where to pick up a new petcock?

I'm not a big fan of our local Suzuki - Honda dealer. I'm all about supporting local business, but they act like it is an inconvenience to deal with older bikes & they will end up ordering a part that typically takes longer to get and costs more than most online sources.

I've been dealing with Boulevard Suzuki lately, and I have no complaints with their service or pricing.

http://www.boulevardsuzuki.com/fich...y=Motorcycles&make=SUZUKI&year=1982&fveh=2115