Suzuki GS550 – Common problems for Suzuki GS550’s

3 Jan 2015 | Author: | Comments Off on Suzuki GS550 – Common problems for Suzuki GS550’s
Suzuki GS 550

Mike’s GS550 motorcycle blog. Location: Honolulu, Hawaii

After removing the carbs and the carb boots, I took the carbs apart and cleaned them.  The pilots were dirty, the other jet systems were pretty clean.  I had a replacement carb o-ring kit but didn’t put it to use when I realized the carbs would have to be unbolted from the rack and completely disassembled.

 That’s a lot of work!

After reassembly, I cleaned the bodies of carbs 1 and 4 (the carbs you can see when they’re mounted on the bike), along with the carb tops.  Then I painted on a clear coat, using a paint brush.  The clear coat is called “Diamond Finish” made by KBS Coatings.

 This is a great product, it makes the metal look shiny, is easy to brush on and it’s fuel resistant.  The carbs look much nicer.

By the way, the carb boots were wasted.  No way they could be re-used. And Suzuki carb boots have O-rings that fit between them and the head.

 Make sure and replace your O-rings or you’re begging for hard times riding your bike.  Air will leak through that space, causing a lean condition and crummy throttle response.

I was prepared and had bought a used set of carb boots in good condition off E-bay.  I also bought brand new O-rings from Suzuki.  Don’t try using regular O-rings from the hardware store as replacements.

 The O-rings for these carb boots must fit right and they are made of Viton, a fuel resistant rubber.  O-rings from the plumbing department at the hardware store aren’t fuel resistant.

Putting the carbs back on was another chore.  These are the hardest carbs I can remember putting on since I had a Honda CB400F 30-something years ago.  The squeeze getting the carbs into the boots is tight and then you’ve got the airbox right there in the way too.  Make sure you get the throttle cable on before the carbs are all the way back into the boots or else!

 I didn’t connect the cable then had to pull the carbs halfway out to get the cable back on.  It’s not easy.

Carbs on, airbox on, time to ride.  I took it out a few times around the neighborhood.  The jetting was very lean.

 Doing some research, I saw that when these models came out, the motorcycle manufacturers were struggling to meet new emissions guidelines.

Jetting fixes:

Drill out the cap over the pilot screw and adjust it to make a richer mixture at idle.  The pilot screw and its cover is just forward from the big cap that fits on the top of the carb.  The cap has a little hole in it – stick a small drill bit in there, carefully drill through it and don’t push too far down or you’ll damage the pilot screw.

 Then, take a wood screw, stick it in the hole and pry the cap out.  Or at least that’s what I read.  I couldn’t pry the caps out so I took a larger drill bit and opened the holes enough so that I could turn the screws.  Carefully turn the screw clockwise until it bottoms, then back it out 2 turns to start.

 There are four carbs so you have four holes to drill and four screws to adjust.

With a richer off idle mixture, I rode around the neighborhood some more and noticed surging at part throttle.  Reason – lean needles that control the mid-throttle power.   Researching a bit more, I removed the top from each carb, pulled the slide out with the rubber diaphragm (careful not to damage the diaphragm, they are very expensive to replace) then took a snap ring plier, removed the snap ring inside the slide and pulled the needle out.

 The needle has a plastic “doughnut” on the top of the e-clip and a washer underneath.  I bought some washers at the hardware store (#6 size).  I placed two washers on top of the e-clip and one on the bottom (plastic doughnut not used anymore).

 One problem with the washers was the outside diameters were too big to fit in the slide hole.  Luckily I had bought brass washers, which were easy to file down around the edges.  #4 washers have the right outside diameter, but the inside diameter of the ones I found at the store would not go around the needle.

Taking another spin around the neighborhood, now the bike idles well and runs into the midrange pretty well.  Still hesitating at full throttle!  I don’t know why, the Suzuki is using the stock exhaust, stock airbox and stock main jets.

 Maybe we’ll have to go up on the main jet sizes, unless something else is causing this problem.

GS550 Electrical issues

Feeling more confident, I rode the GS550 further around.  I drove from my house down to Kapahulu. not that far just a few miles.  I stopped the bike, met someone and then jumped back on.  Pressing the starter button, it would barely turn over.

Riding a few miles with the headlight on almost killed the battery (which is new, by the way).

Stator and regulator/rectifier problems are common with Suzuki GS models.  I had suspected the bike would need a new stator a year ago when I bought it.  And I had a new stator stored away, I had gotten it for a good price on E-bay.

We’ll talk about that in the next post.

Suzuki GS 550

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