79 GS550 not running properly

[Guest]

Evening.

I bought a 79 Suzuki GS550 at the end of April. It ran when I got it but wasn't running well. I've been tinkering on it since.

What I've done so far:

• replaced the petcock
• stripped carbs completely and soaked for 24 hours in carb cleaner (thats a lie, I didn't disassemble the slide/jet needle assembly because I thought it would mess with the sync and I had no way to sync it when I did this)
• new Suzuki needle valves and seats
• new Suzuki floats (25mm between carb body and float on both sides)
• new gaskets on top and bottom of carbs
• new o-ring kit from Robert
• new o-rings for intake boots
• Fuel screw turned out 7/8 of a turn and air screws 1.5 turns out (not sure of factory settings)
• new spark plugs and the caps that screw on the end of the wires
• synced the carbs
• after this I ran a bunch of tanks of seafoam through the bike.
• checked shim/cam clearances for valves and replaced shims so they are all between 2 and 3 thousandths
• installed new stator
• installed used SH775BA
• installed new battery
• set the points/gaps
• new clutch cable
• oil filter/oil change multiple times (mostly due to having issues with stator haha)
• put on a new flasher relay and took off the awful LED turn signals and installed my friends old Yamaha turn signals (those stupid ugly LED turn signals actually wrecked multiple LED flasher relays)

So I may have done things a little out of order but the very last thing I just finished on that list were the valves....

So here is my issue. While I am driving the motorcycle, at times it seems to run perfect and at times it hesitates/bogs. Even when the bike was running it's best, the fastest I was able to drive it was 120 KPH (75MPH).

Tonight I took the bike out for a drive and as I started out it did the usual hesitating/bogging thing. At one point it was like all the stars aligned and the bike drove so well - it had more power than it ever has before. I took it out of the highway and got it up to 140 KPH (87 MPH) and probably could have pushed it harder.... (I am assuming this had something to do with me doing the valves?). It seems like my chances of it running best is after its warmed up (not just a little bit warm but hot). Anyways, I really noticed tonight when it was running its best it accelerated really well between 7K and 9K RPMs which it hasn't done before which was great. I think the motorcycle runs best in the lower RPMS.

Anyways, after continuing to drive it, it sort of goes back and forth between running good and then hesitating/bogging. It might just be my mind making it up, but the bike sounds better (louder and throatier) when it is running great.

As I am driving it, every once in a while, I hear a bit of a noise. It almost reminds me of sand being crunched between your teeth. Sounds like possibly a small piece of grit is being sucked through something? Or grinded a little bit? Doesn't happen very often... Not sure if this has anything to do with the bike not running great?

Anyways, I am kind of out of ideas as what to do. The bike is completely stock - air box/carbs/exhaust. I may not have the pilot circuit set correctly....

I am thinking of taking the carbs apart and again and cleaning them. My friend has a parts cleaner and has offered to let me use it. I live in Canada and had a hard time finding the recommended carb cleaner to use. After I cleaned the carbs I was sucking/blowing through the vent lines (that attach to the top of the airbox) and one had some dirt in it I sucked out....

Anyway, before April I new nothing about motorcycles or mechanics in general (I am an electrician which helps with the electrical side but that's about it). I have no idea what to do next to fix the problem. It's really no fun to drive and bothers me a lot because it's not working properly. I am at the point I'd almost like to find a good mechanic to take it too but I really shouldn't spend the money and part of the reason I bought the motorcycle was because I wanted to learn how to wrench on it and get into it with my son when he gets older (he is 2 and has a brother on the way).

In my very limited expertise, my thinking is it must be some sort of an air/fuel mixture issue? What do you guys think and what do you think I can do next to try to fix the issue?

[londonboards]

The on off nature of this problem points to electrical in my eyes.

Carb / fueling issues tend to be consistent, not coming and going. If you have an air leak, for instance, it won't just fix itself and then unfix itself.

Electrical issues can be more random, especially poor connections, broken or burnt wiring, bad earthing, bad switches, coils shorting and so on.

I would start going through the wiring. Check plug wires and coils first and work back.

[danbobberino]

The on off nature of this problem points to electrical in my eyes.

Carb / fueling issues tend to be consistent, not coming and going. If you have an air leak, for instance, it won't just fix itself and then unfix itself.

Electrical issues can be more random, especially poor connections, broken or burnt wiring, bad earthing, bad switches, coils shorting and so on.

I would start going through the wiring. Check plug wires and coils first and work back.

I took the plugs out and held them against the engine and turned it over and I'm getting spark on all the wires. How else do I test this?

[Big T]

New points and condensors needed. You have misfires

[danbobberino]

New points and condensors needed. You have misfires

Weird. Just put on a new condenser, set gaps to 12 thousandths, set the timing so the light came on at the fire mark, and now it runs like garbage!

maybe it's dyna time? What would I need to buy for it? I know not much about it.

[Big T]

One new condensor? It has 2
Are the points burnt?

Since the problem comes and goes, would seem to be electrical

How do your spark plugs look? Pull them and post up some pics

[mvalenti]

get a dyna ignition....