Bike won’t start

[Guest]

Evening gents. I bought a 79 suzuki gs550 a year ago and have enjoyed the journey of learning about bikes.

Last year the bike had a few issues and I feel as though I got them all fixed up and the bike ran well! The gentleman who had the bike before me cleaned the carbs but didn’t keep the pieces together and mixed up the needle valves/seats so I replaced them with genuine Suzuki new ones so the carbs stopped leaking. I was having a difficult time getting the bike running on 4 cylinders as well - I put in a Dyna s ignition, new Dyna coils, wires, and spark plugs and also completely disassembled the carbs and cleaned them - both soaked them in carb cleaner and again in an ultrasonic cleaner. I replaced all of the o-rings with Robert Barr’s kit as well as the o-rings on the intake boots. The battery wasn’t charging so I put in a new stator and a genuine Shindengen sh775ba. I also checked my shim clearances and changed some of my shims.

The motorcycle seemed to run well for the rest of the summer although struggled at times to start in cooler weather.

I live in canada where it’s cold so I parked the bike in November with a full tank of gas with a bunch of seafoam in the tank/carbs.

The other day I went to pull the bike out of the garage (battery was inside all winter and I put a tender on it a few times to keep it topped up - the battery was also new last summer).

I noticed it it was quite hard to start (it was probably in the 50’s or low 60’s Fahrenheit or low to mid teens celcius). After a while I finally got the bike started but it took a while. I realized maybe the bowls had emptied out and I did not put the petcock to the prime position(sorry the petcock was new last summer too). I let the bike warm up and took it out for a ride. It ran well like it did last summer on all cylinders. I got it home and parked it again. It got cold (below freezing) over night. I tried to start it over the next couple of days but could not get it started. The weather definitely was not warm out(same as the first day I started it or colder). I tried with the choke on and off, I tried kick starting it as well as electric, opening throttle and not..... but to no avail. The starter was even beginning to make funny noises (I know, I tried too long). It seemed to have the best chance of starting with the choke on and the throttle twisted ever so slightly.

I took the carbs apart and they seem clean - I notice the fuel mixture o-ring was sliced and fell apart when I took it out so I ordered another o-ring kit from Robert and am going to use my friends ultrasonic cleaner again when he gets home from vacation to clean the carbs.

I am am unsure of why the bike is so hard to start. When I was trying to start it I could get it to ‘idle’ on 1 cylinder - it would run for maybe 10 or 20 seconds and then die and only the exhaust for cylinder 1 was warm - the majority of the time it turned over without firing.

The other thing I should mention is I changed the oil between the first time I rode it this year and the second time I tried to start it - the oil cap says 10W-40 but I could only find Rotella t4 15W-40 so that’s what I put in.

my fuel mixture screws are 1 turn out each and air mixture screws 1.5 turns each (I am not sure where they were set from factory because the previous owner messed with them).

I understand that you need fuel, air, and spark to fire. Can anyone let me know why my bike may not be starting or what to check next? I am going to clean the carbs and reassemble - my heart tells me maybe it needs more fuel on start up with the fuel mixture screw turned out a bit more but I don’t know much about it - all of the spark plugs seemed wet after trying to turn it over. I took the spark plugs out and wiped them all off multiple times and tried to let the cylinders dry out from possibly being flooded while I was trying to start it.

Any help would be appreciated.

[roeme]

Before going further; check ignition coils, and connectivity. Measure resistance on primary side, and on secondary.

Judging from what you're telling, I'd assume the carbs are fine - or at least good enough (air&fuel) and compression is good, so that leaves us with spark. From the current information the culprit could be coils, wires, spark plug caps and the spark plugs themselves.

When one of my 550s acted up, it was a loose primary side connection on one of the coils, with left me with intermittant/weak spark. Yep like you I got it to idle this way, like your bike not all exhausts warmed up.

[danbobberino]

Okay, I took the bowls off the carbs and cleaned with a spray can of carb cleaner - they were fine. When I took the first bowl off I took out the fuel mixture screw. The o-ring was lacerated and broke when I removed the screw. I reassembled without the o-ring and didn’t remove any other fuel mixture screws. I adjusted the fuel mixture screw from 1 turn out to 1.5 turns out. The bike started rather easily! I took the bike for a ride and it seemed to sputter a bit when driving. I then adjusted the air screws from 1.5 turns out to 2 turns out. It ran better. I think it is still running a bit rich. I ordered a pit posse pp2590 so I could adjust the screws without removing the carbs. I think I’m going to turn them in 1/4 turn so they are 1.25 turns out....

My question is, is there some info I could read somewhere how to properly set the fuel and air mixture screws? I followed the carb disassemble/reassemble guide I was told to when cleaning carbs/replacing o-rings... I noticed when the fuel screws were 1 turn out each the choke worked, but now that they are 1.5 turns out the bike doesn’t like the choke. I’m not sure if it will work better now that I’ve turned the air screws out to 2 turns from 1.5...

My other question is, is it bad to have the o-ring missing on 1 of the fuel mixture screws?

thanks.

[danbobberino]

Can someone point me to some info on how to set my fuel and air mixture screws? I think this is the issue with my bike not starting well.

Last summer fuel screws were 1 turn out and air screws 1.5 turns out. Ran pretty good.
This spring I had a hard time starting motorcycle (cold outside - last summer had a hard time starting bike in cold).
Tried turning air screws out to 2 turns by recommendation of friend - didn’t help to start bike.
Took carbs off bike and adjusted fuel mixture screws out to 1.5 turns and air screws back down to 1.5 - bike started more easily (was also a bit warmer outside) but was sputtering a bit while driving.
I turned air screws out to 2 turns. The bike was now warm but started easily and sputtering seemed to go away.

i tried to start the motorcycle today (cold and raining) and it was more difficult to start again.

i know when I cleaned/rebuilt carbs the tutorial had some info on setting the screws properly but I can’t seem to find a link to that anymore.

help!

[Steve]

I did not see any mention of pods or a pipe, so will have to assume that all is stock.

The fuel screws should be about 3/4 turn out from lightly seated. After all the tuning is done, the air screws might end up about double that, but start with them at 1 turn out. After the bike starts (and runs long enough to do the tune), slowly turn them out. Engine might speed up a bit when you hit the "sweet spot", then start to drop off. Turn the screw back in about 1/8 turn, continue to the next carb.

You might also need to refine your technique. When using the "choke", you might not need to apply it fully. It's not an on/off type of thing, you can apply it part-way, as well. Whatever amount of "choke" you apply, do NOT open the throttle. The enrichener circuit (the "choke") needs the high vacuum of a closed throttle to work properly.

.

[danbobberino]

Steve, you said to start at 3/4 turns out for fuel screw and 1 turn out for air screws. Then you said to start turning out slowly until you find the sweet spot. Are you talking about only turning the air screw out or also the fuel screw? Do you run the engine at 1500RPMS while doing this? And the RPMS should increase as I turn the air screw out?