Problem starting...sometimes

[Taervyn]

I'm looking to see if anyone can help me out with this.

I'll start saying I read the Carbs 101 article, but haven't attempted the "wild" cleaning yet, only the "mild", as I haven't purchased the parts yet for an '05 Suzuki GSX600F.


My bike starts most of the time, but when it does, it requires a full choke + full throttle combo. It goes up to about 3500-4000 RPMs and bounces between the two for a few seconds while warming up. Once it warms (usually 3-5 seconds) on choke alone, without throttle, it sits at approx 4500 RPMs. I can then let off the throttle and drop the choke, and it idles around 950-1000 RPMs. (which I know is low, it should be around 1100-1250 per my Suzuki maintenance manual)

If I ride it around, the idle eventually raises after about 20 minutes of riding and it will idle at the correct RPMs (the manual also suggests setting idle after a ride, so I'm assuming this is correct).

When the bike doesn't start is usually after a fresh rain (I live in St. Pete, Florida, and we get a lot of it.) or in the mornings. What happens:

I get on the bike, drop the kickstand, put the bike in Neutral, straighten it up, open full choke, turn the ignition on, engine kill switch off, clutch, full throttle, and hit the engine start switch.

The ignition coils turn over, and the engine fires, bike revs up to about 3500 RPMs, then immediately drops back down dead. It will not start again after this unless I wait at least 4-6 hours (by not start I mean that I can hear the ignition coils rolling, but I never hear the engine fire up). After waiting 4-6 hours, it starts no problem with full throttle/choke.

This concerns me because I know it should be able to start with choke only and not throttle.

What I've done so far:

• Inspect and replace the spark plugs (checked gap myself per service manual instructions). The old plugs were good, new plugs are good and fire.

• Replace Air and Fuel filter. (use K&N for air filter, and a generic fuel filter from Advance Auto parts that fit correctly. I can confirm that fuel flows through the filter without problem by visual inspection starting the engine with the fearing off.)

• Replace Oil and oil filter.

• Clean the big black plastic section surrounding the air filter. Note: The run-off tube there had about 3mL of liquid in it.

• Replace all fuses in the fuse box.

• Paid a local shop to do a fuel system flush. (about $60)

• I've also ran through the "mild" cleaning from the Carbs 101 article in this forum here, which involved draining the carb bowls, some mild inspections, checking a few of the screws/torque, gap headings, etc. I did not drill down as far as the pilot jets, etc.

Background info on the bike: I bought it used at around 13,000 miles and it does have a drop mark on the right side, so I assume it's been dropped at least once. No visible engine or casing damage as far as I can see. I also have no idea how well the previous owner broke in the bike, as no maintenance records were provided, but this isn't my first bike, or first engine for that fact, I'm just purely stumped at why it starts 80% of the time and not the other 20.

Any advice would be incredibly helpful.

Thank you,

Brandon Johnson

[1990gsx 600]

sounds like its running lean.....but then you throw in it will start after a few ore hours of sitting..... does it get sunny when you fire it back up........thats my best guess someone else will chime in..... running lean means not enough air gets to the fuel so it dosent like to start on cold days..... but if it gets sunny than it will warm the block and it will fire right up

[kevin2502000]

The rain problem sounds electrical unless you have a hose off somewhere that is letting water into the intake (but I doubt it). Take some dielectric grease and pack all the electrical connections going to the coil and inspect the wires and caps for cracking. That does sound correct for the choke raising the rpms, that is how it works. If you want to raise the idle a tad it wouldn't hurt.

[Taervyn]

@Kevin, I don't think it's electrical given that I have this problem even if it doesn't rain, but during the morning hours of the day. Granted I live in Florida, which has 60-80% humidity year round, so it could be moisture, but the ignition coils are rolling and I get the clicking sound. Think it could still be it?

@1990, It usually is sunny when it starts, yes, and I made the same assumption...but I really don't know what more to open unless it's a clogged pilot jet (which I haven't purchased the parts to take the carbs that far apart yet.)

[kevin2502000]

Have you checked for spark when it doesn't start? I'm not sure what you mean when you say the coils are rolling and you get a clicking sound. You need a HEALTHY spark that will jump 1/4-3/8" to ground. That is EXACTLY how mine would act before I heat shrinked all the plug wires and sealed all the ends. (mine is 15 years older though)

[Taervyn]

I haven't yet checked the spark when it doesn't start. Usually at that point I've had to jump on and take another vehicle (have a couple goldwings and a Vulcan lying around for when I run into problems).

Might not be a bad idea, although it does take almost an hour to pull off the whole fairing and gas tank/mounting bar to get into the spark plugs.