600F Problem

[batman]

I started noticing small problems with my bike, and now a week later it wont start. The following are the symptoms I noticed in order during a span of a week:

-Stopped turning over on first crank.

-Became increasingly difficult to start. Would have to play with the choke and turn the throttle to get the bike to start.

-From a dead stop, bike would be hesitant to take off, and would almost bog down.

LAST NIGHT
-Bike stalled at two redlights as soon as I came to a complete stop. Would not start again unless I was giving it a lot of throttle and took off as quickly as possible (pretty much popping the clutch).



This morning the bike would not start at all. There was a meduim size puddle of fuel under the bike. The petcock and #1 and #2 carb were dripping. After taking out the spark plugs (which were brown) all cylinders sprayed fuel. The #1, 2, and 4 continued to spray fuel after a few more starts (no throttle given).

I replaced the spark plugs after draining the cylinders, still would not start. I tested the spark, it sparked fine before the electrode, but with the electrode and spark plug attached the spark seemed pretty weak.


My theory is the bike started missing, and everything became saturated with fuel (hence the leaks). Since the spark was fine before the electrode, I think the coils are fine. I'm going to fix the fuel leaks and replace the plug wires.

If you have any other theories I would appreciate to know them. Thanks.

[Kreylyn]

I started noticing small problems with my bike, and now a week later it wont start. The following are the symptoms I noticed in order during a span of a week:

-Stopped turning over on first crank.

-Became increasingly difficult to start. Would have to play with the choke and turn the throttle to get the bike to start.

-From a dead stop, bike would be hesitant to take off, and would almost bog down.

LAST NIGHT
-Bike stalled at two redlights as soon as I came to a complete stop. Would not start again unless I was giving it a lot of throttle and took off as quickly as possible (pretty much popping the clutch).



This morning the bike would not start at all. There was a meduim size puddle of fuel under the bike. The petcock and #1 and #2 carb were dripping. After taking out the spark plugs (which were brown) all cylinders sprayed fuel. The #1, 2, and 4 continued to spray fuel after a few more starts (no throttle given).

I replaced the spark plugs after draining the cylinders, still would not start. I tested the spark, it sparked fine before the electrode, but with the electrode and spark plug attached the spark seemed pretty weak.


My theory is the bike started missing, and everything became saturated with fuel (hence the leaks). Since the spark was fine before the electrode, I think the coils are fine. I'm going to fix the fuel leaks and replace the plug wires.

If you have any other theories I would appreciate to know them. Thanks.

Your primary issue is more than likely carb related, in that they need to be cleaned. Not just sprayed with carb cleaner in a spray can, but actually fully cleaned. The issues you describe point towards at least one float needle not sealing right and flooding out things. That fuel collects in the oil with in the crank case and eventually you end up with more issues.

Clean the carbs, test the float needles, reinstal, change the oil, go from there.

The spark is always weak... comparatively. Make sure your battery is fully charged and the coils are getting minimal of 11v or your bike won't start.

Also... choke/throttle together is a big no no. Choke adds fuel. Throttle adds air. Pick one!

Krey

[batman]

Your primary issue is more than likely carb related, in that they need to be cleaned. Not just sprayed with carb cleaner in a spray can, but actually fully cleaned. The issues you describe point towards at least one float needle not sealing right and flooding out things. That fuel collects in the oil with in the crank case and eventually you end up with more issues.

Clean the carbs, test the float needles, reinstal, change the oil, go from there.

The spark is always weak... comparatively. Make sure your battery is fully charged and the coils are getting minimal of 11v or your bike won't start.

Also... choke/throttle together is a big no no. Choke adds fuel. Throttle adds air. Pick one!

Krey

Thank you for your input.



P.S. I thought the choke subtracted air from the air/fuel mix in the carbs, and the throttle opened the butterfly valves which increases the amount of mixture going into the cylinder.

[Kreylyn]

Thank you for your input.



P.S. I thought the choke subtracted air from the air/fuel mix in the carbs, and the throttle opened the butterfly valves which increases the amount of mixture going into the cylinder.

Normaly that would correct for a "choke". What suzuki calls a choke on these bikes though, is actually a fuel enrichment system. So... it adds fuel by opening a vacuum line that suckes fuel from the bottom of the bowl and adds extra directly into the cylinder.

Krey

[batman]

Ordered four of these.

https://www.denniskirk.com/k-and-l/carburetor-repair-kit-185061.p173488.prd/173488.sku

I'm taking the carbs apart now. I have an ultrasonic cleaner that I will use for the jets and etc. I usually use some mean green and water. I'm wondering if I should disconnect the carbs and soak the entire carb, or just the pieces and scrub the carbs while they are connected.

If this doesn't fix my problem, what should I do next?

[Kreylyn]

Ordered four of these.

https://www.denniskirk.com/k-and-l/carburetor-repair-kit-185061.p173488.prd/173488.sku

I'm taking the carbs apart now. I have an ultrasonic cleaner that I will use for the jets and etc. I usually use some mean green and water. I'm wondering if I should disconnect the carbs and soak the entire carb, or just the pieces and scrub the carbs while they are connected.

If this doesn't fix my problem, what should I do next?

I strongly recomend complete disassembly. This includes removal of the a/f screws... this tends to get overlooked due to the brass plug caps put on at the factory. Also, once re-assembled be sure to do a bench test of the carb float needles. Fill with fluid, blow on the fuel line once the bowls are full to make sure they are seating, and not allowing any air to move through. Also, address any issues that may come appearant due to the cleaning... for example, if you find rust or sediment in the bowls of the carbs you obviously should find out where it came from and resolve that issue also... or your newly cleaned carbs will just collect it again and cause more problems.

Once the carbs are fully cleaned, bench synced, and you put everything back on; make sure your oil is not contaminated. If it's been a while anyways, a fresh oil change is not a bad idea.

If you have issues at that point, we need to know what they are to further diagnose.

Krey

[boomer_95]

Ive never had much luck with an ultrasonic cleaner for the jets. we had 2 at the shop and after a while i noticed the jets just turned color and didn't really get clean, but the bodies were usually spotless. i stopped using then all-together as i could do a much better job in a shorter time with pro Honda carb cleaner, a small brush, and brake clean (to remove the carb cleaner)

but i'm in agreement with krey. the carbs need to be cleaned if there leaking fuel. then go from there

[ManQu]

any chance the petcock is also faulty letting fuel through when not running?

[92xjunker]

any chance the petcock is also faulty letting fuel through when not running?

Prime setting would free flow by design. carb floats should stop it.

[Frozt]

Have you checked for flow of the petcock? Sounds like the vacuum line to me.

Easy check: lift the tank. Remove the fuel and vacuum line. Using a spar line, hook it to the vacuum port and gently suck on the other end. If you taste fuel, faulty petcock diaphragm. If there isn't any flow of fuel, faulty petcock.

Sent from my phone

[batman]

I took the petcock off and reattached it. It doesnt seem to be leaking now. I'm still waiting on parts to arrive for the carbs. Ill update you after I get them installed.

[batman]

How many turns out is the idle mixture (pilot) screw? I forgot to count when I took it out and I'm ready to re-assemble.

[Wild-Bill]

Set the A/F screws to 2.5 turns out from bottom.

[batman]

Set the A/F screws to 2.5 turns out from bottom.

Thanks!

[batman]

I got the carb kit in and I have cleaned the carbs with an ultrasonic cleaner. The carbs are reassembled and installed on the bike. I am doing a compression test now, and then a carb sync afterwards.

I thought the holes for a carb sync were usually on the manifold. I don't see anything on this Katana. Where do I hook up my BikeMaster Carburetor Synchronizer test set?

I see these rubber boots on the carbs themselves near the manifold. One of them has a hose that goes to petcock as a vacuum line. Is this where I hook the carb sync up?