GS650 - can't go faster than 50mph - what gives?

[duaneage]

Sounds like you are running on 2 cylinders only. Maybe the coil connections got bumped off or a wire is loose. check the coil connections. Use a wet paper towel on the exhaust pipes when you FIRST start it to see which ones are cold, chances are you will find two are not running.

The pipes are around 1000 degrees when hot so be careful and only do this on an overnight cold bike,

An inductive timing light is great for quickly verifying you have spark. Black wet plugs are another indicator.

If by the rare chance the ignitor or pickup coils are bad (highly unlikely) I can help you out with one as I have a few lying around.

[chef1366]

check the ignition. Could be the igniter.

[Fenixgoon]

well, I cleaned off the connectors to the ignition coils. I guess they had dielectric grease on them or something? It was pretty nasty looking, kinda powdery/gunky. I also sanded down the leads on the coils to expose some fresh metal.

I tried taking pictures of my spark plugs, but it didn't work out too well, so here's the best description I can do by words:

Plug1: light, off-white colored coating on top of some black stuff (presumably carbon buildup?)

Plug2: virtually pristine. only a minor amount of carbon buildup

Plug3: much stronger white coating than plug1

Plug4: almost pristine, minor carbon buildup

Finally, and this is probably the dumbest thing of all.. I want to check to make sure I have the right coil connectors going to the right plugs.


Left side of bike
Right side "connected"
Come to think of it, I should have taken the same picture of the left as I had of the right, but they're wired the same. The outermost high tension lead for the spark plug goes to the outermost cylinder
Thanks again, everyone!

[Fenixgoon]

well i found out cylinders 2 and 4 are not working properly - the exhaust pipes are cold (well, ambient temp) once the engine is running.

what kind of things should i be checking now?

[mike_of_bbg]

I think your last note indicates the problem. The coils are supposed to fire 1&4 and 2&3 together. If you have 1&2 and 3&4 on the same coils, you're only firing on two cylinders. Switch the wires for 2&4.

[Fenixgoon]

I think your last note indicates the problem. The coils are supposed to fire 1&4 and 2&3 together. If you have 1&2 and 3&4 on the same coils, you're only firing on two cylinders. Switch the wires for 2&4.

ok, just switched 2 and 4 wires.

edit: idled a little more, 3 and 4 are firing (exhaust pipes are nice and hot), 1 and 2 are cool :confused;

also, there was smoke coming from my right exhaust pipe o.O (like from the very, very end). is it from all the unburnt stuff building up in my cats?

[mike_of_bbg]

Is that just idling, or does #2 heat up if you open throttle? If you still haven't sync'd your carbs, #2 could just be very closed at idle. That may also be why #4 is taking a while to heat up. Is the #2 plug wet with gas when you remove it?

[Fenixgoon]

Is that just idling, or does #2 heat up if you open throttle? If you still haven't sync'd your carbs, #2 could just be very closed at idle. That may also be why #4 is taking a while to heat up. Is the #2 plug wet with gas when you remove it?

opened the throttle up to about 2000 rpm and still nothing from 1/2. definitely some smoke coming from 3/4 during operation - means i'm running too rich?

[mike_of_bbg]

So #1 was working until you switched the plugs for #2 and #4? Are you getting a strong spark there? Looks like there's been some wire work judging by the picture of your coils. Again - plugs wet with/smell like gas? Are you getting any gas in there?

What color is the smoke? White? Probably gas if it is. Sounds like you're either rich or leaking on that side.

[Fenixgoon]

So #1 was working until you switched the plugs for #2 and #4? Are you getting a strong spark there? Looks like there's been some wire work judging by the picture of your coils. Again - plugs wet with/smell like gas? Are you getting any gas in there?

What color is the smoke? White? Probably gas if it is. Sounds like you're either rich or leaking on that side.

plug 1 was definitely wet. nothing really covering plug 2.

and yeah, the smoke was white-ish.

[mike_of_bbg]

Sounds like you're not getting spark on #1; can you verify that? #2 carb is not letting fuel through, and either #3 or #4 (or both) is running very rich and/or is leaking past the inlet o-rings.

I know you said you cleaned the carbs. Elaborate. You followed the instructions per the CV carb rebuild guide? Dipped for at least 24 hours? Installed new o-rings? Any other parts replaced?

The racing idle sounds like a vacuum leak. Did you replace the intake boot o-rings? Were the boots in good condition? You're using the correct vacuum petcock with no leaks? And if you're not, the vacuum tap on carb #2 is plugged?