Did the rain screw up my bike or was it a coincidence?

[Spiff]

So I picked up a gsx 750 last month that had stood for the last 5-6 years. Non runner.
I cleaned the carbs and got it running. Carbs where caked with old fuel residue, most jets clogged etc. Got it running, ran good for the night then I parked it waiting for some new tires and parts. Couple of weeks go by and On Sunday I decide to take it for a ride after fixing the forks and new tires, it had been parked outside for the night in the rain so it ran a little rough to begin with but after half an hour on the road it ran like a gem, absolutely smooth like butter. I'm thrilled!
I fill it up with some 98ron and ride the half hour home to my girlfriends house and park it for the night, again outside.
Next day its been absolutely pouring down the entire night and morning. I don't think much of it but when I go to start the bike it doesn't wanna catch at all, I run out of battery. Borrow some jumper cables and eventually get it running but it doesn't wanna idle anymore, have to hold the throttle, choke didn't seem to have an effect at all(made it worse it seemed.)
And half of my fuel is gone after trying to start it!
I baby it home, trying to get it over 4k revs it just brakes up.
I drain the air filter box of fuel, I drain the float bowls, I get it running, drain the oil which is full of fuel. And now I wonder how the rain could have f***ed up everything or if it was just a coincidence and that something loosened and lodged itself in the needle valve or something like that when I tried to start it.
I also noticed today that my regulator might be bad so that might be why it went out of starting power so fast and why it seemed to brake up under high load.
I put the drained fuel to the side but it didn't separate so I don't think water entered the carbs..
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[Big T]

More likely plug wires or caps

 

[Suzukian]

Spray WD-40 (it's a water displacement0 and that should get the water out of there. If the bike just starts a wee bit better, you need new plug wires and boots (for the spark lugs, not your feet).

 

[Rijko]

Attack issues one by one.
I would start with the fuel issue.

I fill it up with some 98ron and ride the half hour home to my girlfriends house and park it for the night, again outside.

... half of my fuel is gone after trying to start it!
... drain the oil which is full of fuel.

For this to happen, 2 things have gone wrong :

* the petcock kept supplying gasoline with engine turned off.
Either left on PRIme, or needs checking/refurb/replace.
* One or more carb needles let fuel through while they should be closed.
Needs cleaning/refurb/replacement.

 

[Nessism]

I agree with Rijko

It sounds like more than one problem.

Float valve not sealing, or a failed petcock, or both, flooding the engine with fuel.

Secondly, the rain could well have gotten into some electrical connections, causing one or more cylinder to misfire.

I'd do as suggested, and deal with the gas issue first. Also, go through the Newbie Mistakes thread and make sure all your bases are covered.

 

[Spiff]

Attack issues one by one.
I would start with the fuel issue.



For this to happen, 2 things have gone wrong :

* the petcock kept supplying gasoline with engine turned off.
Either left on PRIme, or needs checking/refurb/replace.
* One or more carb needles let fuel through while they should be closed.
Needs cleaning/refurb/replacement.

I've checked the petcock, it works as far as I can see and only supplies fuel when it's supposed to. The O-ring on the needle valve on carb 2 was shot though. I replaced it and nothing is leaking now.
I have since spent the day doing some fault finding and here's some of my findings:
-Charging system: stator delivers all the voltage you want. The regulator however isn't suppying the +14 volts it should, I fully charged the battery yesterday but I'm not reading much more than 13.5volts, even lower if I turn on the headlight and rev it to 5K as per the fsm. Should I replace the reg/rec?
-After lots of idling I checked plugs, which where pretty sooty, manual states 3.5 turns out and that's what they are. This is what it was when I got the bike too.
-To clear the plugs I spent 30-40 minutes riding it in absolute anger, and from idle it pulls great right up until about 3.5-4k RPM then it kinda feels like it doesn't accelerate as hard anymore, like it isn't getting enough fuel.
I checked plugs afterwards and plugs 1 and 4 where pretty white. Number 2 somewhat greyish brown(slightly sooty) and number 3 tan brown(looks ok). I'll upload a picture of them soon.
But It seems at least 1-4 isn't getting enough fuel or perhaps weak spark?
The bike has a 4-1 exhaust but engine is otherwise stock.

 

[Spiff]

Sparkies

 

[Suzukian]

13.8V is normal. 14+ is too much. The plugs don't look that bad. I'd spring for a new set, put a timing light on each plug to see how they are firing. You could have a bad coil, or as I initially said, plugs wires. I still think your wires should be checked, but you haven't stated how the bike runs when it's all dried out.

 

[Spiff]

13.8V is normal. 14+ is too much. The plugs don't look that bad. I'd spring for a new set, put a timing light on each plug to see how they are firing. You could have a bad coil, or as I initially said, plugs wires. I still think your wires should be checked, but you haven't stated how the bike runs when it's all dried out.

Oh yeah, last point on my previous post. That's from today after everything has been dismantled and dried and checked. Like I said it rides ok but feels kind of sluggish under acceleration.
It's tempting to throw the coils and wires from my other gs on to see if it's the coils or wires as I know that bike ran good last time it ran.

 

[Rijko]

I've checked the petcock, it works as far as I can see and only supplies fuel when it's supposed to.

I take it this is the vacuum operated petcock, and you did not leave it on prime.

Let's think about what happens when you shut off the bike and the petcock functions correctly.
The engine stops, the vacuum disappears and releases the hold on the petcock which stops the flow of gas to the carbs.

You have one or more carbs with failing float valves : so now all the gas that is above that float valve will leak somewhere.
Drip out, or into the engine or air filter ...

Think about how much gas that is.
A little bit in the fuel hose from petcock to carbs, and a little bit of gas in the carbs.
Not the gas below the float valves, in the carb bowls, that can't go anywhere.
Alltogether less than a shot of tequila

BUT ... you lost half of a full tank of gas, had to drain the air filter box, and have the oil full of gas.
With a properly functioning petcock, not left in PRI ... that's NOT possible.

See, that's why i said you have an issue with one or more float valves AND the petcock.
So even if it may look like the petcock is functioning properly now ... it's not.
Not consistently, reliably, thrustworthy.
It WILL fail again.

Make sense ?

 

[Grimly]

Originally posted by Suzukian
"13.8V is normal. 14+ is too much."​

13.8v is the just off charge voltage of a resting battery.
Normal charging voltage is 14.0 to 14.5V.

 

[Spiff]

Originally posted by Suzukian
"13.8V is normal. 14+ is too much."​

13.8v is the just off charge voltage of a resting battery.
Normal charging voltage is 14.0 to 14.5V.

I'm inclined to agree, the manual states "if it's less than 14 or more than 15 the regulator should be replaced".
And my gs with a regrec from Rick's for a LiFePo battery charges a steady 14.1V.
So I feel this bike is not charging enough, I rode in the dark tonight and when I put on my indicators you could see the headlight beam go dim in sync with the indicator lighting up.

 

[Spiff]

So according to the great internets a weak spark can cause a lean condition. A lean condition can also induce blueing of the chrome pipes. Now I've noticed that the header pipes have had a blueish tint to them since I picked up this bike. So what I suspect is: someone has put on the 4-1 exhaust, hasn't rejetted the main jets and that's why it's leaning out under full throttle pulls.
Or adjusted the needle, what do you guys think? Up the main jets or try to shim the needle?
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[Suzukian]

I'm inclined to agree, the manual states "if it's less than 14 or more than 15 the regulator should be replaced".
And my gs with a regrec from Rick's for a LiFePo battery charges a steady 14.1V.
So I feel this bike is not charging enough, I rode in the dark tonight and when I put on my indicators you could see the headlight beam go dim in sync with the indicator lighting up.

On my '83 GS750ES, at idle, 14.8 is the optimal voltage, that is the voltage you should have. If the bike were putting out 15 bolts @ 5000 rpm's, then that would be fine. You should be checking how much your battery drop when you have it fully charged, and see how low the voltage goes to when you hit the start button. If it drops down to 9 volts, you need a new battery. If you manual says 15 volts, then you have a bad battery. If your manual says 15 volts at idle, which is how you normally check your charging system, then it's 15 volts. You could have a weak battery and a charging problem. They go hand in hand many times.

I think you have a petcock issue also. You should change all those hoses, they may be dry rotted. A crankcase full of oil has nothing to do with the needle valve, unless it's being pushed open by a faulty fuel petcock. I think you have a few issues going on. Fix one at a time. Best of diagnosing and fixing to you.

 

[Spiff]

I take it this is the vacuum operated petcock, and you did not leave it on prime.

Let's think about what happens when you shut off the bike and the petcock functions correctly.
The engine stops, the vacuum disappears and releases the hold on the petcock which stops the flow of gas to the carbs.

You have one or more carbs with failing float valves : so now all the gas that is above that float valve will leak somewhere.
Drip out, or into the engine or air filter ...

Think about how much gas that is.
A little bit in the fuel hose from petcock to carbs, and a little bit of gas in the carbs.
Not the gas below the float valves, in the carb bowls, that can't go anywhere.
Alltogether less than a shot of tequila

BUT ... you lost half of a full tank of gas, had to drain the air filter box, and have the oil full of gas.
With a properly functioning petcock, not left in PRI ... that's NOT possible.

See, that's why i said you have an issue with one or more float valves AND the petcock.
So even if it may look like the petcock is functioning properly now ... it's not.
Not consistently, reliably, thrustworthy.
It WILL fail again.

Make sense ?

Like I said in a previous post: The float valves where fine, it was the O-ring on one of them that failed and allowed it to leak. And I think I need to clarify a little more because I didn't loose all the fuel in an instant. It was over two days. And yes the petcock was left intentionally on prime on day two to see if it would still leak, and because the bike was on the centerstand and tilting forward the gas ran into the engine(which is impossible for me to see from the outside). It wasn't untill I jacked up the front end to tilt it back that it started to run into the airbox and out the drain hose where it filled up a jar pretty quickly.
Also you have to consider that even with a running engine the amount of fuel trying to enter the carb outweighs the amount of fuel being used (at low throttle at least) so with a failed needle valve or o-ring the carbs are still gonna leak fuel at a decent rate.
Again I checked the petcock several times yesterday and didn't found it faulty.
There is one of those see through fuel filters on there so it's easy to check fuel supply.
And even so, lets say the petcock is faulty and fuel runs all the time: As long as the needle valves and o-rings are good the carbs will not overflow, because they shut of the fuel.
Anyways, not saying you're wrong, not saying I couldn't have accidentally put the petcock on prime instead of on after i filled her up and fuel started leaking on the way home and kept leaking all through the night....
And I will definately keep an eye on the petcock(and order an o-ring kit and needle valves.

On my '83 GS750ES, at idle, 14.8 is the optimal voltage, that is the voltage you should have. If the bike were putting out 15 bolts @ 5000 rpm's, then that would be fine. You should be checking how much your battery drop when you have it fully charged, and see how low the voltage goes to when you hit the start button. If it drops down to 9 volts, you need a new battery. If you manual says 15 volts, then you have a bad battery. If your manual says 15 volts at idle, which is how you normally check your charging system, then it's 15 volts. You could have a weak battery and a charging problem. They go hand in hand many times.

I think you have a petcock issue also. You should change all those hoses, they may be dry rotted. A crankcase full of oil has nothing to do with the needle valve, unless it's being pushed open by a faulty fuel petcock. I think you have a few issues going on. Fix one at a time. Best of diagnosing and fixing to you.

If where talking regular led or agm batteries like on this gsx then yes, but my gs runs a lithium battery so I opted for a lithium specific regulator with a lower charging voltage for that one.
The battery on my gsx is brand new and was fully charged before I ran the tests. The fuel hoses where changed when I cleaned the carbs.
I'm trying to fix it but it seems as soon as I fix one thing another thing pops up And then fall and winter is creeping up real fast over here now so I'm also fighting the clock, to late and I have to wait untill next year to do anything....​

 

[Rijko]

... And I think I need to clarify a little more
... And yes the petcock was left intentionally on prime

thanks for clarifying that, indeed that was the point i was making

 

[Cipher]

The o rings that seal the brass seat of the needle valve age and allow fuel to seep slowly past.
They are a bugger to remove without damaging the brass.

I had a sump full of gas once because of this. valves fine o rings dead.

 

[Suzukian]

Like I said in a previous post: The float valves where fine, it was the O-ring on one of them that failed and allowed it to leak. And I think I need to clarify a little more because I didn't loose all the fuel in an instant. It was over two days. And yes the petcock was left intentionally on prime on day two to see if it would still leak, and because the bike was on the centerstand and tilting forward the gas ran into the engine(which is impossible for me to see from the outside). It wasn't untill I jacked up the front end to tilt it back that it started to run into the airbox and out the drain hose where it filled up a jar pretty quickly.
Also you have to consider that even with a running engine the amount of fuel trying to enter the carb outweighs the amount of fuel being used (at low throttle at least) so with a failed needle valve or o-ring the carbs are still gonna leak fuel at a decent rate.
Again I checked the petcock several times yesterday and didn't found it faulty.
There is one of those see through fuel filters on there so it's easy to check fuel supply.
And even so, lets say the petcock is faulty and fuel runs all the time: As long as the needle valves and o-rings are good the carbs will not overflow, because they shut of the fuel.
Anyways, not saying you're wrong, not saying I couldn't have accidentally put the petcock on prime instead of on after i filled her up and fuel started leaking on the way home and kept leaking all through the night....
And I will definately keep an eye on the petcock(and order an o-ring kit and needle valves.



If where talking regular led or agm batteries like on this gsx then yes, but my gs runs a lithium battery so I opted for a lithium specific regulator with a lower charging voltage for that one.
The battery on my gsx is brand new and was fully charged before I ran the tests. The fuel hoses where changed when I cleaned the carbs.
I'm trying to fix it but it seems as soon as I fix one thing another thing pops up And then fall and winter is creeping up real fast over here now so I'm also fighting the clock, to late and I have to wait untill next year to do anything....​

Thanks for clarifying the type of battery you are using. That kind of detail helps a lot of people, and educates others like me.

 

[Spiff]

Here's some more info for you on the case:

-seems you where right about the petcock after all, it does dribble a little in the ON position. It's tight in the RES position though. This is probably why this didn't happen untill I filled it up. Also this leak was two small to be noticed though the fuel filter. I stand corrected.
-ignition system has been checked. All plug caps are wack except for one. Coincidentally the same one that shows a richer mixture then the others. The worst plug caps where on 1-4 with over 800k ohms, the plugs with the leanest condition.
I'm gonna steal the caps of off my 1100 and see if it accelerates as it should.
Stay tuned...



(see what I did there?)

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[Rijko]

see what I did there?

you came here for advice, learned something, and improved your bike is what it looks like to me.
And reported back so we could see the advice was sound. (we learn from that, too)

Sounds like WIN-WIN to me ... thanks