Recent sputtering

[pharris1992]

Hey guys, I'm back for more help. I have a 1983 gs750es that has been great so far. Yesterday coming home from work I came up to a stoplight and as I stopped the bike started running rough, very choppy like. It would go between idling normally (about 1500 rpms) to very low(just about 1000 rpms). As I accelerated it started surging back and forth between low and regular power. Now it still starts up, but goes from running smooth one minute, to running like crap the next.

I had about 3/4 tank of gas when this happened, from the same place I always get it.

Thanks so much for any help!

 

[tom203]

At 3/4 tank of gas, sounds like you filled up recently. I'd dump this gas into my car (from tank and fuel bowls) and try different gas and see what happens. Anyplace can give you bad gas- water in gas does funky things.

 

[pharris1992]

Thanks! I will definitely try that tonight. If that doesn't do it where should I go? New plugs maybe?

Thanks again!

 

[razor02097]

intermittent running issues almost always points to electrical problem. I would make sure the connections to the coils are clean and check the plugs for fouling.

 

[pharris1992]

I will check that too. Has anyone ever had luck finding plugs at auto part stores? I believe the service manual calls for ngk d8ea. Thanks again!

 

[ssbrazo]

I've had luck at some napa's. But not all napa franchises are created equally.

If you go online most of the major auto parts stores have "in stock" status if you set your local store and search the part number. I would definitely call first even if it says they have it.

 

[Loki]

I will check that too. Has anyone ever had luck finding plugs at auto part stores? I believe the service manual calls for ngk d8ea. Thanks again!

Don't know your location but, Advance, O'reilly's stock them. Run some Seafoam in that fuel, see if it clears up then continue troubleshooting, hard to say what it could be, maybe list what you have done maintenance wise and other conditions / symptoms.

 

[pharris1992]

I will call around. Also Loki are you recommending trying seafoam in the gas I already have in there? I have about a third of a bottle, or ~5 oz sitting in the garage.

 

[Loki]

I will call around. Also Loki are you recommending trying seafoam in the gas I already have in there? I have about a third of a bottle, or ~5 oz sitting in the garage.

Yes, throw a couple ounces in, take it out and run it hard for a bit, see if it clears up.

 

[BassCliff]

Hi,

There's really not enough information, measurements, or diagnostics here to form an accurate diagnosis.

It could be contaminated/dirty gas that has deposited some gunk in your carbs.

It could be ignition, anything between a faulty plug cap to an intermittent igniter.

Let's see how the Seafoam does and we'll go from there.


Thank you for your indulgence,

BassCliff

 

[pharris1992]

I just added some seafoam, swished it around in the tank for a little and then went for a hard ride. This is my best attempt at describing what happens: The bike idles without stalling, although at 1000rpms, instead of the usual 1500. (it seems to me from an amateur perspective to not be running on all cylinders at this point.) I believe this because under light throttle (up to around 2500 rpms) it seems to 'kick on' the extra cylinder(s). When riding it seems to kick back and forth between running normally, and running poorly.

Also, the previous owner had put on pod air filters. I'm not sure whether the carbs were rejetted properly or not. But because of the easy access I pulled off the carb 1 and 4 pods to see if I noticed anything. There appears to be fuel in the carb 1 pod. Not much, but noticeable in smell and in liquid around the boot between the pod and the carb. Number 4 was dry.

Thanks again so much for all the help. This forum has been awesome!

 

[tom203]

Your first post said it had been great so far (or something similar), and then suddenly started running rough- maybe pods are to blame, but I'd look for other things first. gas in carb/pod #1 probably means fuel float seat ain't right. Check petcock operation- do you use kickstand?

 

[pharris1992]

I do use a kickstand. I guess that makes sense for pod one gravity wise. I will check the petcock. Correct me if I'm wrong, but I am making sure that fuel doesn't flow with the engine and petcock on, as well as making sure no fuel goes through the vacuum hose. Should I still be replacing plugs?

 

[pharris1992]

I haven't been able to look at the bike more but I have done more research. Could fuel through the vacuum line in the petcock cause my problem? Also could pods and not rejetting foul my plugs bad enough to cause this? Thanks!

 

[MisterCinders]

If the bike ran and then didn't, something changed. What was it?

You should know your jetting from cleaning the carbs. Sounds like that is worth doing.

If there is gas in your pods, check your oil level and smell. If fuel is overflowing the carbs, especially from a leaky petcock, it can seep into your oil/crankcase. This is ~bad~ for you. If the oil level is high or it smells like gas, change your oil and filter before starting the bike again. This is important.

 

[pharris1992]

So I tested the petcock and then replaced the spark plugs. While I had the side panels off I played around with electrical connections. I can take a picture if needed but there is a black box just to the left of the fuse box with two plugs going in a the bottom. With the bike running if I pull the plugs towards me (increasing the connection I assume) then it runs normally. Without this extra pressure it runs rough. Is there any way to repair this without replacing?

 

[tom203]

The black box with two plugs is likely the ignitor- it likes clean connections, or it will behave erratically; contact cleaner, fine sandpaper, etc. But this doesn't explain gas in pod #1.
So you tested petcock ? In "on" or "res" spot, no gas flowed when bike was off? but flowed well when you sucked on vacuum line-and no gas appeared in vac line? best to use clear vinyl tubing as vac line during testing!

 

[pharris1992]

So you tested petcock ? In "on" or "res" spot, no gas flowed when bike was off? but flowed well when you sucked on vacuum line-and no gas appeared in vac line? best to use clear vinyl tubing as vac line during testing!

Yes to everything, with the exception of clear tubing. There was no gas in the vacuum line when sucking on it, and I figured if any was coming through I would have tasted it. If you think I could have missed it I will retry with clear tubing. Would running a long piece and watching it while the bike was running accomplish the same thing?

 

[tom203]

Your petcock is good- no need for further proof. Gas in #1 must be related to kickstand use combined with leaky float needle seat- do you still have a centerstand? if so, try using it.

 

[pharris1992]

I do have a centerstand, it just needs to be put on the bike. I have been meaning to do that though. Also, with the ignitor, if cleaning the contacts doesn't help, would it be worth re soldering the connections inside? I would like to avoid replacing if possible