3 and 4 apparently not firing

[JMHJ]

I just got a '91 GSX1100G...

I did a valve clearance adjustment today plus a few other little things. I put it back together and now it's dumping fuel out the right side exhaust drain holes (at least).

After just a few minutes of running and seeing there was a problem, I felt the #s 3 and 4 pipes and they weren't hot but 1 and 2 were too hot to touch. I thought I got the plug wires mixed up, but they are correct, at least as far as how they are labeled. They seemed to push back onto the plugs properly also.

I don't know what I did; I'm going to pull the tank off again tomorrow and trace the plug wires back, but I thought someone might have a suggestion.

Thanks...

 

[JMHJ]

Not making sense to me here; pulled the plugs this morning - 3 and 4 are wet, 1 and 2 are dry, matching what I saw last night with the cold/hot pipes.

The plug wires seemed right, with the ones from the left side coil going to 1 and 4 (as labeled), and the right side coil going to 2 and 3.

It would make more sense if 1 and 4 were out or 2 and 3, but it's 3 and 4. It's like only one wire from each coil is powered (that's not possible, is it?).

Surely this is something really simple that I'm just not seeing.

btw, I'm sort of looking at this thing as a somewhat modernized GS, even though it doesn't technically fall into the year range here... it certainly seems very similar to me as the GSs I've had.

 

[Nessism]

I suggest you check spark on 3 and 4. If you have spark, the problem is not the wires.

 

[JTGS850GL]

I put it back together and now it's dumping fuel out the right side exhaust drain holes (at least).

Thanks...

I suspect that there is your problem. Fuel being dumped into right side is not electrical. Cylinders 3 and 4 are not tied together alone buy any single electrical component. 1 & 4 are fire together and 2 & 3 fire together but not 3 & 4 so it's carbs/fuel related. Check and make sure you connected all the fuel and vent lines correctly when the tank was replaced after the valve job.

 

[tkent02]

Both plugs on a coil are in the same circuit, the current goes in one spark plug, around and around inside the coil, then out through the other one. It's not really possible to have a spark on one but not the other, excpt for a bad wire leaking sparks to ground, or a bad spark plug cap.

Any chance you got a couple valves way too tight? Did you mess with the carburetors?

Confirm it was running fine before you did anything to it?

 

[GSX1000E]

Leaking fuel at the O-ring around the fuel needle seat is the usual culprit. Mr. Barr sells the correct O-rings for them as they are the same as the 34-36CV carbs.
He also has the tiny little O-rings that seal the fragile choke tubes to the carb body. It is well worth buying his CV carb kit just for those two O-rings.

 

[tom203]

"....plug wires mixed up, but they are correct, at least as far as how they are labeled"

skip labels and confirm directly that left coil is connected to 1 and 4 and right is to 2 and 3

 

[JMHJ]

Many thanks for the replies here.

It's a fairly low mileage bike (18k) that has sat some while the PO was out of the country. It needs the carbs cleaned. I rode it home to OK from CO 700miles this week and it did fine on the road (i.e., above about 4k rpm), but shuddered in town at lower speeds/rpm.

Before I saw any replies here I swapped the 1 and 4, and 2 and 3 plugs (left coil was in fact 1, 4; right was 2, 3; and the wire labels look like factory), and tried it again. It spit gas briefly again from the right side, but the pipes all began to warm up. I rode it a couple of times since it had stopped blowing gas right out onto the pavement, and by the time I got back from a 20 mile or so ride, it was back to "normal" - responsive, with lotsa power outside the low rpm range, but not right at low speed.

I didn't run anything through it except gas on the trip, but I'm going to try some B12 Chemtool for a tank or so before I tear into the carbs, though I don't have a lot of hope in that. I noticed it seemed to be idling higher when I got home this week than it had on the trip. I parked it and didn't run it again after that until after the valve work (I set all the intakes @ .13-.14, and all the exhausts @ .19-.20mm; none of them were off by much, but I thought it was noisier than it should've been).

I'm goint to put some cleaner in the gas, and get it out on the road here again in a bit I think.

Thanks for the O-ring info., btw; I was hoping I could get them from him, but I didn't know.

 

[tkent02]

The changing idle could just be an elevation thing, but you didn't say.which you went for 700 miles, so maybe not.
Clean the carburetors, they need it.

 

[JTGS850GL]

The higher idle could also be from a better valve adjustment.

My guess is that the original problem was caused by leaking float valves. It's very possible that you have a leaking petcock as well. Both are very common problems with a 30 year old bike. The combination would leave you with raw gas flowing into the engine and flooding the related cylinders causing a no fire situation on those. Wet plugs would confirm this as well. Check your engine oil and make sure you don't have a gas smell from there. Also verify that the oil level is not high. If so, change the oil and filter right away.

I feel a carb rebuild is in your future...

Here's a link that will help you with the rebuild: Carb rebuild tutorial

Take a gander here as well: BikeCliff's Website. Tons of information along with many factory service manuals there.

 

[JMHJ]

Yep, doing the carbs is not an option; no carb cleaner in the tank is going to fix this. It's still spitting gas out the exhaust drain, apparently intermittently, and I'd say it's not even rideable after the jaunt I just took. Maybe I barely made it home from CO.

I changed the oil before I did the valves, but I'll check to see if it's become contaminated. The stuff I drained was normal.

I'm sure I'll be posting up in the carbs section before too long, tutorial notwithstanding, .

My wife warned me, sigh... "isn't it going to have the same problems as your other one, carburetors, etc.; why don't you get a newer one?" "Well, the newer ones are a liiittle bit more expensive, besides I like these." I guess it's time I learned how to do the carbs part of having an older bike.

 

[JTGS850GL]

Sorry, but that tutorial wont be of much help. Just realized that yours is a 1991 GSX and not a 1980's GS. Not going to be much help at all. Assumed GS because that's what this site is devoted to. GS series bikes from 1976-1987. You still have a carb issue though.

 

[JMHJ]

Au contraire, I think it will be of great help, in terms of general info. about blasting out the passages and so forth; I'm going to reference the other one from Cliff's site also. GSX1000E's post notes that the o-rings are also the same, if I understood right.

I've got them out and laying on a piece of cardboard in the garage now; that's as far as I got. I'd like to be able to get that airbox out to make sure it's clean inside, but I don't think that's happening; not w/o taking the alternator off (which is under it on this bike, not on the left side like a stator). And even then maybe not... I'd like to do away with it and get some nice pods, but I have a better chance of getting this right w/o messing w/rejetting, etc.

I looked at the oil too - there is more of it now; that is, it's more full, so yes, it must have some gas in it. I hope the 35 miles or so of riding I did today didn't hurt anything.

BTW, my first bike ever was a '88 GS450L (the bike that started it all ), titled as such and everything. I've found few references to that year though; usually '87 is given as the last year.

Sorry, but that tutorial wont be of much help. Just realized that yours is a 1991 GSX and not a 1980's GS. Not going to be much help at all. Assumed GS because that's what this site is devoted to. GS series bikes from 1976-1987. You still have a carb issue though.