gs750 missing

[Anonymous]

I have a 1983 gs750e and I was out riding all day today and it ran great. I have put 600 miles on it tihs year and it has been running great. Today when I was coming home it started to miss a little and seems like one cylinder is kicking in and out. What would cause this to happen? Bad wire? Any help would be great. Thanks!!

Matt

[earlfor]

Re: gs750 missing

If its only one cylinder, could be nothing more than a fouled spark plug or a bit of carbon debris jammed in it. Possibly a loose plug wire to plug cap connection.

Earl

I have a 1983 gs750e and I was out riding all day today and it ran great. I have put 600 miles on it tihs year and it has been running great. Today when I was coming home it started to miss a little and seems like one cylinder is kicking in and out. What would cause this to happen? Bad wire? Any help would be great. Thanks!!

Matt

[Anonymous]

I just changed the plugs, and all the wires seem to be in ok shape. The problem is still there. When it is idling, you can hear the fourth cylinder just kind of sputter in once in awhile. When riding it, there isnt very much power. Any suggestions on what I have said?!

[RacingJake]

What does that #4 plug look like compared to the others.
You can swap 1-4 leads and see it the problem moves to #1 cylinder, if it does it's electrical, if not then a carb/fuel problem.

[DMPLATT]

You just changed the plugs, first, I would read the plug. If it's lean, then it MAY be a carb issue.

A few months back I lost a cylinder on my 750 on the way to work. Turns out a Plug Cap blew on me. I understand this to NOT be common at all, however you could check the ohms on the plug wires and see if they are similar.

I put new NGK plug caps on and she's never run better.

[Anonymous]

I had a look at all the spark plugs and they are all the same colour, and it looks like it may be running a little lean, as all the plugs are on the white side. It was only 5c (58f) today so I am wondering if the lack of power could relate to the carbs being on the lean side and the motor not getting enough fuel. When I was in florida a few weeks ago, the bike ran beautiful, and then when I was back in atlanta, it got colder and the bike all of a sudden started to run like garbage. ANy ideas?

[DMPLATT]

Should run fine in the cold temps. Even though I'm in Florida, I've ridden to work a few times with the temps in the mid 30's. 8O
For me, that's damn cold. Bike was fine though. Ran great. Usual couple minute warm up.

My advice is limited to my experience with MY '83 750. It ran great for a few months, then went south. I took the carbs off, cleaned them - Yada yada yada.
Ran better, but not well. I didn't have the funds for the carb synch tool.
Then my Plug cap blew.

Long story, but the moral is: When I finally got all this fixed, then got the Carb Synch Tool and synched my carbs, I became a believer. I used to have to choke it for a long time, then idle was a bit off. AFTER the synch, she runs totally sweet. Choke only for a couple minutes at best. Then a nice sweet 1400 RPM idle. (I know guys- it's a tad high, but my Tach isn't great and this is what she likes!!!).

Good Luck.

[SqDancerLynn1]

This time of year their is a big possibility of getting water/crap in the fuel especially if the station had gas delivered within an hour or two of your last fill up. Drain the fuel bowls and some fuel out of the tank into a container & check it

[Anonymous]

I was just outside having a look at things, and I pulled the pluigs to have a look at them. The number 2 cylinder plug (I just put a new set of plugs in) appears like it isnt getting fuel. Either it isnt getting fuel or the plug isnt sparking. I changed the plug with one from a different cylinder, and still it seems like it isnt firing. I put a timing gun on it and it appears like it is sparking, so maybe fuel?? Just wondering if it is possible for a carb to all of a sudden stop delivering fuel (like a float suck down)?

[DMPLATT]

Very possible. Could be a number of things. Did you smell the plug?
Also, you can hold the plug against the block and crank it over. SHould be a nice fat blue spark. If it is, then it's gotta be fuel. Unless the worse has happened and you have no compression in that cylinder. But we won't talk about that, ok? :?

Well, after reading your post again, you used a timing lite. That would mean that you are gettin juice thru the Plug Cap.

Sound like you'll be visiting the carb clean up series in the garage section of the main page. :?

[DMPLATT]

Just re-reading you initial post.

Last summer, after I'd had this bike for a few months, I stopped in to get gas. Then a few miles down the road I started to get a rough idle of sorts. Not real bad, just not as smoothe as before. So I figured I got some bad gas. Well, a couple tanks later it got better. Well, another month or 2 went by and it happened again. This time when I was cruising, I could hear this miss. The idle at stop lights would go up to 2500, then down to almost quitting. I couldn't get it to clear up. So I ended up into the carbs.
Be forwarned. These bike are the devil himself as far as the carbs are concerned. Getting them out wasn't too bad, but getting them back in was a nightmare. I swear that If I ever have to do that again, I'm going pods.
Moral of this story is that it cured my problem. Then, after I finally synched them, My choke problem disappeared as well. I used to have to keep it choked at stop lights almost til she hit operating temp. Now, just a few minutes and she idles at 1400, nice and smoothe.

Good Luck.

[Anonymous]

I just ohmed out the primary and seconday feeds on the coil. My problem seems to be on #2 and #3 cylinders, which comes off the same coil. The primary for both coils is the same at 5ohms and the secondary (plug end) is quite different, the 1&4 coil is 52ohms and the 2&3 coil is 32 ohms. The book i have for the bike said it should be between 30 and 50 but would this difference cause a shy spark?

[duaneage]

Check the intake boots between the carb and the head, spray wd-40 around them when it is warmed up and idleing. If the idle quality changes in anyway the boot or the rubber seal against the head is bad. Happens all the time to the older bikes, fortunately they are available for about 15-20 dollars each. Expensive but worth it, IMHO.

[DMPLATT]

I just ohmed out the primary and seconday feeds on the coil. My problem seems to be on #2 and #3 cylinders, which comes off the same coil. The primary for both coils is the same at 5ohms and the secondary (plug end) is quite different, the 1&4 coil is 52ohms and the 2&3 coil is 32 ohms. The book i have for the bike said it should be between 30 and 50 but would this difference cause a shy spark?

Easiest way for me was to hold the plug against the engine and crank. Should see a nice fat blue arc.When I didn't have spark, I pulled the coils and started with the meter. I'd say 32 AT the Plug cap would be good.

I'd also try the WD 40 trick. That'll let you know about the intake boots.

[Anonymous]

I guess the biggest thing is the difference between the 1 and 4 coil and the 2 and 3. The 1 and 4 is 52, the 2 and 3 is 32. If I take either 2 or 3 cap off while it is idling the rpms dont drop where if I take 1 or 4 off the motor will quit. It is sparking according to the timing gun, but maybe not enough to ignite the fuel?!?!