2 and 3 cylinders cool to touch

[gs54]

Have a 1980 gs750L with 23,000 miles on it, Took it to work this morning and ran good, started it after work and it wanted to stall at every red light, got it home and I could put my hand on 2 and 3 cylindes while it was running Ido think it needs valve adjustment its tappin pretty good and has a clunkin noise in the center of the engine, I need this bike for work any ideas?

[DimitriT]

When it starts stalling, cut the juice and pull a spark plug. Check the color. Is it wet? Oily? That will tell us a bit about where the problem might be.

Also try this. swap the ignition cables: swap #1 with #2 and #3 with #4. Does the problem move to cyls #1 and #4? Then it might be the coil. If it stays with #2 and #3 then fuel system is suspect (carbs).

[gs54]

when I put 2 into 1 and 3 into 4 it wont start

[quakeholio]

2-3 fire while the pistons are near TDC, while 1-4 will be going to BDC. Engine can not run if the wires are switched from the set they were ment for like that. Try swaping the whole coil, and that should get the problems to duplicate on 1-4.

[DimitriT]

My instructions worked on the my 550 so I don't know what's up. Maybe the 550 fires at both TDC and BDC? I guess you may need to physically swap coils to test it out.

[wiredgeorge]

First, you really need to develop a different technique for checking the pipes to see if they are hot. They get hot enough from radiant heat from the pipes next to them... I use a spray bottle. If the cylinders are not firing, the water will roll off and if they are, it will vaporize... If you don't have a spray bottle, you can improvize by... ah never mind, I would prefer to be discrete about the technique I was about to describe... hehe

OK... 2 & 3 indicate electrical issue. 1&4 fire from one coil and 2&3 the other. FIRST you need to do some trouble shooting and you were on the right track but just took a wrong turn... If you have a bad coil, the easiest way to figure it out is to remove the 1&4 coil and swap it for the 2&3 coil. You don't need to unbolt the coils.... just swap wires. Here is how:

1. two wires attached to the 1&4 coil. One is from your ignition and the other is power. It doesn't matter how they are attached on the two coil lugs. Pull them off. Remove your 1&4 plug wires. You might want to mark them hehe Do the same for the 2&3 coil. Put the wires that HAD BEEN ON the 2&3 coil on the 1&4 coil. These wires make the coil a 2&3 coil so make sure the plug wires connect to 2&3 spark plugs. OK.... you have a set of wires left that need to be hooked up so do the same for the other coil. You have swapped coils.

2. Fire up bike and check to see if 2&3 still get cold. If not and the problem moved to 1&4, you now have isolated the problem a bit.

If the problem DID NOT move, then both the 2&3 plugs are bad or there is a carb problem when those cylinders are not getting gas or you suddenly lost compression; probably due to valve clearances not being there.

If the problem DID move, then your problem was in the coil or the ignition. Not sure if you have points or an electonic inition but if it is points, then the points or condensor for that side has died. If you have an electronic ignition, the pickup coil or igniter may have died. Test the coil first using a multimeter. If you put the meter in OHMS on lowest range and put the probes on the two coil lugs, you should get about 4 Ohms resistance. If you get less or more, the coil is likely bad. Then put the meter into 20K Ohms range and put the meter leads on the two plug ends or pull the plug wires and put the leads where the plug wires went in the coils. You should get about 13-15K Ohms. If that doesn't test out, the coil is likely bad. If the coil tests OK for both primary and secondary impedences (the two checks you made), then the problem is in the the other ignition areas I just mentioned... a manual will help for testing the pickup coils and igniter if you have an electronic ignition. If you have points, just replace the points/condensor.