I need some help pretty bad - '78 GS1000

[KnuckleBuster]

I just got my '78 GS1000 put back together after replacing a cracked piston. I've only owned the bike for about a year and have only put 500 miles on it. My problems arose as I was taking the bike apart and when I started it this evening after reassembly. They are as follows:

1. My headlight, guage lights and turn signals no longer work. I had a problem once in a while with the turn signals, but never the other lights. Just before I tore the engine down I noticed that these lights no longer worked. Fuses seem okay and the Neutral light and oil pressure light work. Starter works and horn works with no problem.

2. When trying to static time the ignition as per the Clymer manual, I set the points to the reccomended gap, but when it came time to turn the plate to time the ignition I had to turn it quite a ways (clockwise) to get the points to open. Once the 1&4 points were timed, it was nearly impossible (not enough travel) to get the 2&3 points to open at the right time. I was using a multimeter checking for continuity as per the manual and found that there was half the continuity when the points were wide open as when they were closed. There shouldn't be any, right?

When I got the bike started, I tried using a timing light to set the points. I had to turn the plate as far as I could and still the timing marks for 1&4 were not quite right. Then I went to the 2&3 side and moved the points from one extreme to the other with no cahnge in the running of the engine or movement of the timing marks.

3. It seems that the engine is only running off one cylinder. Three of the four headers were cool - slightly warm to the touch while the fourth almost gave me blisters. The spark plug from that cylinder was pretty sooty while the other three looked gas fouled.

Where do I start? Solid state ignition? New plugs?

Also, can anyone identify these carbs?



They were on the bike when I bought it and were soaking the inside of the intake ports with gasoline. I took them off and put the originals back on but it runs like crap now. Will these carbs fit my bike and if so am I better off with them or the stock carbs? I have a DynoJet kit for the stock carbs that I haven't installed yet.

Any and all help will be greatly appreciated.

Thanks,
Jay

[SqDancerLynn1]

I would go back and adjust the point gap with a feeler gauge .012-.016 Then try to check the timing again. Not sure what the carbs are from, If they were onthe bike I would take them apart and clean the needle & seat assembly and replace the O ring on the seat assembly. Check the electrical connector plug under the tank

[Anonymous]

The carbs are newer constant velocity jobs, could be off an 80's model 1000 or an 80 and up 750,850 1100 etc. Measure the bore on the butterfly end and that will tell you the size; 30, 32,34mm etc.

[KnuckleBuster]

SqDancerLynn1 - that's where I have the gap set now. For some reason I just can't time the thing. The reason I took the carbs pictured off the bike is because they were dumping fuel right into the engine. I put the original carbs back on, but now it runs even worse. I'm stuck here.

On a different note, what kind of Dyna ignition should I get for my GS? I'm thinking the Dyna S or the Dyna III. Any thoughts one way or the other?

Thanks,
Jay

[SqDancerLynn1]

The dyna S is all you need if that is what you want to do, you will also have to change the coils. You can make the points work just fine . Just make sure the points are on the high spot of the cam and adjust the gap if the gap is not correct you will have a problem adjusting the timing. Another possibility is that you are trying to set the timing at too high of an idle speed. The closer to 1,000 rpm's the better, otherwise the timing advance starts to work. Or the timing advance mechanism could be stuck in the advanced position

[focus frenzy]

those are 80 or later mikuni CV carbs, if they are from a 80 or later 1000 or 1100 they would require the intake boots from a 80 or later engine to fit on a earlyer small port engine.
if you used the intake boots that were on the engine with the cv's carbs when you put the original carbs back on you probably have vacume leaks at the intake side of the carbs.

[saaz]

I also have a 78 GS1000.

The carbs are off a later model bike. Was it running ok before, as the air intakes, boots etc are quite different between the 78 slide carb models and later CV carb models. If it was running ok, make sure no air leaks and vacuum and petrol hoses are connected correctly.

The cool/hot exhaust pipes sound like either problems as per the above, or a really bad carb synch/tuning problem - the timing being way off alos affects this.

Points..wonderful things but I prefer my replacement electronic ignition. What you describe is a common problem as the points age. Assuming the condensors are ok (they stop the points wearing even more and arcing...looks good in the dark!) what you have to do is either put in new points, or modify the gap on the 1&4 so you can get the timing right and set 2&3 correctly. When you have to perform this juggling the point are due to be replaced. Old CB 750 points works, as do GS750 etc. You should be able to get it running with the points, but an electronic ignition is a better long term bet. (I used to own a GT750 with three sets of points, so the GS is simple!!) I used to set the timing so it was spot on at full advance. Older points do bounce around a bit and the timing is less stable. The static method does not work well with older points as the actual point of opening is different to what the point gap is (the wear, pitting and electrical resistance changes with age). I used to use a dwell meter while it was running to get it right, as what you are trying to do is set dwell by approximating with a points gap.

As to where to start, gets the points and timing right, check the basics with the carbs (right conections etc) before fiddling too much. The spark and carbs have to be up and working before you can identify other problems.

[KnuckleBuster]

The carbs are off a later model bike. Was it running ok before, as the air intakes, boots etc are quite different between the 78 slide carb models and later CV carb models. If it was running ok, make sure no air leaks and vacuum and petrol hoses are connected correctly.

It seemed to run great before, but this is my first bike, so who knows....

It had a cracked piston when I bought it (I didn't know it at the time) and still seemed to run strong. When I took the carbs in the pictures off the bike, gas literally ran out of the filters and intakes. My plugs were all carboned up, as were the pistons and inside of the head. The tip of the exhaust pipe was also carboned up pretty well.

Someone had attatched the filter pods to these newer carbs using what looks to be radiator hose. As for the intake side of things, both original carbs and newer carbs seem to fit into the intake boots snuggly. However, it does seem as though when I tighten down the clamps to hold the carbs in the boots they bottom out but could still be a little tighter.

I've got a Dyna S ignition on the way along with a set of 3 ohm coils and 8mm plug wires. I think I may have a short somewhere, so I'll try to sort that out.

I don't have an airbox, so all this is being done with pods on the carbs. Should I install my Dynojet 3 kit before I go any farther, or stick to the stock jets 'til I get things sorted out?

Thanks very much, you guys are really helping me out,
Jay

[Anonymous]

If you are using pod filters, you've got to rejet. It just won't run for s**t unless you do and you'll just end up chasing you're tail.

[KnuckleBuster]

Thanks Gary. As soon as the rain stops out here, I'll try it.

[saaz]

It sounds like you have a lot of different things going on at once here! I am not a CV carb guru, but keep us posted on how you are going. US 78 Gs 1000 types have to stick together )