88 GS450, Dies going in gear & other weird stuff

[kb9lae]

I have been trying to revive my 88 GS450 getting ready for riding. The symptoms are:

It starts up and idles fine, revs just fine as well. As soon as I put it into first gear or second gear it dies. Sometimes I was able to get into gear and test drive it but it dies either in 1st, 2nd, or 3rd. Never made it more than 100 ft distance test driving it.

What I've, done is the following:

Cleaned and dipped carbs, they are clean now. Took air filter out cause the engine was sucking bits of it into the carbs (gonna order one soon). Cleaned gas tank and installed inline fuel filter. Left cylinder was dead and not getting hot, so I installed new plugs fixed that problem. I thought that maybe it might be the clutch safety switch but I unhooked it behind the headlight in the bucket and closed the circuit and no change. I also tried disconnecting the side stand switch but no change. I checked for air leaks around the intake boots by spraying carb cleaner around the carb to intake and the carb to air cleaner boots, no change either. I thought that initially the clutch might be stuck and went through all the gears and rocked it several times back and forth. That did seem to help the bike shift easier. I adjusted the clutch cable and the screw and jam nut behind the small cover on the left side engine case and no change either other than better clutch handling (at least it seems so).

I am at a loss and could use your help trying to determine what is wrong. I am thinking I might need to check compression, check timing (but I do not know how to do it), or adjust valve clearances (don't know how to do that either). Do you guys think I am on the right track or should I look somewhere else?

Sorry about the long post.

[kb9lae]

Carb Adjustment screws

I was searching info on the 88 GS450 carbs and found posts concerning fuel mixture screws and and drilling to expose them because they are hidden. I have two adjustment screws facing up between the carbs and the intake boots (not air cleaner). Are these the screws the posts were refering too or are there truely another set of mixture screws hidden somewhere?

[snark]

A couple of dumb ideas...but worth trying from my expierience with '80's and '81's.

First, make sure that you are getting a GOOD spark on both cylinders. I've had them idle o.k. and rev fine with one dead on, but die when I put it in gear and put a load on the engine. I actually made it home on one cylinder once, but the bike was struggling. New plugs will rarely fix a dead cylinder.

Second, and don't laugh...how old is the oil and how long did the bike sit before it was revived? There is a small possibility that old oil is gumming up the clutch and tranny making it too stiff. This didn't stall the bike, but one I revived shiffed a lot smoother and had better clutch feel after 3 oil changes.

If the spark is your problem, test the igniter. These bikes have a solid state ignition so there is no way to set the timing.

[txironhead]

Actually, I believe your problems are much simpler in nature.

#1: These bikes do not like to run without a filter. There has to be something creating a slight vacuum coming into the carbs. Doesn't seem like much but it can affect a lot.

#2: Inline filter. As much as I hate running anything without an inline filter as backup, they wreak havok on GS bikes. With a simple vacuum-operated siphon petcock, even a high-flow filter will starve your carbs under load. Clean the screen in the tank, make sure the tank's clean and rust-free, toss the inline filter and run high-quality gas (reputable stations, not necessarily high-octane) and keep the tank full as much as possible.

[kb9lae]

I took your advice and changed the oil and filter, also put in new a air filter element. I took out the inline fuel filter and checked the fuel petcock. The diaphram looked good and it was doing what is supposed to do under vacuum. So far it starts up and goes into all gears just fine until it warms up (about 15-20 minutes) then it dies going into gear and acts very tempermental. If I let it cool down and try again it shifts just like it's supposed to until it warms up again. The only thing I've done that I forgot to mention was I added about 1.5 oz of seafoam to the fresh gas I added into the tank. I've owned another GS450L about 4 years ago and based on that I haven't noticed any strange noises coming from the engine. In fact it sounds pretty normal. I don't have a manual yet and am stumped at this point.

[txironhead]

The only other thing I can think of is possibly timing (which apparently isn't adjustable on this bike?) or weak spark. Some electrical components work fine when cool then overheat when the bike is warmed up. Might be possible that your charging system is the culprit, if something overheats and doesn't produce enough of a charge, the coils can't produce a hot enough spark. Just trying to "linear think" this....

Maybe you should follow the stator papers, or check the resistance of the coils. I don't personally know how to do that on your bike but there's plenty of posts on the subject here.

[kb9lae]

Problem Solved

After trying to test drive it again with no luck. My dad and I started to diagnos the electrical system and by shear luck almost immediatley noticed that when the side stand was bumped just the right way the engine would die. Sure enough after a more thorouh look. The side stand safety sensor was the culprit. We took it off and cleaned it but it didn't fix the problem it only made it worse. It turns out that the smallest bump would move or wiggle the side stand cutting the engine off. I guess the springs that hold it up are a little weak. So we bypassed the switch and it works reat now. I guess that I only need to get the registration done now and hit the road. Thanks for all your advice guys.