Very Problematic GS650

[JamesH]

Hello all-

I am working on an 82' GS650 GL-Z. I am not the owner of the motorcycle but I am working on it for a friend basically for the cost of parts.

I have posted here a few times and received useful advise in diagnosing a short in the kill switch housing area.

This is my situation: I am at a loss for why this bike will not run. Every time I do something, I have the hope that it will fix whatever of the big 4 (air, compression, fuel, spark) the bike is missing to run. Here are the details of what has been done recently by me:

• Valve clearance measurement & adjustment, all now within spec.

• Re-wiring of kill switch to fix a short caused by wire crushed against handlebars.

• New air filter

• Complete carb removal and dismantling, dipped all carburetors minus rubber & plastic bits, blew out all passages with compressed air, reassembled with new O-rings from cycleorings.com. Mixture screws are roughly 2 turns out and butterfly valves are at roughly the same spot. Carbs are ready to be balanced with vacuum gauges assuming the bike would actually run...

• New intake boot O-rings from cycleorings.com

• Most recently, the coil relay modification. I was hesitant to do this but the voltage at my coils was low. Now voltage is upwards of 10v.

Yesterday is when I reinstalled the carburetors. I was sure that the dipping and new O-rings would solve my problems. It ran, or should I say didn't run just as before. I already had the parts for the coil relay modification so I went ahead and did that. It seemed to work for what is supposed to do, which of course is to increase voltage at the coils. The bike still will not start.

The bike will run for about 3 seconds on starting fluid, on 2 cylinders. Cylinders 1 and 3 before carb work, now cylinders 2 and 4 (maybe, hard to tell).

Something I did notice is that the carb slides on 1 and 4 were kind of binding a little, getting stuck. I oiled them and that seemed to help. Maybe the 25 year old slide springs are tired? I'm not sure, this could be the problem or it could be trivial.

I basically went through the process of elimination with this bike, and the first time I pulled the carbs I did not dip them or install new O-rings...hence my doing it again a week ago to do it the right, recommended way.

Any advise for me? I really want to get this thing running so I don't have to truck a non-running bike back to the owner with a sense of failure and a lot of wasted time (although it has been a learning experience, knowledge I can apply to my own kz900)

[tom203]

Please lose the starting fluid ASAP. You know that 1 and 4 fire together, while 2 and 3 fire together, right? You did the coil relay mod, but you only get 10 volts to coils- I get that without that mod.Make sure that you put petcock on PRIME to fill up all fuel bowls before cranking.Binding carb slides shouldn't interfere with starting as long as they are at bottom.
Try Mr. Matchless test for ignition circuit. Remove signal generator cover, remove plugs from 3 and 4, reattach plug wires and hold against head. With ignition on (and kill switch on), pass a small screwdriver tip across the signal generator coil for 1 and 4- plug 4 should fire; also repeat for other coil-plug 3 should fire.

[Steve]

I agree with Tom, GET RID OF THE STARTING FLUID.

I have not yet found a weather condition or any other situation that would require starting fluid on a GS.
If it is so cold out that it won't start, you're not going for a ride anyway.
All of my GSes start very easily when the temps are below freezing.

Let's look at some of your statements:

Complete carb removal and dismantling, dipped all carburetors minus rubber & plastic bits, blew out all passages with compressed air, reassembled with new O-rings from cycleorings.com. Mixture screws are roughly 2 turns out and butterfly valves are at roughly the same spot. Carbs are ready to be balanced with vacuum gauges assuming the bike would actually run...

You did not mention verifying that the float level was correct.
I would also suggest turning the mixture screws out to three full turns.

Most recently, the coil relay modification. I was hesitant to do this but the voltage at my coils was low. Now voltage is upwards of 10v.

If you are only getting 10 volts at the coils after the relay mod, you have problems. You should have full battery voltage, so if your battery only has 10 volts, it's time for a charge or a change.

The bike will run for about 3 seconds on starting fluid, on 2 cylinders. Cylinders 1 and 3 before carb work, now cylinders 2 and 4 (maybe, hard to tell).

Make sure you have the wires on the correct spark plugs. The left coil should be connected to 1 & 4, the right coil should be connected to 2 & 3.

Something I did notice is that the carb slides on 1 and 4 were kind of binding a little, getting stuck. I oiled them and that seemed to help. Maybe the 25 year old slide springs are tired? I'm not sure, this could be the problem or it could be trivial.

I would recommend removing the slides (you don't have to pull the carbs for that) and clean the oil off the slides. They are supposed to be clean and DRY when installed.


What little corner of the world do you call "home"?

One of us might be close enough to stop by and lend a hand.

.

[1_v8_merc]

If it only runs for a couple seconds and cuts off, sounds fuel related or electrical.
These bikes can cut off immediately or quickly if the mixture screws aren't set right.(even a slight turn can cause them to Not start at all!Hard to believe, but true.)

Not guaranteeing it's your problem, but definitely check it out.
Those screws must be correct.

And work your way down the checklist.

99% of the time, it's something completely simple and stupid with these bikes.

[JamesH]

I know that I need a new battery, but according to today's tests after the battery was charged I was getting 11.5v at the coils. Before the relay modification with a fairly charged battery I was getting between 6 and 8. Like I said, yes I know I need to get a new battery.

Yes I know 1&4 and 2&3 are the coil pairs. The plugs are wired correctly, which is one of the things that I fixed upon initially receiving this bike and troubleshooting. They were originally wired backwards along with other things wired backwards (starter relay/solenoid) and a short in the killswitch housing due to improper reinstallation of the housing/throttle control. Those are examples of why I took this on in the first place, this poor guy had this bike sitting in a local scooter repair shop because one of the 'mechanics' there supposedly knew something about older Japanese bikes. The first 20 hours I worked on this bike I spent fixing their screw-ups.

To add to my list in the original post I also installed the correct plugs (D8ES) with the correct gap. The scooter shop put incorrect plugs in. That seemed to help it run for about a second more!

The good news: Earlier this afternoon after reviewing what I had done I adjusted all the idle mixture screws to 2.5 turns out. They received new O-rings with the rest of the carbs about a week ago. Merc- I believe you are right with this, as I have been playing around with the settings and this so far has yielded the best results

It seems/seemed to me that at this point it HAD to be a fuel issue. I pulled the drain screw out of #1 and whaddya know? no fuel in there! Even though I had these things apart a week ago the damn fuel inlet valve was hung up! So I dropped the float bowl and got it loose...and there comes the fuel!

*note: I am running this right now with no tank, a fuel bladder, and the vacuum port on cyl. #2 plugged.

At this point I put the bowl back on and gave it a shot...It started under its own power! Like I said before, it was running earlier today on 2&4 very ****tily and not running on 1 or 3 at all. So now it is running strong on 1&2, slightly on 3 or 4 when I give it more gas. This is first time in the course of my work on this bike that I have actually been able to control engine speed with the twisting of the throttle!

So this basically tells me that it is now in the realm of carburetor adjustment and balancing to try and get 3&4 going as they should.

Another note: I have never ridden this bike at all. I picked it up from the owner with the intent to try and help him out. I loaded it in my truck and have been working on it in my backyard in spare time over the course of the last few months. My goal is to be able to ride it back to him. When I received it the bike wasn't even receiving power when the key was turned to 'on'...

[JamesH]

So it looks like I've narrowed this down now to carburetor balancing. I guess this thread will now belong in the fuel/air/exhaust section eh?

Does anyone have any tips for adjusting the balancing screw between #2 and 3? I left all of the nuts loose from my dipping and reassembly with this in mind. It is very difficult to get to with the throttle/choke cable bracket in the way. Any tips?

[Larry D]

From Cliff's site. Get the tool, it's the best and easiest way.

http://members.dslextreme.com/users/cbsaunders/gs/carb-balance.pdf

[Matchless]

So it looks like I've narrowed this down now to carburetor balancing. I guess this thread will now belong in the fuel/air/exhaust section eh?

Does anyone have any tips for adjusting the balancing screw between #2 and 3? I left all of the nuts loose from my dipping and reassembly with this in mind. It is very difficult to get to with the throttle/choke cable bracket in the way. Any tips?

Rather do a proper bench synchronization before you try and balance them on the bike otherwise you are just going to chase your own tail.

Did you check whether the jets fitted are as per factory spec and not some "tuned" sizes and the air cleaner is fitted and properly sealed? These can affect starting and running quite a bit.

The motor should run well with a only a bench sync. Are you starting by just using the "choke" and no throttle? The "choke" will control the speed when cold, using the throttle to start when cold will not work.
The "choke" is an enrichment circuit and not a real choke on your carbs.

[JamesH]

Larry- Ill check out the tool. I was able to reach down there with a very long screwdriver from in between the frame where the seat would be for now...

Matchless-
Jets are factory spec...Air cleaner is fitted and cover is on. The new one i just got seems kind of difficult to cram in the box but it is definitely the correct one.

I should also note that I am in New Orleans...its in the 70's outside right now.

When I start with the 'choke' on (aka enrichener) the rpms go very quickly to about 5k. I am unsure if all cylinders are running at this point. When I disengage the choke, I am running on cyl. 1 and 2. If I give it throttle, 1 and 2 will rev the engine to about 5k where 4 and or 3 kick in.

There is very sluggish and delayed throttle response at this point...which is a byproduct of only running on 2 of 4 cyl. unless at 5k or above.

Did a rough bench sync before carbs went back on bike. This basically means I made sure the openings left from the butterfly valves were all as close as I could get them.

[SqDancerLynn1]

If it kicks in at higher revs, you still have carb problems.

[Matchless]

If it kicks in at higher revs, you still have carb problems.

It sounds as if 3 and 4 may have idle/pilot circuit problems. Did you strip the carbs completely and dip them? Were the pilot jets and pilot screws taken out and cleaned. Were the passages cleaned by squirting carb cleaner through the passages and coming out on the other side?
Did you properly dip the carb body overnight? You mentioned that these were done, but if not done properly, you will have problems.
I am assuming you changed the pilot screw o-ring and the intake o-ring already.
Good luck.

[tom203]

When you had carbs apart, did you inspect the slide diaphrams for pinholes? Sounds like 3 and 4 might be not responding till decent throttle openning. By the way, how are you detemining which cylinders aren't behaving- exhaust pipe feel or actually disconnecting plug wires?

[JamesH]

Matchless-
The carbs were stripped completely, each body dipped overnight, all passages then cleaned with carb cleaner & had compressed air blown through. All O rings were replaced with the kit from cycleOrings.com.

Tom-
I did inspect the condition of all the diaphragms...might be pinholes though..? Hope not. I am determining the cylinders not running by exhaust feel and the fact that when they kick in there is a rush of exhaust out the right side pipe which is fed by 3&4.

Unrelated note, and I am going to post this in the correct section also, but does anyone know where to get (or a good idea for making?) those airbox clips? They were not with the bike when I recieved it. Up until now I have just wedged a rod in to hold the airbox cover on, but that it is obviously not a permanent fix...

I am waiting till my new gel battery comes in then I will maybe hook up my motionpro carb sync tool to the bike.

[Matchless]

Just a thought. Does your carbs have the rubber plugs in the bottom of the pilot jet tube?

Are you using a separate fuel filter, if so mounted facing down for gravity feed. I have found some of these with extra long fuel lines and having an airlock in them.

[waterman]

Matchless-
The carbs were stripped completely, each body dipped overnight, all passages then cleaned with carb cleaner & had compressed air blown through. All O rings were replaced with the kit from cycleOrings.com.

Tom-
I did inspect the condition of all the diaphragms...might be pinholes though..? Hope not. I am determining the cylinders not running by exhaust feel and the fact that when they kick in there is a rush of exhaust out the right side pipe which is fed by 3&4.

Unrelated note, and I am going to post this in the correct section also, but does anyone know where to get (or a good idea for making?) those airbox clips? They were not with the bike when I recieved it. Up until now I have just wedged a rod in to hold the airbox cover on, but that it is obviously not a permanent fix...

I am waiting till my new gel battery comes in then I will maybe hook up my motionpro carb sync tool to the bike.

I just checked with Alphasports and it appears the clips are still available from Suzuki for a couple bucks or so. Alphasports is generally fastest site to check but usually more expensive so do some comparison shopping.