Excessive heat problem and Can't get any speed out of her

[rahlberg]

First off, thanks to all who've helped me with my 81 GS650 thus far. I've got the engine up and running and am in the process (I guess), of debugging her now.

Quick background:
I had problems getting the engine started and running, so I followed the procedure to completely disassemble and clean the carb. Also, I wasn't getting a good spark from the coils, so I added the relay mod specified here. Then I was having more problems with the spark, so I replaced the igniter/signal generator with a Dyna ignition system.

All this has made major improvements in getting it started and idleing/running. But now that I can run her longer, I'm seeing a few other problems:

1.) After say 5-10 minutes or so, the right exhaust pipess (from the #3 and 4 cylinder) are heating up extremely high. I don't have a temp on these, but just holding my hand near it (as compared to the #1 and 2 exhaust pipe), it's very very hot.

The carb is clean, and iIhave new O rings all over, and I can't find any leaks in the intake boots, so am I running lean? Why would the #3 and 4 side be running that hot?

After it gets significantly hot, I can start hearing a ticking sound (valve?)

And having a friend ride behind me, he says he can smell a lot of gas (I'm guessing un-burnt). Does that mean it's too rich?

2.) Now for the other issue. Despite the heating problems (or maybe that's contributing to this one), I can run it up through 1st gear, and 2nd gear and into third gear. But at this point, there's no more power to go to 4th or 5th. I can shift into those, but the RPM's just drop. It's like I'm maxing out in third and there's no more power.

Any thoughts to these two issues? Thanks to all that have helped so far.

Russ

[n1elkyfan]

It sounds like you need to do a valve job

[BassCliff]

Hi Mr. rahlberg,

Mr. n1elkyfan has a point. I didn't see valve adjustment and compression check in your list. Make sure nothing is burned or broken, then continue with the carb adjustments.


Thank you for your indulgence,

BassCliff

[rahlberg]

Thanks guys. A valve adjustment and compression test have not been done, so I'll add those to the list.

Russ

[TheCafeKid]

Not to sound like a jerk, but you should have started with the valves first. Your problem sounds to me like you are LEAN, at least on the 3 and 4, and maybe not firing at all on 1 and 2. Take care of the valves, then do a compression test. If you're good on compression, check your spark. Assure that all the plugs are firing, and have a nice BLUE spark to them. Then move to the carburetors. Are we dealing with a stock intake and exhaust system? If so, it will be easy to dial in your carbs once you have the valves in spec. IF not, it will take a lil tinkering, but we can get her there. VALVES before you do ANYTHING else if you dont want to ruin this bike, however.

[JTsGS650]

First off, check and adjust those valves. Second, I'm wondering what your spark plugs look like? Are they black and wet or dry and whiteish/gray? The exhaust pipes do get very hot. Maybe you're running too rich in cyls 1 & 2? Is your petcock operating properly?

[Steve]

First off, check and adjust those valves. Second, I'm wondering what your spark plugs look like? Are they black and wet or dry and whiteish/gray? The exhaust pipes do get very hot. Maybe you're running too rich in cyls 1 & 2? Is your petcock operating properly?

Exactly what I was thinking. You will want to take the plugs out when you check the valves, anyway, so take a look at them and let us know what you find.

.

[rahlberg]

Exactly what I was thinking. You will want to take the plugs out when you check the valves, anyway, so take a look at them and let us know what you find.

I finally got a chance to do the compression test. All 4 cylinders were reading 148-152psi. It's a bit on the low end (as per the manual spec of 142-199 psi). But they are within spec and within the 28psi of each other.

I also checked the valve clearance. All are within the .03-.08mm spec as well.

One thing I did notice, was the main head/valve gasket was really beat and torn up. I tried taking the valve head off as carefully as possible (to see if the gasket may have been bad), but I don't know if I did any of that to it. Anyhow, I have a new one in the mail, so I can get it all buttoned up shortly.

One other thing that I did notice (not sure why I didn't catch it before) has to do with the coils. I did replace the coils a bit ago, so I had all the wires off the plugs. Looking at each spark plug wire off the coil, I see a 1-3 label and a 1-4 2-3 label (on one wire) and a 2-4 label on the other wire (see below). I'm wondering if I may have had these on wrong and the firing sequence was all off, which was why the 3 and 4 side was getting so hot and I wasn't getting as much power as I could have.

Thoughts??

[rahlberg]

Oh, also, I checked each plug, and there was some very very slight carbon marks on them. Nothing out of the ordinary though. They looked almost brand new.

[Steve]

One other thing that I did notice (not sure why I didn't catch it before) has to do with the coils. I did replace the coils a bit ago, so I had all the wires off the plugs. Looking at each spark plug wire off the coil, I see a 1-3 label and a 1-4 2-3 label (on one wire) and a 2-4 label on the other wire (see below).

Some rather confusing labels there. :shock:

One coil should connect to plugs 1&4, the other should connect to 2&3. 8-[

.

[flyingace]

Good compression rules out the compression related issues like valves, gaskets, rings, etc. This leaves fuel mixture and spark.

Is it possible something got screwed up with the new ignition system, and now only two cylinders are firing? That would explain the serious lack of power and the smell of unburned gas. Take the plugs out and tape the bases to their corresponding head position and spin the starter. Do all of them fire? Then spin the engine slowly with a wrench and ign switch on to check the spark timing to see if it happens just before TDC on compression stroke on all cylinders.

Since you also worked on the carbs, they can also be a source of the problem. Once the iginition issue is ruled out, check the fuel float levels to see if they are within spec. Then check to make sure the carbs are in synch with a rough visual check (do they all actuate at the same time) and then a vacuum gauge test. Verify your choke lever is working properly and not staying in the 'on' position. That would also explain the symptoms.

[rahlberg]

Still working on it.

It's been a while since I've been posted on this issue. I have a few updates and I want to run it by everyone to get their thoughts.

The right exhaust pipes were getting extremely hot and the left weren't (after a few minutes of running). So I was wondering if the #3 and 4 cylinders were firing and the 1 and 2 weren't, were 3 and 4 doing all the work and over heating?? So while the engine was running, I pulled the spark plug wire off #1 and the engine didn't even hiccup. I put it back on and pulled #2 (still while running). Same thing. The engine didn't even change. So I pulled #3 and the engine died. Put it back on, started it up, and pulled #4 and it died.

So this told me that 1 and 2 weren't doing anything. Could it have been something with the coils? I pulled the plug out of 1 and 2 and checked for a spark while running, and couldn't see one on either one. So to cross the coils off the suspect list, I broke down and bought a set of the Dyna 3 Ohm with new cables. I have confirmed that I'm getting a spark on tehse two, but this didn't solve the problem. With the new coils, there was no change to this situation. It's still running hot.

One thing I should mention, is back on post #8 of this thread(http://www.thegsresources.com/_forum...12&postcount=8) I posted a pict of the plug wires and the labels showing which went where. Everywhere I read, it says one coil goes to 1-4 and the other to 2-3. When I set it up that way, it flat out will not start, let alone run. After trying to start it for a few seconds, I'll get this amazing backfire that sounds like a shotgun going off next to your ear. If I set it up with one coil going to 1-3 and the other to 2-4, it'll start, idle, and run....but I have this heating problem.

Is there a reason why I might be getting it to run with the coils on wrong and it won't run when they're on right? Could that be causing the overheating?

Thanks again for all the help. This site is amazing with the combined knowledge here.

Russ

[seuadr]

i'm not sure about the coils, but i had a very similar problem with my gs.. and it was the two non firing cylinders were very, very lean. the o-rings between the boot to the head and the carb had cracked.

[rahlberg]

When I cleaned the carbs, I installed new o rings everywhere on the carb and on the carb-to-engine intake boots. The actual boots themselves are 20+ years old, but they're still pliable and have no cracks in them. To make sure they were sealed to the flange, I added some high temp silicone gasket...just in case.

[TheCafeKid]

Id start looking to your ignition system for sure. For starters, it doesnt matter WHAT those sticker say. The plugs for one and four should come out of one coil, and the plugs for two and three should come out of the other. The ingition works on the premise that this is the case. The wires coming out of the coils (not the plug wires) one should be orange and black, those go to one coil. The others will be orange and white. those go to the OTHER coil. I cant remember which one is which, but the black wire tells one coil when to fire, the white tells the other when to fire. the orange wires are the power wires for the coils. if THESE are not hooked up like this, you have a problem. ALL GSs to my knowlege operate this way.