i've spent the entire day trying to fix my 1990 GS. Again the problem is it will run great for the first 15 minutes or so and then it will lose ALOT of power. I changed the petcock out and it's getting plenty of fuel, I checked the Float Bowl Height, and I ALMOST synched the carbs but still working on that one. I checked the vacuum ports on top of the carbs and they are closed off, I checked my fuel lines and they are fine. It almost sounds like one of the cylinders stops working. After a while (a few hours maybe...) everything will run fine again for another 15-20 minutes.
The bike will continue to move once it's lost power, but I REALLY need to crank the throttle to get it going... and sometimes it might just die. I plan to check the valves tomorrow morning, but I'm not sure this could be the issue, right?
HELP!!!
Rolly
15 mins to lose power...
Crank trigger...funny thing is my bike used to act fine if you get on the highway in under 15 mins and run wide open...till you shut the throttle and let the revs fall to ~3K...one cylinder will cut out then. The crank trigger fails when hot. Right side of the motor under the round cover...the t things the advancer touches creating advance. Mine died at 35K miles BTW.
Cool.
Srinath.
Is it posible to be getting TOOO much fuel?
I know I had this issue BEFORE I started changing the fuel lines, but is it possible that after getting rid of the petcock and making a more direct route into the carbs I might be letting in too much fuel and it's drowning the carbs?
Hmmm...
Rolly
I doubt your fuel supply is TOO messed up. If it were, you wouldn't get that first 15 good minutes out of it.
I'm with Srinath on this one. It sounds like you're switching from two cylinders to one on-the-fly. The tricky part is going to be testing for spark, etc. when you're flying down the road... :roll:
If you want to pursue this line of reasoning, let me know. I'll go back and look up the threads that I started on this topic. My '99 was cutting out on one cylinder, and I eventually traced it to a bad wiring connection. It was caused by corrosion from the battery dripping onto a connector ... that routed wires to the "crank trigger" Srinath mentioned.
I made a spark checker tool, and it looked for all the world like I was getting a good spark, but the resistance measurements in the wiring system didn't lie. New connectors - problem solved!
I'd be willing to try most anything at this point.
I could always wait until the bike starts acting up and then hop off and check the spark, right?
Hmmm... I've got no patience for electrical problems, dammit!!!
Oh well...
Lemme know what you think my next step should be and I'll give it a shot...
Thanks a million!!!!
Rolly
OK, here are the relevant threads I could come up with:
Here is my initial plea for help, with a lot of diagnostic info:
Running on one cylinder.... (http://www.gstwins.com/forum/viewtopic.php?t=811)
In this thread I went down a wrong path. But it contains a picture of the spark checker tool I mentioned. It also contains Srinath's early guess that hit pretty close to the actual problem. (It's the same guess he expressed to you....)
Ignition switch assembly (http://www.gstwins.com/forum/viewtopic.php?t=1515)
My posts in these last two threads came AFTER I fixed my problem. They contain some of the step-by-step electrical tests I did.
no spark now (http://www.gstwins.com/forum/viewtopic.php?t=1696)
problem starting it, then it dies, help! (http://www.gstwins.com/forum/viewtopic.php?t=2020)
I checked the cyl it ws cutting on...then swap coils and see if it goes to coil or still cyl, then swap the trigger with another bike and test it...or test electrical resistance when hot or put it in the oven and set it to say 250 and test them...some like that...I swapped with my other GS...
Cool.
Srinath.
Not sure if it may be related but the blinkers on this bike also don't work. At all! I've yet to really look into it, but all I've found so far is when I switch the blinkers on, I get a click from a relay on the side of the bike and that's it. Or maybe it does the click when I release the blinker switch.
Anyway, I'll start looking through the electricals this morning. I do know (and not because anyone told me right out...) that the bike was crashed on it's lright side (also not sure if it was high-speed or low...). I've noticed a different brake lever and master cylinder than what should be stock (no adjustment on the brake lever?) and a few other scratches, scrapes, and rash.
Thanks for the advice, I'll let you know what I find...
Oh yeah - WHAT IS A CRANK TRIGGER????
Is this the actual term for it or what? And where would this crank trigger be located?
Thanks.
Rolly
MOTOR RIGHT SIDE UNDER THE ROUND COVER...Look for physical damage...That cover is paper thin...under it is a few 100's worth of electricals...you do the math...people totally neglect it cos it dont leak oil when cracked...you drop it again...and it could blow a hole easy and break the electrics...and voila...running on 1 cyl. BTW that wont happen when hot only...you on your own there...just a rant.
Cool.
Srinath.
I tried out the sparkplug test (where you touch the plug and wire to the cylinder head to produce a spark...) and I've found a few interesting things. The manual mentions a few times a THICK BLUE SPARK... I've got a spark but certainly not what I would consider thick and really not blue either... Anyway, I was getting a "weak" spark on both cylinders. After running the bike until it acted up, I hopped off, and checked the plugs again and my left cyldiner was not getting any spark at all. The right would spark a little.
I'm hoping I'm narrowing down my problem. I also went over my wiring and everything looks okay... old, but okay. I did notice that the manual shows relays that don;t look like mine. My bike is set-up with one rubber-covered "relay" with several wires going into a connector and then into the relay and then a 2nd relay in the middle with a 2 wire connector attached. There is a black/white wire coming from this area but it's not attached to anything and has a female end on it.
I did notice before that my plugs are looking a bit different.
The left plug (the dead cylinder I'm assuming) has a black coating of fuel on it (from the cylinder quitting and unburnt fuel covering it) and the right cyldiner looks pretty hot. It's got a white/gray coating on the tip and the rest has got a light "carbon"-ish lok to it. So I'm figuring the one cyldiner is crapping out and the other is then overheating from working to hard, right?!?!?!?!?
Sorry so long, but I'm getting closer!!!!
Rolly
I tested the coils by switching between the 2 and still the same problem.
I'm sre it must not be the Coils. I also looked at the parts under the right-side cover (the ignition advance and the signal generator?) and they LOOK fine.
I'll hunt down my OHM meter and see what comes up. Bought this meter a couple years ago and only used it once. Hope I can figure the thing out again...
Anyone have a step-by-step process on how to check the signal generator?
Thanks again...
Rolly
Quote from: Rollin668I tested the coils by switching between the 2 and still the same problem.
I'm sre it must not be the Coils. I also looked at the parts under the right-side cover (the ignition advance and the signal generator?) and they LOOK fine.
I'll hunt down my OHM meter and see what comes up. Bought this meter a couple years ago and only used it once. Hope I can figure the thing out again...
Anyone have a step-by-step process on how to check the signal generator?
Thanks again...
Rolly
Be a bit more specific...You swapped coils side to side and the problem didn't swap sides. Is that what you meant by "still the same problem". If so crank trigger is the likely culprit. I'd try to run the left coil to the right cylinder and the right one to the left...(anyone know if that can cause detonation) You basically cross spark plug wires across above the motor.
The other option is to get a trigger plate...from someone here or new (Parts depot or Ron ayers...but they are not cheap and you want to be sure that is the issue). The thing looks fine in any case even if it was bad. I dont know how to test it but you want to sit the parts in a oven set to ~220 or so and then test it and see what it does...when cold it will probably show that its good. I just put them in from my other bike and it turned out that cured it...so I knew it and I bought it from a wrecker...So I cant help you there.
Cool.
Srinath.
Quote from: Rollin668Anyone have a step-by-step process on how to check the signal generator?
Please read through my post in the "no spark now" thread that I mentioned in my previous response. Also, I found another old thread that shows a picture of the repair that finally fixed my problem.
i think its a carb problem but im not sure, please help!!!I won't promise that your problem will be in the same spot, but I'm betting that it's a similar kind of thing.
I had a lot of black box issues from corrosion...but they dont appear when hot and disappear when cold...They stupidly show up and when you disconnect and re connect it...it suddenly fixes itself...Very very frustrating.
Cool.
Srinath.
I'll take another look around my wiring, Kerry - thanks for the info.
I'll need to get out (and figure out how to use...) my ohm meter and test the difference wires in that area. I'm trying to get a CDI from ebay (just in case...).
I'll take another look tonight and let you know how I fair after getting the ohm meter on the wiring and connectors.
Rolly
Your CDI is fine...it doesn't suffer from temperature changes...nor does it have a timeout feature...
Cool.
Srinath.