GStwin.com GS500 Message Forum

OK Gino's bike... Its carburetion... we got it to fire up briefly... then it is refusing to start again... The carbs on my bike make it start easy, we put them on his.. and nothing, his carbs also make mine start easy and again nothing for his, His has new spark plugs gapped perfect and makes a good blue spark.. the only one of the 3 Gs'es that makes blue anything, He has good compression, good valve clerances, good gas supply, valves timed right, it even briefly started... but then nothing.
Anyone had one of those days where nothing worked... well the last 2 weeks have been that for me where gino's bike is concerned.
Any help is appreciated.
Cool.
Srinath.

I know you probly checked this but have you looked at the timing??  If so it was just a thought.

OK ignition timing must be pretty close...cos it did start up 2-3 times... in the last 15,000 tries. Valve timing is perfect.
Cool.
Srinath.

Could there be water in the tank or just bad gas?

What about switching the leads to the coils?

The bike running off an IV tank... clean... The other one also were tried with the same IV and it all started fine. It has spark, and it did start 2-3 times.Its some jetting crap... but starting uses choke circuit right... and the choke is fine on it, and the other bike starts fine with the same carbs. The carbs were un touched...we just transfered them to gino's and its not starting. Its a mystery...Tried 3 sets of perfectly good carbs, all of which work on mine, all carbs are squeaky clean, fuel flow is there on all and we have even tried stock and V&H pipe. It has spark.. probably the best spark of the lot.
Cool.
Srinath.

The only other thing I can think of is the air jets. They just don't get messed with that much because they're so darn small, and because they're soo small, i think they get clogged easier, but not noticably. I think they get clogged behind the jet, in the passageway. Did you remove the jets and blow cleaner and compressed air backwards through the air passageways?

Oh, whoops, I just re-read the last post; squeeky clean.

The crank is turning in the correct direction?

There's not a mouse in the exhaust? Either of 'em? And the airfilter?

Squeeky clean... and not squeeking cos it has a mouse in it... How's that.
No air filter though we tried it with that as well, exhaust.. I dropped wrenches down it... well it was off the bike so say its in the motor... and crank is turning in the right direction. The carbs make the 89 run...easy first touch start and it runs fine. On this... disaster. These carbs were clean... They were the ones Rashad cleaned like 100 times before he send it to me... and o rings were bad and springs missing making the choke stay 1/2 open all the time. Anyway nice carbs once I got the parts fitted in. But any carbs on gino's makes it not run. No matter what.
Cool.
Srinath.

This just reminds me of an '82 750 Virago I worked on once and switched the leads bewteen the front and rear coils so the front cylinder was getting spark when the rear cyl was supposed to. Now you know why I'm a former m/c mechanic, my weekness has been revealed :lol: . Anyway, the bike would run! Albeit, like crap...o.k. it wasn't even ridable, but it took a long time to start it, which is kinda like what you're experiencing. Everything else is perfect. Carbs are fine. Have airflow. Have fuelflow. Mechanicals - fine. Spark is fine, just maybe misplaced a little bit?

I hope this helps, I'm not trying to be a smartass.

Did you check the compression?

Compression... 140 psi cold...in both cyl.
I'll try the right plug on left coil, left plug on right coil...we got it to run briefly and it sure was crappy... so possible its getting spark 90 degrees out... and it gave off some misfires that made 4th of july look quiet.
Cool.
Srinath.

THis sounds just like when i had that bent valve..

Of course, if you have good compression, then it cant be that right???

Or maybe its just bent enough to have good compression with the oil sealing it enough, but bent enough to not run right?

Ohh yeah, those carbs... you could EAT OFF THEM!! :thumb:

* Does your '89 run using fuel from the "I.V. Unit"?

* Even though you have a blue spark, you still may want to check the resistance values (ohms) in the signal generator coil circuits ... and in the igniton coils too.

If the carbs work on another bike, and the valves open and close at the right times, it has to be the ignition. Maybe the fact the spark looks better is bad!

Make sure the right igntion sensor is firing the right coil when the right piston is near TDC and the valve are closed. If that's OK, start swapping ignition bits - sensor plate, ignition box. It's got to be in there.

yeah ,i would have to check that the cams arnt 180 out, or that the crank/rotor wasnt out of place. carbs are good, valves and rings are sealing fine, only thing left is timing of the spark, pull the rotor and see if locator pin is sceared off

Ok swapped Blackboxes ... no diff, valves open and close at the right points, the ignotion advance rotor has been swapped 3-4 times... Not swapped ignition plates so far or even tested it... I should do it tonight. The 89 does run with the IV quite fine. The valves cant be bent...even slightly cos the valve clearance has been set perfect... 1.5 on intake and 2.5 on exhaust... That pretty much rules out valve bending right unless they were both set to be quite a bit open before the valves were bent...
Cool.
Srinath.

Sounds like what I went through.  Swapped black boxes, swapped rectifier/regulator, swapped carburetors.

When I tried to start the bike I would get a "tuh tuh tuh TUH tuh tuh tuh TUH tuh TUH tuh TUH tuh TUH tuh tuh tuh TUH tuh tuh tuh TUH ...." as I leaned on the starter button.  Does that sound familiar?

Switching the ignition plate sounds like a good idea (I never got around to that), but it won't help if the problem is in the wiring or connectors like it was for me.

Why not take a few easy resistance readings before you go to the trouble of switching the plate?

I have a plate that is shot sitting right on the tail of the bike...was going to put it in and try when Gino was here but never did cos of the other carb crap we were testing. Tonight its getting the spare plate. The plate is shot only when hot. It loses the left cyl... so we'll know if it runs and then if it loses the left ... Big deal... his plate is bad and we need to replace that.
Tonight we'll know. Thanks for all the suggestions... BTW you bike made spark and cranked over just fine but didn't start because of the ignition plate?? How did you fix it if you didn't swap that and what was in the wiring/connections...
Cool.
Srinath.

Here is another on for your how to pages... possibly...
Simple carb synch... Take off the carbs and hold them to vlew through them. Look from the air filter side into good daylight or a bright wall or somehitng, and turn down the idle screw till one of them shows no light, then twist the synch screw till both show approximately same amount of light, then lower the idle screw till again you see no light, and twist the synch screw till equal... You get the idea... Worked for me.
Cool.
Srinath.

You can also use a drill index, thats what we do instead of the tubes and water and all that. Same thing as what you are doing.

I have tried that...never got it to work with them. What's the water method though...
Cool.
Srinath.

Quote from: seshadri_srinathBTW you bike made spark and cranked over just fine but didn't start because of the ignition plate?? How did you fix it if you didn't swap that and what was in the wiring/connections...

Go to the recent Still got problems... thread and check out my second post for links to threads with pictures and electrical diagnostic procedures.

My 3rd post has a link to a thread with a picture of my fix.  Basically, I "replaced" the second connector away from the "Ignition control unit", on the way to the "Pulse generator coils".  The connection/s for the Black/blue wire was/were bad:

Quote from: seshadri_srinathWhat's the water method though...

Surely you remember seeing KevinC's My $5 carb balancer.... with the blue food-colored water....

OK read all of the related posts... thanks for posting them Kerry.
The black blue wire from the black box to the trigger plate... On gino's bike that and everything else is cherry. Of the 9 GS'es I have taken apart so far this was the cherriest... But the trigger plate could be bad even though it has spark is what your posts indicate. So its getting swapped. T will look at the connections for extra assurance. Thanks Kerry, you have the memory of an elephant...
Thanks.
Srinath.