Reviving my old GS

[vasama]

Hi guys
After a VERY long absence from this forum, I'm back, and sure enough, it is because I started wrenching again on my old GS. Suffered an accident last year in a Ducati I had bought. That one is now dead, but I am not, thankfully. That's not the topic of this post. This is:
Last year, I had my cylinders re-bored, and got new pistons with rings for them. That shop also resurfaced the valve seating areas, and I have put everything back.
Bike is not starting. Have checked:
-Fuel: carbs have no obstructions. No needles clogged. There is fuel in the compression chamber. I even sprayed a bit of starting fluid in there, and after that I even dropped some actual gas in both chambers, just to eliminate my doubts that it simply was a matter of carburation.
-Spark: Have current, and can see sparks in both plugs when I pull them and crank the engine.
-Compression: Have very good compression.
-Cycle timing: Have confirmed that the camshafts are in the correct position for the engine timing, by way of seeing the camshafts marks as assembled, and the generator marks on the right side of the crankcase.
I'm going to do one thing as a last resort: I'm getting new spark plugs today and will try again tonight. Barring success with that, I think the only option left will be to simply take the bike to a dealer shop and get ready for whatever money they take from me.

[mr72]

Are the plugs wet?

Only thing I can think of. Actually I think considering you had the head and jug off, it's most likely something related to your re-installation of everything, so I think you should retrace your steps. Double, triple check valve timing, ignition timing, ground, fuel line connections, etc.

[sledge]

If I had to put money on it I would say timing, but that is only because timing is what seems to catch most people out after they have had the top off. Realistically it could be anything or any combination of things and at this stage its impossible to say what.

You need to start all over and systematically check everything again.

[vasama]

Thanks.
I'd like to avoid disassembling the whole thing again. I don't see how the cylinders could be misassembled, or the rings, or the valves, for that matter. The engine turns. It does not emit crazy (grinding) noises. The engine cycle is what will not get going.

[qcbaker]

Thanks.
I'd like to avoid disassembling the whole thing again. I don't see how the cylinders could be misassembled, or the rings, or the valves, for that matter. The engine turns. It does not emit crazy (grinding) noises. The engine cycle is what will not get going.

The engine doesn't need to make grinding noises for the timing to be off enough to not run properly. I think both sledge and mr72 are giving good advice. You should tear down what you disassembled, triple check everything, then put it all back together.

[vasama]

OK, that is the plan, then. Not for nothing did I decide to post back here.
Thank you all. Will tell you how things turn.

[mr72]

FWIW I don't think you need to pull the head or re-check the cylinders etc. Do a compression check to verify your rings are seating, and then move on with re-checking the cam timing. Just pull the valve cover, absolutely verify the cam timing, then verify the ignition is timed with the correct part of the cycle (degrees BTDC whatever the spec is). When you are hand-turning the engine look for the piston through the plug hole and do the verification of TDC vs. valves you can actually observe opening and closing.

I would also pull the carbs, the right-side engine cover, the intake boots, verify the ignition wiring, coil resistance, etc. etc. you know the drill. That's all easy to remove and put back together.

It could be that there is no air getting in through the little teeny orifice for the pilot circuit in the carbs. Worthwhile to run a wire through the orifices in the carb. If the pilot jet is clogged then it won't start, and it's easy for it to become clogged after you hook up the fuel especially if there's any chance of sediment in the fuel. It's only four tenths of a millimeter in diameter. Worth it to verify all of this. I have had no-start conditions due to air leaks and bad o-rings in the carbs.

[vasama]

Asking for help, please. Reading my manual, it suggests measuring resistance, in the coils and in the signal generator. For the coils, it talks of a primary and a secondary circuit. Pic 1 shows the right-side coil, and Pic 2 shows the wires attached to it. I think that I'm supposed to measure resistance between each of the terminals in the coil and the wire that comes out of it and goes to the spark plug cover. Is this correct? The book says "ignition coil resistance". This is it, right? Also it talks about primary and secondary resistances, and I simply don't know how should I measure them. I mean, I don't know exactly what should I contact with my multimeter pins to get the correct reading.
Also, as far as the signal generator is concerned, the book says to measure continuity and resistance at the connector of the signal generator, but is not too clear regarding which wires should be touched when measuring that.

UPDATE: Found where/how to measure primary and secondary resistances for the coils. Still unsure about the signal generator resistance check.

[vasama]

...posting pics...

[vasama]

[sledge]

If the plugs are sparking when the engine turns over the problem is unlikely to be electrical 

[vasama]

SHE LIVES!!!
Thanks to the encouragement I got here, I ended up not taking it to the stealership, but at the end, it was a matter of timing. The feeling of accomplishment I can't put in words. Remembered that my crankshaft actually came from Adidasguy, rest his beautiful soul in peace.
This is truly a milestone in my life, after having had that pretty bad motorcycle accident last year.
SHE LIVES!!!

[Watcher]

Congratulations!