Help, Coils gone?

[metalforever]

Right i hope you Gs experts can help me out here!

Im restoring a 1990 GS500e at the moment and i've had it running however theres one or two problems i've got. And just for reference everything i've done ahs been in neutral, the bike hasnt been on the road in three years.

This is the main one, my left downpipe isnt getting hot, well, not as hot as the right and its easily noticeable if you hold your hand infront of it.
I've checked the plugs, both sparking, however i think one of them may well be giving a weaker spark, swapping the plug onto the other coil gives a slightly better spark.
I've canged and cleaned the carbs.
I've checked the fuel lines are ok, i've also checked the 'petcock' inside the tank for blockages, alls fine.
I've charged my battery, it's holding a full charge.
All my electrics work on the bike.
The air filter is clean.
Engine oil is new + New filter.

So, i had the bike running today to see if by switching the left hand side coil (The same side as the cool downpipe) to the right hand side if i would solve the mystery of the cool downpipe, it seems as though the left downpipe is still remaining cool however. Im beggining to get the impression this could be normal...

Anyway after ten minutes or so of idling the bike just cut out, no bogging down, no funny noises, it just died. And now it wont start.

The bike turns over perfectly, the plugs are sparking when tested against the cylinder head and air is getting through, however im not so sure about fuel as the plugs are coming out dry, but an ok colour, not biscuit brown as they should be, but not black, more a silver/white colour with maybe a hint of biscuity goodness.

It's been suggested that the left coil (well the coil that was originally on the left) could well be on its way out. But now that the bike wont start (It was warmish when i tried to start it but it had been given 20-30minutes to cool down before i tried again) i can't really find out.

Any ideas what might be going on, any advice would be great, many thanks!

[bobthebiker]

what color is your spark?   bright blue is a healthy spark,  orange/yellowish is a weak and sick coil. 

also have you got clean carburetors? it gives me the impression you have something limiting fuel to one side which is making it not get as warm as the other pipe.

[metalforever]

Yeah the carbs are clean and this is the second set i've had on the bike as my original set wasn't allowing much fuel to the left cylinder. The colour of the spark varies from blue to orange, im nto sure why.

Looks like i might see about buying a new coil or two!

[MArkRD]

Have you been able to check the compression? Maybe the right cylinder (cold one) is low on compression and won't fire properly.
It could be worth checking before you start to change parts out.

Most bike shops have a meter, maybe they could check it out for you. It's a 5 minute job.

[metalforever]

Theres just no fuel getting through to the cylinders by the looks of it now. i mean theres not much in the tank anyway so i've had it set on reserve, might go get a couple of gallons and fill the tank, see if that helps.

On the note of compression i thought of that but never really took it much furthur than a thought! ill have a look at a compression tester

[MArkRD]

Theres just no fuel getting through to the cylinders by the looks of it now.

Hmmm. Fill the tank & check again. If it's still no good, pull carbs and rechack float needle function. If you can't find the solution in the carbs i'd go for a compression check.

btw. like the name metalforever. i totally agree!

[beRto]

Theres just no fuel getting through to the cylinders by the looks of it now. i mean theres not much in the tank anyway so i've had it set on reserve, might go get a couple of gallons and fill the tank, see if that helps.

Fill the tank first!

Then use this method to check if the float levels are ok (and to confirm that fuel is getting to the carbs):
http://www.bbburma.net/FloatHeight.htm

[metalforever]

Thanks guys, well it's my 18th tomorrow so im taking the day easy, sunday ill get some fuel into the bike, there's probabaly only 2 litres in there at the moment.