Major Service and now it won't start

[MDerrett]

Really embarassing when your first post is that it won't work, but I'm outa ideas.

I bought my 93 GSX750F about two months ago to commute. It was running a bit rough (stalls at lights, hesitates on throttle) so I thought I'd do the full major service to get it back to running right.

Did the usual stuff (fork oil, oil, brake fluid etc etc as per the Haynes manual) and thought that it would be a good idea to clean out the carbs.

Followed the Carbs 101 tutorial to the letter. Only difference was that I couldn't soak anything as you can't get carb soak anywhere in Sydney (probably some well meaning but unknowing greenie thing) so I was restricted to compressed air and pressure can carb cleaner spray. All jets soaked in cleaner over night and blown out with pressure (all seemed to flow OK)

Replaced the o'rings, all went back together ok. New plugs, coil mod, new battery, cleaned up some dodgy wiring and back together it went, 2 1/2 turns on the air mixture screw and 14.5mm or close to it on the float level. New air cleaner.

And nothing. Not even a pop or phart. Starter turns, nice and healthy and fast, but no firing. Not even a simple pop.

Starter turns so I assume it's not some sidestand or clutch cutout (tested the sidestand relay just to be sure).

I checked the valve clearances but only had to reset half of them and then not by much, so I don't think it's that. Pulled a plug lead and with one of the plugs (tried it with old and new) got spark at the tip, so I don't think it's electrical (didn't change spark timing at all). Removed the coil mod and changed it back to scratch just to be sure. Still nothing. Redid the carbs again, nothing. Redid the carbs again, replaced the original o'rings just in case. Again, nothing. Air box off, nothing. vacuum port blocked, unblocked, still nothing.

Pulled a plugs and I swear the plugs are almost bone dry, so it makes me think it's something to do with the carbs, but what could I have done that so totally nafs it that I don't even get a pop?

I'm going to try to get a can of starter spray and try that tonight, but in the meantime, any suggestions?

Thanks and Best Regards

Mike

[MikeyZ]

What is this coil mod??? Is it getting spark?

[MDerrett]

Hi,

Coil mod uses the original coil power (orange and white lead) to bring power direct from the battery via a relay to the coil instead of going through the ignition switch

http://katriders.com/vb/showthread.php?t=116991

It was getting spark before, getting it with it connected and after when I disconnected it. Probably not the hottest, bluest fattest spark I have ever seen but still should be enough for something.

Thanks for replying.

BR
Mike

[jetmerritt]

I'd try the starter spray first and see if it fires, then chase fuel problems if it does, electrical if it doesn't.

[MDerrett]

I actually dosed a syringe of fuel in through the carbs, didn't get much except the the biggest single sheet of flame I have ever seen out a bike exhaust in my life. Scared the bejesus out of my wife, who unfortunately chose that moment to stand behind and laugh at my inability to get it working. Bike won't run, but wife did......

[Malarky112]

Did you put the bike on prime after you cleaned the carbs to fill the bowls up? And did you remember to hook up the vacuum hose to your fuel petcock?

[jetmerritt]

I actually dosed a syringe of fuel in through the carbs, didn't get much except the the biggest single sheet of flame I have ever seen out a bike exhaust in my life. Scared the bejesus out of my wife, who unfortunately chose that moment to stand behind and laugh at my inability to get it working. Bike won't run, but wife did......

[MDerrett]

Hi,

Fuel tank was disconnected, using a little (vented) test tank I made up and I also checked the carbs were getting fuel by cracking the drain plug on No 1 carb and then refilling it. The first time I deliberately left the vacuum pipe to the petcock open just to see if it would run lean but then I plugged it and tried again. No go.

[Kreylyn]

Couple of things to check...

1. Voltage at the coils with the key on.
2. Voltage on the battery with key on.
3. Voltage on the battery with the starter engaged.
4. Voltage on the coils with the starter engaged.
5. Plug wire order
6. Did you bench sync the carbs?
7. Have you purchased more beer?
8. If you cover the breather hole with your hand almost blocking it, does it make a diff?
9. Are all the lights on the bike working properly (headlight, dash indicators, turn signals, etc)


Krey

[jetmerritt]

Hi,

Fuel tank was disconnected, using a little (vented) test tank I made up and I also checked the carbs were getting fuel by cracking the drain plug on No 1 carb and then refilling it. The first time I deliberately left the vacuum pipe to the petcock open just to see if it would run lean but then I plugged it and tried again. No go.

Have you tried the starter fluid yet? excellent diagnostic tool, it will take all the fuel system and carbs and petcock out of the equation. After I fixed my GS, I had the carbs off, sprayed a little starting fluid at the intake boots and it flashed up > then I knew electrical was good and head/valves were good. Then I proceeded to fight with the carbs.

I just think you should narrow it down because you have changed so much at once. At least you could chase a system instead of

[MDerrett]

Tried the starter fluid this morning. Still no firing so I guess that means electrical. I'll go through the ignition system tonight when I get home. Maybe I left off a wire somewhere when I did the valve clearances.
Still can't understand why it would be electrical if I get a spark at the plug though.

BR

Mike

[jetmerritt]

Are you sure the engine isn't flooded, plugs dry?

And wires to correct coils so timing is correct?

Plug wires right order?

Exhaust not plugged with anything?

Just trying to help, hope you get it going man.

[Thomas Dylan]

Unlikely but check firing order again and at least visually check that ignition timing is at TDC

[MDerrett]

Thanks for replying.
Mr Kreylyn,
In order of priority, it is a matter of national pride that the beer fridge remains stocked. Mine is no exception (and a free good quality Australian beer to whoever cracks this!).
1. Votage at the coils (no coil mod) 11.5V
2. Battery Voltage key on 12.4V
3. Battery voltage starter engaged 11.0 volts
4. voltage on the coils with starter engaged not measured, Ill check tonight
Note: (possible that the voltage readings may be a bit furry, had one hand on starter, one on postive lead, one on neg lead on meter, one hand on throttle
5. Plug leads Labelled before removal and back in same order
6. Carbs bench synched
7. Beer cold and ready
8. Will try tcovering the breather hole tonight
9. Half the instrument bulbs were blown so I went round and replaced them all but I'll check all lights and circuits again tonight.

Mr Jetmerritt, I'm pretty sure that the plugs are dry, certainly don't look like they are fouled. I labelled the plug leads before I did the valve timing so I'm sure they are in the right order. Good idea about the coil wires, possible that I got them mixed when installing or removing the coil mod wires. I did plug the exhaust with plastic bags while I had the exhaust off, but I have four bags on the floor but I'll check tonight. All help appreciated at the moment.
Mr Dylan, given the "no pop" situation with the starter fluid, I was going to go through the whiole ignition circuit and will check this.
News again tomorrow morning!

Thanks again to all (and the beer offer stands!)

[TRPUT]

Bwahaha!

Just hope you aren't trying to convince these people that Fosters or even Crown Lager are "good" Australian beers!!! Watcha got?

If you have tried with and without the coil mod and you have spark but no action, and assuming some good old "Start Ya B...ard" didn't work ...

If plug leads are correctly installed - are the coils wired correctly L and R?

Thread caps off plugs so the lead clips seat properly? And even then the lead caps need to be pushed on very firmly to seat them.

Fuses??? - Although you need them for spark.

Earth???

Probably going to be something really simple when you nail this.