M750 not starting

[MongoReturns]

OK, riddle me this:

M750 hasn't been starting for about 2 months.  Motor spins & spins; I've tried on several occasions.  I was convinced it was the petcock; fuel pump recently rebuilt & was running like a champ.

Took petcock off today (I HATE PLAYING WITH GAS!!!) and connected the line directly to the carbs.  Apart from fuel coming out of every nook&cranny of the carbs, still no go.  WELL CRAP!!!

Not wanting (more) fuel going all over the place, I reconnected the petcock.  Still no go.  Figured last ditch was to get some starter fluid.  None in my immediate are; a tire place had some throttle cleaner around & gave me the can.  Couple of spins then a hellacious backfire.  Few more spins, and bat was about toast.  No go.

Figured maybe a bit more juice in the bat would do it, so connected old 1098 bat in parallel.  Or sequential.  Whatever, negs to negs & pos to pos.  STARTED RIGHT UP!  Shut her down; started right up again.  Went on nice ride; got coffee, started right back up.

So, to the questions:  why didn't it start cold?  Why did it start with the extra bat hooked up?  Is it possible the bat has enough juice to freely spin the motor, but not start it?

Thanks in advance.  Happy the carbs aren't currently sitting in my apartment, waiting to be taken apart.

[ducpainter]

Is it possible when playing with the battery you moved a connection on a coil or black box and that was the impetus for it to start?

[MongoReturns]

I don't think so - I'm REALLY careful when hooking up jumper cables.  I suspect the throttle body cleaner I used actualy cleaned something.  In my previous start attempts, my plugs were bone dry.  Wouldn't I get once cyl working if one box was messed up?

[ducpainter]

If the plugs were bone dry after all that cranking you weren't getting fuel.

Maybe when you reconnected the petcock you took a kink out of a line and fuel started flowing.

Hard to say from this distance.

[MongoReturns]

Check, that's why my prime suspect was the petcock.  But then it wouldn't start without the petcock, and fuel coming out from evreywhere on the carbs.  I opened one of the drain screws too, to double check.

I'll see what it does tonight - my choke has been a little strange for a couple years; maybe the cleaner cleaned that out.

[ducpainter]

The cleaner, sprayed into the openings, wouldn't clean the enrichment circuit.

Your choke could very well be the culprit though.

[MongoReturns]

I thought the odds were low the cleaner would weasel it's way in there.  Started tonight on the first pump; 22k miles & all original carb parts except for the Stage 2 jets & needles (7 years ago I think).  Guess it's time to take it apart.  Ugh.

[ducpainter]

Does the cable feel like it's working?

[MongoReturns]

It works, but I only use about 1/4 turn of it.  All the way, doesn't start.  It's also very tight; much like my throttle cables which don't spring back to their original position quickly.  On the plus side it requires very little effort to hold the throttle open.  I just have to also twist it closed.  Lubing all the cables is on my list, next to changing the belts, getting new brake pads, and even filling the rear resevoir up (I've even got a bottle of fluid in my closet).  My laziness with the monster has increased exponentially over the years, it's quite sad.

Is it possible something in the choke circuit got stuck?  I have no idea how that thing works.

[ducpainter]

It works, but I only use about 1/4 turn of it.  All the way, doesn't start.  It's also very tight; much like my throttle cables which don't spring back to their original position quickly.  On the plus side it requires very little effort to hold the throttle open.  I just have to also twist it closed.  Lubing all the cables is on my list, next to changing the belts, getting new brake pads, and even filling the rear resevoir up (I've even got a bottle of fluid in my closet).  My laziness with the monster has increased exponentially over the years, it's quite sad.

Is it possible something in the choke circuit got stuck?  I have no idea how that thing works.

Yes...

The cable lifts a small plunger in the carb which opens a fuel passage. Do your plugs look OK? How's the mileage?

Check your grip to make sure it isn't rubbing on the housing.

[speedknot]

Figured maybe a bit more juice in the bat would do it, so connected old 1098 bat in parallel.  Or sequential.  Whatever, negs to negs & pos to pos.  STARTED RIGHT UP!  Shut her down; started right up again.  Went on nice ride; got coffee, started right back up.

After my M750 sat for about a month, it took some time and a 1x battery charge to get it going.  After crankin and goosing the first time, it wouldn't start.  I smelled gas from the exhaust so it was getting fuel.  I took the proverbial coffee break as well and came back after the batter got a full charge.  The bike started right up.  No rhyme or reason.  I was told not to twist the throttle when starting, but it I don't do that, it has a harder time kicking over.  As with your issue, is it possible that there isn't enough spark to ignite the fuel?  Still scratching my head. 

[MongoReturns]

Yes...

The cable lifts a small plunger in the carb which opens a fuel passage. Do your plugs look OK? How's the mileage?

Check your grip to make sure it isn't rubbing on the housing.

Hmmm choke lifts a little plunger... wonder if something got stuck in there and I pushed it out by flooding the carbs.  Seriously gas was coming out of everywhere on those things without the petcock (and not running).  Don't think grip is rubbing on the housing; it seems to get better after everything gets hot.  But I'm not terribly concerned with things that won't leave me stranded.  I just need to get off my a$$ and do some actual maintenance.  Did I mention I've had new belts sitting in my apartment for over a year...

[MongoReturns]

After my M750 sat for about a month, it took some time and a 1x battery charge to get it going.  After crankin and goosing the first time, it wouldn't start.  I smelled gas from the exhaust so it was getting fuel.  I took the proverbial coffee break as well and came back after the batter got a full charge.  The bike started right up.  No rhyme or reason.  I was told not to twist the throttle when starting, but it I don't do that, it has a harder time kicking over.  As with your issue, is it possible that there isn't enough spark to ignite the fuel?  Still scratching my head. 

I noticed it cranked even slower with the throttle open too, seemed counterintuitive to me.  Also when it did start, I had to hold it at around 1500rpm's to keep it going - apparently the charging system doesn't kick on till around then, and a dead bat doesn't have enough juice to keep it going by itself.  1098 does that too.  Of course, my plugs are at least 5 years old.  I have no idea what a fouled plug is; mine are always textbook perfect-looking.

[speedknot]

Did I mention I've had new belts sitting in my apartment for over a year...

Sounds like me.  I buy the shit and never find the time or motivation to do it.