GS750 no start

[theinsuranceguy]

It feels like there is no combustion happening (obviously)... the starter is cranking away (sounding healthy) when using the button start, but when using the kick starter there is no resistance on the way back up. It feels like everything is in place (fuel, spark and air) but no combustion...I'm truly at a loss here. I don't feel like doing a whole engine rebuild here but is that what I should be doing to figure out the problem?

Is there a way to check fuel is actually making its way into the combustion chamber?

[tom203]

If you crank for a while with "choke" system activated, then remove spark plug, you should see signs of fuel on plug. No fuel likely means your enricher (aka,choke) is not working - not supplying extra fuel dose.

[roeme]

It feels like everything is in place (fuel, spark and air) but no combustion

"Feels like" ain't gonna be enough.

So, as usual, the things required: Spark, Fuel, Air(/Compression). You confirmed Spark, so that leaves Fuel and Air (and the proper mixture of them).

Old trick here is to drop a teaspoon of gasoline down each cylinder. By the time you've screwed in the spark plugs back in, you should be able to get at least one to two firings.

[theinsuranceguy]

"Feels like" ain't gonna be enough.

So, as usual, the things required: Spark, Fuel, Air(/Compression). You confirmed Spark, so that leaves Fuel and Air (and the proper mixture of them).

Old trick here is to drop a teaspoon of gasoline down each cylinder. By the time you've screwed in the spark plugs back in, you should be able to get at least one to two firings.

I did the trick as suggested and sure enough she fired right up. It was the first time, I have heard the bike running in over 5 months.

I take it this confirms there is no fuel entering the cylinder? How can I narrow down the problem from here?

Thanks

[hannibal]

If the bowls have fuel but the fuel isn't reaching the engine, then the carbs could have some blocked passages.

What are your fuel and air screws set at? I think 3/4 tirns out on the fuel screw and 1.5 turns out on the air screw is what's recommended. Hopefully, one of the more experienced guys will correct me if I'm wrong.

[theinsuranceguy]

If the bowls have fuel but the fuel isn't reaching the engine, then the carbs could have some blocked passages.

What are your fuel and air screws set at? I think 3/4 tirns out on the fuel screw and 1.5 turns out on the air screw is what's recommended. Hopefully, one of the more experienced guys will correct me if I'm wrong.

I will look in the carb section to see if I can find a write on the adjustment of these guys and which ones were which. I have a manual that I followed when putting the carbs back together - but nice colour pictures and diagrams are better for me.

[Big T]

You need a new definition for carb cleaning

Go here

http://members.dslextreme.com/users/bikecliff/

and follow the VM carb cleaning tutorial

[roeme]

So, as usual, the things required: Spark, Fuel, Air(/Compression). You confirmed Spark, so that leaves Fuel and Air (and the proper mixture of them).

Old trick here is to drop a teaspoon of gasoline down each cylinder. By the time you've screwed in the spark plugs back in, you should be able to get at least one to two firings.

I did the trick as suggested and sure enough she fired right up. It was the first time, I have heard the bike running in over 5 months.

I take it this confirms there is no fuel entering the cylinder? How can I narrow down the problem from here?

Thanks

It doesn't necessarily mean that no fuel is entering the cylinders, in your case here it's most likely not enough. The problem is located in (or around) your carbs. Given the history we know so far, unknown fuel quality and storage conditions, but running ok prior, it's likely that your carbs are clogged up.

So as the others have suggested, you need to re-clean your carbs.

Did you stabilize your fuel and drained the bowls prior to putting the bike into storage?

[BurntKittyForge]

I had a similar no-start problem for four days that had me baffled recently.
I'd left the MC sitting a week and went to start and it stalled. Then just turned over and over.
Figured maybe need to clean carbs again (like another EFFIN' REDUNDANT task...)

Anyway, I've been working too hard, spending all free time working on my '82 Mercedes (parked next to bike), so I sprayed a quick squirt of starting fluid onto each pod filter. Nothing, not even a single pop...

Next day I added 2.5 gallons fresh(er) gas. Then disassembled and fully cleaned the cut-off switch on handlebar, still nothing. (I've moved very close to ocean/beach, corrosion worries)
I removed each plug, checked the gaps, inspected, looked new.
Ground one to a fin and had faint spark (in sunlight)., still no pop even with starting fluid (not good but I'm lazy) right into carb intakes...

So on the fourth day she / (he whatever, more like a stallion anyhow) fires right up...

LOL, why? FLOODED and it took that long to dry out...
(despite in my overworked/ lazy free-time I could've removed all four plugs same time, cranked engine with no choke and cleared it, faster than my other efforts).

Had to have been flooded and my guess coupled with the remnants of some stale gas/ethanol/stabil mix , despite stabil directions followed precisely. (had petcock on "RES" since gas was low. Bad position since all the goop at bottom enters my garden tractor filter...

Only issue now, think need a new starter solenoid because during the ordeal it stuck on start a few times and in one event such, I raced to karate chop style the top of battery, which worked somehow but cut my finger bad on the gas tank edge there...
That's my .02 on it anyway. (Had to get it off chest also).
... plan on getting caught up on some missed riding too.

[Steve]

... I could've removed all four plugs same time, cranked engine with no choke and cleared it, faster than my other efforts ...

You could have left the "choke" ON and had the same results.

The "choke" system on our bikes does not block off the intake passage like a car's carburetor. Instead, it opens separate air and fuel passages to provide a richer mixture (that is why it is called an "enrichment system") for starting. It also relies on the high vacuum of a closed throttle. With no spark plugs in the engine, there will be NO vacuum, therefore the "choke" will not work.

All that matters is that you hold the throttle open (with "choke" on or off) while cranking, you will clear a flooded engine quickly.

.