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Discussion Starter #1
So, my Suzuki GS500E cut out as if it wasn't getting fuel all of a sudden when I was riding on the freeway, with only a little warning with the bike reducing power slightly then going back to normal at the start of the ride.

It wont start at all now, I can't get any signs of fuel getting into the ignition chamber, although the float bowls are filling up with fuel.

Spark is fine.

The air filter is quite old and have a new one ordered.

The cylinders are getting compression of 110 and 105psi which is low but have been told so far that shouldn't be low enough to stop getting fuel sucked through.

The valves appear to be on the tighter side of the scale, I don't have a feeler gauge small enough to check accurately.

The seals between the carby and intake seem fine.

I took the carbys apart, they didn't look that bad, I cleaned the main and idle jets then put them back together which didn't seem to change anything.

Any ideas on cause of the problem or what to try?

Cheers.
 

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Can only be fuel not getting into the cylinder/s caused by the carb circuits from the float bowl onwards...if, as you say, the bowls fill up correctly... or the valves not working properly. As you had the carbs apart I would start there and run some heavy duty fuel cleaner through.

A simple test for the valves is pull the plugs and stick your finger over the hole...rotate the motor to bring the piston up to the compression stroke....you will feel the pressure build up on your finger. Continue to rotate the motor to the exhaust stroke and if the pressure disappears then you know the valves are at least working.

I dont like the "a bit tight" valve scenario...you may have a severely burned valve face due to this...a cheap set of feeler gauges is all you need and a valve clearance check is simple...in fact if you are going to do that then you will see the valves opening and closing as you rotate the motor manually.

Other things to check are spark...outside the cylinder. air filter and make absolutely sure the carb boots are secure and not leaking....over-tight is as bad as too loose.

Good luck
 

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Other things to check are spark...outside the cylinder. air filter and make absolutely sure the carb boots are secure and not leaking....over-tight is as bad as too loose.
Test, test, test. Don't guess except as a last resort.

Test for spark on all plugs.
Test your fuel theory by using a little starting fluid or propane put into the intake while cranking.
Make sure the battery is healthy and fully charged. Some modern designs won't start if the engine doesn't turn fast enough.

What other "mechanics" have been involved and exactly what did they tell you ??
 

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Discussion Starter #4
Thanks for the replies,

Finally got it started.

I had another mechanic mate help who had more experience with motorbikes.

Got it going by squirting a bit of oil into the spark plug ports to help compression, then took 15 minutes of cranking with a jump pack attached and a slight bit of help from spraying starter fluid in once and eventually she started sucking fuel through and seems to be going alright now.

Strange that it would take that long to start sucking out though when the float chambers were filling up straight away.
 

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Sucking fuel from the float bowl to the engine involves a lot of tiny passages and jets and a few parts that must work together faultlessly...so its not that strange when you consider the bike is 20 years old and has sufficient wear to have low compression. As ER says run some good fuel cleaner through and leave overnight if possible.

Good Luck
 
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