Bogs down with throttle - video!

[rowdyrandy]

I get this "breathiness" when I give my bike any throttle now. I had this problem once last year but it went away overnight and now it's back overnight. It seems to be carb related but I cleaned them and the jetting hasn't changed. I've been riding it for a year plus with the current jetting - but seems like its starving for fuel. Valves are good, mechanical advance is good, timing is good, coil is good - still its hard to start and has no power, just bogs when you give it any throttle. Ex500 carbs with a pamco. I advanced and retarded the timing just a bit in either direction too just to see if it would make a difference - no dice. Any advice? I'm stumped.

 

[TwoManyXS1Bs]

Remove the air filters and watch the carb slides. See if they move smoothly with throttle, or rapidly jitter up/down.

Weak ignition can do this, too. Don't know what you've got there...

 

[figure8]

Open the gas cap when giving throttle?

 

[rowdyrandy]

i did have the filters off at one point and they do jump and chatter around. I'm running a pamco and Hugh's pma

 

[retiredgentleman]

I'm not familiar with EX500 carbs, so this is just guessing. With BS38/34 carbs, when the engine will not rev up like you have, it means the pilot circuit is not supplying enough fuel/air mixture. Could be dirt in the pilot circuit.

May be wise to measure float levels, and remove and confirm that the pilot jet is fully clear.

Does you fuel tank have rust in it? Do you use fuel filters?

 

[rowdyrandy]

Tank is clean and I've got a filter in place. I took the carbs apart yesterday and cleaned them but they didn't need it - I checked the float levels as well, all good at 17mm. I was actually praying they'd be dirty but doesn't seem to be that simple. I'm starting to think it is an issue of weak ignition.

 

[retiredgentleman]

Tank is clean and I've got a filter in place. I took the carbs apart yesterday and cleaned them but they didn't need it - I checked the float levels as well, all good at 17mm. I was actually praying they'd be dirty but doesn't seem to be that simple. I'm starting to think it is an issue of weak ignition.

I don't want to insult your intelligence, but I have to ask this question. Everybody says they "cleaned the carbs", but not surprising, quite a few lads don't know what a pilot jet is or where its located. Did you actually remove the pilot jet and check that it's not blocked?

 

[rowdyrandy]

Ok well seems to be an issue of ignition. I've been running a small 12v .8ah battery in my set up. Pma with a pamco, led turn signals and tail light, no gauge lights, 55w headlight. Just now I hooked the standard 12v 14ah battery inline and once started, it ran *better*. I tried to show this in the video below. It died shortly after this though.

 

[rowdyrandy]

No thats cool, I know all this stuff has to get repeated just to be sure. No, their clean. I'm sure - pulled all the jets and the diaphragms too. Just put up a better video of whats going on. I think it may be electrical..?

 

[retiredgentleman]

With the way those slides are fluttering, you should have a good look around the carb manifold area to see if you have air inleakage.

 

[TwoManyXS1Bs]

+1 RG. I'm also not familiar with EX-500 carbs. But, the intake sound and the beginning of slide flutter when the symptom occurs leads me to think that there may be a leakage between one of the diaphragm chambers and intake manifold.

In these links is a description/diagram of the XS's BS-carb fuel enrichener valve, which connects the intake manifold with the enrichener fuel jet and a source of air (the atmospheric pressure side of the diaphragm chamber).

http://www.xs650.com/forum/showpost.php?p=412504&postcount=4
http://www.xs650.com/forum/showpost.php?p=417989&postcount=26

The main idea here is that sufficient intake manifold vacuum pulses occurring in that chamber can induce slide flutter.