The history

I was out riding a few weeks back, and at about hour 5 my bike died on the highway (2000 GS500 13500 mi). When it started up it would seemingly buck back and forth for a few blocks and then die again. I took it to a suzuki mechanic and he said it probably overheated, and suggested that he replace the K&N pod filter with the stock and rejet the carbs back to stock as the bike was riding incredibly lean (the first owner must have bothced something) He showed me the spark plugs and they were bright white.

When I get the bike back I take it out on the highway. At around 75 MPH it topped out (I've been 90+ with plenty to spare.). The bike seemed to bog down at around the 5k - 6k rpm mark in 5th and 6th gear.

As per Srinath's suggestion, I truly thought it was one of the diaphragms.  So after researching where the hell the diaphragm is, and how to remove it, I took tools to the bike.

The good  I was able to put the bike back together despite sropping pieces all over the damn place.  The bike ran. Wooo!

The Bad  I think I'm missing a hose thats suppossed to go to the tank.   The one in the middle by itself. Overflow hose?

The WTF  It wasn't the diaphragm.  Both were fine.  Looked like clean smooth supple rubber.


The joy of motorcycling is leaving me. Its replacing it with a giant boot right up my ass.

Well whatever the problem may be you have very good literary skills.  I would persue a career in writing...possibly creative writing...or fiction.  Anyhow...what was your question about your bike..  Honestly all i know is how to ride them and get them all rusty.  :dunno:

Sorry and good luck..

Nah I'm an accountant.    

The question is... wtf do i do now. LOL

OK its diaphragm was fine, were you having fuel flow ... crap in tank, in carbs in lines ... somewhere ...
Cool.
Srinath.

Well you could probley keep your k&n but you need to figure out what you need for jets before you ride again.  Im assuming the bike just started to act up after your long 5 hour ride?  If so I suppose it could be posssible that you could have gotten your pistons up to their melting point and burnt your engine down.   A sure way to check this would be to perform a compression test, if you have good compression you have nothing to worry about, if not then you can start to tear down.  I had my snowmobile melt the front half of the piston off and the mechanic couldnt figure out what was wrong until we did a compression test, it was so hard figure out because it still ran very decent unless you knew how to make it act up, so it could possible be that yours has sort of the same problem my sled had.  Thats just an idea I had when I was reading your post.

Well I have to assume the fuel flow was ok...    I guess I just don't know.

When I looked down to where the diaphragm used to be it looked blazingly clean, but I have no idea what that means if anything.

I guess its back to the mechanic for a compression test...

Could needing a valve adjustment cause this?

High speed and it gags ... and no I doubt its valves ...
Compression test ... ironically ... that's one thing I am certain of ... good compression ... motor will first lose the bottom end if its poor compression ... my 89 has pathetic torque under 4K especially.
Its carbs and fuel ... nohting else ... electrical maybe, but we should see if the engine heat has anyhitng to do with it ... maybe when it gets very hot ... I guess you should try and see if you can find an empty highway, load it in a trailer on a cold day and go to the empty part and unload and start it and try to see if you get that problem, then again try it after it fully get hot ... cold and high speed is bad, so it should be just warm ... maybe 2-3 mins of riding.
tank petcock is clogged or somehitng is fooked up ... fuel and carbs ... guaranteed.
Cool.
Srinath.

Srinath.... I'll give it a go.    Maybe I should check the plugs at that time too to see if they're white?  That would be an indication of it running lean still right?

If thats the case, and running lean is only affecting it in the upper range, maybe it will just take a turn of the fuel screw right?

Thanks for the help.  I cant help but get the feeling mechanics everywhere are screwing me

Fuel screw only affects idle and under 2K rpm ... high speed is Main jets and needles ... however you aren't getting fuel to the carbs ... blocked hoses, or clogged tank petcock.
Cool.
Srinath.

The diaphragms on my GS400 were bunk. When i took them out they looked fine. What you have to do is stretch them a wee bit, as if they are under preassure, and little pinholes start to appear. Testing with water is good too.

why not just replace the diaphragm just to be sure?  how much do they cost?  if ur not sure if its good or bad just replace them if its not too expensive. that way u know its not the diaphragm..

Heard back from the shop and wanted to update everyone else in case this problem comes up for someone else.  In short..... the first shop really, REALLY sucked.   This is what the shop told me:

1) Missing O-rings in the vacuum something or other.   It was apparently affecting my idle.  My idle did SUCK.

2) Low end was jetted too lean

3) TOP END WAS JETTED TOO RICH.  The bike was apparently gagging on itself when the revs started pushing into the high end.


Other nonsense:  missing a clip between the airbox and the carbs, and my air filter was soaked in gasoline.


Picking it up today, hope all is well with it.   They did do a full diagnostic with compression, spark, and timing tests, so that makes me more confident in the work they did. Wish me luck  

OK sounds like BS and a lot more of it to me.
Stock jetting ... no way you were "jetted" rich up high. However you may have had a stuck or overflowing float in one or both carbs making it rich especially after soaking the filter. So essentially you had to have the floats checked and reset.
Cool.
Srinath.