Problem with gs500e- I think it may be the carbs...

[Maye]

Ok, so I have a problem that I would love some help with from you guys - perhaps you can help me narrow it down for me.

My bike won't start. The things I have checked so far are:

The compression: although it is a little lower than I would like it to be, I'm pretty sure it's enough for the bike to start on at least. The compression measured was about 1000kpa or 10kg/cm2.

The spark plugs: I have spark/the sparkplug fires.

Starting gas: The bike starts on starting gas.

Fuel supply to the carburettors: There is fuel getting to the carburettors - all the way to the float bowls. I checked this through opening the float bowl drains. Both of them.

Cleaning of the carburettor: I have cleaned the carburettor about three times, the first time through soaking it in water and dishwasher for about a day then blowing it clean with compressed air, the second time I used a fine wire to clean it and the third again compressed air -  still nothing. Im absolutely positive there is no clogging of the emulsion tubes, the pilot jet, the choke or the air inlets, etc.

Important/Here is the problem!
I have checked the fuel supply through the carburettor through lifting up the slides while twisting the throttle and revving the engine - even though there is a fuel supply to the float bowl, nothing comes up through the emulsion tubes. Anyone know what this is symptomatic of?

I would be forever grateful if you guys could help me solve this problem - I've spent all summer trying to figure this one out.

Best wishes

//Johannes

Update:Made some changes to make the text easier to read.

[rayshon]

"wont start" as in you press the start button and nothing at all happens?

or you can hear the starter motor doing it's stuff but the engine won't actually fire up?

[BaltimoreGS]

You seem to have the suck, squeeze, blow concept down; have you tried eliminating the carbs from the equation and see if it fires on some starting fluid?

-Jessie

[Paulcet]

I think "starting gas" means starting fluid spray.

[Maye]

yes, starting gas is the same/equal as starting fluid spray. To answer the first question - when I push the start button the engine cranks, but wont fire up without using starting gas.

[twinrat]

have you checked your float level?

[Maye]

No - I have not. I was thinking it was either the float level or perhaps some leakage in the needle valve. Although i'm not sure if a flooded needle valve would cause the symptoms I'm having.

[mister]

Just so we are clear, the under tank petcock is turn to allow fuel to flow, isn't it? And you do have enough gas in the tank, don't you?

Seems like silly question but we did have one situation like this a while ago and while assurances were given fuel was adequate it turns out the tank was empty (DOH!)

Michael

[bigfatcat]

You're not getting a hard enough vacuum in the carbs to pull the fuel thru the jet(s) while cranking - maybe cranking to0 slow (weak battery) or :

There's a carb vent hose tee'ed to both carbs, up near the top (don't confuse with fuel supply tee lower down) - must be open to vent the carbs or fuel won';t flow - insects like to build nests in small hoses  like these - as found out by a member on here several months ago

[The Buddha]

Important/Here is the problem!
I have checked the fuel supply through the carburettor through lifting up the slides while twisting the throttle and revving the engine - even though there is a fuel supply to the float bowl, nothing comes up through the emulsion tubes. Anyone know what this is symptomatic of?

I would be forever grateful if you guys could help me solve this problem - I've spent all summer trying to figure this one out.

Best wishes

//Johannes

Update:Made some changes to make the text easier to read.

So why are we lifting the slides while revving ... dont the slides lift on their own ? If they dont, look for rip in diaphragm.
And as always check for vacuum leaks from everywhere and exhaust leaks too.
Cool.
Buddha.

[Maye]

Important/Here is the problem!
I have checked the fuel supply through the carburettor through lifting up the slides while twisting the throttle and revving the engine - even though there is a fuel supply to the float bowl, nothing comes up through the emulsion tubes. Anyone know what this is symptomatic of?

I would be forever grateful if you guys could help me solve this problem - I've spent all summer trying to figure this one out.

Best wishes

//Johannes

Update:Made some changes to make the text easier to read.

So why are we lifting the slides while revving ... dont the slides lift on their own ? If they dont, look for rip in diaphragm.
And as always check for vacuum leaks from everywhere and exhaust leaks too.
Cool.
Buddha.

I dont think they are unfortunately. Always though that was odd, but figured there needed to be enough pull from the engine for them to lift(see the engine needed to be running) I will check the diaphragm during my next workthrough. Also I will check the carb vent hose as well. where do I need to check for vaccuum leaks?

Update:I checked the slides again while revving - The slides are lifting, although not more than 0,5 cm tops before they fall back down again. Should they be lifting all the way up while revving? I also checked the carb vent hose - it's not clogged.

[The Buddha]

Higher rev = higher lift, but go slowly ... @ 4-5K they have to be up say 1/4-1/3rd way. They wont stay steady there.
However non lifting slides due to pin holes in teh diaphram will let the bike not rev over a certain rpm but that rpm is gear dependent. 1st gear 7k, 2nd 6K, 3rd 5k, 4th 4K 5th 3k etc ... however a jammed spring in the slide will easily let the bloody thing not even lift at all ... and it will not even get off the driveway. It wil lstart and idle well, but nothing else.

Jetting and slide lift is dependent on throttle position. So you should put your observations on paper with throttle position as reference.

Cool.
Buddha.

[Maye]

Well the bike is not starting at all. I probably should have used another word than revving - Cranking the engine? Is that what you do when you push the starting button, making the starter motor pull the piston forward?

Anyway, I think bigfatcat might be onto something - Im probably not getting enough vaccuum, and the slides not lifting is just a symptom of that. Although I have already checked the carb vent hose for clogging. Is there anything else that could be causing low vaccuum pressure to the carburettor?

[bigfatcat]

Is there anything else that could be causing low vaccuum pressure to the carburettor?

Air leaks between carb and cylinder head ?      Try spraying starting fluid in this area as you crank - if the engine momentarily fires you've got an air leak.

What is the year and mileage of your bike;  do you have any idea how well the previous owners maintained it  ? ? ?

[Maye]

I have no clue to be honest.

I thought he took good care of it when I bought it, but with this I am getting less and less sure.

Anyway, I kind of forgot to mention this - the rubber pipes connecting the carb and the cylinder head were damaged. I've ordered new ones, and in the meantime I temporarily glued them together again with superglue (I know thats nowhere even close to good enough, but it was temporary damn it ) I though I got them together good enough, but perhaps there is still a leak?  Anyway, I guess we will find out when I get the new ones

[Maye]

Nope, not the intake hoses. Anyway, whatever it is I have now ordered a carburettor over ebay.I got it for under  100 dollar with shipping, so It's not such a big deal. I hope that will fix the problem, but if not I at least know its not a problem with the carburettor.

[Maye]

Hey guys - still working on the bike. It wasn't the carburettor unfortunately. But I need to ask you guys something else.

I was working with the bike when something happened. The thing I was trying to do was to eliminate the petcock out of the equation and set the fuel tank up directly to the carburettor to see if there where anything wrong with it(the petcock that is).

Anyway - after doing just that the bike wouldn't even start(as in - it wouldn't even try to crank). I just kept hearing this clicking noise whenever I pushed the starting button. I've seen this before when working on the bike, you remove something, and suddenly the bike wont start - like a safety mechanism or something. Unfortunately I have yet to figure out why? Anyone know what it is?

And before you ask - yes, the battery do have juice. I left the charger plugged in overnight.

Update: Missed the first lines in the wiki - doh! On a related note - anyone know where the engine cut of switch is located?

[Big Rich]

Engine cut off switch = kill switch on handle bars.

But if you are hearing a clicking noise, it's not any safety switch. Are you sure your cylinders didn't flood with gas when trying to bypass the petcock? Probably a weak battery (charged or not), dirty electrical connection, etc.

[Maye]

well, I can't be a 100% sure, but the battery was working just fine yesterday. Could be that the cylinders flooded with gas when I bypassed the petcock, but shouldn't the starter motor att least try to crank then?

[twinrat]

take your spark plugs out if you think you have filled your cylinders with fuel or you will damage something
trying to turn engine over