Puzzled

[stuart9726]

Hi all,

Im getting rather frustrated and hope that one of you talented fellas round here might be able to point me in right direction of where I could be going wrong.

1st up, its a 1992 GSX750f, im living in far north QLD in Australia. I have not done any mods what so ever in regards to the engine, with exception to the coil relay mod I did 4 years ago.

Heres whats happened, I noticed a lot of rust build up in my tank, so after numerous google searches I went down the apple cider vinegar route. It actually removed about 95% of the surface rust, so was very happy there. Washed it out with clean water, then swilled 2 litres of metho around the tank and then 2 x 10 litres of fuel and emptied all this out. At the same timr I stripped and cleaned the carbys, soaked it all in carb cleaner (ccouldnt find any of the paint tins you get over in the states, so de canned about 10 cans of spray carb cleaner into a clean metal tin) followed carbs 101 to the letter. Put the carbs back together, bog standard, as per the manual, needle 3rd clip, frEsh o-rings gaskets etc. AF screw set to 2.5 turns back. I also rebuilt the petcock as per the how to walk through

Now here is the problem, when I start her up she starts 1st time, no problems and idles pretty damn good, approx 1000rpm, very little bouncing. I shut her down to attatch the carb syncer and when I start her up again I have to have the throttle wide open and she wont get about 400 rpm and dies as soon as I let go of the throttle she dies. She will continue to idle as long as I have the throttle wide. Changing the petcock from on to prime makes no difference. Adding choke to richen the system makes no difference. If I leave her over night, she will fire up again 1st time no problems, same again, shut her off and she wont idle again.

Replaced all fuel lines with oem ones. Fuel flows freely with the tank removed on prime, reserve and even in on, with the vacuum line engaged.

Im sure its gonna be something really small that ive missed, but I just cant fix her this time, im puzzled. Stripped the carbs and petcock down several times in case I missed anything. Timing is spot on. Intake valves are set to .006 and exhaust .009. Also put in fresh spark plugs.

Sorry for the long story, but I wanted to get all the info I have. Thanks in advance

Stuart

[92xjunker]

Sounds like your flooding, check your oil for fuel smell.

[sbcmighty]

Are you conecting vacuum ports to sync tool prior to startup. Vac leak could cause problems.

[Kreylyn]

Are you leaving the tank and petcock connected when you switch to the sync tool, or no? Cause if the petcock vacuum line is being disconnected and left unplugged... your making a massive vacuum leak.

Krey

[stuart9726]

Hi guys, thanks for the replies. I forgot to mention that it also does the same with the tank still on the bike. When I do removed the tank for syncing, I do reconnect all 3 lines back to the tank though.

Will check the oil when I get home from work tonight 92.

Cheers

[stuart9726]

Back again guys.

Dropped the oil, as younsaid it smelled of fuel. So put fresh oil in. Started her up and started 1st time again. No choke, no throttle. Reved her a little bit, she stopped at 3000 ish and then after 20 or so secs dropped back down to idle at 1000. Left her idling therenfor about 5 mins or so. Went to rev her again and she bogged down and died.

Tried starting her up again and she wouldnt start without the throttle wide open. So is the engine flooding out everytime I start her????

[ZukiFred]

Left idling for 5 mins will foul out the plugs.

[maniac1886]

If there was fuel in your oil, it must have gotten there somehow. It sounds like your carbs are flooding. I think it starting after an oil change was coincidence. Smell your oil again. If it smells like fuel again, your carbs are dumping gas into your head which is flooding your bike and fouling your spark plugs, then leaking down around the pistons into your crank case. If thats the case, the carbs are going to need to be pulled and cleaned.

[stuart9726]

Ok, so stripped the carbs down, again, they looked clean, but im gonna soak them for 24 hours again anyway.

As I was stripping them down I noticed that the little brass insert thingy that stops the emulsion tube from turning is no longer there. Does this have another function, or is it just to insert the emulsion tube correctly?



Also, I pulled the plugs and they were black, not wet, but like a sooty black.

Thanks for your help so far guys.

[ZukiFred]

Also, I pulled the plugs and they were black, not wet, but like a sooty black.

Thanks for your help so far guys.

That would be the fouling from sitting idling too long.

[92xjunker]

Did you install a rebuild kit. Bad needles will cause flooding. It you can start a cold engine without the choke, I would be concerned with flooding.

[stuart9726]

Hi 92. After all that it appears to have been the fuel tap. Ended up just replacing it with a brand new one. She is run ok now. A wee bit lean, throttle hangs when I blip it, but I think one of the boots on the air box has popped off when I installed them agaiagain. Thanks for your help and suggestions guys.

Happy again. No longer wanna sell old girl.