Crank, No Start Condition

[sr73087]

Hi everyone, so I just purchased a 99 GSX750F and it has a crank, no start condition. I have not really begun to start the diagnosis however, are there any standard issues these bikes typically have that I should be on the look out for? What cold compression figures do these engines have when healthy?

[92xjunker]

Dude, just clean the carbs. No major issue specifically. Download the manual and follow the maintenance schedule. Download the carbs 102 manual and follow it to a T, then do it again. Once that's done, then if it doesn't start hit us up.

[shpielers]

Welcome aboard.

What ^ said, it's likely your carbs need cleaning.

Something else you can check is the voltage at the coils while the starter is turning over (extra set of hands makes that much easier) needs to be over 11V to really work. Teeny bit below and it might crank but not have a strong enough spark to catch.

It's also possible the carbs are empty - pulling enough vacuum with just the starter turning the engine over to suck enough fuel to fully fill them and make it to the engine is hard. Try turning the petcock to prime for ~30seconds to fill them with fuel first. Then try starting again. Still might take a bit to suck fuel through all the jets/etc, but much easier than filling the carbs first. If you try using starter fluid, don't use a lot. Like seriously, just a teeny bit.

There's a manual available for download on here, it'll have the compression numbers in it.

[sr73087]

Thanks guys for the info, that is really helpful.

Regarding the fuel petcock, what direction is prime vs on vs off?

[shpielers]

Should be labled.

On is straight down, prime is towards the back of the bike, reserve is forward. No off.

[maniac1886]

Since we are talking about it, there is no off because the peacock is vacuum actuated. There should be a vacuum hose from number 4 carb (throttle side) that connects to the petcock. As the motor turns it generate vacuum and opens the diaphragm allowing fuel to flow. Better make sure it's there or u won't ever get gas to the carbs.

[sr73087]

Thanks guys. I will take a look at this in the morning. Appreciate the help.

[sr73087]

I was in the process of cleaning the carbs. Pretty easy so far btw, almost the same as all single carbs i have done. I flipped the carbs over and noticed thi washer and an oring the same size on my workbench. Any idea where these came from? I checked everywhere and I am thinking it may be at the seat of the main jet?

[92xjunker]

Try this http://www.bikebandit.com/oem-parts/...7769#sch257655

[sr73087]

It was number 26 from the diagram. Thanks.

[sr73087]

After cleaning the carbs and changing the plugs I went to start it up tonight and still nothing. The battery seemed weak and tested at 10.xx static voltage. I will charge the battery and let to know my results.

If it is not simply an undercharged battery now, are ignition coils the next thing to check?

[shpielers]

Voltage at the coils while the starter is turning over.

[92xjunker]

Needs to be 11v

[sr73087]

Battery static voltage: 12.63
Key on Engine Off Voltage @ coil: 11.10
Cranking Voltage @ Coil: 9ish (jumps around)

Battery is from previous owner but looks to be dated from this spring.

[92xjunker]

9ish is going to be an issue. Try cleaning all of the plug connections to bring that up. Try jumping off a not running car.