98 750- List of symptoms, what else should I be checking?

[Jtegg007]

Hi all, my brother and I took this 98 katana off a friend over a year ago. The bike is in rough condition and has been downed, but its really rarely ever been ridden. We're the 3rd owner, bike was bought with 5200 miles and now has 6000. When we bought it, it wouldn't stay running. We figured it was gummed up and just needed some basic love. I did an oil change, ran some carb cleaner through it and rode it for 750 without much issues. At that point is started running rough, losing power, bogging out and completely not responding to throttle input.

I was to busy to mess with it and put it on the back burner for another year, and just started tearing into it. Here's what i'm finding and what I think i need to do to make progress.

-Cant remember how full the gas tank was when I parked it, but I know I didnt turn fuel off. Found the gas tank completely dry.
-Got it running, blowing smoke (grey), doesnt want to idle. Either revving at 3k+ or stalled.
-Noticed the crank looked over full. Smells like fuel. Drained it and its about 1/3 oil, 2/3 fuel and 2.5 gallons total.

So, all this said, I'm guessing I have gas flowing past gunk'd needles, into the cylinders and into the crank. Im thinking Ill need a needle kit, some deep carb cleaning and an oil change. Ive also read that the carb boots crack at the head so ill be looking for those.

My first question is, can fuel really just flow through the carb into the intake? Doesnt it have to travel uphill from the bowl to the needle? I would think thats only possible under vacuum/when running??

Second question is, would the crank being full of fuel actually cause it to stall? ...I'm guessing the fuely-oil would be flooding the bike while oil is pouring into the cylinder.... So could this also be my original issue that caused me to park it in the first place?

[Kreylyn]

Hi all, my brother and I took this 98 katana off a friend over a year ago. The bike is in rough condition and has been downed, but its really rarely ever been ridden. We're the 3rd owner, bike was bought with 5200 miles and now has 6000. When we bought it, it wouldn't stay running. We figured it was gummed up and just needed some basic love. I did an oil change, ran some carb cleaner through it and rode it for 750 without much issues. At that point is started running rough, losing power, bogging out and completely not responding to throttle input.

I was to busy to mess with it and put it on the back burner for another year, and just started tearing into it. Here's what i'm finding and what I think i need to do to make progress.

-Cant remember how full the gas tank was when I parked it, but I know I didnt turn fuel off. Found the gas tank completely dry.
-Got it running, blowing smoke (grey), doesnt want to idle. Either revving at 3k+ or stalled.
-Noticed the crank looked over full. Smells like fuel. Drained it and its about 1/3 oil, 2/3 fuel and 2.5 gallons total.

So, all this said, I'm guessing I have gas flowing past gunk'd needles, into the cylinders and into the crank. Im thinking Ill need a needle kit, some deep carb cleaning and an oil change. Ive also read that the carb boots crack at the head so ill be looking for those.

My first question is, can fuel really just flow through the carb into the intake? Doesnt it have to travel uphill from the bowl to the needle? I would think thats only possible under vacuum/when running??

Second question is, would the crank being full of fuel actually cause it to stall? ...I'm guessing the fuely-oil would be flooding the bike while oil is pouring into the cylinder.... So could this also be my original issue that caused me to park it in the first place?

Yes, fuel in the oil will cause the issues you describe.

Yes, the fuel was leaking past either the float needle or the float needle seat oring. Rebuild kits would have the parts needed to fix that.

Yes, if fuel is getting past those point... it will over flow into the cylinders very easily and drain into the crank case. Does not have to be running at all, if the petcock is allowing fuel to flow. Normally "on" only flows with vacuum (running). Prime will flow all times, or a faulty petcock. Fixing the petcock does not fix the issue though, as the real issue is the leaking float needles.

The boots issue is more often an o-ring isssue where it mates to the engine, but that said... I'd check if they are leaking once running before taking them off. Check for vacuum leaks when the carbs are back on and the bike runs. You will need to do a sync on the carbs, and that is a great time to do the vacuum leak test too.

Krey