Understanding carb (VM26) leak issue on GS750L

[Guest]

Hi all,

I was wondering if anyone could help me understand whether my garage having a puddle of gasoline is caused by my screw-up (will get to it in a moment) or if I need to take apart and re-clean my carbs/get new parts.

The good news: I cleaned my carbs, replaced valve shims, replaced intake o-rings, adjusted points gap, and got this project bike running!
The bad news: The bike didn't run all that well and I made several mistakes along the way including:
- Running the bike without the petcock vacuum tube (or plug). Didn't realize what it was. I'm guessing this is the reason that the bike started idling slowly and then slowly increased RPMs (without touching throttle)
- Didn't dip the carbs or take off the mounting frame
- Left the bike in PRI overnight

More details:
- The floats were adjusted and were bouncy and "happy" feeling
- I did not take the floats off or remove the float valve (because I'm terrified of breaking the posts)
- Only carb #3 leaked. 1, 2, and 4 had no indication of a leak (the overflow tubes weren't installed, so I know where the puddles would be).
- The carb leak appeared to be coming out of the drain, however it's hard to say for sure

So here's my question: Is leaving the tank in PRI the root cause of this issue, or is there something else wrong? Since the fuel goes into carb 2 and 3 first, maybe it just comes out of one those first? Are the float valves supposed to stop fuel 100% or just 99% and hope that the engine can suck the gas fast enough?

Thanks!

[Big T]

Yes, the fuel needle should stop the flow of fuel

Now, go back and clean your carbs correctly, and review the Top 10 Newbie mistakes

[skobovm]

I figured that would be the response I got

Well, hopefully a thorough cleaning, dip and disassembly will fix everything up!

[Big T]

Maybe not, but you can remove carbs from the list of possible problems

Have you read the VM tutorial?

[skobovm]

Yep, read through it a few times -- very thorough. Unfortunately I got the bike from someone who paid someone else to just barely get the bike running. It has a new petcock, new jets (allegedly), but was backfiring so hard I felt like I was on a rocket. That may have been because the pilot fuel screw was turned out 2.5 turns (which seems super high, compared to the recommended ~1 turn starting point). But I'm not sure if that was just to compensate for the 4-1 exhaust that's on it, instead of rejetting. I was able to get it to idle nicely with the screws out to the punch mark (1.25 turns-ish) but maybe I'm making it run too lean? Will have to do the spark plug check once the leak is gone.

That said, this is exactly what I signed up for, and really enjoy doing the work and getting my hands dirty. Glad I chose a bike with such a supportive community and plethora of resources.