Leaking BST36's

[Chxr]

I picked up a MK2 Bandit as an engine donor for my knackered Slingshot project. The bike didn't run but turned over when I bought it, the previous owner said it was running well but he rebuilt the carbs and on the way back from a long distance trip the number 1 & 2 carbs started leaking and the bike was parked when he got home. The bike fired right up when I got it home and put a new battery in it, but the same carbs were still pissing out fuel. My goal is to get this thing ridable for a family members visit then pull the engine and wiring harness this winter and install in the GSXR.

I've since rebuilt the carbs and installed a dynojet stage 3 kit as it'll be running pods on the Slingshot. The float valve seats & needles have been replaced, as has every o-ring the fuel pipes between the carbs have been replaced, and with the carbs upside down the fuel rail's holding air pressure overnight. I've set the float heights to 14mm with the needles just touching the seat, this corresponds with the dynojet instructions of 11mm with the carbs upside down. When the carbs get fuel on the dummy tank I still have fuel leaking from the main jet holes on those same carbs at the bottom of the intake side. The other 2 carbs that weren't a problem to begin with are still are perfectly fine.

I think whatever issue sidelined the bike for the previous owner is still a problem, but for the life of me I can't figure out what it is. I've quadruple checked the float heights, I've tried setting the height on the 2 leaking carbs higher so the fuel level isn't as high in the float bowl but have had no luck. At this stage I'm out of ideas. Could it be emulsion tubes? What else is in the main jet circuit that could possibly cause a leak? Any advice would be appreciated.

 

Cheers.

[Upshotknothole]

Double check your float valves. Try swapping them from carbs 1/2 to 3/4. What brand of float valves did you use? Try swapping the floats as well. Sometimes tapping on the side of the float bowl while they're leaking can free a stuck float.

The Dynojet kit and the emulsion tubes are separate from the float valves, so won't be causing the problem.

[Chxr]

7 minutes ago, Upshotknothole said:

Double check your float valves. Try swapping them from carbs 1/2 to 3/4. What brand of float valves did you use? Try swapping the floats as well. Sometimes tapping on the side of the float bowl while they're leaking can free a stuck float.

The Dynojet kit and the emulsion tubes are separate from the float valves, so won't be causing the problem.

Thanks for the idea of switching the float valves, I'll give that a go & see how it fares. I bought the K&L kit, the same one Dale Walker was selling before he closed shop, so I figured it was decent.

[Upshotknothole]

I'm pretty sure the K&L kits we get are the same as the Tour Max kits they get in Europe. Usually pretty good, and a hell of a lot cheaper than the Mikuni parts Suzuki sells.

Save yourself some trouble and don't bother mounting the carbs back onto the bike until you can bench test them with fuel and they don't leak anymore. It's most likely going to be either a stuck float or a float valve that's not sealing completely. With swapping the parts around you should be able to figure out what's leaking.

[Chxr]

So it seems that the main problem was stupidity on my part. I pulled off the float valve seats to swap between carbs and noticed some debris, same with the other carb. I thought I had cleaned out the fuel rail but obviously not, or at least not good enough. Blew out the rail with carb cleaner and compressed air, reset the float heights, leak tested the carbs and they were good. I'm not sure how debris under the seats would be a problem but hey sometime correlation is causation. I threw the rack on the bike and my next problem is a very high idle.....One problem down, probably a few more to go. 

[Upshotknothole]

Check for vacuum leaks, is the vacuum line to the petcock hooked up? Adjust the idle down? Does it hang at a high RPM? Spray a little carb cleaner or starter fluid around the intake boots on the head with the bike running to check for intake leaks.

[Chxr]

1 minute ago, Upshotknothole said:

Check for vacuum leaks, is the vacuum line to the petcock hooked up? Adjust the idle down? Does it hang at a high RPM? Spray a little carb cleaner or starter fluid around the intake boots on the head with the bike running to check for intake leaks.

Will do. I think the most likely culprit is that I buggered up installing one of the throttle cables, it seemed a little tighter than normal. Plenty of time for that tomorrow, I'll celebrate the small victory with a beer. Cheers for the help!!!!