odd issue

[oldyam80sg]

So I went to start my SG today and turned on the gas and some spilled in the driveway. It came out of #4 carb and as I could see the stain on the air filter housing. Shutting off the fuel, I tapped on #4 carb bowl with the screwdriver handle.to maybe unstick the float. I started the bike and no more fuel spill. I decided to warm up the bike to see if maybe a 2nd sync was needed. I had to turn the idle speed up and then down as the bike warmed up. I hooked up the sync gauges and revved the throttle but all the gauges were the same. # 2 gauge seemed to want to go down but giving it some throttle the gauges didn't move much if at all. No more popping now but nothing changed except me replacing a vacuum cap. I ordered a set of carb tune gauges off of E bay and will check the carbs with them. The bike seems really smooth with no fuel tank in place, only using my Motion Pro auxiliary tank.

[Socer4m]

hopefully no gas went into the crankcase, that will cause the popping if gas leaks past the carb, if you can completely shut off fuel with petcock after running then chances are no gas leaked. Anyway, I usually check the carbs, but pulling them off, a PIA, holding them upside down and blowing hard in the inlet line,,,,,,no air should go in,,,if it does I can hear which carb needle is leaking. So, hoping all is good, a synch is always good, anymore popping I would check the oil for gas by smelling a stick stuck in the crankcase via the oil filler. Worst case scenario, a leaking carb needle,,,,fix by carb cleaning and new gasket. Ride ON.....Mike in San Diego

[oldyam80sg]

I can assure you that no gas leaking into the crankcase. After running the bike it runs fine-no popping when I started it up multiple times. I have the Motion pro auxiliary tank still hooked up so when I get the carbtune this week I will sync it again. Worse case scenario I will look at different pilot jets but that is a worse case scenario.

[oldyam80sg]

So looking at the bike today I'm wondering since I set the float height on #4 a month or so ago, Is my leak from the float needle seat O-ring? They have never been changed since I have owned the bike(1986). Would that cause the leak? The leak has not happened since I set the float height. It is only coming out #4. I bought a set today so I can do all the O-rings.

[Socer4m]

Howdy Old Yam,while your in the carbs blow carb cleaner through every orifice, front and back,,,make sure the bowl gasket isnt on the inside of the bowl, if so, trim with a razor- even a small piece can hang up a float, use a spring loaded punch, available at most hardware stores, to push out the float pin, hold while pushing- they break very easy,,,,,after your done do the upside down blow through the inlet fuel hose line and NO air should go through if carbs are good,,,if air goes through you can hear which carb needle is leaking,,,,make sure each float is exactly the same height at rest,,,use a ruler, I think mine were 25 mm from bowl to top of float,,,,good luck, keep us informed...Mike in San Diego

[Socer4m]

almost forgot ,,,,,yes even one bad o ring will cause leakage at the needle, especially if they are old, ,,,,do the upside down blow trick on the carb bank and check it,,,,anyway a good cleaning and new o rings solve a lot of problems

[oldyam80sg]

The carbs are super clean. The floats are the right height-I use a Mitutoyo digital caliper to check. There is no fuel in the oil-I did do the stick test. I'm going to replace those O-rings as they are original and never been replaced. I have a spare float seat and that O-ring tore when I went to remove it. I was very careful so it was probably due to be changed.

[oldyam80sg]

So going with the APE Superpro air individual filters as the bike was originally set up for K &N individual air filters. They will be here the end of this week and also have the new O rings coming in this week. I started the bike today and popping is almost nothing now.

[LAB3]

You had mentioned replacing a vacuum port cap, a leaky one would certainly create the problem you're describing.

[oldyam80sg]

The vacuum cap I replaced was a thin walled cap and the replacement is thicker walled. No popping now-maybe that did the trick.

[LAB3]

You had mentioned in another thread about changing your intake boots, mine look like parched clay out in the sun a long time. Luckily I've not had a reason to remove my carbs or vacuum caps, I'm certain they'd fall apart if I did.

[oldyam80sg]

I have the new boots but I really want to just ride the bike. Boots might be winter project.

[cajun31]

I have the new boots but I really want to just ride the bike. Boots might be winter project.

If it is running right then go for it. Sounds to me like it is.

[oldyam80sg]

I got the Morgan Carbtune in the mail today and have to put the dampers in the hoses and will hook it up this weekend. I also got the small O-rings for the float seat today.

[cajun31]

I got the Morgan Carbtune in the mail today and have to put the dampers in the hoses and will hook it up this weekend. I also got the small O-rings for the float seat today.

The Morgan Carb Tune to me is a very good and reliable set of gauges. If properly taken care of they last forever and get the job done. From all that you have described about your bike I would think you will find that the carbs are probably in synch. The bike will probably run OK like they are. The only thing that you probably could do to make it run a bit better is to get the pilot jet screws dialed in properly. There have been numerous discussions over the years concerning that. Many different methods. The only one that I have any confidence in is the Color Tune product. I can see what I am doing with that product. I always get each screw tuned to just the hint of a yellowish orange color, meaning each carb is running just a tad on the rich side. I prefer that because theoretically it means they are running a tad cooler while at idle. It also effects the carb performance a bit at all ranges of speed but not as much as at idle.