The Ongoing Chapters of the 650B2A.

Make sure the carbs are getting a constant supply of fuel. If the petcock screen is clogged, petcock is not working well, or if the fuel line is kinked or if anything else is preventing a steady fuel flow to the carbs the engine will idle up and then die. If you want to be positive the problem is not related to the petcock, petcock screen, fuel line, etc. You could rig a temporary fuel supply from a different container using a different supply hose and see if you get the same results. BE CAREFUL WITH FUEL! Ed

Will do! One of the first bits that I did to this bike was redoing the inside of the tank! Even though I'm pretty sure that tank is not from a 1978 KZ650! Haha.

On a side note, does anyone know if there is a stock needle clip position? Because I was thinking it over and though that if the needle did not set all the way down then it would cause more fuel than is needed for idle and may cause this insane idle I'm having. If anyone knows I'd greatly appreciate that information as my manual sadly does not cover that. They are VM22 carbs with 15 pilot and 90 main. I am attempting to rejet this carb from not happy podfilters to a stock airbox configuration. I have stock main and stock pilot. The only other thing I can think of adjustment wise that is carb related is the needle clip on the slide. Also. I have set all of the pilot screws (The ones on the bottom of the float bowls to approximately 2 turns in (Just past the point at which the needle gasket is inside the little tube in which it fits).


Also. The condition of all of the carb holders/boots seem managable, although they seem a little rough around the edges I'm going to do some research and see if I can find a way to repair or at least clean up the surfaces. Seeing as I do not have another hundred at the moment to drop on new carb boots.

-Thanks!

Have you thought about a Dyna electronic ignition in that bike? Set it and forget it. There are enough areas that need tinkering on these old bikes. I don't miss adjusting points at all.

I have thought about it. But that would require some more cash and some more research before I can the points. Because at least I know the point are set up correctly since I just did them. But I feel like that would be an amazing idea reliability wise in the future.

There are the pilot jets! A50 and a 15. I see there was an option for an A15 jet. But for this carb set with a 272 serial number. It reccomends a A50. So should I leave it or decrease It to an A15? Jetting is quite an adventure! Even though I'm just trying to work backwards.


Also! The float says 114 on it.
At least on cyl one carb.

A quick update. I feel like this runaway idle then sudden Stalling for no reason could be caused by 2 things. The first being that the float height is way off causing some serious issues with gas into the carbs. The second issue I feel may be that since I at one point had a stuck idle adjustment screw that had to be removed, I may have slightly opened that hole causing more gas than need be to be shoved into the engine upon idle. Also I have a feeling I should move the needle clip up more in an attempt to make sure that on file no extra fuel is finding its way in. Just for double checking, does anyone know what stock float height should be for VM22's?

The stock float height for the VM22 carbs is the same as that of the VM24 carbs: 2.5 - 4.5mm. Here's a pic showing where to measure. Ed

I'm assuming you can do this off bike and simply use water as a substitute for gasoline? I currently am going back through the carbs and replacing every o ring that has a vac seal. Then its chemtool B12 and a little bit more than healthy dose of compressed air.

You can perform the clear tube test with the carbs off the bike. To do so it is best to mount some old carb holders to a board and then clamp the board in a vice or other device to hold the carbs level.

HOWEVER -
Water is not a good substitute for gasoline for setting fuel levels (adjusting floats). This is because gasoline has only about 70-75% of the density of water (0.739 vs. 1.00). So if you set the fuel level using water the floats will rise higher in the water than they would in gasoline because water is more dense, and this would cause the float valves to close prematurely which would cause the level of water in the carb bowls to be too low. This would then lead you to bend the float tangs to adjust the fuel level higher. Then when you switch to gasoline to run the bike the floats would not rise as high in the gasoline as they did in water because the gasoline is less dense. This then would cause the fuel level to rise too high before the float valves closed and might cause an overflow condition. If you want to use something other than gasoline you will need to find something that has the same (or nearly the same) specific gravity as gasoline that will not damage or clog carb parts.

The density of alcohol is fairly close to that of gasoline. To see a chart of specific gravitys do a google search using the words: specific gravity liquid . This may help you decide what to use for your clear tube test if you decide not to use gasoline.

Ed

As always thanks Ed. My only other question is what is the stock needle clip position? At the very least I'm going to make sure these carbs are airtight and everything that can be adjusted to stock can and will be. I also noticed that one of the choke bodies that screw Into the carb on carb #1 was a bit loose when compared to the other 3. So it may have been something simple.

In the chart I provided under the “B2A” heading in the row marked “jet needle” notice it shows “5CL10-4”. That “4” after the dash denotes the clip goes into the 4th groove. Ed

Ah so this is way off by then. That is the second groove down with washers it seems.

Needle also read Y63. Not 5CL10.


Edit: Found original needles from rebuild. They read 5CL10. Also have clip at second one down. Compared the needles and they look the same.

Edit Part 2: Ah that would explain why any throttle stalls the bike. Due to the fact that running that smaller jet size and also having it set to be so lean. Alright so that problem I imagine will fixed once everything is back together. I assume now the only real problem will be that idle issue. But I imagine that would be from a float issue considering that there is definatly gas traveling into all 4 carbs.