My SR B carb stopped working. The stock tank is flowing fuel. It ran great until it stopped, so it’s not fuel delivery to the carb. The float will be full, but the carb is not delivering to the manifold. I’ve taken it apart several times and today I completely disassembled the carb and soaked it in the ultra sonic tank for a couple of hours. Does anybody know how to disassemble the check valve in the bottom of the bowel? Does anybody have any SR specific diagrams and instructions?
You need to make a tool to fit at least two of the holes in that brass plug. That plug is threaded. Mine was a bitch to remove. Had to soak it for days in seafoam plus a little heat. That check valve is for the pump side only. Most guys that run Winfields used to block them off by turning the gasket one hole either way. The pump is not needed. That alone will not stop your carb from running. I would check the screen above the float needle. That could be clogged. Might let enough gas in to fill the bowl but starve it when trying to run.
I thought that it may be threaded, I stuck a couple of 1/8 drill bits in two of the holes and promptly bent the drill bits while cranking with a large crescent wrench. I’m gonna keep trying. I would think that it should start with the fuel bowl filled. I’m going to check the screen in the tank. The screen in the carb had nothing clogging it. It ran great with the gravity feed, so I don’t think it needs to be pressure fed. I’m missing something. I read that the idle ports gets fuel from the intermediate chamber, but I can’t find anything clogged. I’m almost stumped. I might try rotating the pump diaphragm to separate that system.
I know you said you have fuel from the tank but is it constant. Might check to see if it stops anytime after turning on. You are correct it should run for a few minutes with just the float bowl full. Be very careful with that plug, bust anything and you need a new bowl. You can can check that fiber check disc by pushing down on it. It is spring loaded so if it returns there is not much else to concern yourself with. These are very simple carbs try not to overthink it. I ran a SR for years on gravity so no pump is needed.
The fuel seems to be flowing from the line to the carb at a decent rate. It fills the bowl in a few seconds. I definitely don't want to risk breaking the bowl. I'll push down on the disk and check it. maybe see if it holds gas before I push it down. There's got to be a piece of dirt in the idle passage from the bowl to the throttle chamber. Everything in the throttle chamber is clean. I'm gonna drain the tank, rebuild the shutoff valve, change the shutoff screen, install a glass sediment bowl, finish cleaning and reassembling the carb (again), get a dead chicken and swing it above my head several times and then maybe it'll fire up.
Sounds like your doing everything right. If you take your time and study the passages you will understand where to apply air pressure to blow them out. Hard to understand that it just quit without running poorly first.
The check valve disk does not move at all. It also lets fluid go both ways. I’m gonna soak it in WD-40 overnight and check it tomorrow. If it doesn’t move tomorrow, I’m going to install the diaphragm with the passage over one hole and try that.
What i do to remove check valves is to soak it really good, place two drill bits that fits real nice in two of the holes of the check valve in the wise with the smooth end upp, place the float champer over the drill bits into the check valve and turn the float chamber by hand. Has worked on all of them.
Was thinking about this and it reminded me of all the trouble I had with my Harley last fall. I tried everything to start it with no luck. Turns out I had bad gas that wasn't that old. Filled it with new stuff and it fired. When you said it runs on quick start that got to thinking about my bike.
I got the check valve out. I set the bowl on the rack above the stove under the heat lamps in the morning and tried again after work. The wafer in the valve moves around, but I’m still afraid to try and get it out. The valve must split in half. I’m pretty sure the jet with all the holes goes in the intermediate and the other goes in the high speed chamber. Am I correct? I reassembled the carb and filled the bowl with fresh gas. Still no fire. I can pour a little gas down the throttle and it starts right away. I took it apart again. And blew every port and stuck thin safety wire through everything I could. I’m still stumped. Back on it tomorrow.
I believe your correct on the jets. It has been a while since I had a SR. I changed to S models years ago. Did you also remove the spray tubes in the throttle body? Are they installed correct? With just the float bowl in your hand and some fuel in the bowl try to either blow or suck into the spray tube supply holes. I would use an eye drop or something small as a plunger as not to make a big mess. This should show which is clogged. Also check to see if you have a gap between the mounting flanges. If there is a small leak you might not have enough vacum to pull the fuel to the throttle body.
Thanks for the tips. I could only get one of the set screws for the spray tubes out. I did blow air and carb cleaner through the supply ports for the spray tubes, they seemed fine. I'll try again with some fuel in the bowl. I'm gonna set the throttle body under the heat lamp while soaking with WD-40 and get the set screws and tubes out. I'll also make sure that the flanges are perfect.
Well, the threads for the jets were a little boogered up, so I picked up a 1/2-27 tap and cleaned the threads. I also resurfaced the the flanges. I put it back together and it runs. Miracles exist. I have no idea what I did to fix it except all of the above. I guess I need to throw the choke in the ultrasonic tank and get that paint off of it. Thanks for all the help.
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