So let's get into this. About 5 years ago I scored a mint 81 cb650 custom for a song. 500 beans! Less than 15k original. It had the usual issue of the o rings in the head leaking oil. And it had a bad head gasket. After about 25 mins of riding it would start to spit and sputter. I went through about the checks. I looked at the coils, the igniters, wiring, connections, everything. All checked out good. Figured I'd make a play on a bad set of coils so I replaced them. Same issue. Sooo time for some teardown and rebuild. As projects go there is really no time frame so I began to work slowly and carefully. I made a mistake during the tear down that I would come to regret. I damaged the factory air box. Being an idiot instead of fixing it I threw it away. I decided I would run pods. Everyone else does it, why can't I right? Well I was wrong but we will get to that later. I got the top end of the engine torn down and I rebuilt it with an athena kit. I even trued up my head surface myself. New valves, seals, guides, the whole nine. I got it all back together then life punched me right in the baby makers. I lost my job. Then a whole #$%* storm followed. Long story short the bike and my famity moved 3 times since I got it. Mind you this is while it is still in multiple pieces. I just got around to doing everything I wanted to do to it starting this past January. I rebuilt the carbs. Vb44a to boot. That was fun. I managed to figure out a way to get the pressed in idle jets out and upjetted to 38's and then 130 on the mains as I like straight pipes
I got the carbs all back together and found I had a slightly bent choke rod. Nothing I can really do at this point so I rigged the split linkage to work as one. It works but is just a little harder to pull the cable. No biggie. Got my pods on order but I wanted to hear her sweet cb song again. So I dug through my parts and had the v stacks from the factory airbox. I figured what the hell, I'm up jetted so it should at least start. Got them on. Went to put the exhaust together and #$%*! I somehow misplaced 4 of the 8 split collars to lock the pipes to the head ports. Hop online and begin searching. I could not find them anywhere. Spent hours making calls. Finally tracked down 4 nos out in Texas. Guy said he'd let him go for 80 a piece. BeING the #$%* head I am and by now being several beers in I promptly told him where he can send those parts
so now what do I do? I started looking at the problem at hand. I needed these parts and that was all there is to it. Some 1.5" exhaust tubing, a chop saw, angle grinder, and welder later I made my own. With a hope and a prayer I begin to fit the exhaust. To my joy they worked!! I was ecstatic. I now had moved one step closer. I got the wirING and everything put back on the frame and I also model the battery box to use a larger amp hour capacity battery as our charging systems are not the greatest so I wanted a larger buffer. I also noticed now that my carb boots were f'ed. Great now what. Back online I went searching. They were to expensive for my taste so back to the brainstorming I went. Gotta have something that is resistant to fuel right? It's a fairly large diameter. I thought radiator hose. No bad idea it would gum up and read havoc on the carbs in a matter of weeks. RealizING that these things need to be stiff and sturdy I thought about fuel filler nneck hose. Eureka it fits! Got carbs mounted and then changed oil and filter with new o rings. Awesome here we go. I plugged in the controls and gauges then threw together the front connectors. Finally connected the negative on the battery and turned the key. When I saw the red oil light come on and the gauge back lights I damn near cried. Finally after all I have been waitin for my baby was about to kick over for the first time. One more problem to solve. How to run a fuel iv. Didn't have an old gear oIL bottle around so I used the next best thing. A dawn dish liquid bottle. Worked perfectly. Got fuel into the carbs. Wait! Oh no! Carb two is dumping fuel out its drain port! What am I going to do!!! Thinking quickly I went for the most obvious solution, a quick snuggling of the drain screw. The flow slowly waned to a stop. Whew! That was close. A speedy clean up later now we are ready. I stick the key in and crank the engine over with the coils unplugged. Got to get fresh oil to the top end first. Okay good to go. Put the coils wires on, pull the choke, crank the throttle 6 times to prime with accelerator pump. Only six due to empty fresh carbs. I pause, praying I will hear this engine once again. I hit the starter button with a gusto. To my absolute pleasure the engine sputters and coughs a little. Ok it's a start right? I figure might need to give the old girl a little go gas. Out comes the starting fluid. I give a quick spray to the v stacks, nail the choke, and bash the start button. Bam she coughs to life. I Rev her up and it sounds sooo good. Like a song you love but have not listened to in ages. I begin checking things over as it happily bumbles away on choke warming up. I give it three mins and drop the choke. Instantly dies. Well crap. I try again several more times and the same result. I pull each plug wire and check for spark with a gap tester. All good. Tried switching igniters just to see if maybe under compression things could be different. Nothing same result. As I am fumbling around I burn the ever living Mary out of my finger on the third cylinders pipe. I reel back and begin to fall so I grabbed the closest thing near me to catch myself. It was the number 4 pipe. As I instinctively wince for the terrible pain that is sure to come I quickly realize it's about as painful as grabbing a cold beer. What the hell man? It was running fine why is this one so cold and 3 so hot. I began to investigate. 3 and 2 were hot 1 and 4 were not. Ok gotta do some more investigsting. Out comes the multimeter. I checked everything from the pulser to the grounds and everything in between. Nothing all checked out good. This made no sense. So I checked my base timing. Nope all good. Checked valve clearances while doing a compression test at the same time nope all good as well. Plenty of compression. Now what the heck could be wrong. I decided to give it another go. Started it back up this time off choke and it comes to life. I revved it to around 3-5k. No excessive clanging or rattling. It's then I notice a nice mist coming from carbs 1 and 4. What the heck I think! So I catch some On a piece of paper, straight fuel! Now why on earth are you not going in but coming out you stinky gas I say to myself. Surely if that end is blowing the other end must be sucking. So carefully I placed a shop towel in the path of the 1 and 4 pipes. My goodness! The exhaust is intaking and the intake is exhausting!!! I thought it could be my timing again. So I checked it once more but that would be impossible right? After hours of racking my brain trying to figure out how half my cylinders are doing what they are supposed to and the other half are drunk I finally figured out the problem. It was such a simple rediculous dumb ass mistake that I could have went back in time and beat my own ass.
I will ask you fine fellas if you can guses the problem.
Facts
Good compression, valves in spec, new parts, fresh gaskets, new coils and wires, base timing spot on, good igniter, pulser adjusted and operating correctly, wiring sorted, fresh larger battery than stock, no noise, no binding, no noise at start up, fresh rebuilt carbs, no weird issues on cylinders 2 and 3.
With this information can you tell what was making cylinders 1 and 4 literally defy the laws of the universe and rebel against the natural order of things?
