Popping from right side exhaust.

[barelycompetent]

Hey all, I know this question has been asked and answered many times, and I have done a search on it, and read MANY of the different threads, all this did was confuse me lol. Sorry to ask the same question again so go easy on me. I have also read the carb guide several times. Just need some clarification on a few things. Ok so the bike is an 81 special, that when I bought it was running a stock exhaust, with pod filters. The pod filters are the 54mm? ovals from Mikes XS, and the carbs on it are the BS34's, but I cant tell you the jet sizes right now as the PO sealed the float bowls to the carb bodies with some type of unknown sealant. The bike was running pretty well but I did have a slight popping noise coming from the right side exhaust, seemed to be worse when the outside temps were cooler, but less noticeable when warmer weather. I just put a Gordonscott 2-1 exhaust on it with a 12inch stainless open muffler on it, and I fired it up yesterday. I had the exhaust headers ceramic coated black so on the coaters advice I let the bike run for about 25-30mins. The bike started right up, seemed to run fairly well, but about the 20-25 min mark the popping sound started, and it seems amplified now because of it being a 2-1 exhaust. I know that I need to get into the carbs to find out what jetting is in there, trust me I know, just trying to figure out how to break the bowls free without damaging them. So my questions are, since I had the popping with the stock exhaust, what does this indicate? Would the extreme cold temperatures make the popping worse? I have replaced the carb boots and checked for leaks as well, and all is good there. Am I running lean on the right side or rich? I should also mention the PO had two different plugs in the bike when I bought it, one was the BP7es, and the other was a BP6es, if I remember correctly, the 6 being on the right side. I replaced with brand new 7 plugs both sides. Thanks for any tips or advice, and thanks for not jumping all over me for asking the same question again lol.

 

[5twins]

Popping is usually a lean indicator. You probably need to re-jet richer if it hasn't been done already. Yes, cold weather can make the popping worse. You need a richer mix when the bike is cold, that's why there's a choke for cold starts.

Notice I said popping is USUALLY a lean indicator. In your case, it may be a too rich condition in that right carb. The fact that the P.O. was running a hotter plug on that side may indicate that. Maybe he had to to keep it from fouling out that cylinder. You may have a float setting or float needle and seat problem. That carb could be slowly over-filling and flooding out. You need to get inside those carbs like right now. You know enough to get yourself in trouble? Well, you're there, lol.

 

[barelycompetent]

Thats kind of what I figured lol. Any suggestions as to how I can get into the sealed float bowls? Im gonna pull the carbs this evening and bring them inside overnight, I may or may not be able to get to them this evening. Im gonna need new float bowl gaskets for sure, but I hesitate to order them in case I need to order new jets as well. Oh the joys of PO's. I should also mention when I pulled the plugs and realized they were different plugs that the right side was completely fouled out. I have only put maybe 75 miles on the bike since replacing the plugs, and I havent ridden it all since putting the new exhaust on yesterday. Guess I will pull the plugs as well and take a look at them. 5twins, I appreciate the advice, and your carb guide is excellent. I will check back in once I get into the carbs and find out the jet sizes.

 

[RcRider89]

Soak them in hot(out of the tap) soapy water and try to pull the bowls. If they used something like yamabond or silicoln it may loosen it up enough to get em apart. just make sure you blow em out really well asap.

 

[5twins]

Yes, apply some heat. A hair dryer is good, hot but not too hot.

Something else to check would be your new exhaust mounting at the heads. Have the gaskets crushed (you did use new ones, right?), allowing the pipes to loosen up? Also, uncap the mix screws if it hasn't been done and set them to at least 3 turns out. You must do this. They come set way too lean from the factory, sometimes down as low as near 2 turns out. That's way too lean, especially when you start modding things.

 

[barelycompetent]

All good ideas on getting into the carbs, I think I might try the hairdryer method first, and if that doesnt work I'll just go all hamfisted with a deadblow lol, kidding. I did use new exhaust gaskets, and there are no leaks at the heads that I can detect. Its weird to me that the popping showed up at the 20-25 minute mark while the bike was running. Regardless I know I need to get into those carbs, I just hope there are no more surprises when I do finally get in there.

 

[RcRider89]

I get in trouble when i grab my girls hair drier lmao. maybe i should just go buy one.

how cold was it when you ran it?
What ignition? Might have something going on spark wise too. just a thought, jetting/carb clean first though

 

[barelycompetent]

Oh it was about 20-22 degrees lol. Its a stock ignition. I really wish I was home right now so I could pop them off the bike and get busy on them, gonna have to wait. I just had the charging and ignition system completely gone through and everything checked out good there. Course that was with the stock exhaust on. The bike hasnt been started in a month and half as I was busy doing a cafe conversion on it. The exhaust yesterday was the last piece of the puzzle that I needed to be done with the build, and move on to the fine tuning and tweaking. Well, here comes the fine tuning and tweaking lol. I need to completely clean the carbs after getting into the bowls and seeing what jetting is in there. Im guessing I need to check the float level as well, but first things first, getting the bowls off.

 

[RcRider89]

Jetting should get you goin. 22 degrees,That makes for a long warm up. I'd say something about how great the south is with the mild winters and all...but its 20 degrees and snow on the ground

 

[5twins]

You may encounter tuning problems with those oval pods from Mike's. Any K&N type pleated pod doesn't work that well on these CV carbs. The UNI foam pods are best.

 

[barelycompetent]

Im hoping the jetting gets me going lol, and yeah it seems winter is rough all over this year. 5twins, I may actually end up going with the UNI's. Can I throw another thing in the mix? After it was running for awhile and right about the time the popping showed up, I noticed what appeared to be exhaust coming out of my breather filter, which is running on a tube down between my pod filters. A friend said oh thats normal, its just condensation from the motor, but Im not buying that. I just stumbled across another thread that says when switching to a 2-1 exhaust you may need to go up on the mains because of exhaust scavenging. Im hoping thats all it was, or is there a bigger issue going on? Again, I know I gotta get into those carbs lol, stupid work thing is getting in the way of that.

 

[5twins]

Well, let's hope this isn't it but running overly rich for a long period of time is a bad thing. It appears the P.O. may have been doing that with his hotter plug "fix" instead of actually fixing the real problem. Excess fuel in the cylinder can wash the oil coating off the cylinder walls, promoting increased cylinder, rings, and piston wear. When that wear reaches a certain point, you start losing compression past the rings into the bottom end (called "blow-by"). That can over-pressurize the crankcase which could show as excess output from the breather.

Have you done a compression check? If you do and find that right cylinder reads a bunch lower than the left, you may need some top end work. That's not a bad thing. Most all of these are in need of having the top ends gone through. I ran mine 2 seasons before going into it. It was needed. Cam chain was stretched, front guide falling apart, valves leaking, ring end gaps out of spec - you might find any or all of these things (as I did).

 

[barelycompetent]

I have not done a compression check, mainly because I dont know how to, and dont have the tools required. Im going to work on the carbs and jetting first, fix one problem before trying to fix another, or else Im going to be chasing my tail lol. I HOPE thats not the case, only time will tell. Thanks for the advice, now Im going to have to get to these things tonight, curiosity is killing me!

 

[5twins]

Well, here's the thing - the bike isn't going to run right or good if the compression is too low. You won't be able to tune it or get it running correctly. There have been others in the past here on this site that tried for weeks or months to get their 650s tuned correctly and running right, only to find their top ends were shot after finally doing a compression check - which was usually suggested to them right at the beginning of their ordeal.

You can usually rent or borrow a compression tester from a local auto parts store. Google "compression testing" and you'll find lots of "how-to's". It's very simple to do.

 

[barelycompetent]

Well I have a buddy locally that is very knowledgable on the xs650's, gonna see if I he might be able to help me do a compression test. Once thats done, its on to the carbs. Thanks for the advice, gonna see where it takes me lol.

 

[barelycompetent]

Well I decided to start my journey into the carbs tonight, and its gone about like I expected. The hairdryer trick worked great, got my bowls, off, and man were my carbs dirty. Not varnish, but dirty. From what I can tell on my jets I have 142.5 on the mains, and as far as I can tell I think 35's on the primary. My floats have e1 on the left, and e2 on the right side carb which Im assuming is the left right designation. I havent taken the floats completely out yet. I also have not checked to see what my air fuel screws are set at yet. Now Im thinking that I need to do a complete cleaning and rebuild, so I took the choke rod off, and here's where I ran into a problem. There are two little bb's and a small spring, that I neither saw where they came from or know where they go to put them back. This is the first set of mikuni's I have worked on, done many of the keihins. Once I get the floats out Im going to do a leak test on them, and I am going to split the carbs and soak them in chem dip. As I stated before the bike seemed to run pretty well with this set up and stock exhaust, but after inspecting my main jets, the jet in the right side carb appears to have been boogered up and has a piece of brass that is not covering the fuel opening but it is in the opening of it, hard to describe and no way for me to get a good close up clear pic of it. Im going to order new bowl gaskets, and I think Im going to order some new main jets and primary jets as well. Do you think I should order a few different sizes on the jets, or just another set of 142.5 and 35's? I dont think that I am far off the mark with those jets, and I think a complete cleaning will help some. Well thats all for now, hopefully I can figure out where those little bb's and tiny spring go.

 

[barelycompetent]

I should also mention that I just pulled the plugs and both sides are fouled out, so Im guessing Im too rich somewhere in the circuit, be it the 142.5 mains, or 35 primarys. Any thoughts or suggestions are much appreciated!

 

[RcRider89]

the spring and bbs go in from the top where the choke rod goes through. the are what hold the choke out.

as far as jetting, ill let the carb guru do his thing on that one. tech by trade but each bike has their own ways.

 

[barelycompetent]

Whelp the fun continues lol. Just checked my air fuel mixture screws, and the original brass stopper is still in place, sooooo from rereading the carb guide that means the screws are still at the stock setting, and the PO went at the pod filter mods with just jetting changes. Hmmm gonna do a thorough cleaning on the carbs, replace the bowl gaskets, and then I think Im going to start from stock jetting and go up from there, unless 5twins has better advice lol. Luckily my local contact is going to help me go through the carbs, clean, rebuild, set float height, and sync them, and a compression check, so hopefully in the next couple of weeks my bike will be dialed in and running as its supposed to. Man, I am not a fan of PO's right now.

 

[barelycompetent]

Also what I thought was my primary at 35 is my pilot air jet and after cleaning it is either 35 or 135, cant really tell. The jets that I removed from the float bowl in front of the rubber plug that I was calling mains, well those are either 42.5's or 142.5's cant really tell, and Im not sure what the proper name for those jets are. Im confused lol, time to put them down and walk away. I do know for sure the air fuel mix screws are at the stock setting though lol. Hopefully 5twins can straighten me out lol.