Installed 3 ohm coils, STILL missing in the Philippines!!!

[hanger10]

Howdy again all. Well, Ive made quite a few posts here about my 80 SG missing when I hit a constant speed for a second, the try to accelerate slowly, it misses, no matter what gear. No set rpms, it just happens when I reach a steady speed in any gear, and also when I take of slowly. Ive made a vid for you, and pray someone can tell me what is wrong!!!! We just put on new 3 ohm coils, and it still does it, and Im pretty sure weve just about exhausted all electrical things, including PU wires, all connections, etc. The vid quality aint great, its two short vids, and also please watch the second one too, as you can hear the miss clearly when I take off. Now, I didnt go fast, as wind noise makes hearing hard, but Ive captured it pretty well hopefully. SOMEONE PLEASE HELP!!!!!!!! LOL!!!! Thanks for watching, and I greatly look forward for replies!!! Take care, and mabuhay from the Philippines.

Randy

ps-the miss doesnt sound quite as bad as it really is, coz of the wind sound! on the second vid, you hear it clearly when I take off, and that is also how it sounds at speed, although you wont hear it as clearly
video_ http://www.youtube.com/watch?v=5pL03q6syx8

[DAVINCI]

Well, if you truly have exhausted all possible electrical issues, the only other thing it could be is carbs. From the sound of the miss, I'd look for a vacuum leak at the slide diaphragms. They can get dislodged when installing the carb tops. BTDT. Bike acted just like yours.

[DGXSER]

Is it one specific cylinder, can you ride it slowly around and not give it much throttle then stop and spray the headers with water. See if one of them is not getting hot? That could isolate it down to which cylinder.

when I first rebuilt a set of XS11 carbs, I took the needle valve out of the slide to be sure to clean it all up nice. Well, it did not need it, so I only did the one. When I reassembled, I got the order of the needle spring and washer and such backwards. So that one cylinder was WAY rich at idle and low rpm, low power. It would miss bad after sitting at idle until I rolled it up to decent speed and power, then the miss would go away until I let it idle or low rpm again. I fought with that for over a month. Until I finally figured out my error in assembly, and all four fired up great after that.

A bad diaphram would probably cause the same type of symptoms.

[Tom Andersen]

Is it one specific cylinder, can you ride it slowly around and not give it much throttle then stop and spray the headers with water. See if one of them is not getting hot? That could isolate it down to which cylinder.

when I first rebuilt a set of XS11 carbs, I took the needle valve out of the slide to be sure to clean it all up nice. Well, it did not need it, so I only did the one. When I reassembled, I got the order of the needle spring and washer and such backwards. So that one cylinder was WAY rich at idle and low rpm, low power. It would miss bad after sitting at idle until I rolled it up to decent speed and power, then the miss would go away until I let it idle or low rpm again. I fought with that for over a month. Until I finally figured out my error in assembly, and all four fired up great after that.

A bad diaphram would probably cause the same type of symptoms.

I did the exact same thing, this will cause problems for sure. Also while doing a carb synch I turned an idle mixture screw out a half a turn which caused similar problems.

[hanger10]

carb Diaphragm

Is there a special way to test them, if its a pinhole?? I think thats what it might be is a diaphragm, and we will take it apart Sat and check them. Also, if thats what it is, can it be repaired, with liquid rubber or something like it? And, if it cant be repaired, all the diaphragms Ive found to buy, say for 1981, 82 xs1100. They wont work on an 80 SG? Here is a link to one of the ones for sale I found, so you can read it. Man, I hope this is it!!!!! And, I sure hope it can be repaired!! Thanx!


Randy

link_ http://www.carbkitscapital.com/carb_...a&model=XS1100

[bikerphil]

Hold the diaphram up to the light and look for pin holes. Yes they can be repaired with plasti-dip or liquid tape. The diaphrams in the link are the correct ones for the 80-82 carbs, hope you don't need to buy a new one(s) at +$80 apiece.

[crazy steve]

Pinholes or small tears you can fix with liquid rubber or rubber cement. But if the repair interferes with the free movement of the slide, you'll need to replace. And you don't need to buy the whole diaphram/slide assembly either; the diaphram by itself can be removed/replaced (it's a finicky job, but can be done) on the slide, and these are all the same on the BS34 carbs. So you could even find a used one for repair off any of the various models, you just have to make sure you get the orientation right. The slide diameters aren't all the same, so you can only swap complete assembies if they match.

To me, it acts like a vacuum leak. It may be a leaking diaphram, but could also be a small leak at the boots/carbs. Try using a propane torch (unlit!) and put propane around the intake boots and carb throttle shafts. If the motor speeds up, you've found a leak...

[hanger10]

Checking things tomorrow

Thanks so much for the input guys. Taking the bike in in the morning, and gonna follow all of your instructions, and PRAY we find out!!!! This is driving me completely nutz!!!! Hell, Ive already got a new voltage regulator, new 3 ohm coils, new plug wires, if I can fine whats causing the miss, it oughta run nice!!! Take care, and thanx again. Wish me luck tomorrow!

[hanger10]

Going NUTZ!!!!!



Well, this thing about has me beat!!! We did isolate which cylinder was doing the missing. The boots are only two years old, and they were not leaking. He took out the diaphragms, and all looked good, except the one on the cylinder that was missing was more worn. I have included pics of it. It was chafed in spots, but nothing went all the way through. Anyway, he used liquid rubber over the chafed areas just to be safe, reassembled it, and still the exact same miss!!!!! What the hell is going on????? Im afraid Im gonna have to get rid of the bike, and I sure dont want to do that!!!! We have exhausted any electrical issues, and now its no the diaphragms, at least we dont think so, that is why I included the pics for your opinion. Keeeeeeeerist, what are we missing????????

pics

http://www.flickr.com/photos/56053262@N03/5590660528/

http://www.flickr.com/photos/56053262@N03/5590070953/

http://www.flickr.com/photos/56053262@N03/5590660412/

ps-I ran it to exactly describe the miss, and the best way I can put it is that it misses when there is little load on it, thats when you either accelerate slowly, or hit speed and back off the throttle, then give it just a bit of throttle. It doesnt matter what the rpms are, or speed, its just whether there is load on it or not!!!

[skids]

ps-I ran it to exactly describe the miss, and the best way I can put it is that it misses when there is little load on it, thats when you either accelerate slowly, or hit speed and back off the throttle, then give it just a bit of throttle. It doesnt matter what the rpms are, or speed, its just whether there is load on it or not!!!

Good compression? Good pipes? Good pick-up coils? You might be running a bit too lean and this is a tough thing to determine unless you color some plugs at the rpm ranges that give you trouble.

[hanger10]

Miss

Good compression, good pipes, all new PU coil wires, the cylinder missing is leaned about as much as it can be, we are just lost!!!!!

[hanger10]

Miss again,

Sorry, I forgot to say again, rpms dont really matter, nor does speed, its just whether there is a load on the engine.

[cywelchjr]

That diaphragm doesn't look too good to me. Did you hold it up to a bright light source to see if you could see light through it? Really the only way to see if that is the issue is with video of the them working under load, where you can see all of them and see if that one is working differently. You also might try swapping that one with one next to it, and making sure that the springs are all the same length and tension as that affects how they work as well.

Another good test of them is to lift the slide up, block the vent hole in the carb bell, and time how long it takes to drop back down. Do this with each carb. It should take the same amount of time for each of them. If that one is significantly different, you have found your problem, if it's the same, it's probably not.

[bikerphil]

the cylinder missing is leaned about as much as it can be, we are just lost!!!!!

Maybe try going in the other direction, richen it up. Lean will cause a stumble. Don't give up, you'll find it!

[petejw]

hi hanger,
what float heights have u set the floats at?
the float hieghts come into play under acceleration,
for the 80 model im pretty sure there set at 23mm.

have u changed out any pilot jets for after market ones,
some of them being sold on ebay for the xs arent the correct ones.