diaphragms

[hanger10]

Howdy guys!!! Merry Christmas!! Ok, here is my problem. Bout 4 mos ago, my 80SG started running like sh##t!!! My mechanic here in the Philippines couldnt get if figured out, and referred me to a top notch mechanic. Well, he was right, the guy got it fixed, told me it was the diaphragms, and that he fixed them with rubber cement or something, but that it was temporary. Ok, now, when I start the bike, it runs great until it warms up, and then starts running just like it has a float stuck, missing and backfireing. Its not a float, Ive tried that!! I know I need new diaphragms, and have a friend thats gonna bring them here when he comes in Apr. My question is, can the daiaphragms cause missing and backfireing???? Thanx in advance, know I will get many helpful replies. Merry Christmas, and Happy New Year Amigossss!!!


Randy

[motoman]

Howdy guys!!! Merry Christmas!! Ok, here is my problem. Bout 4 mos ago, my 80SG started running like sh##t!!! My mechanic here in the Philippines couldnt get if figured out, and referred me to a top notch mechanic. Well, he was right, the guy got it fixed, told me it was the diaphragms, and that he fixed them with rubber cement or something, but that it was temporary. Ok, now, when I start the bike, it runs great until it warms up, and then starts running just like it has a float stuck, missing and backfireing. Its not a float, Ive tried that!! I know I need new diaphragms, and have a friend thats gonna bring them here when he comes in Apr. My question is, can the daiaphragms cause missing and backfireing???? Thanx in advance, know I will get many helpful replies. Merry Christmas, and Happy New Year Amigossss!!!


Randy

Rule of thumb for these issues, whether it be a bike or 'old school' automotive........primary/secondary ignition sources before fuel/carb issues. With saying that, bettin' your issue is pick-up coil wires. Pull that left side ignition cover and every inch with both hands pull those wires. Any broken place will stretch the insulation like a rubber band. Also, make sure that vacuum advance assembly is floppy loose and rotates easily. Having the mechanical advance(plates/springs), they get crudded up over the years. That's just some of the secondary ignition issues that pop up. On your primary side, with key on, check voltages at the brown wire coming from the voltage regulator, voltage at each coil primary wire. Should all be 12V minimum. If not, trace out where the weak link is, causing voltage drop, including all grounding points.

[bikerphil]

You could check the diaphragm operation by removing the airbox and thru the rear of the carb, lift the slide up to the top and put your thumb over the oblong hole. If the diaphragm are working properly, the slide should drop slowly down. If they drop fast your diaphragm(s) are leaking. I agree. first check your pick up coil wires again for a break.

[hanger10]

Will check the wires today! Dont know if I made myself clear, but after the guy fixed it, it ran great for about 4 mos. Just started with the missing and backfiring when warm. One thing I would like to know is, what are the symptoms of leaking diaphragms???? Thanx!

Randy

[motoman]

Will check the wires today! Dont know if I made myself clear, but after the guy fixed it, it ran great for about 4 mos. Just started with the missing and backfiring when warm. One thing I would like to know is, what are the symptoms of leaking diaphragms???? Thanx!

Randy

First symptom would be to follow bikerphil's advice for a check. Otherwise they have to get fairly bad before causing a bad stumble, rich cond,etc. Stick to the electrical checks first, as that's likely where the issue lies. Carb related issues will rear their ugly head gradually, and are consitantly the same. Electrical, immediately and sometimes intermitently.

[bikerphil]

Another easy thing to check is those vacuum caps on the carb boots. Sometimes they crack and will cause a backfire/popping in the carbs due to a vacuum leak.

[tarzan]

Bad diaphragms can cause back firing, running lean, and rough running. Also can cause a stumble or the bike to die.

[mack]

electrical connections

I'd imagine it's pretty humid where your are almost year round. You may want to clean all the electrical connections, switches too during the monsoons.