More 80SG probs in the Philippines!!!

[hanger10]

This forum has been a lifesaver, and I hope you can save me one more time!!! About 3 mos ago, bike started running bad. Took a while, but it ended up being the diaphragms. My mechanic fixed them with glue, but said it was a temp fix. It ran perfect for a month or so, and then started missing badly. I ordered and got new diaphragms from the States. I had no choice but to drive the bike around 15 miles to the mechanic on 1 cylinder. Didnt want to do it, but no choice. He put in the new diaphragms. I got the bike, but was missing on one cylinder under light throttle. Doesnt matter what rpm or speed, does under light throttle, especially when taking off. Under heavy throttle, runs great. Took da bike back to the mechanics yesterday. He synched the carbs, messed with the diaphragms, played with the mixtures, etc. He never did get it running correctly, still missing on the one cylinder under light throttle. Left it there for him to tinker with. Ok, anyone have any ideas what the heck it could be?? Like I said, it ran wonderfully for about a month after he fixed the diaphragms, then screwed up again, we are at a loss thus far!!!! HELP PLEASE!!!!! (ps-I shimmed the valves a little over a year ago, so it shouldnt be that!)

Thanx in adavance

Randy

[motoman]

This forum has been a lifesaver, and I hope you can save me one more time!!! About 3 mos ago, bike started running bad. Took a while, but it ended up being the diaphragms. My mechanic fixed them with glue, but said it was a temp fix. It ran perfect for a month or so, and then started missing badly. I ordered and got new diaphragms from the States. I had no choice but to drive the bike around 15 miles to the mechanic on 1 cylinder. Didnt want to do it, but no choice. He put in the new diaphragms. I got the bike, but was missing on one cylinder under light throttle. Doesnt matter what rpm or speed, does under light throttle, especially when taking off. Under heavy throttle, runs great. Took da bike back to the mechanics yesterday. He synched the carbs, messed with the diaphragms, played with the mixtures, etc. He never did get it running correctly, still missing on the one cylinder under light throttle. Left it there for him to tinker with. Ok, anyone have any ideas what the heck it could be?? Like I said, it ran wonderfully for about a month after he fixed the diaphragms, then screwed up again, we are at a loss thus far!!!! HELP PLEASE!!!!! (ps-I shimmed the valves a little over a year ago, so it shouldnt be that!)

Thanx in adavance

Randy

Pick-up coil wire/wires broke internally would be first suspect.........gonna have to clean or replace plugs also.

[hanger10]

pickup coil wires

Wires were replace about a year ago, and we checked them again, they are fine. Also we put in new plugs.

[jetmechmarty]

Are all the slides in correctly? A friend of mine was having carb trouble and it turned out the slides were in backwards. Could you have picked up some debris in one of the carbs? You have checked for a vacuum leak?

[hanger10]

Yes amigo, weve checkerd all that!!!! Are at a complete loss!!! I bought the entire diaphragm, slides and all. And, it was running so well before all this crap!!!!! Thanx for the suggestion thought!!!

Randy

[crazy steve]

Start with basic diagnostics; run a compression test first. It could be missing under bigger throttle opening, but just is being 'masked'. Do you know which cylinder is missing? Check header pipe temps. After you know which one is 'it', then it's either compression, spark, or fuel mixture. If you swap plug wires/plugs between each 'pair' (1/4 and 2/3) and the miss moves, it's spark. If it doesn't, it's fuel.

I'd look for a vacuum leak, or a bit of crap in the carb.

[hanger10]

slides

One more question please? How can the slides be put in backwards??? Still waiting to hear from the mechanic on the other issue!!

Randy

[mlew]

One more question please? How can the slides be put in backwards??? Still waiting to hear from the mechanic on the other issue!!

Randy

There is a air bleed hole in the bottom of the slide, it is suppose to face tward the engine. If it faces away the slide will not lift at the correct rate. The diaphram does have a tab that will keep the hole in the right direction. That is true if the slide has not been turned in the diaphram.

[jetmechmarty]

One more question please? How can the slides be put in backwards??? Still waiting to hear from the mechanic on the other issue!!

Randy

If your mechanic replaced only the diaphragms, it is possible that they are not properly oriented as Mark has pointed out. The tab on the diaphragm must be oriented exactly as it was on the original diaphragm.

If the motorcycle was running fine before the work was done, then we know the problem you're having was induced at the shop. We need to start there.

This eBay listing has a good tutorial on replacing the diaphragms. 4pcs CARB SLIDE DIAPHRAGM YAMAHA XJ900 XJ1100 XS1100

Is this how it was done?

[hanger10]

diaphragms orientation

I got the entire assymbly, slides and diaphragms already on the new slides. Got them from Sirius. So, they should alll be right, right????

Randy

[Cuda 69]

If the running problem started with a torn diapham and after glueing it ran fine for awhile,could the glue have come apart from gas and a small piece got lodged somewhere in the carb? Do you no what cylinder is skipping,that would be the suspect carb.

[jetmechmarty]

I got the entire assymbly, slides and diaphragms already on the new slides. Got them from Sirius. So, they should alll be right, right????

Randy

The assemblies should be good. We have to assume the problem was induced during the repair.

[CaptonZap]

I got the entire assymbly, slides and diaphragms already on the new slides. Got them from Sirius. So, they should alll be right, right????

Randy

Well, yes, unless someone at the factory is hung over on a Monday morning, or their significant other gave them an ultimatum before they left for work, or,,,,,,.
You get the idea.
Here is the quick way to check.
Imagine you are setting on the bike, looking down into the top of the diaphragm/slide assembly. Actually, you could be looking, and with the tank off, it would be easy. But I digress.
Looking down at the slide, the little bump on the outer edge of the diaphragm will be at the seven o'clock position.
Using your X-ray vision, look down at the bottom of the slide, where the needle sets and goes into the main jet well. The needle is at the center of the slide, and about 5/16ths of an inch, (8 mm) forward from the needle, (towards the engine, 12 o'clock), is a hole about an eighth of an inch ( 3 mm ) in diameter, in the flat bottom of the slide.
The factory slides have the diaphragms securely fastened to the slide, but some of the replacements might not have been properly secured, or misaligned, or, , ,,,.
Takes but a minute to check, and that's one more variable crossed off the list.
Actually, if the carbs are off, you can check without taking the lids off, by raising the slides, and peering in the intake side of the carb, and checking the position of the holes.
CZ

[GLoweVA]

...... I had no choice but to drive the bike around 15 miles to the mechanic on 1 cylinder. Didnt want to do it, but no choice. .......Randy

Randy, this one sentence is what really concerns me.
If you did indeed limp it back to the mechanic then you may have burned a hole in a piston. I've 'limped' my bike home twice and both times I burnt holes in one or 2 of my pistons.
Compression test will show it right away, so do as Crazy Steve says and put a tester on it and make sure all 4 are good to go. If they are, then you can chase this thing down to either fuel or spark.
Spark is easy to diagnose, swap plug wires around and see if the problem moves by checking header pipe temps.
If it doesn't move then it's a carb issue.

[Rasputin]

Randy, this one sentence is what really concerns me.
If you did indeed limp it back to the mechanic then you may have burned a hole in a piston. I've 'limped' my bike home twice and both times I burnt holes in one or 2 of my pistons.
Compression test will show it right away, so do as Crazy Steve says and put a tester on it and make sure all 4 are good to go. If they are, then you can chase this thing down to either fuel or spark.
Spark is easy to diagnose, swap plug wires around and see if the problem moves by checking header pipe temps.
If it doesn't move then it's a carb issue.

That question does not concern me at all. I have never seen a 1100 run one just one cylinder. I do however agree with both you and Steve on how to go about diagnosing it. If the checks are done and the plug wires swapped it will tell you what is wrong.
It's kind of like baby talk....it is telling you something and you just have to listen or adjust things for it to really let you know what it needs.
Shims adjusted a year ago simply is time... not showing any actual mileage or if it was done correctly the last time.
Pick up coils were done and re-checked so all is supposedly good with that.
Have you checked for a bad plug wire at the last 1/4 inch thing?
Any electrical connections that need attention?
Looked at the solder joints on the TCI?
Any exhaust leaks that could be affecting how it runs?
Battery is completely up to snuff on it?
Just a few things that come to mind that may ring a bell with others trying to help you out here.