Giving up on the 80SG in the Philippines

[hanger10]

Here is how it all started. Bike was running great. I slowly developed a small popping when I let off the throttle. I asked about it here, and almost everyone here said it was dirt in the carb. So, I took it to the guy that I have working on it now. Hes had the carbs off and cleaned them on the bike many times. Well, he cleaned them, put it all back together, and it ran terrible!!! He tried all he knew, and never could get it diagnosed. He is the one that suggested the guy that replaced the slides and diaphragms. I took it to the new guy, and he said it was the diaphragms, and fixed them with glue, and it ran great for a month or so, and then developed the missing again, so I just got new slides and diaphragms and had him replace them, and after he did, I am where Im at now with the missing problem again!!! But even I didnt think it needed valve seals and rings, so I took it back to my original guy. No oil burn, and runs great when we get it right!!!

[bikerphil]

Couple of thoughts, it could be something as simple as a loose pilot jet. It could be bad shaft seals if the carbs were dipped in a caustic carb cleaner bath. Could be the carbs just need a good cleaning again. Could be the float heights got disturbed somehow. Check the alignment of the hole in the diaphragm pistons, they should face forward towards the engine when installed. You guys keep at it, you'll find it. Always check for simple things first like pinched fuel lines, plugged fuel filter, etc. Good luck bro.

[WMarshy]

Pop on decel typically a lean condition. Take all 4 plugs out and post a picture of them so we can see. Might be a wacky float height or loose jet like previously mentioned or could be one of the vaccum lines or carb boots leaking air. You can check for leaky shaft seals and carb boots by letting the bike idle and spraying carb/choke cleaner or starting fluid on the boots and end of the butterfly shaft ... change in RPM = air leak.

[hanger10]

Does the compression sound like its ok guys????

Randy

[Schming]

Does the compression sound like its ok guys????

Randy

As Ras asked in post #15 :

"Can you convert those numbers into PSI as that is what we are most familiar with?"

We have no idea of what increment of measurement you are using.

[donebysunday]

Drain the fuel from each float bowl into a clean cup, I like to use a Can't Believe It's not Butter 1/4 LB container cut down with scissors to fit under the float bowls. See what comes out (what's in the fuel after it sits 2-4 hours) that will tell you what is coming to the carbs from the tank. Look for small black particles and little droplets floating at the bottom of the fuel this would be water mixed with fuel, this can act like gum in the pilot jets plugging them. The black specs are either rust from the tank or just plain dirt. Yes the filters only stop some , not all of the garbage.

[jetmechmarty]

compression

Your compression is probably OK. I think you're allowed +/-10% difference between the cylinders. You're squeezing, so I don't believe it's the problem.

Normally, I would rule out all possibilities of an electrical problem before going into the carburetors. Perhaps you've done that, and it's a good rule to follow. In this case, you had a good running bike (for a while) until you did the slides. It sounds like doing that made it worse than it was. I'll add to what Phil said. Make sure all of the slide needles are in the same position. Make sure the slide needles are all the same. This thing won't run if the slides aren't properly oriented.

[CaptonZap]

I bought the entire assembly, slides and all already assembled. Ive taken the bike to another good friend that worked on it since I got it. I was there, and he did a compression check. 3 of the cylinders varied slightly from 7.8 to 8.5:1. One varied 8.5 to 9.0:1. He thinks that is ok, but wanted me to ask here and see what you all said. As long as the compression is ok, he is just gonna systematically go through everything, including the suggestions here. He is a good mechanic, he is very thorough, and has lots more patience than I do. I told him to take his time, Im in no hurry. Ive showed all of your posts here to him also. Just let me know if the compression sounds ok, and we will take it from there!!! Thanx again all, so very much for all the help!!!!! I love it here in the Philippines, but it sure is a pain with this bike!!!!

Randy

Great!
Sounds like you found someone who can do you some good, and not just take your money.
The stock minimum compression is 9, with a variance of not more than 1 across the 4 cylinders, so it sounds like the three are a little low. DO NOT LET THAT DISCOURAGE YOU.
It could be that when the valves are adjusted, or the motor has run a few miles, that the compression will increase.
Get everything else in order, and then check it again.
The reason for the advice to check compression before anything else is that it gives some indication of the overall health or problems of the engine so that you can decide to buy it , or work on restoring it. After EVERYTHING else is brought back to specs, it then gives an idea as to the relative strength of the engine. (Lower compression, HP, means less stress on the bearings and drive train, and if it runs OK, it should last a long time in that condition.)
If your mech has any more questions, let us know.

CZ

[Geezer]

If the valve guide seals are bad, often the will build up burnt oil on the back side of the intake valves. I've seen engines with such low compression from this they would barely run. The only fix I know for this other than a tear down, is to take the bike a fast run keeping it at close to red-line for as long as possible. We used to call this the I5 tune up. When a bike with this issue came in for service, one of use would take it out a lunch time and run the pi$$ out of it on the freeway, the next day the bike would be serviced as usual.

Tony