Possible Bad Coil?

[Steve]

I'm going to do a full clean and make sure nothing was missed before. Probably going to dip them too just to be safe.

You do realize that you are being redundant, right?

The ONLY way to do a "full clean" is to dip them.

Do yourself a favor, do NOT follow the directions on the can.
The directions say to dip them for 15-20 minutes. Those directions were likely written when the chemicals inside the can could actually do the job in that amount of time. You will be far better off dipping them for 15-20 HOURS, instead. Follow that dip with a HOT water rinse, then a quick burst of carb spray through the pilot circuit and starter circuit, then blow it out with compressed air.

Be SURE that none of the parts that are dipped have any rubber.
You only need to dip:
- carb body
- float bowl
- main jet
- pilot fuel jet
- pilot air jet
- needle jet
- fuel needle

Do NOT dip:
- "choke" plunger
- slide and diaphragm

If you didn't use them last time, get new o-rings for the carbs and the intake tubes from cycleorings.com.

.

[jlyon40]

Got it Steve

[Wingsconsin]

Here's another option --

Take the carbs off --
Place them in a box --
Seal said box ---
And ship them to Steve for the best possible results -
HE will rebuild them and they will work --

I know from personal experience -- Just my 2¢

[jlyon40]

Haven't had time yet but later this week I'm planning on pulling the carbs and dipping them for the recommended 15-20 hours. I had a leaking petcock so I'm guessing gas got into the carbs after I emptied them for the winter and gummed up. I'll keep you guys updated on how it goes.

[jlyon40]

Update:

1 Carb dipped and 3 to go. I'm almost 100% sure the carbs were the problem considering how much the first one cleaned up. I'll keep you guys posted on if this fixes the problem or not.
IMG_1064.jpg

[Brendan W]

90% of carb trouble is electrical.
If you have an under performing charging system you will have weak spark at low rpm.
Check what voltage is at the coil supply plugs at idle and what the battery terminal voltage is at the same time.
The originl coil plugs can look fine on the outside but hide a mess of corrosion.

[jlyon40]

Thanks Brendan! I've already checked the charging system and the coils and everything is good. So hopefully I've narrowed it down to it being the carbs.

[Big T]

If you had a leaky petcock, check your oil level and remove the oil filler cap and see if your oil smells like gas

[greg78gs750]

fwiw, i drain the old gas in the spring and replace with new, even though I put stabilizer in it. It does make a big difference. Sounds like this isn't your issue, buuuut......

[jlyon40]

Well after dipping the carbs they came out a LOT cleaner and shinier. Everything looked great in the carbs. No gunk or anything in any of the jets. Made sure to clean thoroughly after the dip (Rinse with warm water and soap, spray carb cleaner through every passage, then use an air compressor to blow out everything).

Got the carbs back on the bike and started up fine but I'm still having the same issue when the bike gets to 3-4K RPMS. I've check the charging system and that's good, Checked the spark plugs and boots and wires and the resistance is good in all of those.

I've heard that it could be the timing is off. Never looked and that and not sure how to look into that. But I remember someone saying the advance mechanism (Retard) might be getting stuck and it may need to be cleaned off. So I'm going to look into that and check that out. If anyone has any other ideas as to what the issue could be it would be much appreciated.

[fastbysuzuki]

The auto advance/retard kicks in around 2500 rpm so it's well worth checking out make sure the mech is free to move on the springs as for timing the operation is in the workshop manual, my manual shows the ignition has points but in fact the 81gx has electronic pickups not points ignore the points and follow the procedure.

[jlyon40]

Will do thanks for the input!!

[jlyon40]

Okay after checking out everything I noticed that the bike acted as if it wasn't getting enough gas. As I looked into it more I noticed that the petcock was leaking and that maybe it also wasn't allowing enough fuel to flow into the carbs. Once I looked into it more I could see a clear sign that it wasn't putting enough gas through even in prime. So I have a new petcock on the way that I got from Georgefixit. My air boots are also quite hard so I have new air box boots on the way as well.

Once I hooked up an "IV fuel line" to test it without the tank I noticed that the carbs were filling up properly and the bike wasn't hesitating in the mid range anymore. I believe this has been my problem all along. Even though I probably didn't need to dip the carbs, I'm happy I did. Thanks for all the input from everyone I seriously appreciate it!

[jlyon40]

Got the new air hoses and petcock in and installed. The bike ran very well but in the low rpm's when I would give it just a little gas there would be hesitation. Upon further review and using a clear fuel line I saw that the fuel was getting caught up in the inline fuel filter and this was causing it to allow gas to go through when I really hit the gas but not enough when I was just giving a little gas.

Bottom line; I took the filter out and now she run's even better than before. It only took dipping the carbs, replacing the air box hoses, replacing the petcock and taking out the fuel filter to get there. But I'm happy I did all of those things because now she runs even better.

Thanks everyone for the advice and for having me check everything I needed to. This was the first thing I've ever had on a bike that completely stumped me and I'm so grateful for this site and everyone on it to help me get through it. Now it's just time to get my dad's running properly . His has the same problem mine did so I'll take the same steps and hopefully his will be up and running before I know it.

[Brendan W]

Some in-line filters are intended for pumped, pressurised fuel systems but will not flow enough in gravity systems.