1982 GS850 carbon problem...

[tomch]

Wow... lots of stuff in the previous posts about carbon problems! I hope I'm on the right track...

I just bought a 1982 GS850GL. It has 15,000 miles, and was sitting for 2 years. It ran, but not very well.

When I got it home, I noticed that the #2 spark plug was carbon fouled (black and fluffy). Other plugs looked great.

I cleaned the carbs as per the instructions on this website (what a great tutorial!) and put it back together. Air screws are 2.5 turns out (this is how I found them). Floats are adjusted to .88 inches (halfway between .84 and .92) - measured without gaskets.

Good blue spark to all cylinders.

Balanced the carbs with a manometer.

I installed a paper fuel filter between the petcock and carb, because I found some rust in the float bowls when I opened them up. (wanted to catch the junk before it got to the carbs).

I timed the bike, checked the valves (they were perfect).

Put the bike back together, and... same issue! #2 is still carbon fouling. I'm getting intermittent sputtering / lagging acceleration - but not all the time. It seems to get better when I have a full tank. (Maybe the paper filter is holding things up and it needs the added pressure of 3 gallons of fuel? I dunno...)

Bike is stock, except for a K & H (I think...) air filter instead of the oil version. When I opened the air box, I noticed half of the "foam" had deteriorated (under chrome covers), and removed the rest of the foam to avoid having it ingested by the engine somehow. After reading other posts, I'm getting the feeling that I shouldn't have done that... too much airflow. But I don't think this would cause carbon problems to #2 only, would it?

From other posts, I think I should check my o-rings between the boot and the head next. I'll try this tomorrow and update the post.

Another idea: maybe it's the petcock...? One post mentioned a possible hole in the diaphram (I think he was talking about the petcock diaphram...) and said to test it with setting the petcock to "PRI" and see if the problem goes away. I'll try this tomorrow, too.

Some posts mentioned having the pilot fuel screws 1.25 turns out... I don't think this applies to this particular carburetor, does it? As I remember, all brass jets were bottomed out.

Any other ideas? I'm hoping that someone will have a similar bike and say - "Hey... I know what's wrong with Tom's bike!" and keep me from experiencing too many more hours of frustration!

Thanks much for your help! Sorry this post got a bit long...

[SqDancerLynn1]

Through the paper filter in the trash it will restrict fuel flow. The # 2 carb has the vacuum tap for the petcock, if the petcock is bad it can suck fuel thru the vacuum line & make the #2 cyl very rich SO make sure petcock is working. If you haven't replaced the intake O ring it would be a good idea just as preventive maintance if nothing else

[bwringer]

I agree with SQdL on all points.

#2 fouling is the textbook sign of a leaky petcock diaphragm.

IMHO, it's not worth farting around with a rebuild kit (if one is available) -- buy a new petcock for $50 - $60 and forget about it for another 20 years. You can order OEM through your favorite Suzuki parts supplier or from CRC2 or Z1:

http://crc2onlinecatalog.com/

http://z1enterprises.com/

The GL and G model petcocks are different, so make sure you order the correct one. Buying a petcock from eBay is a little iffy, because they usually have errors in their application charts. You don't really save any money anyway.

As nice as it would be to have a second fuel filtration step (the primary filter is the fine screeen on the petcock), it's very difficult and probably impossible to get enough flow through a filter that will fit in the available space.

If there's crud coming from your tank, you may need to treat or line your tank with Por15. Kreem is a more widely available (and more expensive) tank treatment, but it's useless krap in my experience. Use the Por 15.

http://por15.com/PRODUCTS/COMPLETEKITS/CYCLETANKREPAIRKIT/tabid/103/Default.aspx

[tomch]

Thanks for your help! I removed the vacuum line from the petcock and noticed gas seeping out... confirmation that the petcock needs replacement. I haven't ventured out yet, but I'm pretty confident that this will fix the #2 problem - hope I'm not jinxing myself!!

Thanks for your links to the parts sites. I hadn't found those yet. I ordered a new petcock (and a valve cover gasket to boot). I also got the POR15, and will line my tank at the next opportunity. Thanks much for the info!

Also... I removed my in-line paper fuel filter (and threw it in the trash as directed!). Noticed that the gas line was a bit kinked in the process - yeah, there's not a lot of room under there for a filter, is there?

I'll wait until Tuesday to order the manifold O-rings from my local Suzuki dealer - couldn't find those online. That will make a good project for next weekend, eh?

I love this site - thanks for the help!