So, I recently posted

• http://gstwins.com/gsboard/index.php?topic=69251.msg833226
• http://gstwins.com/gsboard/index.php?topic=69363.msg834359

I have recently finished my exploratory surgery on the bike and have found the following things.

• Fuel Tank - reserve/main fuel lines miss-routed (reversed) - Straw on fuel tap literally 'came out' from the rest of the assembly while trying to remove fuel line
• Air filter - clean, but gave it a once over anyway
• Carbs - Main jet on both bowls 127.5. Bowls overall fairly clean, but have some rust/rust coloured gunk that needs to be cleaned out.
• Carbs cont'd - Pilot jets unknown, they are in tight, don't trust using my jeweler's screw drivers to get out w/o damaging carb body or jet
• Carbs cont'd - float bowl, gaskets on bowls seem to be pliable/good order
• Carbs cont'd - fuel inlet has build up on either side of gunk, when moving seems to dribble fuel - not sure what to make of this, assume its from moving the hose around
• Air Mix Screws - either 3 out or 6 out, refer to picture below (yes I am this dumb)
• Spark plugs - left cylinder EXTREMELY SOOTY, right cylinder less sooty at contact point, otherwise same. Gaps to spec

Only other major consideration on the table atm is the vance/hines exhaust. I am assuming this can play in some what. I am presently working on refinishing a stock exhaust, the exhaust came with down pipes, the ones I have right now are rusty as hell (btw, does anyone know how I take the chrome guard off? the screws look like they take Allan keys but they have a weird pip in the middle).

I pulled this picture out of google, it comes from GStwin. Black writing is mine. Apologies I'm in the wrong for borrowing someone else's photo....



So, why post?

I have no clue where to go from here. I worked down my tank after my highway fun time, and I am still getting about ~130km on 10 L of fuel. I'm going to get carb cleaner, some wd40 to cut thru the gross crap on the outside of the carb body, since it is out anyway. Planning on grabbing some tools to get the pilot jet out. I'm really not sure at this point what would fix my issue, and I'm assuming that stepping down from 127.5 to 122.5 would not change fuel consumption much, unless it would?

I'm also taking the wild leap that with my plugs being so sooty, it likely is something cause a fuel rich situation, thus destroying my fuel economy as opposed to a pin hole leak that is allowing the fuel to off gas into the atmosphere, thus loosing my fuel instead of actually using it, ending up with a tank that runs down fast anyway...

Any input would be greatly appreciated. Many thanks to those of you who have already put up with my questions.

Stock air filter?  If so, then probably don't need to have 127.5 mains.  125 would do.  Anyway, this is not your issue if you are getting 30 mpg.

Have you checked your float level?  Check the gas level in the float bowls with a clear tune from the drain.  If the level comes up past the float bowl gasket, then you have too much gas in your bowls, and that would be your problem.

Quote from: bombsquad83 on July 31, 2015, 01:52:20 PM
Stock air filter?  If so, then probably don't need to have 127.5 mains.  125 would do.  Anyway, this is not your issue if you are getting 30 mpg.

It appears to be the stock, canister style air filter. Is there a solid way of telling if its stock or not? My Haynes manual does not seem to reference a part number that would help confirm this.

Quote from: bombsquad83 on July 31, 2015, 01:52:20 PM
Have you checked your float level?  Check the gas level in the float bowls with a clear tune from the drain.  If the level comes up past the float bowl gasket, then you have too much gas in your bowls, and that would be your problem.

I get what your are saying to check for but can you dumb that down at all?

Edit: any insight on my question re air screws?

It should read clear tube instead of tune.   I believe there is a link on the gstwin.com main page about how to do this.

http://gstwin.com/float_height_check.htm

Quote from: bombsquad83 on July 31, 2015, 02:15:07 PM
It should read clear tube instead of tune.   I believe there is a link on the gstwin.com main page about how to do this.

http://gstwin.com/float_height_check.htm

Got it, this make more sense. Time to find clear tubing to use.

Biggest PITA about knowing about this is that I'm going to have to partially reassemble the bike in order to provide a fuel flow to the carbs in the first place -_-

Thanks.

aquarium air line from the pet store works.  It will harden due to gas exposure over time, but it's much cheaper than RC fuel line.

Yes it is rich but i doubt its because of jets or exhaust.
My bike has 140 mains with k&n filter and slip on, i'm 150kgs and my bike works pretty hard.
I get around 270km roughly 13litres.

Think i have linked the pic of the sparkplugs right.

Funny thing there.

Left cylinder looks exactly like the sooty one. The right cylinder looks like half way between the sooty one and normal one..

Carbs balanced?

How disassembled is the bike?

If the carbs are off, you can manually measure float by removing metal covers and, well, measuring (I believe that's covered in Ye Olde Service Manual). Thing about the float height is that you have to remove the carbs if you find out the height is wrong anyway...

Before putting my carbs back on I balanced the carbs by sight. My one black/one grey plug problem went away (again, covered in service manual).

Because all I have is a hammer, this feels like a nail.

And that nail is a vacuum petcock leak, which will cause fuel to be pulled into the left cylinder through the vacuum line - a little leak would waste fuel and cause a sooty plug, a lot will flood out the left cylinder so badly it won't fire, will puke smoke and will make nobody want to buy it.  I know this because that was all that was wrong with my $350 GS500, which now runs like a top after spending $30 on a new-to-me petcock. 

Did the vacuum line have any fuel in it when you pulled it?

Quote from: cWj on August 07, 2015, 08:03:42 AM
Carbs balanced?

How disassembled is the bike?

If the carbs are off, you can manually measure float by removing metal covers and, well, measuring (I believe that's covered in Ye Olde Service Manual). Thing about the float height is that you have to remove the carbs if you find out the height is wrong anyway...

Before putting my carbs back on I balanced the carbs by sight. My one black/one grey plug problem went away (again, covered in service manual).

Not balanced, have tool on the way to help out with that. Bike is currently back together, needed the garage space back. Measuring the float bowl in that way is covered in the service manual, at this point I'm probably going clear plastic tube route.. figure getting the right size tube will be good anyway, if down the line I have to diagnose something again.

Quote from: floatingLomas on August 07, 2015, 08:40:38 PM
Because all I have is a hammer, this feels like a nail.

And that nail is a vacuum petcock leak, which will cause fuel to be pulled into the left cylinder through the vacuum line  ................ which now runs like a top after spending $30 on a new-to-me petcock. 

Did the vacuum line have any fuel in it when you pulled it?

Not so far as I could tell. Vac line has always been wonderfully dry.. again as best I can remember