Poor running

[Jeff P]

Howdy folks.  It's been quite some time since I posted.  Also been a while since I've been able to do much riding, which leads me to my current predicament.

I was able to get my bike to start yesterday with full choke and persistence with the starter.  Let it warm up for 5 or 10 minutes and started backing down on the choke as the rpms rose.  Taking the choke all the way off caused the bike to die immediately.  I was able to keep it running with no choke by giving it some throttle, and by cranking the idle set screw way way up.  But once I backed the idle back down it would die. 

The bike was running sorta weakly the last few times I rode it in the fall.  Bad throttle response, stumbling during acceleration. 

I'm guessing that I probably should drain the tank, give the carbs a heavy duty cleaning, get a fresh tank of gas, and maybe replace the fuel lines.  Any other suggestions?

jeff

[GSnoober]

OK, I'm in a rush, so I'm going to copy-and-paste an extract from some advice (slightly modified for clarity) that I posted to someone else:

Buy the cheapest carb cleaner you can find (Berryman's?), and add some (4 to 6 ounces) to the gas every time you park the GS for a while. The idea is to add it to the gas, then ride the motorcycle until the engine is warm (20 to 30 minutes?), then park the thing overnight, or longer. The carb cleaner will mix with the gas and soak the carb jets clean gradually, which should eliminate any problems you might be developing from the long period of non-use.

A lot of people add carb cleaner before a long ride, then ride until they empty the gas tank, and refill it WITHOUT adding more carb cleaner, but that is NOT the correct way to do this. The carb cleaner works by SOAKING the crud off, so you have to get it into the float bowls and then give the chemicals enough time to work (overnight is good, but 24 hours or more is better). Using only a few ounces at a time is the best way; if you use too much carb cleaner, you can make it much more difficult to start the engine. Moderation in all things... Use a few ounces each time until the can is empty, and you shouldn't have any problems with gummy jets... You can also do the same thing if you have to park the GS for an extended period; just keep fresh gas and some carb cleaner in the tank (and float bowls), and at least the carbs (and valves) will be clean if you have to work on them.

Also, adding fuel stabilizer has a similar effect; it keeps the gas usable for an extended period of time. Without stabilizer, the "aromatics" in the gas flash off quickly (evaporate into the atmosphere). Once that happens, the gas is much harder to burn, and it begins to build a gummy residue on everything it touches, especially the tiny little passages through the carb jets.

Some people think that this method is just the lazyman's way to avoid cleaning the carbs, but that isn't really true. If you use this technique but still have problems, you'll have to disassemble the carbs anyway, but the treatment with carb cleaner will help to reduce the crud you have to deal with when you get the carbs apart. Whenever I have to disassemble carbs, I use this method, and when I pull the jets, I soak them in a small amount of the carb cleaner while I work on the carb bodies.

Hope this information helps you; if time allows, try it for a week or so, and let us know how things turn out.

[ben2go]

Don't for get to check the petcock for debris and faulty vacuum diaphram.Not sure what year your bike is but this may help if you have a faulty vacuum diaphram. http://gstwins.com/gsboard/index.php?topic=19363.0

[jt_234]

So, I got the same thing today.  I haven't ridden my bike since January, it hasn't stopped raining 

I changed plugs, checked the air filter, and changed the oil.  It didn't have much gas in it, so I took the car to the gas station to get gas.  I gassed it up and added some carb cleaner.

I started it, had to be fully choke (its 85F here) and it ran poorly--spit and sputtered, backfired a few times, rpm all over the dial and stalled out when I touched the throttle.  I let it run for a few minutes at a time like this to let the bike warm up. 

It was running a little better, but still idles roughly and won't idle without choke, but will respond to throttle.  I took it for a spin a couple blocks down the road to see if that helped, but it didn't.

I've not had to do any engine work on this bike and don't know if I have time to take this on if I need to pull the carb.  I've only put about 2K miles on this bike since I've owned it (its at 8500mi. now).

Do you think I need to drain the gas?  Clean/rebuild the carb?  Am I missing something???

[jt_234]

So I decided to go ahead and pull the carb.  I get it apart and it looks good, this is the most dirt I can find:



The rest looked good:




...so, I'm going to dump the tank and start over with fresh gas and inspect the petcock.  I'm befuddled. 

[beRto]

It looks like the float bowl is coated in varnish; likely from sitting for several months without fuel stabilizer. It is possible that your carb jets are blocked with the same stuff. You can either try Seafoam or similar carb cleaner in your gas (cheap, easy, may-or-may-not fix problem), or further dismantle the carbs and clean them thoroughly from the inside.

If you go for the full clean you will need to remove the jets to make sure they are not clogged. Spray carb cleaner inside the carb body, but be careful not to get it on rubber seals etc.

Good luck!

[jt_234]

Yeah, I went ahead and tore it the rest of the way down and cleaned all of the jets and float bowls with carb cleaner.  I'm going to dump the tank of gas I have now and start over fresh.  I'm going to buy stabilizer and use it a little more regularly.  I never intended on leaving the bike sit as long as it did, but next year I'll have winter to deal with. 

Any of you know where the quickest place to get new jets would be?  I"m going to rejet while I'm at.  The bike runs VERY lean with a drop-in K&N and an aftermarket .  I'd like to have my bike back on the road by Tues. night...may be wishful thinking.

BTW anyone else who has to get into their carburetor, the screws are cheap brass.  I had to Dremel 6 of the 8 screws to get the float bowls off.  The screws are 4mmX0.7mm and 10mm long.  I bought stainless allen head screws at Home Depot to replace them.  I would just anticipate having to do it.


JT

[jt_234]

Got the carb cleaned up and back on.  Its running better, but I think I bunged up one of the 0-rings.  It looks like its leaking a small steady film of gas around the float bowl rim.  I plan on using Permatex gasket, we'll see how it goes.

[beRto]

Got the carb cleaned up and back on.  Its running better, but I think I bunged up one of the 0-rings.  It looks like its leaking a small steady film of gas around the float bowl rim.  I plan on using Permatex gasket, we'll see how it goes.

I'm a bit confused; you messed up one of the float valves? I agree that the carb shouldn't be leaking around the float bowl rim and this probably requires a new gasket. Maybe the float level is set too high or a float valve is sticking?

[jt_234]

Got the carb cleaned up and back on.  Its running better, but I think I bunged up one of the 0-rings.  It looks like its leaking a small steady film of gas around the float bowl rim.  I plan on using Permatex gasket, we'll see how it goes.

I'm a bit confused; you messed up one of the float valves? I agree that the carb shouldn't be leaking around the float bowl rim and this probably requires a new gasket. Maybe the float level is set too high or a float valve is sticking?

This is with the bike on the left kick stand I get a little bit of fuel running over the lip of the bowl running or not.  When I took it off, I noticed the black o-ring in the picture above had gotten pinched.  I also remember that with the carb off of the bike, upside down the floats were not in the same position.  I thought maybe this was just the way it was.  Would you not expect fuel leaking if the left gasket was bad and it was on the side stand? 

I haven't tested the synchronization yet, that's the next day or two.  I just got a call, the shop has my new jets...so I'll be taking it back apart to put those on.

Do I need to adjust those?  How do I adjust them?

[beRto]

This is with the bike on the left kick stand I get a little bit of fuel running over the lip of the bowl running or not.  When I took it off, I noticed the black o-ring in the picture above had gotten pinched.

Well, that answers that question! The gasket should be ok if you "unpinch" it. If the leak persists, you will likely need a new gasket.

I also remember that with the carb off of the bike, upside down the floats were not in the same position.  I thought maybe this was just the way it was.  Would you not expect fuel leaking if the left gasket was bad and it was on the side stand?

Dunno    If the gasket was pinched, it's possible the carb would leak even if the float height was correct. If the the float heights are incorrect, they should be set as per the repair manual (sorry, I don't have it nearby to look it up right now). An easy method to check if the heights are correct is to attach a hose to the drain and see what the resultant fuel height is. See Kerry's page for more details:
http://www.bbburma.net/FloatHeight.htm

I haven't tested the synchronization yet, that's the next day or two.  I just got a call, the shop has my new jets...so I'll be taking it back apart to put those on.

Do I need to adjust those?  How do I adjust them?

Are you asking, how to adjust the jets? Sorry, I don't have any expertise with jetting.

[jt_234]

I haven't tested the synchronization yet, that's the next day or two.  I just got a call, the shop has my new jets...so I'll be taking it back apart to put those on.

Do I need to adjust those?  How do I adjust them?

Are you asking, how to adjust the jets? Sorry, I don't have any expertise with jetting.

I meant about adjusting the floats manually with the carbs off.  How do I do that?  I didn't see anything about it in the Clymer.

[ben2go]

Have you tried this with the bike on the center stand? http://gstwin.com/float_height_check.htm There should be tabs that the float needles hang on.Gently bend them until the fuel level is right at the split in the carb bowl/body.

[jt_234]

Have you tried this with the bike on the center stand? http://gstwin.com/float_height_check.htm There should be tabs that the float needles hang on.  Gently bend them until the fuel level is right at the split in the carb bowl/body.

Unfortunately my GS is sans center stand.  I don't know if it didn't come with one or if the previous owner didn't like it.    I am going to buy a bike jack soon...maybe.   

When I looked at the float needles they looked like they were at the same level, but the floats themselves looked out of whack. 

Regarding adjustment of the float needles, you're talking about this tab right?

http://picasaweb.google.com/taylorj/Carb04272008/photo#5195931107357998178

Edit: Picture link take 3--Google's being stupid, you have to click on the link to see the pic.

[ben2go]

If there was a pic it didn't come thru.You can check them off the bike, sit them on a box with a hole for the idle screw.You can also hang them.I use rubbing alcohol when bench testing instead of gas.I cut a hole in the alcohol bottle cap and insert the fuel hose into it.Turn it upside down and watch where the alcohol stops in the clear test tubing. I use a clean soda bottle to drain the carbs into.

[jt_234]

If there was a pic it didn't come thru.You can check them off the bike, sit them on a box with a hole for the idle screw.You can also hang them.I use rubbing alcohol when bench testing instead of gas.I cut a hole in the alcohol bottle cap and insert the fuel hose into it.Turn it upside down and watch where the alcohol stops in the clear test tubing. I use a clean soda bottle to drain the carbs into.

Thanks man.  Off to Wally World for some aquarium tubing and valves...

[jt_234]

So, I got the new jets on today, checked the sync of the carbs (they were fine), and got the bike running even better.  I still need to adjust the air screw to correct the leanness...and replace the fuel line I busted