2005 GS500F, help identifying carbs (BSR34SS ??), troubleshooting hard start

[petro]

This is my first time pulling the air box, and these carbs don't look like the one in the Haynes book or any other photos I've seen. No prior experience with CV carbs.
Does anyone have info about these specific carbs, or at least tell me which air vent does what?  Searching on-line it's as if they don't even exist lol.

The bike idles OK at 1100 RPM and runs great when fully warmed up, but will not start unless I open the throttle (regardless of choke). I REALLY don't want to remove the carbs or take them apart.  Hoping I can maybe spray some cleaner or blow some air to clear things up.

There's probably some flooding due to a leaky petcock (the usual known problem), but I'm wondering if there's anything else I should look at.

I have ALWAYS used premium fuel with zero ethanol, and occasionally add extra cleaner during a fill-up. There might still be some gunk due to sitting around for months, but I don't think it would be too bad.

I need to strip & clean the chassis petcock because it's leaking fuel even with the engine off.  Fuel in the airbox and oil.  It's the second time happening, so I've done this before.  Could this alone be causing all the grief?  Is there a rebuild kit for the chassis petcock?

Any good info and advice much appreciated!

[ajensen]

I recently rebuilt my frame-mounted petcock--kits are available.

Usually, if you have to open up your throttle to start, gas has been running into your combustion chamber(s). I see that you have already found gas in the oil--big problem if you run the engine without changing the oil.

Idling at 1,100 rpm is a little low. Mine idles at 1,500.

My 2007 has the same carbs--do not be afraid to take them off and clean them. There are rebuild kits available if you need parts. Also, get a JIS number 2 philips screwdriver--the screws get missed up really easily if you use a regular number 2. Take pictures as you take the carbs apart.

I put a little washer under each of my needles and adjusted the low-speed screw so that it is richer. The gas mileage suffered about 10%, but the bike is no longer cold-natured--more fun to ride. I can release the choke almost immediately after starting.

Do not be tempted to put on individual air filters. Keep the stock filter in the stock air box.

Buddha is the guru about carbs and most everything else.

Best Wishes

[ajensen]

P.S. There is a YouTube video about cleaning GS500f carbs--not the best, but it will give you a good idea of what to look for. I do not know why he did not get a spray can of carb cleaner with a plastic tube on it.

Also, you can Google carb rebuild kits and petcock rebuild kits.

[petro]

P.S. There is a YouTube video about cleaning GS500f carbs--not the best, but it will give you a good idea of what to look for. I do not know why he did not get a spray can of carb cleaner with a plastic tube on it.

Also, you can Google carb rebuild kits and petcock rebuild kits.

Already tried all of the above (including this site) with no luck, so I ended up asking here.

[ajensen]

Where do you live?

[mr72]

Carbs probably just need standard cleaning, particularly the pilot jets. I would just replace the pilot jets rather than trying to clean them.

If it runs good when warmed up and only has hard starting issues, this is way inside the domain of fixable with simple carb cleaning.

[HPP8140]

folks love to remove carbs on this site...make sure your exhaust valves are in spec...tight ex valves lead to difficult starts but will run well when warm and idle low and fix the leaky petcock

[petro]

I recently rebuilt my frame-mounted petcock--kits are available.
Usually, if you have to open up your throttle to start, gas has been running into your combustion chamber(s). I see that you have already found gas in the oil--big problem if you run the engine without changing the oil.
Idling at 1,100 rpm is a little low. Mine idles at 1,500.
My 2007 has the same carbs--do not be afraid to take them off and clean them. There are rebuild kits available if you need parts. Also, get a JIS number 2 philips screwdriver--the screws get missed up really easily if you use a regular number 2. Take pictures as you take the carbs apart.
I put a little washer under each of my needles and adjusted the low-speed screw so that it is richer. The gas mileage suffered about 10%, but the bike is no longer cold-natured--more fun to ride. I can release the choke almost immediately after starting.
Do not be tempted to put on individual air filters. Keep the stock filter in the stock air box.
Buddha is the guru about carbs and most everything else.
Best Wishes

Which kit did you use for the petcock. I found 2 options and trying to figure out which is better.

I used to idle at 1500, but I'm trying to set up the bike to run as described in Josh Karnes excellent blog post.  I don't mind babying this reptilian engine with the choke.  Premium gas is selling for up to CAN$2.50/L here so I want good economy to compensate for my guzzling M5.

JIS screwdrivers for sure I need some!  I noticed that about the screws. I've been careful but it's only a matter of time.

For various reasons I don't have the space/time for a carb rebuild right now.  Trying to sort what I can as-is.

Unfortunately I DID run the bike with fuel in the oil before realizing the problem.  Hopefully the Amsoil helped mitigate any issues. I did a 2x oil change & new filter to flush it.

[petro]

Carbs probably just need standard cleaning, particularly the pilot jets. I would just replace the pilot jets rather than trying to clean them.
If it runs good when warmed up and only has hard starting issues, this is way inside the domain of fixable with simple carb cleaning.

Just noticed your signature. You wrote that blog on carbs?  Very helpful!

I've never taken a carb apart, but seems well within my comfort zone.  I just don't have a decent space to do it right now.  I'm hoping sorting out the petcock will solve most of the issues.  I was also hoping I could just spray some carb cleaner into the air vents.  But stories about destroyed seals & o-rings are making me hesitate.  Maybe throttle body cleaner is safer?

[petro]

folks love to remove carbs on this site...make sure your exhaust valves are in spec...tight ex valves lead to difficult starts but will run well when warm and idle low and fix the leaky petcock

Never checked the valve clearances. That's good to keep in mind!

I'm sure pulling the carbs gets easier & faster the more often you do it.  But I'm trying to take the "if it ain't broke don't fix it" approach.  I've used nothing but zero ethanol premium hoping to avoid ever having to get into the carbs.  I will take them apart if I have to, but need to get by for now.

[mr72]

Just noticed your signature. You wrote that blog on carbs?  Very helpful!

Yep, I just figured it'd be easier than answering the same questions over and over. Speaking of which:

I'm hoping sorting out the petcock will solve most of the issues.

Maybe. If it's flooding when sitting then the hard starting might simply be due to this, plus you having to open the throttle to start it could be caused by too much fuel in the float bowls. Does fuel come out of the overflow?

  I was also hoping I could just spray some carb cleaner into the air vents.  But stories about destroyed seals & o-rings are making me hesitate.  Maybe throttle body cleaner is safer?

DO NOT DO THIS.

You should spray some carb cleaner on a balloon to see what will happen to the diaphragm in your carb if any carb cleaner gets in contact with it. Carb cleaner (or TB cleaner, same problems) will accelerate degradation of the o-rings but likely won't ruin them immediately, but it can and will ruin the diaphragms immediately. You should only use carb cleaner on a fully disassembled carb. I'm sure this was in my blog post

I have had slightly good luck running Seafoam in the gas to passively clean stuff like the pilot jet. It's worth a shot if you don't want to tear down the carbs. You can't really clean the pilot air passage without the carbs torn down because you need to force a solvent like carb cleaner into the passage and then blow compressed air through it with the carb open so whatever is clogging it gets pushed out of the carb altogether. If you try this with it assembled it may screw up the diaphragm or just dislodge the gunk and leave it inside the carb where it will find its way into another place.

[petro]

Maybe. If it's flooding when sitting then the hard starting might simply be due to this, plus you having to open the throttle to start it could be caused by too much fuel in the float bowls. Does fuel come out of the overflow?

Yeah, the first thing I notice is fuel dripping out of the airbox drain tube. And my air filter smells like gas. I assume it's overflowing out of the throats.
I didn't notice fuel in my oil till MUCH later in the game unfortunately. Level was mysteriously above F, smelled like gas, and the shifting in&out of N was difficult.

You should spray some carb cleaner on a balloon to see what will happen to the diaphragm in your carb if any carb cleaner gets in contact with it. Carb cleaner (or TB cleaner, same problems) will accelerate degradation of the o-rings but likely won't ruin them immediately, but it can and will ruin the diaphragms immediately. You should only use carb cleaner on a fully disassembled carb. I'm sure this was in my blog post

It was indeed in your blog! I don't intend to spray anywhere near the diaphragms but your point is well taken.
I wanted to dig deeper and better understand the issue. I noticed that all the different types of cleaners use various chemicals depending on application.
For example CRC carb cleaner uses (in desc order) methanol, toluene, acetone. But their throttle body and marine carb cleaner are almost entirely acetone!
Gumout carb cleaner uses xylene, acetone, benzine. But their small engine cleaner is mostly acetone with a bit of toluene.

I suck at chemistry, but it seems you can roughly group the above into acetone, methanol, and everything else.
Acetone is relatively safe for rubber, and for plastic it REALLY depends on what kind.
I've gone down a rabbit hole but this is really interesting stuff! (probably deserves its own thread)

I have had slightly good luck running Seafoam in the gas to passively clean stuff like the pilot jet. It's worth a shot if you don't want to tear down the carbs. You can't really clean the pilot air passage without the carbs torn down because you need to force a solvent like carb cleaner into the passage and then blow compressed air through it with the carb open so whatever is clogging it gets pushed out of the carb altogether. If you try this with it assembled it may screw up the diaphragm or just dislodge the gunk and leave it inside the carb where it will find its way into another place.

I've never tried Seafoam, but always use premium gas and occasionally add some extra treatment (especially after prolonged storage)
I found this video to be very informative. Not ready to blindly follow this procedure, but I would be curious of your opinion on it. This particular carb resembles mine so it caught my attention.
https://www.youtube.com/watch?v=EYRVHkIXlEw

[mr72]

Yeah, the first thing I notice is fuel dripping out of the airbox drain tube. And my air filter smells like gas. I assume it's overflowing out of the throats.

This is likely your starting problem.

It was indeed in your blog! I don't intend to spray anywhere near the diaphragms but your point is well taken.

You can't prevent it from getting into the vacuum chamber. You spray carb cleaner in there, it's going to squirt up into the vac chamber. I mean, sure someone's going to come along and say "I've done that 100 times with no problems" but you know how everyone's an expert on the internet.

I suck at chemistry, but it seems you can roughly group the above into acetone, methanol, and everything else.
Acetone is relatively safe for rubber, and for plastic it REALLY depends on what kind.
I've gone down a rabbit hole but this is really interesting stuff! (probably deserves its own thread)

Also depends on what kind of rubber. IDK what the diaphragm is made of but certainly there are different o-ring and fuel hose materials which are better or worse at ethanol resistance etc. Since the carb diaphragm was not intended to come into contact with fuel, there would be no reason to choose a material which was resistant to the types of solvents that can be found in fuel. So I just wouldn't risk it.

I have a spare set of carbs with diaphragms ruined by carb cleaner from the previous owner. It's just one of the hundred things that was wrong with my GS when I got it, but I learned my lesson by replacing the entire set of carbs.

I've never tried Seafoam, but always use premium gas and occasionally add some extra treatment (especially after prolonged storage)

Additives like Sta-bil or Star-tron don't do anything really to clean the carbs. You can run Berryman's B12 or Seafoam added to the gas to get some passive cleaning going on, it's basically like adding carb cleaner to the fuel. I wouldn't do that while your bike is flooding, fuel with extra solvents in it will wind up getting in places you don't want it. But Seafoam seems to work well.

BTW, you don't need premium fuel, but you definitely should be using ethanol-free fuel. I use ethanol-free with Star-tron 1 oz. per gallon and since adopting this regimen my GS comes out of storage and fires right up with zero issues. Considering I only ride it like once or twice a year, this is critical to me.

I found this video to be very informative. Not ready to blindly follow this procedure, but I would be curious of your opinion on it. This particular carb resembles mine so it caught my attention.
https://www.youtube.com/watch?v=EYRVHkIXlEw

Nope!

I mean, why in the world if you have the carb on the bench would you not remove the vacuum chamber top and remove the slide and diaphragm entirely? And the float bowl? What, six screws? Then you can begin to properly clean it. The main o-rings you would want to remove (and replace) are the float needle seat o-ring and the pilot needle ("screw") o-ring. Once the carb is apart, this is very easy to do. Just take the float needle seat out, take out the pilot needle/spring/washer/o-ring assy, take out the jets, clean everything, run a wire through every little orifice you can get to, blow compressed air through the air holes (where the guy in the video is spraying carb cleaner...), then put it back together with new float needles, float needle seat and o-ring, new pilot jet and your other jets cleaned. If you have a fresh float bowl gasket, use that. And while the carbs are off, take the intake boots off and replace the intake boot o-rings (yes, they are kind of expensive and you have to get it from the dealer...).

The whole carb cleaning/service job takes maybe one hour, most of this time is pulling the tank and airbox off and putting them back. The actual time to do the carbs once they are off the bike is like 5 minutes per carb.

[petro]

I mean, why in the world if you have the carb on the bench would you not remove the vacuum chamber top and remove the slide and diaphragm entirely?

He said at the beginning that he only took the carb out to make it easier for us to see what he's doing.  The whole point of the video is to show what can be done without removing the carb.  Right now I have no suitable place to work so I want to know what's possible with it still on the bike.

[mr72]

To get to the carb throat, you have to remove the tank and airbox. If you get that far, it's trivial to get the carbs off. I mean, if you have a place to put the tank and airbox, then you probably have enough space to pull the carbs. Folding workbench with a piece of cardboard and a magnetic parts tray, that's all you need.