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Potentially basic carburetor question

bobl said:
I just remembered another way to determine if the petcock is leaking fuel into the vacuum line. Pinch the vacuum line closed, and run the bike on prime. That will take the diaphragm out of the equasion.
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x1,000
 
Update: There are three ports on the carb. One is fuel feed, one is the vacuum feed for the petcock and one was open. It's not like I spend every day staring at that carburetor so I can't remember if that port was previously capped. Based on how clean and shiny it is I presume there was a cap on there and I blew it to the moon when I was clearing orifices' with air. Some research tells me that port is intended to go back to the airbox. With no dangling available hose present I capped that port. I then pinched the vacuum feed to the petcock and fired it up. It lit immediately and sat there idling contently for several minutes. I was staring down into the airbox thinking we had progress when it suddenly belched a huge load of fuel into the box and kept pumping a steady stream until I shut it down, fast.
I'm back to being aimed at the float but there are too many things there that don't add up.
 
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Aren't you able to find an online manual or fiche that shows where the various hoses go, and the exact assembly diagram of the carburetor, and float height?
 
Yeah, I suppose I'm at the part where I need to download a manual. All signs point to too much fuel/float. As to vacuum routing, that's pretty much sorted out as there are so few options.
My next step is to pull it back apart and check to see if the float valve is stuck.
 
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I think the capped line is the float vent, and should be open.
 
Agreed.
I tore it back down and found the float valve is hanging up. Part on order. $49.00 and a week away.
 
So there's still a chance that I've won this installment of the Barf's Garage Forum guess the problem over the internet game. :party :teeth

Wait.... I think Chris and August Iron also guessed the same... and before me. :x

I wanna be a winner! :laughing :twofinger
 
OaklandF4i said:
So there's still a chance that I've won this installment of the Barf's Garage Forum guess the problem over the internet game. :party :teeth

Wait.... I think Chris and August Iron also guessed the same... and before me. :x

I wanna be a winner! :laughing :twofinger
Click to expand...

There will be enough prizes to go around for everyone if it doesn't burst into flames in my garage first.:laughing
 
I'm still waiting for my float valve to arrive. Frankly, it can take it's time because I'm having a difficult time getting an accurate float level spec. So far, the internet has not been my friend.
Any help finding that number would be greatly appreciated.
1994 Suzuki DR125s
 
gixxerjeff said:
I'm still waiting for my float valve to arrive. Frankly, it can take it's time because I'm having a difficult time getting an accurate float level spec. So far, the internet has not been my friend.
Any help finding that number would be greatly appreciated.
1994 Suzuki DR125s
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Of course a shop service manual would have that….:laughing

Short of that, you could also try googling the carb model and see if there are specs for it alone. Can’t imagine the carb model’s specs itself would have a huge difference from one bike application to the next.

Good luck!:thumbup

Edit: Thumpertalk forum can be a great resource too if you haven’t already posted there for the specs.
 
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Yeah, I'm going to have to pull the trigger on a manual. I just hate spending $30 for one number. :laughing
 
same engine as the Suzuki GS 125?

pilot(slow) jet : 20
main jet : 95
float level : 24mm

* this one has a Brass Float ( I don't know whether all the other GS 125 has brass float, if it is why does this barb keep overflowing)

its a Mikuni VM carb and i really don't know which one is it. I measured the width of the intake side. it was 34mm
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from here ...
 
Thanks John.
I have a plastic float but they could be kind of close. That 24mm number scares me though. I was expecting something closer to 7mm.
I'm also struggling finding a manual on it. My search tends to terminate with recommendations for DR350 (which I also own) despite my typing in 125.
 
gixxerjeff said:
Thanks John.
I have a plastic float but they could be kind of close. That 24mm number scares me though. I was expecting something closer to 7mm.
I'm also struggling finding a manual on it. My search tends to terminate with recommendations for DR350 (which I also own) despite my typing in 125.
Click to expand...

:thumbup

Carburetor; Construction - Suzuki DR 125 Service Manual


MIKUNI VM20SS; float height: 18.9 ± 1.0 mm (0.74 ± 0.04 in)

manual cover sez DR-Z, but pics look like the little air cooled engine, and the float in schematic looks plastic? would think the spec for the brass float would not be helpful, if the float was plastic ... idk.

:dunno
 
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Yes, John. It's a super cool little bike but I'm afraid not many of them made it to the US. I've personally never seen another one like it. Lots of DR200's though.
It's a little frustrating looking for a fairly critical spec and finding "it's probably close to this..." for answers. :laughing
 
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When I don't know the float measurement, I set them with the plate that holds the float parallel to the carb body. Most all end up there.
 
Is your petcock held on with two 6mm bolts? If so you may be able to get rid of the vacuum function. Go get a petcock from the Yamaha blaster atv and see if it fits. You gain a reserve function if you didn't have one already. You also eliminate the vacuum shutoff that can fail. For a bigger bike with a bigger fuel line get a banshee petcock. You will have to shut the fuel off manually now. But this can prevent fuel from getting past the needle and seat when a bike sits a long time.

Also change your oil since it's full of gas now.
 
An overdue update:
The good news: Diagnosis has been confirmed. It needs a new float valve. The plunger has launched out of it's housing and become part of the fuel system.
The bad news: The part is no longer available from the dealer and the carburetor is also no longer available. There are no visible numbers on the Mikuni carb, which is somewhat surprising and may make matching one up somewhat tricky.
So Barf, looks like I’m suddenly on a carburetor hunt. Any tips, tricks, inputs??
The throttle cable threads into the side of the carb housing but beyond that as long as CFM and bore is close I suppose I’m not picky.
What exactly are my options here?
 
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