Carb Circuits

S

Snowshovel

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In my quest to find out wtf blew up my engine, a few people have said clean the carb circuits, I assume these are the little black pyramid looking things on the carb rail with wires coming from them? Sorry complete noob about snowmobile engines, If this is correct how do i clean them, none of the carb cleaning instructions show these being cleaned that i can find or pics of them. Thanks in advance for any help.
 

Found a pic of what i THINK people are talking about, where the yellow arrow is pointing are those the circuits? And if so how do you clean them? anything spring loaded i need to watch for when pulling the caps etc..?

yampwv.jpg
 
You sure did and i appreciate it, where my misunderstanding and lack of knowledge is colliding is at the term "circuit". When I hear the word circuit I think electronics,wiring, solenoid etc.. I see 2 referrences to the word circuit in your instructions.

1) these control how much air the idle and low speed circuit receives

2) if you clean each circuit as you go

So can you please define what a circuit is for me, does it mean a passageway where fuel flows through? a port? a nozzle?

Sorry for the arse pain, just wanting to make sure i learn the terms and phrases right so i know wtf im doing as i plan to rebuild this thing myself with little to no prior experience on sled engines.
 
Carb circuits

Circuits in this text is referring to the various passages in your carbs where the fuel flows.....or should flow. If they are plugged it will cause a lean condition and burn down your motor. From looking at your photo's I think your lower rod bearing gave up the ghost but you should have cleaned the carbs before you rode it. So as far as circuits go.....check your fuel screw circuit (be careful not to loose the little washer, o-ring and spring in each one) as well as the pilot circuit and the main circuit. But if any of them are clogged which may have led to the problems you have right now it would most likely be the pilot.

Good luck,
Madmatt
 
does it mean a passageway where fuel flows through?
Click to expand...
correct, nothing electrical, there are three main "circuits" pilot, covers the lower rpms, needles, your midrange, mains, your topend, that's simplified explanation of course, if you follow those links you'll have cleaned the "circuits", mrvipers has good pics, easy to understand, crewchiefs touches a few areas mrvipers doesn't
 
A small item that can be forgotten:
All the Yamaha TM33s I have on my sleds[ Vmax4,SX600 +700,SRXs] have a small wire mesh "cap" shaped fuel filter under each of the carbs float bowl needle-seat [fuel inlet]. These filters are a little harder to get at as the float has to be removed and the small screw, that holds the brass seat in place, has to be removed. Once the screw is out you gently remove the brass fuel inlet[or seat] from the carb body + on the backside is the filter held on by a plastic retaining ring. All the fuel that enters the individual carb has to go thru this filter! I have found some contaminated at times and they can definately be the cause of an illusive fuel starvation/lean condition. I have always removed them from the carbs on my first cleaning and not replaced them.

CAUTION:
The pins that hold the float pivot arm to the carb bodies can be difficult to tap out the first time! You need the proper size punch, support the carb body and light tapping. It is very easy to break the carb body float arm pivot mounts if EXTREME CARE is not exercised! So if unsure don't try to force the pin out and maybe just try to back flush the float bowl with carb cleaner.
JM.02c
 
Last edited:
sideshowBob said:
A small item that can be forgotten:
All the Yamaha TM33s I have on my sleds[ Vmax4,SX600 +700,SRXs] have a small wire mesh "cap" shaped fuel filter under each of the carbs float bowl needle-seat [fuel inlet]. These filters are a little harder to get at as the float has to be removed and the small screw, that holds the brass seat in place, has to be removed. Once the screw is out you gently remove the brass fuel inlet[or seat] from the carb body + on the backside is the filter held on by a plastic retaining ring. All the fuel that enters the individual carb has to go thru this filter! I have found some contaminated at times and they can definately be the cause of an illusive fuel starvation/lean condition. I have always removed them from the carbs on my first cleaning and not replaced them.

CAUTION:
The pins that hold the float pivot arm to the carb bodies can be difficult to tap out the first time! You need the proper size punch, support the carb body and light tapping. It is very easy to break the carb body float arm pivot mounts if EXTREME CARE is not exercised! So if unsure don't try to force the pin out and maybe just try to back flush the float bowl with carb cleaner.
JM.02c
Click to expand...


2X - just to add another technique for pin removal: I use a pair of opened needle nose pliers placing one tip against the inside top of the tower and kind of roll the other plier tip into the face of the pin which forces it out the other side. Grab the protruding end and pull.

Did that make any sense?

I've had to tap a few just the same but pliers usually works. Since supporting both towers that the pin goes through is nearly impossible when tapping, as SSB suggests - EXTREME caution is advised. I may just be lucky, but I haven't broken a carb yet just taking it slow and lightly.
 
mopar1rules said:
best way to remove the float pin, is w/automatic center punch. nothing works easier than that.
Click to expand...

Do you mean a press pin punch? Never tried one but I suppose it'd work great. I don't usually have to pull out any punches.
 
Be careful with that,,,,,,,,, I use that to break windows to extricate unconscious victims from car accidents..............
 
sideshowBob said:
A small item that can be forgotten:
All the Yamaha TM33s I have on my sleds[ Vmax4,SX600 +700,SRXs] have a small wire mesh "cap" shaped fuel filter under each of the carbs float bowl needle-seat [fuel inlet]. These filters are a little harder to get at as the float has to be removed and the small screw, that holds the brass seat in place, has to be removed. Once the screw is out you gently remove the brass fuel inlet[or seat] from the carb body + on the backside is the filter held on by a plastic retaining ring. All the fuel that enters the individual carb has to go thru this filter! I have found some contaminated at times and they can definately be the cause of an illusive fuel starvation/lean condition. I have always removed them from the carbs on my first cleaning and not replaced them.

CAUTION:
The pins that hold the float pivot arm to the carb bodies can be difficult to tap out the first time! You need the proper size punch, support the carb body and light tapping. It is very easy to break the carb body float arm pivot mounts if EXTREME CARE is not exercised! So if unsure don't try to force the pin out and maybe just try to back flush the float bowl with carb cleaner.
JM.02c
Click to expand...
This should be fun them pins to remove
 
Whammy said:
Be careful with that,,,,,,,,, I use that to break windows to extricate unconscious victims from car accidents..............
Click to expand...
Shouldnt be a problem, as the Yamaha's windows are no where near the carb float bowls LaLaLa Just kidding!!

I use my spring punch as well, works great ;)!
 
go it..used small nail punch..they are in there tight.Had to do a few swift taps..no breakage and no glass flying around..not even a swear word..that is a record for me..lol..Putting them back..now that could be a challenge..brought my sludge hammer along just in case...lol
 
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