Post by JR on Jan 15, 2012 15:02:42 GMT -6
It seems like lately more and more people have carb issues due to dirty carbs and we all know there are lot's of reasons from letting one sit too long with old gas in one from just poor gas to start with. IMO the ethanol isn't helping either. I've even read where the Chinese when testing scooters still use leaded gasoline and we know a carb that sits too long with the old real gas of yesteryear it'll end up dirty.
But what is the real way to clean a carb? One of the first things people say is soak or spray it with carb cleaner. OK it's carb cleaner right so it'll be the best stuff right? Well I tell you there are so many stories about cleaning carbs it'll blow your mind, don't believe it just google it for yourself.
I even recently read where you can remove oxidized material build up from a carb by putting it into a crock pot overnight in antifreeze! Even can use Listerine on a carb again the stories are endless.
But I do know and found lots of readers finding out the same thing I've known for a long time and it's this. Some of these on the counter cheap and quick carb cleaners especially the spray ones can and will leave residue in your carb too. They may help as a quick fix when a carb is dirty or plugged but also may add their or things in the process that needs to be cleaned later also. They in some cases can actually cause your carb to oxidize with white powder deposits. Aluminum which is what makes up a large percentage of carbs can and will oxidize with harsh chemicals.
If you go looking or asking about a carb cleaner and want a better long term solution then you need to ask the questions of what is a good carb "soak" instead of cleaner. Now carb soaks generally involve more time but a quality soak versus a quick spray cleaner in designed to do a better job and there are lots of them still out there problem is people don't ask that question, they ask for a carb cleaner.
Here's an old time brand that makes lots of products and still has one of the best carb cleaning soaks today;
.berrymanproducts.com/" rel="nofollow" target="_blank">
.berrymanproducts.com/
I'll also tell you of one of my carb cleaning secrets and it's one a old time GM mechanic shared with me and it's brake parts cleaner. Yep the same stuff you use when rebuilding the old brakes. Cleans a aluminum carb well with no residue if you want the quick fix cleaner. Myself I use the Berryman old time screw the lid off of the bottle carb soak type cleaner.
As far as the tiny pilot holes and holes in the jets it does a lot better job of getting them unclogged and with a good air hose you'll have better results. You here people say all the time "it was so bad I had to take a tiny wire and unclog the jets". One I try to avoid this at all costs because believe it or not with a wire one can damage the hole where it impedes the flow and harms the carbs performance. I've never had to use a wire on a carb that I allowed to soak overnight in Berrymans carb soak cleaner and I've cleaned some nasty carbs on lots of things over the years.
Also I want to tell you to not soak the diaphragm in Berrymans, this is some bad stuff, it will soften a very stiff old diaphragm and just for a little spell is OK for this but don't leave it in too long, it'll actually dissolve the plastic that holds the diaphragm in place!
Lastly is diaphragm repair. Repair? You can repair a diaphragm JR?
Yep sometimes and it works sometimes for a long time but in lots of cases it will get you buy until you can do better.
It appears there is a manufacturing or design issue in the plastic that clamps the vacuum diaphragm which lifts the needle up to allow more gas to flow. There are two plastic pieces that snap together that "sandwich" the diaphragm to seal the low pressure side (top of diaphragm) and the high pressure side (bottom of diaphragm).
Over time, this loosens up and the seal is compromised allowing the air to pass from lower side to the top side, causing a lower differential in pressure and not lifting the needle as much as it used to.
I had this happen on a GY-6 carb and could not for the life of me figure out what was wrong, just didn't have the top end it needed and I was about to order a new diaphragm slide assembly and that's when I discovered that a few places sold just the rubber diaphragm itself. I thought OK if they sell a new one then one has got to be able to get the old one off.
I discovered they just pull out from under the top and bottom plastic clamps and I also discovered it was loose instead of clamped tightly. I sit the diaphragm upright and put a few drops of gasoline on the rubber and it went right through and dripped out the bottom.
I knew then if gas would go though so would air or in this case vacuum which makes the slide move up and in turn raises the needle to allow gas to flow in the carb.
I cleaned it well and then took a tiny bit of black RTV silicone and sealed it from the top and let it dry for 12 hours. Put it back together, it still is running in my Bali 150 and it raised the RPM and top end by 5 MPH!
Now one needs to remember that if applying silicone the least the better, weight is a factor on the diaphragm and too much of it will impede the diaphragm's ability to move to the fully open position.
Now here's another diaphragm repair tip and it's the old pin hole repair again another way to get by for a spell or maybe even longer. I love to read about old scooter restorations and sometimes finding any parts for them is really tough so people learn ways to fix things themselves.
Carb diaphragms are made of nitrile rubber and finding something that will seal them is a real trick. I mentioned silicone and it worked fine for the problem I mentioned earlier but if you try it on pin hole repair from what I've read it's not very successful due to the fact it's actually not that flexible which is needed for the diaphragm and again it's weight can be a problem.
I read where a guy tried a lot of different things and finally after researching a lot of adhesives and such found the perfect solution and again I tried this on a friends 50cc scooter carb that we knew had a pin hole in the diaphragm.
"Gorilla Glue" has di-isocyanates in it and can be particularly nasty, but cyanoacrylates and di-isocyanates are the only suitable bonding materials for nitrile rubber.
Remember you are sealing vacuum and the diaphragm unlike what people think sometimes is not in gasoline provided the carb is in proper working order. Just a thin film over the pin hole and shes good as new.
Been wanting to write this up for awhile and finally got the chance today and I hope this can help some out there with carb issues when they arise.
JR
But what is the real way to clean a carb? One of the first things people say is soak or spray it with carb cleaner. OK it's carb cleaner right so it'll be the best stuff right? Well I tell you there are so many stories about cleaning carbs it'll blow your mind, don't believe it just google it for yourself.
I even recently read where you can remove oxidized material build up from a carb by putting it into a crock pot overnight in antifreeze! Even can use Listerine on a carb again the stories are endless.
But I do know and found lots of readers finding out the same thing I've known for a long time and it's this. Some of these on the counter cheap and quick carb cleaners especially the spray ones can and will leave residue in your carb too. They may help as a quick fix when a carb is dirty or plugged but also may add their or things in the process that needs to be cleaned later also. They in some cases can actually cause your carb to oxidize with white powder deposits. Aluminum which is what makes up a large percentage of carbs can and will oxidize with harsh chemicals.
If you go looking or asking about a carb cleaner and want a better long term solution then you need to ask the questions of what is a good carb "soak" instead of cleaner. Now carb soaks generally involve more time but a quality soak versus a quick spray cleaner in designed to do a better job and there are lots of them still out there problem is people don't ask that question, they ask for a carb cleaner.
Here's an old time brand that makes lots of products and still has one of the best carb cleaning soaks today;
.berrymanproducts.com/" rel="nofollow" target="_blank">
I'll also tell you of one of my carb cleaning secrets and it's one a old time GM mechanic shared with me and it's brake parts cleaner. Yep the same stuff you use when rebuilding the old brakes. Cleans a aluminum carb well with no residue if you want the quick fix cleaner. Myself I use the Berryman old time screw the lid off of the bottle carb soak type cleaner.
As far as the tiny pilot holes and holes in the jets it does a lot better job of getting them unclogged and with a good air hose you'll have better results. You here people say all the time "it was so bad I had to take a tiny wire and unclog the jets". One I try to avoid this at all costs because believe it or not with a wire one can damage the hole where it impedes the flow and harms the carbs performance. I've never had to use a wire on a carb that I allowed to soak overnight in Berrymans carb soak cleaner and I've cleaned some nasty carbs on lots of things over the years.
Also I want to tell you to not soak the diaphragm in Berrymans, this is some bad stuff, it will soften a very stiff old diaphragm and just for a little spell is OK for this but don't leave it in too long, it'll actually dissolve the plastic that holds the diaphragm in place!
Lastly is diaphragm repair. Repair? You can repair a diaphragm JR?
Yep sometimes and it works sometimes for a long time but in lots of cases it will get you buy until you can do better. It appears there is a manufacturing or design issue in the plastic that clamps the vacuum diaphragm which lifts the needle up to allow more gas to flow. There are two plastic pieces that snap together that "sandwich" the diaphragm to seal the low pressure side (top of diaphragm) and the high pressure side (bottom of diaphragm).
Over time, this loosens up and the seal is compromised allowing the air to pass from lower side to the top side, causing a lower differential in pressure and not lifting the needle as much as it used to.
I had this happen on a GY-6 carb and could not for the life of me figure out what was wrong, just didn't have the top end it needed and I was about to order a new diaphragm slide assembly and that's when I discovered that a few places sold just the rubber diaphragm itself. I thought OK if they sell a new one then one has got to be able to get the old one off.
I discovered they just pull out from under the top and bottom plastic clamps and I also discovered it was loose instead of clamped tightly. I sit the diaphragm upright and put a few drops of gasoline on the rubber and it went right through and dripped out the bottom.
I knew then if gas would go though so would air or in this case vacuum which makes the slide move up and in turn raises the needle to allow gas to flow in the carb.
I cleaned it well and then took a tiny bit of black RTV silicone and sealed it from the top and let it dry for 12 hours. Put it back together, it still is running in my Bali 150 and it raised the RPM and top end by 5 MPH!
Now one needs to remember that if applying silicone the least the better, weight is a factor on the diaphragm and too much of it will impede the diaphragm's ability to move to the fully open position.
Now here's another diaphragm repair tip and it's the old pin hole repair again another way to get by for a spell or maybe even longer. I love to read about old scooter restorations and sometimes finding any parts for them is really tough so people learn ways to fix things themselves.
Carb diaphragms are made of nitrile rubber and finding something that will seal them is a real trick. I mentioned silicone and it worked fine for the problem I mentioned earlier but if you try it on pin hole repair from what I've read it's not very successful due to the fact it's actually not that flexible which is needed for the diaphragm and again it's weight can be a problem.
I read where a guy tried a lot of different things and finally after researching a lot of adhesives and such found the perfect solution and again I tried this on a friends 50cc scooter carb that we knew had a pin hole in the diaphragm.
"Gorilla Glue" has di-isocyanates in it and can be particularly nasty, but cyanoacrylates and di-isocyanates are the only suitable bonding materials for nitrile rubber.
Remember you are sealing vacuum and the diaphragm unlike what people think sometimes is not in gasoline provided the carb is in proper working order. Just a thin film over the pin hole and shes good as new.
Been wanting to write this up for awhile and finally got the chance today and I hope this can help some out there with carb issues when they arise.
JR
