Carb Part Question

[Road_Clam]

Hello,
I have a 1980 GS750L. It has Mikuni BS32SS carbs. When I first got the bike it did not run. I took the bowls off to take a look and there was something that I had never seen before. There is a (previously)rubber plug very close to the main jet. This plug was melted into the bowl. It looked as if someone squeezed silicone into the bowl. Two of them were completely melted, the other two were halfway intact(half-way melted) I removed the mess and cleaned it out completely. What (I will do my best to keep my composure) the $%$# are these plugs for and do I really need them? I got the bike running very well except for a voltage regulator problem. The only other problem that I am noticing is that this thing is eating gas. Now, I am trying to fix one problem at a time and I know the regulator isn't any good, I should get that in a few days. It could be possible I suppose that it could be related to the gas issue, but my main concerns are what the heck are those plugs and do I really need them. If so, what would be suggested to use?

Thanks for reading this mess.

Those pilot jet plugs are a much debated subject. I asked the same question months ago. Bottom line is no one really knows for sure as to their specific exact purpose. All I know is Suzuki put them there for a good reason. My opinion is they are plugged to minimise the possibility of ingesting bowl sedimant, which commonly plugs the pilot jet. I have a new set of plugs installed, and my 1100 runs perfect, as far as the pilot circut. Like Keith commented, they draw fuel from a passage linked to the main jet. So even with the plugs installed, the pilot jet can draw the needed fuel.

[ghwrenchit]

My opinion is they are plugged to minimise the possibility of ingesting bowl sedimant, which commonly plugs the pilot jet.

Good point, never thought of that. Another thought I had was is it possible that with the plugs installed, forcing the fuel to be drawn from the main jet, that when in any throttle position off idle, there is enough vacuum thru the main and needle, that in effect it shuts off the pilot curcuit?

ghwrenchit

[arveejay]

It has always been my belief that they were there to limit how much gas could get to the pilot jets at a time. With plug in place gas would have to go thru a metered passage which would meter the flow, which would in turn make the engine suck gas through a more intended route. Without the plug the gas would be free flowing and not force correct atomization in the jets and passages in other parts of the carb. It probably wouldn't effect much more than the idling and fuel milage. I can't imagine leaving something out the the crafty Japanese intended to put there. Notice the post on the inside of the bowl, it sits against the rubber plug and keeps it in place, tightly. I'm sure a removable rubber plug was used because of the likelyhood of it getting plugged and needing removed and cleaned. The rubber plugs will melt if carb cleaner is left in the bowls in an attempt to get it running and then stopping after a no go. I've seen it many times.

Note, anything posted above is only an opinion based on what I have learned and infact may be wrong, what do you expect with free advice.

[KEITH KRAUSE]

If they were not needed ? why then would'nt muniki eliminate them to save a few pennies

For the same reason they install those cheap metal caps over the mixture screws. They don't want you to change the mixture.

[ruddy]

If the plugs are there to prevent tampering, why wouldn't they have used metel caps instead? The rubber plugs are far too easy to remove as an anti-tamper device. :?

They do, however, hide the pilot jets, so you overlook them when you're trying to clean the carbs! I think you can guess how I know that.

[KEITH KRAUSE]

If the plugs are there to prevent tampering, why wouldn't they have used metel caps instead? The rubber plugs are far too easy to remove as an anti-tamper device. :?

They do, however, hide the pilot jets, so you overlook them when you're trying to clean the carbs! I think you can guess how I know that.

You have to retain access to the pilot jets. They need servicing.
Same thing with the caps over the mixture screws on CV carbs. Easily removed but the service department will know and they can refuse any warranty work.
Same as the separate air screws and pilot fuel screws on some earlier VM carbs. But instead of caps, they wiped a sealant over the screw head that showed them if they were tampered with. The sealant also gummed up the threads and many owners have stripped the screw heads trying to move them.

[Billy Ricks]

Just to back Keith up on this, it doesn't matter how much fuel is behind the pilot, the jet itself will regulate how much fuel the engine gets on that circuit. The sediment theory seems most plausible.