1994 90 TLRS What is red switch next to carb?

[JimParri]

Hi, I have a 90HP Yamaha in my garage that belongs to the Local Boy Scout
troop. I have no manual. I was trying to get the motor to start and took the Carburetor cover off to to spray some cleaner in there. On the side of the middle carb there is a small red plastic switch. I turned it and now can't remember what position it was in originally. What is that switch and what position should it be in?

[99yam40]

That should be the lever to turn the enrichment system from auto position(full counter clockwise)to the open(emergency) position( middle), and to the closed position(full clockwise)

should be in the normal Auto position.
if carbs plug up and motor will not start,it can be used in the open position to get motor started to get to a safe place.
Any owners manual with prime start system will give you info on it

[ausnoelm]

also, just to be clear, you cannot clean carbs by spraying anything.

[rodbolt17]

its NOT for if the carbs plug up.
its ONLY function is to allow a manual override of the enrichment system. only.

if the system fails in a warm position you would turn it to open/ emergency.
this would allow a cold motor to start with the system failed in the warm mode.once running it would have to be turned back to normal or its going to idle very rich.

if the system failed in a COLD mode you can turn it to off/closed and shut off any further enrichment of the automatic enrichment system.once running it would need to be left in the off position or it would run very rich.

the reason why you should NOT run it in any
position other than normal is the oiling system cant add extra oil for the extra fuel your adding in the emergency mode.

like its been pointed out, if the carbs are dirty inside the ONLY cure is to remove them,and the fuel pump and filter, and disassemble and clean them.

[JimParri]

Thanks so much guys. I tried to get the engine to start, but it just sputters and quits. The cleaner and started fluid made it run a few seconds longer, but to no avail. Guess I'll check the fuel filter next. Where ever that is.

[99yam40]

Do not use cleaning and starting fluid on a 2 stroke motor to fire it up, no oil in that for lubrication. You can use a mix of oil and gas in a spray bottle if you must but
Carbs need to be opened up and cleaned would be my thoughts

[JimParri]

Do not use cleaning and starting fluid on a 2 stroke motor to fire it up, no oil in that for lubrication. You can use a mix of oil and gas in a spray bottle if you must but
Carbs need to be opened up and cleaned would be my thoughts

Thanks. Hadn't thought about the oil.