FCR question

So after the winter my bike has been running like crap. Lots of decel popping, won't idle steady at all, hard to keep running, loss of power :worthy:

I tried a tank of Sea Foam. No help. So I bit the bullet and tore everything off and took a can of carb cleaner to it. I took it completely apart and shot cleaner into every hole I could find making sure it came out somewhere else in a stream or spray of some kind. Put it all back together and holy smokes I think it runs better than it did when I first put the carb on. :confused:

Anyway, all that for this question.... There are two compartments on the carb. One on the bottom and one on the right hand side (maybe in a different spot, now I cant remember) that have cover plates that come off. When I took the plates off (very carefuly, not knowing what might fall/shoot out) I found some type of round rubber valve type deal in each one. They also had inlet and outlet holes for fuel (or maybe air). What are these mysterious round rubber valves and what is the purpose for these two chambers?

I don't like not knowing what stuff is. Especially when it looks as important as these chambers/valves look.

Anyway if anyone could shed some light on this I would really appreciate it. :thumbsup:

The YFZ450 carb has the ACV circuit. It is on the left side of the carb. Two screws hold the cover on.... under it is a spring then the diaphragm. There is also an o-ring for the cover port. Make sure the flat side of the o-ring goes against the carb body. The pin sticking out of the diaphragm goes inwards to operate the ACV valve in the carb body.

The other Diaphragm on the carb is your accelerator pump. It is mounted on the bottom of the float bowl. There are two o-rings under this cover along with a spring and the diaphragm itself. The larger o-ring is round and has no installation direction but the smaller one is a D style o-ring and it to must be installed with the flat side against the float bowl (rounded side goes against the AP chamber cap) Make sure the diaphragm is in the coorect orientation when reinstalling it. The stainless pin sticking out of one side is the travel stop for the diaphragm. It hits the bottom of the AP chamber cap so it points outward towards you when installing the cap... the spring also goes on the outside of the diaphragm like the ACV. :smirk:

Be very cautious spraying any type of carb cleaner on your floating slide plate seal. The rubber can be damaged by these types of fluids... so can the diaphragms. :smirk:

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