[99yam40]

Has anyone else found out that the Yamaha carburetor kits do not contain the o-rings that go on the inlet seats? It seems strange that they are not included with the new needle,seats, floats and other o-rings and gaskets . The local Yamaha dealer told me you just have to pull them off the old seats and put them on the new ones. I originally thought that the design was changed and did not require them anymore, but even the mechanic told me to use the old ones and they do not even have them in stock. will have to order them if I want them.
Also when I pulled the carbs back off and disassembled them I found the rubber plugs in all 3 carbs in the bottom of the bowls, not in the hole covering the idle jets where I had installed them.
Has anyone had a problem with this happening to them and what would cause this to happen? A back fire? I know I fully seated them and I have been chasing a problem with idling and a high speed miss. Hopefully this will help out. I will find out tomorrow after I reinstall and test.

[rodbolt]

do I find it strange? yep.
but its kinda normal.
even some of the V motor carb kits dont contain the gasket for the plug that allows access to the pilot fuel jet.
they do include a spare fuel bowl to body screw though.
I dont like reusing that oring, I have but dont like it, I usually have them in stock.
sometimes stock gets depleted faster than replenished though.

[99yam40]

This is really getting strange. my motor still has the high speed cutout or miss, but when I take the cowling and silencer off of the front of the carbs it runs fine WOT, no miss or cut out. when I install the cowling and leave the silencer off it runs good but I can still hear and feel it miss every once and awhile. Reinstall the silencer and it cuts out a lot at WOT. Is it possible that there is a air bleed or orifice that is plugged that I keep missing I have been through the carbs 5 or 6 times in the last month looking for something causing the problems or maybe the jets have been opened up by someone(I am the 3rd owner ) This thing just seems to be running rich if removing the restrictions from the front of carbs makes it run better.

What could be causing these type of symptoms?

[99yam40]

I would also like to find out what kind of a signal does the tach receive from this motor. Voltage , etc, and could it be read by a Digital VOM on a hz setting to reprsent the RPM?