Topic: Do I have the right jet sizes?

[sk8er0918]

Its a 73 CB500 with 4 into 1 exhaust and original air box with an aftermarket sponge like filter. Its always run rich, so I decided to pull the carbs and check things.

The main jet is #100, the slow jet is #40, and the needle has the clip on the fourth setting (from the top). They all look original.

I believe this is the stock setting, but assume with the 4 into 1 exhaust something should have been adjusted.

Thanks

[Don R]

 In the 70's we used to jump a few sizes on the first try. Not sure why.

[dave500]

those jets should be fine even with your 4-1,lower the needle,make sure the sponge filter is clean and not over oiled,better still use the proper paper one.

[flatlander]

yeah the sponge filter may not let through enough air thereby causing a rich condition. i tested a sponge uni filter once against OEM paper on the dyno and also (illegaly speeding) on the highway, the uni was clearly and noticeably more restrictive. plus many people over-oil them. their only benefit is reusability.
of course the OEM paper filter needs to be replaced periodically according to the service schedule otherwise it clogs up and also causes restriction.

i'd drop in a new paper filter first before fiddling with jets.

[AndyH]

My CB500K1 also has a 4 into one.  Stock airbox, filter and jets (100, 40) and jet needle clip 2 down from top. Idles/runs fine.