CB 360 Jets

M

motormayhem

Active Member
Anybody use these jets. They look the same and I know Rocky Mountain has served me well for my KX. They say they are aftermarket so I didn't know if there were any small details that would cause problems. Hell of a lot cheaper than buying a kit when I only need 110 or 112

https://www.rockymountainatvmc.com/p/930/25596/Keihin-99101-393-Series-Main-Jet?term=keihin%2099101
 
What carburetor do you have?...Some of the 360's came stock with 110 jets...
 
Not sure the number, they are stock carbs. These must have been rebuilt because they had 100s in them. I ordered some jets and have been doing to some plug chops to see what it likes.
 
Secondary main jets are fine, they seem to be the sizes marked. I've found problems with the pilot jets though, many are smaller than the marked size
100 is stock size secondary main jet for most CB360's
 
Thanks, I ordered the aftermarket jets and after playing with it 110 seems to be the best. The aftermarket secondaries appear to be pretty much identical so no complaints.
 
crazypj said:
112.5 worked best in mine with long 'quiet' exhaust system
Click to expand...

Whats typically the rule of thumb for jetting? More restrictive exhaust would need leaner jets since the engine cant flow as well?
 
It's not the flow directly, but the velocity and scavenging. A short exhaust cannot take advantage of the momentum of the gas flow to pull more air into the cylinder. Short exhaust flow better, but don't / can't scavenge, as well. A longer exhaust is more restricted but the momentum ends up moving more gas

Sent from planet Earth using mysterious electronic devices.
 
mydlyfkryzis said:
It's not the flow directly, but the velocity and scavenging. A short exhaust cannot take advantage of the momentum of the gas flow to pull more air into the cylinder. Short exhaust flow better, but don't / can't scavenge, as well. A longer exhaust is more restricted but the momentum ends up moving more gas

Sent from planet Earth using mysterious electronic devices.
Click to expand...

That's a very good point. A buddy of mine used 110's but there is a lot to factor in when jetting
 
I got 118s on mine, but I have a bit of a flat spot in the mid range. Not bad, but definitely noticeable.
 
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