Topic: 1982 CB450sc - Right Cylinder Running Much Hotter Than Left

[Looby]

Hello All,

Looking for some help on my 82 CB450sc thats been sitting for 3+ years.


STUFF IVE DONE:
* Cleaned carbs meticulously in ultrasonic cleaner, replaced all jets, floats, needle, and seals so they look and seem clean.

* Bench synced carbs before install and they looked to be REALLY close to one another.

* Replaced old coil/wires

* Did NOT replace spark plugs as they looked barely used. They are iridium but idk if they hold up better or worse to long term storage.


Install carbs and bike fires up with a lot of choke but its always taken a full pull on the choke knob to get up and going. Let it warm up and took for a 5 minute ride around neighborhood. Sounds great and rides just like it used to. Pulls my fat ass (240lbs conservatively) up hills in neighborhood with plenty of torque and feels great.



PROBLEM:
Noticed the right side cylinder (sitting on bike) is running 70-100 degrees F hotter than the left. (measured with ir gun) First thought was the right was way lean so tried adjusting pilot screw and ended up 5 turns out and still not getting cooler. I decided I needed to go up a jet size on the pilot (38 --> 40) and did the main while I was in there (115 --> 120). This doesn't seem to have helped the problem. I even tried 5 turns out on the right cylinder pilot on the bigger jet with no real change in temps.


I tried doing an on the bike sync and notice the gauges bouncing all over the place (bought cheap gauges) but did notice the right gauge was bouncing higher and drawing more vacuum. Couldn't get into the adjuster with everything together and tank on so I got frustrated and gave up for the day.



Bike used to run BEAUTIFULLY but sitting damaged carb floats so it hasnt run in years. I just want to be able to ride again... Any help? Sound like anything someone has experienced?



TEMPERATURES:
Left - 208 (measured at spark plug)
Right - 309 (measured at spark plug)

Left - 170ish (measured at top of exhaust)
Right - 250ish (measured at top of exhaust


CARB JETS:
Pilot - 40
Main1 - 72 (i think)
Main2 - 120
1 shim under needle


COMPRESSION:
Left - 148 psi
Right - 150 psi


MODS:
* K&N air filter in stock unmodified airbox
* Baffles knocked out of stock exhaust. Center section under engine still in place
* Bunch of random stuff that wouldn't impact this issue.

[Bodi]

Probably the sync is just off and one cylinder is working harder than the other? Restrict the hoses to your gauges, even cigarette filter rolled tight and jammed in the tube will help a lot... you want the restriction close to the carb ends of the tubes. Should smooth out the needle bouncing.
Assuming the carb jets and needles are identical and clean, the fuel level in the bowls can change the mixture quite a bit. Make sure both are at the same (correct) level.
Check the diaphragms and springs on the slide mechanism. Not a common problem but they sometimes cause trouble. I'm pretty sure you have CV carbs.

[CBJoe]

Make sure your jets are genuine and not some of the junk ones in the knock off kits.  I’ve seen where the cheap ones have a ton of variation


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