CB450 Jetting

[whataulooknat]

I have a 1974 Honda CB450 that has been bored out by 3mm. from a 70 to a 73mm piston. That ups the displacement from 444cc to roughly 484 if my math is correct. My question is What should I do about Carburetors. Do I need to put a bigger Carburetor on it or can i get by with Jetting. Also I've heard just changing Jets does not Address the mid range fuel mixture. I'm afraid to start the bike on the stock setup as I have heard horror stories of hot seizing freshly bored engines. Any Ideas?

1974 CB450
73mm pistons 484cc
Velocity Stacks With Screens No Air Filters
Stock Mufflers Have been Completely Gutted

 

[whataulooknat]

Well to let anyone know who decides to go with a 3mm overbore. I have the bike up and running. I do not suggest whatsoever running without airfilters. I decided to put on a set of pods. The open air intake leaned out the engine way too much. but anyways It seems to run perfectly with a 150 main jet and a 38 Idle jet. Plugs are a nice light brown. No fouling no white blistering. just the right amount of color. ps sorry for posting this in cafe racer i didn't notice the chopper bobber section.

For anyone who decides to go with a 3mm overbore this should give you an idea of where to start.

1974 CB450
3mm overbore (73mm piston)
Pod air filters
Punched out mufflers.
150 main jet. 38 idle jet. Idle screw set 1 3/4 turns out from full close

 

[Garage_guy_chris]

what were your stock mainjets? I found on mine its likeing the stock 130's and or the 135's when i put 145's in mine it would breakup and hesitate up around 6500 rpm and acted like a slug. I also have pod filters and a fairly open 2 into 2 exhaust. Im also looking to richen the midrange slightly, im going to look at a few things to acomplish this.

 

[whataulooknat]

My stock Jets were a 145 Main and a 35 Idle. What year is your bike? I can't remember what year it was but they started putting bigger jets in them stock. The older models used 130's i believe. I'm still fine tuning my carbs at the moment as my engine is breaking in.

*edit* I believe it was 72 they switched to the 145 jet but don't quote me on it