CB450 Carb Jetting/Tuning

C

COFFINRACER

New Member
Okay so I am sure there is plenty of threads on this topic but I'm new to the forum and I'd rather be as specific and I can. I have a 1973 Honda CB450 that I turned into Cafe Racer (I'm sure some have you have seen it), I love the goddamn bike but I know that it can be running better than it is. I am currently running velocity stacks on the original Keihin carbs and a straight 2 into 1 exhaust. Now I know with a 2 into 1 on these motors you can't really sync the carbs the way it says in the book but I'm pretty sure I have them close. The problem I am having is the motor is running rich and there is no possible way I can give this son of a bitch more air unless I slap a little turbocharger on this thing, I was originally running some coarse UNI filter foam behind the stacks until all of a sudden it decided it didn't wanna fire on one cylinder anymore unless I took the filters out all together. It runs fine and idles fine now but the plugs are still black and riding on New England streets without any filters is probably not the best idea. The Keihin carbs currently have the original jets in them and I bought a jet kit (not thinking) which came with larger jets than the originals and I know that definitely wont solve the problem. Other than it running rich the bike boogies and sounds strong, it's hard to ride above 60 because the exhaust makes my arms feel like jello, but I don't want to be going faster than that anyways. I am dying to ride this thing after that shitty winter but I also don't want to kill it. Any info?

Thanks!
 
interceptor said:
You verified the numbers on the jets in the carbs to make sure they are the stock ones?
Click to expand...

Yes, the are 145's in the main and i forgot what the others were. But i'm pretty sure no one ever had these things apart before I did so I don't see any reason they were changed
 
I just watched a video on youtube with a cb450 - pods and straight pipe, and he's running size 140 main jet?? According to what I found, your bike should take #145 and #38, like you have. Hmmm?
 
interceptor said:
I just watched a video on youtube with a cb450 - pods and straight pipe, and he's running size 140 main jet?? According to what I found, your bike should take #145 and #38, like you have. Hmmm?
Click to expand...

Yeah main jet is a 145. I forgot what the pilot was. I'm just so confused because you think I would need larger jets because there is no air restriction. Unless the lack of back pressure is somehow effecting it that much.
 
If you have access to an exhaust system, or a muffler, put it on and see what happens. At least it's not running lean :)
 
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