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Discussion Starter #1 (Edited)
Hey All,

I’m brand new to the forum and fairly new to the motorcycle world. I have a good bit of experience with cars so a while back I picked up a 1970 CB450 To do a full restoration. It didn’t run and was in pretty rough shape. I’ve got it back together for the most part besides some lighting and controls but after I got it running, it seems to be making an awful knocking noise. I have wrapped exhaust and it looks like it’s getting super hot and burning them. Any input on what this might be or how to fix it would be greatly appreciated.

In addition to this issue, once it idles for a while it starts to rev higher and higher without touching the throttle.

Thank you all.

 

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You are likely running lean and overheating. What did you do to the carbs when you ditched the proper breather and exhaust?
 

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You are likely running lean and overheating. What did you do to the carbs when you ditched the proper breather and exhaust?
Carbs and exhaust are how I got the bike. So I’m not sure what was done. If I put real filters on, should that help? Or could I just have the carbs tuned by someone?
 

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You need to figure out what you have and then decide what needs to be done. Frankely it sounds so shitty it's hard to tell what is roar or rattle. Honda built the bike with much more controlled air intake and exhaust flow. It is why they worked properly for the previous 50 years. When the po stripped all that away the fuel flow would need to be adjusted through carb jetting. Getting the bike to run properly for road use is going to be a challenge.

Do you have a service manual? What carb model is on it? What jets are in them? What does the exhaust look like, a loop with an exit on one side?

When you do get it running right the bike has other issues that need addressing before you hit the road, tire clearance and fork bracing for example.
 

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Knock knock, Torsion valve springs, but that is just a guess because of the model,
by the video the whole thing sounds like a bag of hammers! You got bad clearances, or bad parts somewhere.
I'd be starting with a compression test, those numbers now that it runs might save you a lot of searching.
 

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Carbs and exhaust are how I got the bike. So I’m not sure what was done. If I put real filters on, should that help? Or could I just have the carbs tuned by someone?
Screens on velocity stacks and no fenders, how frequently do you want to be rebuilding your motor?
... about every second race should do it.
 
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