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Discussion Starter #1
I had just bought a 1974 cb450, and it ran great for about three days. I had took it to work one day it ran fine the whole way there, but when I went to leave after I got out of first it would not let me shift. Now the shifter clicks with much more ease but it will still not shift. Still being anxious to ride and spend time with my bike, but waiting for my manual in the mail and afraid to touch anything without it I have been going to the garage and shining everything. Yesterday I took my seat off to get the grime off of the hidden part of my rear fender and I found a floating tube not with a wet interior or anything and not connected on ether side. Not knowing where it came from or how it got there I put it in my tool kit and went to sleep. I woke up the whole house smelt like gas, I checked it out and found the hose it was dripping from I think it is from the carb overflow. So I set my petcock to off and it does not even slow it down. So I siphoned the gas out not knowing what else to do with my dad on my ass...... I want to fix it myself with my friend who also got his first bike a few days before me(he acts very confident on being able to do the job and wants to jump in now... because its not his bike ha). And what I concluded so far and I most likely am wrong about a few things is that my petcock is ether bad or needs maintenance and that should be the first job to ensure that when i fill my tank back up when it starts leaking i can stop it, second i need to fix the leak but i'm not sure how yet, and the shifting is supposedly a common problem with my model where it gets stuck in second and supposedly an easy fix. The last thing i want to do is take it to a shop, i want to know everything about my bike and this is the best way to go about learning I think.... any tips tricks and advice would be greatly appreciated once i get the hang of this site i will post pics and share my progress to whom ever wants to hear it
 

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Sensei
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27,160 Posts
First thing, get that fuel thinned oil out and install new..... I would flush with two clean quarts and drain that as well......

If the petcock will not shut off, fix or replace it....Fuel thinned oil causes catastrophic engine failures.....

Second, get a copy of the Honda factory service manual.......
 

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New petcocks ore rebuild kits can be had had for decent price on ebay or other online retailers. Make sure you set yours to OFF instead of RES, on mine OFF is with the lever towards the front of the bike or all the way counter-clockwise.

Shifting issue can just be the c-clip on the shift shaft under the sprocket cover on the left side of the bike has popped off. If it did source a new one and replace it.

Here's a PDF copy of the manual

http://198.57.59.10/manuals/450-500/CB450 Factory Service Manual (shrunk).pdf

Make sure to read every sticky topic in the DOHC 450 section. Lots of really good info.
 

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Discussion Starter #6
Thanks.. Last night we were able to get it shifting again it was the c clip and we also got all the bad oil out. Now what we need to do is stop the leak, fix the petcock, and I would like to find out why there is so much resistance going from first to second it was like that before the shifting stopped and is pretty aggravating any thoughts on what to do about the leak or the resistance?
 

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Take care with that C-clip. It's probably bent out of shape (the reason it come off to begin with) and will most likely come off again. Its best to buy a new one from a Honda dealer. Don't lose that washer under the c-clip. It may look like an ordinary washer but it is NOT and it's no longer available from Honda.

The resistance is probably due use and abuse before you got the bike. There are some parts inside the right side cover and the trans (star gear on the end of the shift drum, detent roller and shift forks respectively) which wear and make shifting more difficult. The shift prawl (which is also inside the right side cover and is on the other end of the shaft with the C-clip that came off) can become bent after shifting becomes difficult and more force is used to shift. It's a downward spiral...the more wear, the more force it takes to shift. The more force used to shift, the more parts get damaged.

Search the forum and do some reading on cb450 shift problems. Shift issues can all be fixed through repair/replacement but you'll need to read up, ask questions to make sure you understand the issues and to know what to look for. Then you can go into the motor and find out which parts need help. It may seem overwhelming now but you'll get lots of support from the forum members.
 
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