Honda CB450 K3 Refurb!

Sonreir

Oregon
DTT SUPPORTER
I pulled the carbs off and found a few interesting tidbits.

1.) The petcock was only flowing fuel through one of the spigots and so the left side was definitely underfed.
2.) There was a slight gap between the manifold and the head on the left side as well (a bit of Threebond cleared that up).
3.) Carbs appears to be in mostly good condition, but I cleaned them up and replaced most of the brass (the rebuild kit had the wrong style mixture screws, so those old ones were reused).
4.) Float heights are set at 20mm and the carbs are ready to go back on.
 

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Sonreir

Oregon
DTT SUPPORTER
Everything is assembled and back on the bike. Fresh gas in the tank and she fires on the third or fourth kick.

Still have a few bugs to work out. Can't seem to get over 60mph or so. Exhaust note sounds really flat, so I'm assuming the jump from 130 main to 145 main wasn't a good idea. I'm also idling at 3000 RPM once things are warmed up, so I gotta figure that out, too. Other minor things on the to do list include adjustment of the shifter angle and a clutch adjustment.
 

teazer

Over 10,000 Posts
DTT BOTM WINNER
Are the slides fully closed and butterflies also closed? If that's all OK, I'd check the inlet manifolds to see if they are bowed. People overtighten them and they bow and air leaks in so they tighten them some more and it gets even worse.
 

Sonreir

Oregon
DTT SUPPORTER
teazer said:
Are the slides fully closed and butterflies also closed? If that's all OK, I'd check the inlet manifolds to see if they are bowed. People overtighten them and they bow and air leaks in so they tighten them some more and it gets even worse.

The butterflies still a bit open, but I can't get them to close. The stop on the throttle lever is contacting the spring retaining tab (pic of someone else's carbs, attached).
 

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teazer

Over 10,000 Posts
DTT BOTM WINNER
You could remove the quadrant and see if it closes. If it does, just dremmel/grind a little metal off to get it to close. They should not be totally closed though. Just cracked open a poofteenth.
 

Sonreir

Oregon
DTT SUPPORTER
I swapped the 145 jets back to 130s and removed the electronic ignition and put the points back in. Now the damn thing won't start. I get a couple of sputters when the choke is on, but nothing if I open it up. If I try to give it any throttle at all, the bike immediately dies.

Time to take my own advice and actually approach things methodically.

Later today or tomorrow I'll put the 145 jets back in place and see how we go from there.
 

Sonreir

Oregon
DTT SUPPORTER
canyoncarver said:
Why'd you pull the electronic ignition out?

Just trying to rule things out and because I can't get the bike to idle, I can't verify the timing on the electronic ignition.

Anyway... I spent a few more hours at it this weekend and I'm stumped. I'm showing signs of being both rich and lean at the same time and my skills (or lack thereof) in this arena are starting to show.

Here are the symptoms I'm seeing:
1.) Bike will start from cold with the choke, but only run for a couple of seconds before needing the choke to come off.
2.) After that, the bike will not start with the choke and actually needs a bit of throttle to get going. The bike will not start unless I give it about 1/4 turn of the throttle.
3.) Bike immediately dies if I let off the throttle.
4.) If I give the bike more throttle, it will not rev. The exhaust note changes and become very "tinny", but it won't go over 2000 RPM, even at WOT in neutral.

Some other information:
1.) I replaced almost all of the brass and seals using the 4 into 1 carb kit. The mixture screws were different and so I could not replace them. The main jets that came out of the cabrs were 125 and 130 (mismatched sides) and the new main jets that went back in were 140s. Other brass may have been different as well, but not all of the parts were stamped.
2.) The butterfly valves will not seem to close fully. They're not beveled like on my 360 and I've messed with them several times to no avail.
3.) I have not checked compression, but seeing as how I had the bike running and riding just two weeks ago, I think all is good? I will eventually check this, though.
4.) Static ignition timing has been set and points are back on the bike. I've verified that I have spark using a strobe light, but dynamic timing has not been verified because the bike won't idle.

Any ideas?
 

Sonreir

Oregon
DTT SUPPORTER
Well that's better. It's amazing how much better a bike runs when you have the correct brass in it.

https://youtu.be/a4s-SFb2KZc
 

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