Honda Twins banner
1 - 9 of 9 Posts

·
Registered
Joined
·
5 Posts
Discussion Starter · #1 ·
Hi everyone! I snagged a ratty old 1973 CB450 done up cafe style a while back and have finally had the opportunity to work on it! It has rear sets, a fiberglass cafe seat, clubman bars, and a nasty 2-1 exhaust with no muffler. When I got it, it barely idled and popped and lurched at all speeds, but I rode it home anyway :rolleyes:

Land vehicle Vehicle Motor vehicle Motorcycle Car
Sorry for the crappy phone pic...

So far, I've changed the oil, boiled the carbs in lemon juice, adjusted the tappets, adjusted the points, adjusted the cam chain tensioner, installed new coils, condenser, spark plugs and fuel lines, sealed up the intake boot gaskets and butterfly valve shafts, removed the starter and starter clutch (previous owner installed a capacitor in lieu of a battery and I went with it), and cut the exhaust into two tiny headers in an attempt to tune the carbs (the sound now rivals a B-52 flying fortress).

Yesterday I finally got it to idle well at 1200 rpm, so I took it for a spin. Everything was going pretty good, until I decided to gun it a little. I hit 8k in 2nd and with a pop and a puff of black smoke I lost some power. I got back to the driveway and noticed the right side was popping through the exhaust, and I could tell it was running rich my casing was covered in black soot (pipes are THAT tiny). I shut her down quick, and thankfully the compression is unchanged from before (~150psi in both cyls according to my harbor freight tool, a rebuild is probably needed sooner than later), meaning I probably didn't destroy anything too bad...right? I'm going to check the valve clearances and timing later today, and I have a real exhaust coming in the mail. Other than that, any suggestions are more than welcome! You all don't know it, but I couldn't have gotten this far without you! :cool:
 

·
Registered
Joined
·
725 Posts
You would probably be further ahead if you were to re-install the original air box with a proper exhaust. Pod filters, depending on design, can cause problems with airflow into the carbs. This post, from another site, gives a good overview of the problems pods can cause. A Pod Filter Thread for Geeto.....
 

·
Premium Member
Joined
·
3,007 Posts
These motors were designed as high performance engines to start with.

Short of working them into full race motors where they run at 6000 - 9000 RPM consistently there isn't a whole lot you can do to improve their performance.
Anything you do may increase Low End at the expense of Top End or Vice Versa.

Reliability is a different story - YES - You can improve on that with an Electronic Ignition, and the Charging Systems can be improved greatly by swapping out the OEM Regulator/Rectifier for an Solid State integrated unit.
The Solid State units are about 85-90% efficient VS 60-75% for the Old OEM ones.

The previous post on returning it to OEM Intake (Airboxes & Filters) and OEM Exhaust/Mufflers (or close replicas of similar length) is about the best idea we can give you.

These motors like the balanced Airflow the OEM Airboxes provide and the Motors were tuned to perform with the full length OEM exhaust and back pressure they created.

Also get yourself a Front Fender - even if you don't mount the full fender salvage the Mounting Bracket it was the OEM BRACE for the front forks to prevent them from twisting.
You WILL notice a difference cornering with them braced properly.

Last and probably the best thing you can do is read the Post linked below.
http://www.hondatwins.net/forums/53...n/18505-basic-checklist-new-you-old-bike.html
 

·
Registered
Joined
·
9,797 Posts
Welcome to the forum. +1 on all the great advice given in the above posts.
 

·
Registered
Joined
·
5 Posts
Discussion Starter · #5 ·
Dang Brent and Yendor, great info/advice! That pic is from when I first got it, I've since added the UNI 4001 because I figured they were as close to stock as I could get without sourcing a box. Think it's worth it to find one? I've already got a factory exhaust coming in on Saturday, so that should help, too. Front fender is on the list, I think I have a CL style one hidden away in a box somewhere...
 

·
Registered
Joined
·
5 Posts
Discussion Starter · #6 ·
Got the exhaust put on, and decided on some new paint. Pretty good from far, far from pretty good. Still running rough though...I readjusted my tappets, but no dice. Exhaust ports had a lot of carbon, might try cleaning them out.
 

Attachments

·
Registered
Joined
·
5 Posts
Discussion Starter · #7 ·
Update: looks like it's my points...checked them more closely and they were actually pretty dirty, the right one was even pitted. Sanded them down, reset gap and timing and she fired right up. Ran good for 10 minutes then started misfiring again...opened up the points cover and the points were already toasted! I've got a brand new condenser, so hopefully that's ruled out. Who knows how old these points are, it's definitely time for a replacement anyway.
 

·
Registered
Joined
·
13,085 Posts
Update: looks like it's my points...checked them more closely and they were actually pretty dirty, the right one was even pitted. Sanded them down, reset gap and timing and she fired right up. Ran good for 10 minutes then started misfiring again...opened up the points cover and the points were already toasted! I've got a brand new condenser, so hopefully that's ruled out. Who knows how old these points are, it's definitely time for a replacement anyway.
Just avoid the Daiichi brand, they suck
 
1 - 9 of 9 Posts
Top