'70 CL450 Rejuvination Project

[TornadoAftermath]

I picked up this 450 from a local kid who was moving out of town for a little over $1k (I know, ouch). Up until recently it was a great around-town bike and did everything it needed to.

I discovered after I got it that it had some quirks and questionable work done to it by previous owners; things like the front brake lever being broken, the clutch requiring the strength of Hercules to pull in, rough shifting, a broken tach cable, the air filters having their filter elements removed, and the engine only running on 1 cylinder were all things that I had to address before I could ride it regularly. After getting those issues sorted, it was a fun little bike.

Right now the bike is in the middle of what I'm calling it's AliExpress makeover, since much of what I've needed I've been able to find there at bargain prices. I've installed new brake and clutch levers, mirrors, balance beads in the inner tubes, a Shockwave electronic ignition, new controls, and replaced the old cracked plastic headlight bucket with a new metal one large enough to fit a 7" LED lamp, and installed a set of pod air filters to keep the dust out.

Currently I'm fighting some issues with an inconsistent idle that manifested when I adjusted the valves during my most recent oil change and preventative maintenance session. While adjusting the valves I discovered that the cam chain adjustment screw had been broken off inside of the housing, so that will need addressed, and after doing the valves I can't get the bike to idle to save my life. I'll be attempting some troubleshooting steps that were suggested by the Honda 450 Builders Guild Facebook group (one of the members of which suggested that I create an account here), and if I can't figure out my issue I'll be coming back for more help.

I've got more planned for this bike, and the modification I'm most excited for is the exhaust replacement, as I'm tired of the CL-style ankle-toaster exhaust pipes. If anyone has any leads on a CB style 2:1 exhaust for a 450, please send me a link. Bonus points if it doesn't require the removal of the center stand or replacing the footpegs and rear brake pedal to fit. Otherwise I'll be going with a dual exhaust setup which I already have the pipes and mufflers for.

Thanks for stopping by, I'll be sure to post updates!


The day We're first met


The current state of affairs

 

[EzPete]

Before you solve anything else, you need to solve the cam chain adjustment.

The good news is that the cam chain adjuster can be easily removed, much easier to remove that broken bolt on a bench.

Once that is done:

Verify static timing. You may have jumped a tooth on the cam chain - make sure all three timing marks hit exactly.

Verify spark/timing.

Set your valves using the proper method in the FSM. Not that video online. Use the go/no-go method with a .0015” and .002” feeler.

Ditch the AliExpress pods. Get those old filters back out and just reskin the frames with Uni filter foam or buy replacements. If you’re dead set on pods - at least get the Uni long-pods specifically designed for the 450, you need a longer intake plenum with the CV carbs.

Bench sync the carbs. They need to open at the exact same time.

Test your ignition coils. Primary and secondary circuits.

For the exhaust:

Delkevic Full Exhaust for Honda CB450 - Reverse Cone Muffler

Delkevic Full Exhaust for Honda CB450K2-K7 – REVERSE-CONE SILENCER 304 STAINLESS STEEL. Engineered for accurate fitment and a refined finish, this exhaust system offers a straightforward upgrade that…

delkevic.com

 

[ancientdad]

Currently I'm fighting some issues with an inconsistent idle that manifested when I adjusted the valves during my most recent oil change and preventative maintenance session.

Since this DOHC 450 is new to you, there are a few things about it you should know right away if you're not overly familiar. One is directly related to the cam chain tensioner lock bolt that is broken off in the adjuster housing. The videos from those guys in Houston can be very misleading and can actually cause you to create huge problems and damage because they approach one of the most important adjustments on the engine too casually.

Cam chain tension adjustment procedure, clarified [CB/CL/SL350, DOHC CB/CL450, DOHC CB500T]

A few instances of VHT members' accidental misinterpretation of the proper cam chain adjustment procedure for the DOHC 450 have come up recently, and it seems they have been caused by the visual of a moment from a video by those guys in Houston showing the adjustment. It's interesting that no...

www.vintagehondatwins.com

Also, with respect to valve adjustments, please post a picture of both sides (all 4) of your eccentric valve adjustment shaft ends and lock nuts so we can see if your index marks are correctly oriented, it's an easy mistake to make if you're not familiar. This is what I'd like to see on both sides, one obviously requires the points cover to be removed to see it. The tail of the "T" formed by the index mark combined with the screwdriver slot should point away from the spark plugs on both sides when in the correct position for both proper valve adjustment and follower position above the valve stem to avoid damage.



For this reason

While adjusting the valves I discovered that the cam chain adjustment screw had been broken off inside of the housing

EzPete's statement that the broken-off cam chain adjuster lock bolt can more easily be extracted from the housing is obviously correct, but when you remove it from the back of the cylinders be absolutely sure you do NOT attempt to rotate the engine at all or you could easily jump a tooth in cam timing. Prior to removal of the tensioner assembly, position the crankshaft at 90° past LT on compression stroke so all valves will be almost, or completely, closed so there is no tension on the cam chain.

Also, while we're on the subject of camshafts, this engine does not puddle any residual oil under the cams and followers and as such, on a cold start it needs at least 1 to 2 full minutes of low rpm (idle speed if possible) running until oil flow arrives at the top end, fills the hollow camshafts with oil and starts lubricating the followers - OR you'll eventually suffer a less exaggerated version of this:



Honda actually warned of this in the owner's manual back in the day, though they did not do it strongly enough IMO

Important DOHC 450 and 500T warmup information

I have often mentioned the safe approach to warm-up on a 450 or 500T with respect to oil pressure to the top end of the engine when cold. The design of the cylinder head does not allow for any puddled oil to remain under the cams and followers to help keep them lubricated until the oil pressure...

www.vintagehondatwins.com

I'll be attempting some troubleshooting steps that were suggested by the Honda 450 Builders Guild Facebook group (one of the members of which suggested that I create an account here)

Please stop listening to anyone in that FB group (except Dan who encouraged you to join VHT). I was banned from that group for telling the truth about these engines. There are many in the group who subscribe to the voices coming from those guys in Houston who take far too many liberties with the FSM, and those voices claim Honda's engineers didn't know what they were doing when they set the valve clearance spec at .0012" despite Honda designing the engine over 60 years ago during the heyday of their GP road racing domination with 20,000 rpm 5 and 6 cylinder engines built before most of those in that group were born.

For the DOHC 450, you're in the right place now.

 

[TornadoAftermath]

Before you solve anything else, you need to solve the cam chain adjustment.

The good news is that the cam chain adjuster can be easily removed, much easier to remove that broken bolt on a bench.

Once that is done:

Verify static timing. You may have jumped a tooth on the cam chain - make sure all three timing marks hit exactly.

Verify spark/timing.

Set your valves using the proper method in the FSM. Not that video online. Use the go/no-go method with a .0015” and .002” feeler.

Thank you for the advice!
I'll give that a try.

Ditch the AliExpress pods. Get those old filters back out and just reskin the frames with Uni filter foam or buy replacements. If you’re dead set on pods - at least get the Uni long-pods specifically designed for the 450, you need a longer intake plenum with the CV carbs.

Sadly, the OEM filter components are long gone. I would like to make the pods work if possible since I have them, though I've heard that the stock filters and the way that they're connected through the frame create a vacuum which affects performance, so I realize that ideal performance at high RPMs might never be reached with the pods.

Bench sync the carbs. They need to open at the exact same time.

Both carbs have been synced, though for good measure I did it again today to make triple-ly sure.

Test your ignition coils. Primary and secondary circuits.

The coils are good, they're actually both new and came with the Shockwave electronic ignition that I installed.

For the exhaust:

Delkevic Full Exhaust for Honda CB450 - Reverse Cone Muffler

Delkevic Full Exhaust for Honda CB450K2-K7 – REVERSE-CONE SILENCER 304 STAINLESS STEEL. Engineered for accurate fitment and a refined finish, this exhaust system offers a straightforward upgrade that…

delkevic.com

Thank you for the link! I'll be sure to save that for later.

 

[TornadoAftermath]

Since this DOHC 450 is new to you, there are a few things about it you should know right away if you're not overly familiar. One is directly related to the cam chain tensioner lock bolt that is broken off in the adjuster housing. The videos from those guys in Houston can be very misleading and can actually cause you to create huge problems and damage because they approach one of the most important adjustments on the engine too casually.

Cam chain tension adjustment procedure, clarified [CB/CL/SL350, DOHC CB/CL450, DOHC CB500T]

A few instances of VHT members' accidental misinterpretation of the proper cam chain adjustment procedure for the DOHC 450 have come up recently, and it seems they have been caused by the visual of a moment from a video by those guys in Houston showing the adjustment. It's interesting that no...

www.vintagehondatwins.com

Thank you, I admit I did use the video from "them who shall not be named" as well as a Clymer manual to help with the valve adjustment.

Also, with respect to valve adjustments, please post a picture of both sides (all 4) of your eccentric valve adjustment shaft ends and lock nuts so we can see if your index marks are correctly oriented, it's an easy mistake to make if you're not familiar. This is what I'd like to see on both sides, one obviously requires the points cover to be removed to see it. The tail of the "T" formed by the index mark combined with the screwdriver slot should point away from the spark plugs on both sides when in the correct position for both proper valve adjustment and follower position above the valve stem to avoid damage.

View attachment 57961

For this reason

View attachment 57962

EzPete's statement that the broken-off cam chain adjuster lock bolt can more easily be extracted from the housing is obviously correct, but when you remove it from the back of the cylinders be absolutely sure you do NOT attempt to rotate the engine at all or you could easily jump a tooth in cam timing. Prior to removal of the tensioner assembly, position the crankshaft at 90° past LT on compression stroke so all valves will be almost, or completely, closed so there is no tension on the cam chain.

Also, while we're on the subject of camshafts, this engine does not puddle any residual oil under the cams and followers and as such, on a cold start it needs at least 1 to 2 full minutes of low rpm (idle speed if possible) running until oil flow arrives at the top end, fills the hollow camshafts with oil and starts lubricating the followers - OR you'll eventually suffer a less exaggerated version of this:

View attachment 57963

Honda actually warned of this in the owner's manual back in the day, though they did not do it strongly enough IMO

Important DOHC 450 and 500T warmup information

I have often mentioned the safe approach to warm-up on a 450 or 500T with respect to oil pressure to the top end of the engine when cold. The design of the cylinder head does not allow for any puddled oil to remain under the cams and followers to help keep them lubricated until the oil pressure...

www.vintagehondatwins.com

Noted. I also did notice that one of the rocker arms is already getting that type of wear and will either need to be resurfaced or replaced (top-end rebuild, here I come), and I was shopping around but it seems that those are rather difficult to find. I saw that they who shall not be named used to offer resurfacing services, but that has been discontinued on their website. Where is the best place to go for a resurface job or new-old stock rocker arms?

Please stop listening to anyone in that FB group (except Dan who encouraged you to join VHT). I was banned from that group for telling the truth about these engines. There are many in the group who subscribe to the voices coming from those guys in Houston who take far too many liberties with the FSM, and those voices claim Honda's engineers didn't know what they were doing when they set the valve clearance spec at .0012" despite Honda designing the engine over 60 years ago during the heyday of their GP road racing domination with 20,000 rpm 5 and 6 cylinder engines built before most of those in that group were born.

For the DOHC 450, you're in the right place now.

Noted. I really only sought the help of the Facebook group as a last resort, because I knew I'd just be getting a shotgun-blast of mostly useless info and suggestions from amateurs who didn't know what they were talking about. I'm happy I've finally found the place where all the pros hide.

 

[ancientdad]

You posted two pics of the left valve adjusters but those look to be correct. Even though the PO or someone previously used JIS screws, the top end has been apart as you can see aftermarket gaskets on both left side cam bearing covers.

You CAN replace followers (not really rocker arms due to the way they work) with the engine in the frame, but you have to follow strict procedure to do it without causing yourself problems. Dan essentially did it during changing all 4 cam bearing cover gaskets on his, and he'd never done it before. It starts here:

https://www.vintagehondatwins.com/forums/threads/1971-cl450-that-sat-for-40-years.9217/page-3#post-109814

As for refurb of followers, the gold standard is $100 each at last count (8 years ago) from Megacycle Cams, but hopefully we still have things set up with Rocker Arms Unlimited to do the 450 followers though I do not know a price.

 

[ancientdad]

Thank you, I admit I did use the video from "them who shall not be named" as well as a Clymer manual to help with the valve adjustment.

They can be named, but they already get more than enough publicity and internet searches without VHT giving them further undeserved exposure. And while a Clymer manual isn't bad as a second opinion and for maybe a few better pictures, the proper procedures are covered (and between the lines occasionally interpreted by those here who worked at Honda dealerships like myself and more than a few others) in the FSM and you can get it free.

Honda CB450 Factory Service Manual Searchable.pdf

drive.google.com

Here's a member who adjusted his cam chain according to one of their not-properly-proofed videos and the result was bent valves and literally, broken followers, which is why I created that post about correct cam chain adjustment procedure.

Cam Chain Jumped a tooth, SNAPPED ROCKER ARMS! Where do I get new engine parts for my 74 CB450K7? I need valves too most likely.

Just like the title says, my 1974 Honda CB450 K7 was running great until I did a valve adjustment and cam chain adjustment on it. I'm quite confident of the valve job I did being correct, I followed the those guys in Houston collective videos and advice to the letter, and the bike ran well. When...

www.vintagehondatwins.com

 

[TornadoAftermath]

You posted two pics of the left valve adjusters but those look to be correct. Even though the PO or someone previously used JIS screws, the top end has been apart as you can see aftermarket gaskets on both left side cam bearing covers.

Ahh, oops, here's the other side. Responding here on mobile takes some getting used to

You CAN replace followers (not really rocker arms due to the way they work) with the engine in the frame, but you have to follow strict procedure to do it without causing yourself problems. Dan essentially did it during changing all 4 cam bearing cover gaskets on his, and he'd never done it before. It starts here:

https://www.vintagehondatwins.com/forums/threads/1971-cl450-that-sat-for-40-years.9217/page-3#post-109814

As for refurb of followers, the gold standard is $100 each at last count (8 years ago) from Megacycle Cams, but hopefully we still have things set up with Rocker Arms Unlimited to do the 450 followers though I do not know a price.

Thank you, I'll look into those for the wintertime rebuild I'm planning on doing!

 

[EzPete]

It’s actually idle and off-throttle performance that suffers - particularly with those cheap pods. WOT you can have no filters for all the engine cares. The key is a long intake plenum to stabilize the filtered air mass prior to intake. Unstable air creates uneven pressure and limits a clean Venturi effect.

My basketcase is on pods. The long-sock uni ones work solid.

I’d still test the coils. Takes 2 minutes to save countless headaches - never assume the parts cannon hits the intended target.

 

[ancientdad]

Thank you, I'll look into those for the wintertime rebuild I'm planning on doing!

Sorry to hear that you decided to sell the bike. Hopefully you'll remember to come back when you pick up another vintage Honda twin project.