Honda CB450 Valve Adjustment & Cam Chain

www.common-motor.com/honda-450
The valve adjustment as well as cam chain adjustment for the Honda CB450, CL450 Scrambler and CB500T is part of the regular tune up procedure. Cam Chain and valve clearance should be set every 1500 miles (2500KM).
Parts and Tools Used:
Feeler gauge set: www.common-motor.com/feeler-ga...
Honda CB450 Service Gasket Set: www.common-motor.com/honda-450...
Cam Chain adjustment is easy and straight forward. While the valve adjustment is a bit more elaborate.
From the factory Honda values for the valve clearance at 0.0012" (0.03 mm), which is too tight in our opinion, leading to worn cams and cam follower. We do and inspection the camshaft lobes prior to adjusting the valves.
We set the valves at a looser 0.003" (0.08 mm) and get there with our overshoot method of using one size larger feeler gauge at 0.004" (0.10 mm). A tight 0.004" is close enough to a loose 0.003".
Finally we give the cam lobes a coat of assembly lube and pre-lubricate the cam chain and the rest of the valve train components. We want to make sure there is ample lubrication upon restart.

[@martinhauk1852]

I agree with your procedure with one big exception. You are setting the clearance WAY too loose. Unlike most over head cam engines where the rocker arms are a class 1 lever, with the pivot point between the force applied (cam lobe) and the load (valve end). Much like a child's sea saw. This engine uses a cam follower that is a class 3 lever. The pivot point is on one end and the load is on the other end with the force applied in the middle. In this case exactly in the middle. Measuring the clearance between the cam and follower will result in the clearance at the valve end being twice that of the clearance at the cam lobe. In the case of the factory clearance spec of .0015" clearance will result in a clearance at the valve end of .003". This is very much in line with all the other Honda models. Setting the clearance at .004" will give you a clearance of .008" at the valve end, which is more than twice the twice the recommended clearance. Honda designs their engines to run with a .002" - .004" clearance at the valve end, with the wider gap on the exhaust valve. The reason that the clearance on this engine is so tight is to get .003" at the valve end. It is measured at the cam lobe simply because it's impossible to get a feeler gauge in at the valve end on this engine.

[@aaroncutting]

Thanks to your comment I ended up setting my clearance at somewhere between 0.0015 and 0.002 - here's hoping that works

[@kemitchell]

I've made a habit of tapping the rear end of chain tensioner housings like these with a rubber mallet or the soft handle of a screwdriver after loosening the set screw. Every once in a while I'll hear movement only after a tap. On a new-to-me bike, I think I'd just go ahead and pull the assembly off the first time I do the service. I don't know CB450 well, but on 350, it's fairly easy to pull with the carbs still on, and to save (or replace) the gasket. That way you can clean out the assembly, force the plunger all the way back and lock it down before reassembly, and feel it pop forward when you loosen up again.

[@Common-motor]

Kyle, not a bad idea as that plunger can get stuck.

[@8788luigi]

All common motor video has been helpful for my CB500T. Thanks a lolt. Even ordered parts hereat.

[@Ian_in_an_ocean]

Wow! One of the best instructional videos yet! I especially liked the bench view. I could really get a sense of what was really going on in there. Thank you.

[@poetapex]

You guys rock. Every piece of advice you've given and parts I've ordered have always been a great customer experience. Keep it up.

[@UncleRobsGarage]

This has refreshed my memory,and they were a pain.

[@TN_HondaDad]

Wow, can't believe with all the great engineering Honda had, that they wouldn't have a 90 degree mark stamped on there from the factory to go with the tdc and firing marks. Great video btw, CMC has some of the best videos out there which has given me confidence to to a lot of maintenance and troubleshooting on my 69 CL450.

[@michael184272]

Wished all your videos were around back in the 70's... Excellent quality and extremely helpful.. Thanks for sharing 😊

[@Common-motor]

Glad you like them!

[@justinharder3875]

I just bout a 73 and followed the three videos of yours to a tee and now the bike is running so smooth and kicks over immediately every time. The manual is confusing and hard to follow. Thanks guys. Also just ordered a bunch of parts off the website as I found they’re almost impossible to track down and some are discontinued.

[@vincehebert3652]

I actually have a 1974 Honda CB450 and it is licensed and insured and is a daily rider. Thanks for taking the time to make this video. And I do totally agree with a slight extra valve clearance on these engines.

[@Common-motor]

Thanks! Yes the few extra thou on the valve clearance makes all the difference!

[@Quatra05]

Seriously helpful, 🙏 thank you!

[@djantix1200]

Great info. Thanks!

[@nils_on_wheels]

Super cool video guys! Love it.

[@Common-motor]

Thank you!

[@ClumsyToast]

Awesome vids guys! Subscribing for sure

[@Common-motor]

Yes please!

[@stevearcher4365]

excellent job!

[@Common-motor]

Thank you!

[@Paul-kp1tu]

This seems like a clever system to adjust the values, different to other engines, perhaps there are finite adjustment limits based on the amount of concentric movement if that shaft but what are the other issues given that this method seems unique i

[@nigelmitchell351]

So the adjust system can and will alter the max lift of the valve. I like it, looks expensive though.

[@chrish236]

Any suggestions for when the lock bolt on the rocker arm adjuster is seized? Turning the bolt just turns the screw as well, no matter how much force I keep on the screw.

[@piersimonestamati738]

Hi mate, it is not clear for me the adjustment of tensioning chain cam. As per your video you are positioning the rotor in the middle of LT and T, but as per service manual it is mentioned las follow. Why? What is correct? Cam chain adjustment: a. Remove the dynamo cover, turn the dynamo rotor counter-clockwise and align the “LT” mark with index mark on the stator

[@noodlebrain3665]

Is it the same for a 1984 cb450? Also is the oil gasket kit the same?

[@jonathanlloyd2306]

Are you going to show setting the valve timing?

[@noname-gw7jj]

So i'm having an issue, i have the mark at LT, i did the intake valve perfectly but when i try to adjust the exhaust valve the rocker is way way too far off and actually can wiggle quite a bit. I cant figure out what im doing wrong.

[@Common-motor]

Hey Aaron, you're probably going to need to do a bit more investigation. If your valve isn't adjusting as it should quite a few things could be happening. I'd recommend scheduling a tech support call with us and we can find out what you've checked and give you some insight on where to look next.

[@kylecomeau3684]

The Honda factory service manual for a CB500T doesn’t mention anything about rotating the engine to 90 degrees past TDC on the compression stroke for LH cylinder prior to cam chain adjustment, could you clarify why it doesn’t? What is to be gained by having the engine rotated to the position you state?

[@swedishsam12]

I noticed this as well, but the explanation makes sense..

[@Common-motor]

Hey Kyle, reach out to our technical support on our website for a more in depth explanation. We can definitely help you over there.

[@thomaslockley945]

so the exhaust valve clearance is same as intake

[@CbrMikey]

What kind of oil is in that oil can? is it a mixture?

[@mikeindel]

Will this procedure work on an 85 nighthawk cb450

[@Common-motor]

No

[@tankacebo9128]

oh boy.... my valve adjusters go ALL the way around... I'm actually afraid to open this thing up and see how bad the metal shavings are....

[@ebbsspeed]

Why did you just finger tighten the cam chain adjuster lock bolt? Seems quite risky to me.

[@talldrummer1]

You didn't tighten the cam chain adjuster bolt before locking it down.

[@rwhite36]

I take it you guys skipped doing the CB450 engine assembly part 2 then.

[@Common-motor]

Nope, we still have not released all the videos in that series, there are another 3 videos in that series to go live. This is simply some basic tune-up information that we have been asked for consistently for quite some time. We'll finish up the 450 engine assembly soon.

[@rwhite36]

"soon"

[@dylanclauss9316]

I was getting right into that last video on the 450 build, went to click on the part 2.... couldn't find it!! hopefully its up soon lol. keen to see the whole process and when shes up and running!

[@rwhite36]

Don't hold your breath. It's been almost a year.

[@beaucottington]

exhaust and intake spec both .004 on this? thanks I am working on a 72

[@Common-motor]

support.common-motor.com/hc/en-us/articles/360021017191-What-is-the-valve-adjustment-tappet-clearance-specs-for-the-Honda-CB450-CL450-CB500T-