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Discussion Starter · #1 ·
I have a 1972 CB450K5 and I'm in the process of rebuilding the engine. I've never done this before on any engine, and please understand the only knowledge I have is from reading forums here and watching videos I find on YouTube.

A machine shop bored the cylinders to 0.25 over, replaced the intake valves and did a valve job. The machinist installed the valve assemblies into the head (valves, new seals, torsion bars, etc.)

I gathered up all of the information I could find in these forums regarding how to install the cam followers, cam shafts, timing chain, etc. and believe I've done an excellent job getting things in there (famous last words haha). I used a brand new DID 219T chain with an OEM Honda master link, and the marks on the cams line up PERFECTLY.

As per all of the instructions I could find, the valves are opening at the correct time as I turn the crank by hand, and there don't seem to be any "collisions" happening.

My issue? A "Honda 450 Cam Timing" guide that I believe was written by Bill Lane says at the end, "If everything is ok, you'll hear the familiar 'whoosh' of compression as the pistons reach the top of compression stroke - first at TDC left, then 180 degrees later at TDC right."

I'm not getting the whoosh at all. If I put my finger over the spark plug holes, I'm not feeling the pressure or suction either.

The engine is still on a wooden stand and there's no oil in it -- just assembly lube. The oil pump is not yet re-installed either. It's somewhat dry inside. Valve tappet covers are off, and I have not yet installed the cam chain tensioner or adjusted the tappets (they're still at the 4:00 / 8:00 positions from cam install).

Should I be feeling or hearing this whoosh at this point in time? I really hope I shouldn't because I feel like I'm so close to finishing this project, but at the same time, I don't want to get it back into the frame and find out I messed up.

Thanks in advance for any help!
 

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if the valves aren't opening they can't get air in.
 

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Discussion Starter · #3 ·
if the valves aren't opening they can't get air in.
The valves are definitely opening and closing -- I can see them pretty clearly through the spark plug holes and I can see valve stem tips being pushed down through the valve tappet covers.

I just went out to the garage to triple-check before replying again (don't wanna accidentally post a lie!), and as I was holding my face up to the spark plug holes to verify while turning the crank, I noticed a gentle puff of air now... from both cylinders on their compression strokes... sigh.

I think maybe it's just not as strong as I was expecting... maybe because rings aren't seated in yet and things aren't all so wet with oil?

Before I tore it all down, I'd put a latex-gloved finger over the left spark plug hole and turn the rotor with a wrench to find TDC on the compression stroke and it would almost make a fart noise out of the plug hole against my finger tip. I can't seem to get that to happen right now.

So I guess it's okay? It's hard to convey the magnitude of air pressure in a forum post.

I think I'm going to go with "it's good" unless someone has anything else to add.

Thanks again. I keep posting false alarms, but it's my inexperience and anxiety about screwing it up. Thanks everyone for bearing with me here.
 

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No worries - I've been involved in this stuff since I was 14 and it's hard to remember the anxiety I felt the first time I did a rebuild, but I still have some of that same feeling now when I'm putting an engine together. It's a natural thing to wonder if you've remembered all the little stuff and didn't get distracted while in the middle of an important step that might have caused you to miss something. There are lots of parts in these engines that have to go together in the proper sequence, so for a first-timer there is definitely a lot to consider. That anxiety feeling helps keep you honest, keeps you from throwing caution to the wind as they say. If you're absolutely sure of the cam timing - and 450 cams are known to sometimes have false marks on them that look like the real thing occasionally, so hopefully you avoided that - then install the tensioner, adjust the cam chain, then set the valve clearance on TDC of compression stroke for each cylinder. Once you've done that, squirt a little more lube on the cams and followers and (if you're using the electric starter) use a battery to spin the engine over by grounding the negative to the engine case somewhere and touching the positive to the post on the starter motor using a set of jumper cables. It will spin over much faster than you can turn it with a wrench or socket, and you can then put a finger over a plug hole and get a better idea of whether or not it has any compression
 

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Discussion Starter · #5 ·
Thanks Tom.

I'm as sure as I could possibly be about the cam timing. I studied the forums for a couple of weeks, printed out 3 different accounts of how to do it along with snippets of wisdom from various threads (including some you provided). I assembled the head completely off of the engine, and lined up the marks on the cams (while the head was sitting on a pair of 2x4s to keep the valves up off of the table and safe from impact), then positioned the left cylinder at TDC, and installed the head and ran the cam chain through it. At first, I was off by 1 tooth on the intake side and caught it before riveting the master link. I wasn't sure, but figured I should try moving it 1 tooth and see if it lined up better -- it did. I don't think the marks could line up more perfectly for me. It was "textbook". Just to be extra sure, I verified that when the marks were lined up that my cam lobes were pointing in the approximate "clock" positions as indicated in "Honda 450 Cam Timing" guide -- left exhaust at 3:00, left intake at 8:30, right exhaust at 5:30, and right intake at 12:00. Also compared the valve movement relative to pistons with that spiral-like diagram in the service manual and while that was a little hard to follow, it seemed to match what I have going on.

Honestly, the hardest bit for me was riveting the master link. I planned to use my chain breaker/riveter tool, but the anvil was too deep for the pin head, and when I tried to compress the other end, it just pushed the pin through until it hit the anvil center. I read about other methods like using a hammer as an anvil and a punch (your method of choice, I believe), and others using modified cheap bolt cutters. I actually ended up using the method found in the Clymer manual (of all places hahaha), that involved just using vise grips. My hand is killing me from squeezing them together as tight as I had to to do it, but the end result was perfect and I didn't have to buy anything. I kept squeezing the pins, tightening the vise grips a tad each time, until it was on there good and I had the same amount of side-to-side play on the master link as the other links.

It's funny, the more I turn the rotor on the engine now, the more air seems to be flowing through it. I can even hear the whoosh now. Maybe it just needed to be spun more? I don't know. Maybe I'm turning it faster now. Oh well. I will chalk this up to experience and maybe try the electric starter test you mentioned. I wasn't going to install the start until it was all back in the frame (make it light as possible hahaha), but it might be worth it for piece of mind.

Thanks again.
 

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Maybe your valves/tappets aren't adjusted right, to 0.002".
Also make sure you're adjusting them at TDC of compression stroke - the timing marks on the cams will not align at that point.
 

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Thanks Tom.

I'm as sure as I could possibly be about the cam timing. I studied the forums for a couple of weeks, printed out 3 different accounts of how to do it along with snippets of wisdom from various threads (including some you provided). I assembled the head completely off of the engine, and lined up the marks on the cams (while the head was sitting on a pair of 2x4s to keep the valves up off of the table and safe from impact), then positioned the left cylinder at TDC, and installed the head and ran the cam chain through it. At first, I was off by 1 tooth on the intake side and caught it before riveting the master link. I wasn't sure, but figured I should try moving it 1 tooth and see if it lined up better -- it did. I don't think the marks could line up more perfectly for me. It was "textbook". Just to be extra sure, I verified that when the marks were lined up that my cam lobes were pointing in the approximate "clock" positions as indicated in "Honda 450 Cam Timing" guide -- left exhaust at 3:00, left intake at 8:30, right exhaust at 5:30, and right intake at 12:00. Also compared the valve movement relative to pistons with that spiral-like diagram in the service manual and while that was a little hard to follow, it seemed to match what I have going on.

Honestly, the hardest bit for me was riveting the master link. I planned to use my chain breaker/riveter tool, but the anvil was too deep for the pin head, and when I tried to compress the other end, it just pushed the pin through until it hit the anvil center. I read about other methods like using a hammer as an anvil and a punch (your method of choice, I believe), and others using modified cheap bolt cutters. I actually ended up using the method found in the Clymer manual (of all places hahaha), that involved just using vise grips. My hand is killing me from squeezing them together as tight as I had to to do it, but the end result was perfect and I didn't have to buy anything. I kept squeezing the pins, tightening the vise grips a tad each time, until it was on there good and I had the same amount of side-to-side play on the master link as the other links.

It's funny, the more I turn the rotor on the engine now, the more air seems to be flowing through it. I can even hear the whoosh now. Maybe it just needed to be spun more? I don't know. Maybe I'm turning it faster now. Oh well. I will chalk this up to experience and maybe try the electric starter test you mentioned. I wasn't going to install the start until it was all back in the frame (make it light as possible hahaha), but it might be worth it for piece of mind.

Thanks again.
Sounds like you're on the right track. As Bill mentioned, be sure your valve adjustment is done on TDC of compression stroke (TDC after intake valve opens and closes on the respective cylinder). as for the master link staking - I can do that when I have a partner with enough hand strength to properly hold the "anvil" hammer (aka, not necessarily my wife, she could only handle it once), but since have modified the below-average Stockton tool to use as a staking tool only by grinding a punch-like tip on the useless breaker tip that bent previously. I've thought about modifying a pair of vise grips as they provide a simple clamp method, maybe by welding a punch-like tip to one jaw.

Remember, these DOHC 450s are slow to get oil flow to the cams and followers, so be sure to keep the revs as low as possible for the first couple of minutes to allow oil flow to work its way up the right side studs and fill the cams before revving higher or putting the engine under load
 

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As for breaking the old master link, just find the old one (doesn't matter where the cam marks are) - then dremel off the ends of the pins on one side and tap the link out with a small punch and hammer. Keyword is "tap" here. Once the ends are ground down, they'll tap out easily.
Remove the head right away, so you don't accidentally turn the crankshaft over.

Staking a new master link is a different issue, you do need some sort of tool. I use a cheep Chineeze breaker/staker tool, which I modified so it will fit within the cam opening.
I usually do this on the intake side, but I suppose it can also be done on the exhaust side - that's just the way I learned to do it.
 
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