2013 Recap

Back in 2013 I had the idea to build a hotrod / high compression cb450.
I don’t know why I had this idea. I was bored and wanted to play around with stuff I suppose.
I started with a good condition cb500t engine, which is almost identical to a cb450.
Back then, I bought a Todd Henning 74mm (+50cc) 11.5-1 compression race piston kit.
I thought, 550cc in a cb450 sounds really cool. It is / was.
I put the piston kit in. I kept stock OEM camshafts.
Bike ran pretty darn good.
Measured compression per cylinder with a gauge was about 205psi. Whoa that’s high.
Bike was def quicker than before when it was stock. I was happy.
Well… fast forward about 6-7 years.
The piston kit had originally come with a copper head gasket. It always weeped oil a tiny bit out the front near the headers.
I also had read that boring the cylinders to 74mm made the sleeves too thin, so the bike might run hot possibly? I didn’t care and ignored all this and did the build anyway.
Over the 6-7 years the bike started leaking oil really bad.
Ran a bit inconsistent and somewhat hot it seemed.
Started leaking oil so bad it was unrideable.

2021 updates

In 2020 I decided I needed to do an engine rebuild again.
I figured I’d learn from my mistakes and make it more mellow for more overall longevity.
The bike is a cb450. If you want a hotrod bike, pick something else… really.
I just want to ride the bike around and enjoy it and not have it break or leak oil or run hot.
I bought another set of original 70mm cylinders.
Cometic fiber/composite head gasket. I’m never running a copper head gasket again.
I bought lower compression 10.1-1 Weisco cb450 pistons (same as Charlie-Place kit) that are the shorter skirts to clear 450/500t cranks no problem. But pistons are still higher compression than OEM 450/500t.
Sidenote – In 2016 I had bought Megacycle 120-40 cams on ebay, but then sold them a few months later thinking they were too aggressive.
So … I sent my OEM cams / followers to Megacycle to get their mellowest street grind, hoping this matches the piston kit well. They chose grind “120-10” which is street-mellow. .350-lift / 244-duration@40˚. Stock OEM cam specs are: .330-lift / 230-duration@40˚ (according to MegaCycle). They said they’re currently revising their spec sheet for the cb450/500t engine also.
Anyway, the goal is to have a mellow piston kit / mellow cam … and have it all match and just be a nice street rideable mellow engine.
I have Mikuni VM32 carbs which I had before with pod filters.
A new Charlie place electronic ignition / coil kit, which replaces an old Pamco kit I had.
All new wiring.
Stock seat and little upright bars.
Tried totally open free flowing exhaust, but sounded like garbage on deceleration.
Switched to semi free-flowing Cone-Engineering Quiet-Core exhaust.
Disassembled frame and replaced any messed up stuff. Cleaned / painted everything.
Put it all together and the bike seems to run good so far.
Hopefully this engine combo will have more longevity to it.

cb450/cb500t engine differences

I’ve said this before but i’ll say it again.
Yes, the cb500t engine has different stroke / crank so if you put cb450 pistons in a 500t motor, the pistons will sit a hair lower than deck height. Doesn’t seem to matter or make a difference. Just make sure you get pistons like the Weisco kit that has a shorter skirt to clear the crank. The Weisco piston is slightly shorter skirt than the Todd Henning race piston as seen in the one picture with them side by side where the Weisco piston is on my credit cards to make level height.
And yes, the Todd Henning race piston kit def did work in a cb450/500t engine, but at this point, I don’t recommend it unless you’re actually racing.

Conclusion

If you want to go fast, buy a different bike.
If it’s a normal cb450 / 500t street bike, keep the engine stock, or do the mellow 70/71mm Weisco kit, it’ll work great in either cb450 or cb500t… probably keep stock cams or do mellowest option available. if you want a few extra HP, get VM32 carbs / semi free-flowing exhaust, and call it a day. Just ride it and enjoy its a fun little 40hp bike.

Performance camshafts can add different characteristics of power to your engine.

• Cams with high lift can add mid range punch, while cams with longer duration can add high rpm top end power.
• Cams with both can really add power but you need to make sure the head can flow properly.

It really depends on what you’re trying to do and making sure your parts and set up all match. Even if you have a completely stock motor, putting in a cam with a tiny bit more lift / duration can be a benefit. If you add an exhaust and pods, a very mild cam upgrade will yield a couple HP. And… if you have a high compression piston kit you’ll really get a benefit from cams. Especially if you have head porting done.

Megacycle is a cam company that’s been around for a long time. Ever since doing the high compression piston kit in my 450, I’ve been wanting to add a megacycle cam. Megacycle will take your existing camshaft, grind it down. Weld new metal on the lobes, then grind it down to their new beefier specs. This is called hard-welding. This winter I was gonna send my cams out to megacycle. Ironically on eBay popped up a set of used megacycle cams in the grind I wanted for $200 cheaper than new. I bought them.

I’m having a hard time accurately measuring the lift. It’s obvious to the naked eye the duration is way more gnarly. The lobe is much fatter. I’m going to send the cams back to megacycle to have them verified to ensure they’re still within spec and okay.

They’re stamped from 1992 which is when they were made. Pretty cool.

My 450 set up

• 500t motor bored to a 550cc with high compression Todd Henning pistons
• 32mm mikuni VM smoothbore carbs / pods (powerbarn.com kit)
• pamco ignition
• straight pipes with 8″ baffles
• head is not ported
• stock torsion bar valvetrain set up

So I think the megacycle 120-40 cam grind will work well.

My compression at the moment is just over 200psi per cylinder which is a little too high. These cams should lower the cranking compression to around 170 which will be more comfortable.

Intake and exhaust cams below.

Megacycle 120-40 grind

Grinded by Megacycle in 1992

Stock OEM cam profile below

Megacycle profile below. You can see the different color metal welded on and see how much lumpier the duration is. Holding the valve open longer. More top end high rpm power.

Straight pipes with 8″ emgo baffles … get the shit out as fast as possible. Don’t need much back pressure with the type of set up i’m going for.

Mikuni VM smoothbores

It annoys me when I see cycles on eBay that say “Fresh rebuilt engine. 10 miles on it since rebuild. Runs great.” etc… Fucking stupid. I would never buy a bike like that unless the owner has put like 1000 miles on the rebuilt engine to confirm shit is good.

Anyway… someone asked me if my bike is running good since the rebuild. Figured I’d do a 6 month re-cap of the good and the bad.

If you don’t know about this engine rebuild I did… read about it here. 500t engine in a 450.

8 months ago when I initially thought of doing this high-compression engine build… I couldn’t find comparable info out there for a cb450/500t. I didn’t know if it’d blow itself up after a month, or how it’d hold up as a street bike. So… I hope this post helps somebody in the future.

• Piston Kit –
  Its a 500t engine… not a 450. I’m estimating my compression ratio is somewhere between 10.5 and 11 with the Todd Henning race piston kit and decked cylinders… which is pretty damn high for this bike. I run 93 octane gas and haven’t had any issues. No detonating / pinging. Seems totally fine. *Read the last bullet point for info about the overbore from 70mm to 74mm and if it’s right for your bike.
  Analysis – I recommend that piston kit… even for a street bike
• Head Gasket –
  I had to re-do my head gasket due to it letting a little oil by. let me clarify… I have the copper head gasket that comes with the henning piston kit. Fuck copper gaskets. Pain in the ass to get to seal. I redid it once 2 months ago using the Permatek Copper paste in a tube, and it’s been holding now. It’s a 74mm bore, so I can’t run a oem head gasket. I actually just found that Mark from M3 Racing sells an oversized composite head gasket. I just bought that and am going to pull the head again, and convert to the paper/composite gasket and use indian head gasket sealer… and torque 10lbs over what the bolt spec is.
  Analysis – I do NOT recommend a copper head gasket. Use a paper/composite with indian head gasket sealer and over torque bolts a bit
• Air Fuel Settings –
  I opened my stock exhausts a bit by punching the baffles out. And I run Uni pod filters. I have stock jetting. 38 slow and 145 main. This ended up being the best. I initially increased the main jet to a 150 which totally rips high rpm, but the main jet feeds the slow jet with these carbs… and that wasn’t good. It bogged a bit down low.
  Analysis – with oem constant velocity carbs… I recommend stock jetting is the overall best
• Timing –
  I run the Pamco electronic ignition. The more I advance it the better the bike seems to run and the more it rips high rpm. I don’t think I would ever suggest running points with the set-up I have.
  Analysis – I recommend the Pamco electronic ignition advanced a decent amount – use your judgement.
• Is it faster? –
  Hellz yea it’s faster. For a little 500 twin… The bike rips now. Especially high rpm. I have brand new clutch plates and springs and still lets loose high rpm sometimes. Don’t expect the bike to outrun a cb550 four. It might be a tie. But that’s pretty fast compared to a normal oem stock cb450 or 500t. It def rips up to 100mph pretty fast now, where before it seemed to take longer.
  Analysis – If you want to go faster… bigger higher compression pistons will do it.
• Is it reliable? –
  Umm… it seems decently reliable. When I pulled the head the first time to reseal the head gasket… all the parts looked great. Not overheated at all. No scoring. Nothing fucked up. Other than dealing with a shitty copper head gasket, everything is great. Def install a brand new cam chain!!! Once I convert to the paper/composite head gasket, it should be even more solid. I’ll say this… I rode this bike across the country 4 years ago when it was all stock oem condition. I wouldn’t do that now with the higher compression. Maybe it’d be fine… but I’d rather not.
  Analysis – As a city ripper, yes it seems totally reliable. As a long traveling distance cycle… probably not anymore.
• Would I build it like this again or change stuff? –
  If this was my only bike, I would not bore it out 50cc over from 70mm to 74mm. Apparently this makes the cylinder walls kinda thin which is another reason i’m not sure of the long term reliability. If this was my only bike, I would’ve found a piston kit that keeps the bore the stock 70mm… M3 racing makes a kit and so does Charlie Place. Since I have 3 other bikes, I won’t cry if it blows up in 2 years. I’ll just rebuild it again. I love the way it runs now. Rips through the gears faster and it’s just overall kinda cool to have a cb450 with a 500t rebuilt into a 550cc high compression ripper. Don’t come across them very often eh… people look confused when I tell them what it is, and that’s cool.
  Analysis – If this is your only bike… probably do a stock basic rebuild with pistons that keep the bore 70mm.

• Read about rebuild Part 3
• Read about rebuild Part 2
• Read about rebuild Part 1

Well… the 450 is finished and it runs. Video at bottom.

I’ve riden it about 10 miles so far. Haven’t gone over 5K rpm yet, but it feels super responsive and eager to rev. It’s not dialed in yet though… still have to fine-tune it.

Below pic…
Threw the engine back into the frame.
– put in a new clutch
– installed the Pamco electronic ignition

Damn that shit looks good!

Not a 500… High compression 550cc – boom

Electric starters are lame. Plug that shit. Auto-zone. $3

New (used) OEM mufflers.
I punched them out to make them straight-through instead of chambers. Should flow decent now which is something the high-compression engine is going to need.

Sounds way “punchier” compared to before.

• Read about rebuild Part 2
• Read about rebuild Part 1

Hey guys.
Here’s an update on my cb475 supersport build.

The engine is basically finished.
All that’s left is to put on my high polished engine covers and I’m putting in a new clutch.

I installed new valves seals.

Below pic –
I installed the rest of the cylinder head. I didn’t get to officially test the torsion bars. I used NOS for side B, and the two firmest ones I had out of about 6 possible for side A. It was overly apparent which were within spec and which weren’t based on preload tension. If you can push the valve open with your finger… it’s worn. If you don’t have to pre-load… it’s worn. I also polished the cam lobes and cam follower lobes with metal polish to ensure they’re super slick. It should prevent future wear issues I hope. And… assembly lube is your friend. Loctite everything. Axial cam clearance – check. Cylinder head done.

Installed new pistons. Rings positioned correctly. Slid the cylinders over.

~10.7 compression – 550cc – Boom

Below pic –
I hate a leaking head gasket. The absolute worst. It seems every jap bike head gasket will eventually leak oil. Indian-Head gasket stuff is supposed to be the best, so I used a thin coating on each side of my head gasket. Fucker better never leak or i’ll ride the bike off a cliff.

Engine all assembled. All torqued to spec. In time. Valve clearance done. All loctite’d. Turns over nice and tight and smooth. Also installed a new cam chain and cam chain tensioner.

Not related to the engine…
Devyn from Urban Cycle Works painted my side covers to match my NOS tank. They match damn near perfect. I’m pumped. The 450 is going to look sick as shit.

So –
I’m on the last stretch. This is what I have left. It’ll go quick:
– clean up my frame, and spot paint it
– put engine back in frame
– put on my polished engine covers
– install the new clutch kit
– install the electronic ignition
– polish up everything else that’s gross right now
– put on the new “used” awesome condition OEM mufflers
– put on the new “used” awesome condition OEM gauges
– probably fix and paint my headlight bucket
– clean my carbs again. Increase my main jet to a 150 or 155
– I have all new cables too and all that dumb little shit

• Read about rebuild Part 1

Ok… So, I had a couple different machine shops do a couple different things for me.

First machine shop:

Mar Automotive
4345 Orchard Street,
Philadelphia, PA 19124
(215) 288-7320

They’ve done cylinder head stuff for me in the past:
– they did a valve job on my S2000 like 5 years ago
– they did a valve job on my cb650 like 3 years ago

So, I vouch for them. They’re fast, cheap, and quality.
All they do is cylinder heads and valve trains. All day long every day. That’s it.

What they did:

– 3-angle valve job on the 500t head.
– Blasted it clean.
– Skimmed the deck to make sure it’s flat.

A 3-angle valve job is the best way to get your valves to seat. Think of it this way. If you’re looking to keep costs down… lap the valves yourself and you’ll probably be okay.

I talked to a couple people and they convinced me to get a full on valve job done instead of lapping.

3-angle valve job means, the valve seat has literally 3 angles. Normally 30˚ / 45˚ / 60˚. They actually cut new angles to ensure everything is seating correctly. It’s more accurate than lapping.

Price:

– $100 and it was done in 1 day.

Below pic: Damn that shit looks good.

Freshly cut seats.

Valves cleaned up more.

Pretty sure they painted the head silver after blasting it clean.

Second machine shop:

Powerseal USA
337 Coldstream Road,
Phoenixville, PA 19460
(484) 921-5121

I heard this place does a good job with boring cylinders and milling decks and stuff of that nature. I’ve never used them before.

They’re a bit out of the way being 30 miles away. Fuck it. Figured I’d give them a go.

The guy was cool and said he’s built cb450 engines before. Works for me…

What they did:

– Bore the cylinders out from a 70mm to a 74mm.
– Mill .010″ from the top of the cylinders (raise compression 1/4 point)
– Cleaned everything and honed the fresh cylinders.

Price:

– $180 and it was done in a week.

Below Pic: These are the pistons sitting in the cylinders.

I found a pair of Todd Henning 11.5 compression race pistons on eBay for a price I could live with.
My 500t engine is now a 550cc. Badass. And in a cb450… extra badass.

See how they are sitting just below the deck. If I actually had a cb450, they would sit flush, and would actually yield 11.5 to 1 compression.

After talking to a few people, I finally realized the 500t engine is different with it’s placement of the wrist-pin on the piston. Ahhhhh.

So…
long story short, if you put 450 pistons in a 500t, they yield lower compression because they sit below deck height as seen in the below pic.

So…
These 11.5 pistons really are going to yield 10.5 compression in my engine. This is why I milled the cylinders .010″, to raise compression again and bring them closer to the deck height.

So…
I should have somewhere around 10.7 compression in this engine. Which should be fucking awesome considering stock compression is 8.5 … hahah. Looks like I’m always running 93 octane! Fuck it.

The pistons domes have cut-outs for the valves. Cool.

Another thing to note. You can’t put an OEM cb450 piston in a 500t. It will hit the crank because the piston skirts are longer. All cb450 race pistons made by people like Henning / Hanson / M3 / Charlie Place … all shave down the skirt… so their 450 race pistons all fit 500t engines. Just account for the lower deck height.

For example; Charlie Place cb450 race piston kit is 10.1 compression… So in a 500t this will yield 9.1 because the piston will be sitting lower in the cylinders due to the wrist-pin placement.

Make sense? Okay.

Regardless, I wanted to show the basics of lapping valves.
Figured it’d be good to show a general overview.

I made a quick video. I’m sick today… Hear me sniffling?

This ring below is the valve seat.

You can see below, the valve sits in the combustion chamber and needs to sit as closely / tightly as possible to the ring on the combustion chamber. Over time I guess the seat gets worn and can start leaking which causes lower compression and a weaker engine.

Another view below to see how the angle of the valve sits on the angle of the ring in the combustion chamber. This is really what is happening. You want the angle of the valve to perfectly match the angle of the ring in the combustion chamber.

This is the grinding material and lap tool.

See how the suction cup thing holds the valve.

It looks like I’m not putting a 450 head on the 500t cylinders.
Everything on the 500t is in way better condition so I’m going with it.

Here is the 450 with the 500t engine in it. So long semi-stock bike…
See ya soon when you’re not as lame.

Rip all the shit off it.

Get the engine top end apart.

The 500t combustion chambers are in way better shape then the 450’s were.

Cam followers are worn a normal amount I suppose, but they’re definitely not dished inward like the 450’s were. See the 450’s here. I’m not sure if I have to fuck with these? Seem okay I guess.

The cam has a tiny bit of pitting on the lobes, but it’s pitted inward and overall seems smooth. If the cam followers are smooth and not dished inward, I’m guessing the cams are fine too?

Valve seats look decent. I’ve never lapped valves before, so that should be interesting. I’m going to make a post about it. Hang tight on that one.

Valve seals out…

So far everything has gone smoothly except the valve seal removal, which… I might have a problem here. The picture above is after the valve seal removal. I practiced removing the seals on my extra 450 head, and they came out super easy. piece of cake. So… then I went to do it on the 500t head, which is the head I actually plan on using, and they would not come the fuck out. WTF. Took forever. Seemed like they were glued on there?

Looks like I nicked the top of the bronze valve guides. Fuckkkk. I looked closely with a flashlight and the inside looks smooth. The concern is that the valve going up and down a million times on something that may not be perfectly smooth could put a groove line on the valve and then put wear on the rubber seal, and then allow oil blow by into the combustion chamber, then I’ll throw the bike off a cliff 3 months from now, or do the rebuild all over again.

So… I’m not sure what to do.

Thoughts… Ricky? Jason?

Here is what I’m thinking…

I don’t know if it is bad enough where anything would be affected on the valve operation. The inside looks smooth. I inserted the valve and it feels smooth going up and down. I could run some 2000 grit sandpaper on the inside of the guide to clear any burs (if there are any). Not sure if that’s a good idea though. The guide is bronze right? and valve is steel. Bronze is way softer than steel right? So I don’t see, even if there was a hypothetical bur, I don’t see how it would score the valve. Seems the valve would just smooth it out and it’d be fine?

Not sure if I want to have new valve guides pressed in because i’d almost certainly have to get the valve seats re-cut. I think…

Below see the seal cap getting damaging while removing the seals. I have extras of these from my other head and they’re perfect. The only concern is the guides.

Anyway.

The engine build is going okay so far.

Bike should be pretty quick when I’m done with it. Or blow the fuck up. We’ll see…

cb450 and cb500t have no valve springs.
They have a torsion bar set up.

Let’s take a look at how exactly the torsion bar works. It’s pretty cool.

Pic 1 –
The engines are double overhead cam which means there is a separate cam lobe for each valve. Tuners and people looking to make power like DOHC because you can fine tune the cam duration and lift for hitting each valve. It’s easier to make more power with DOHC compared to SOHC (single cam). Thats probably a general statement, but whatever.

Pic 2 –
Here is the torsion bar assembly all together. Again… no springs anywhere. It took me some time to figure out exactly what’s happening. If there is no actual spring, how does the bar spring back to close the valve?

Pic 3 –
We can see in the below pic it’s the same as Pic 2, except taken apart.

The way the bar springs back to close the valve isn’t by springing… The inner piece of metal actual twists. Yea… twists.
Pretty crazy huh. It’d be like taking a solid piece of steel and placing so much pressure on it, you twist it. ha.

The bar is fixed on the left side, and the right side, it fits onto the outer sleeve which put pressure on it when the valve opens, and literally twists that inner bar to close the valve.

And we can see in the bottom right of the pic… the claw looking thing is what’s attached to the valve, so when the valve gets hit open by the cam follower, this claw thing is what pushes back on the outer sleeve of the torsion bar, to then put pressure on the inner bar to twist itself.

Pic 4 –
Below pic may help clear it all up.

Green arrow is the camshaft. This spins and hits the Orange arrow which is the cam follower.

Orange arrow opens the valve down into the combustion chamber.

Red arrow is the claw which is ultimately attached to the torsion bar which twists itself to push the valve back in the closed position.

Pic 5 –
There are two torsion bars. A and B.
Apparently, over time… the torsion bars can get soft or tired and lead to valve float. I talked to a couple old school Honda cb450 race builders and they suggested a couple things.

Find NOS (new old stock) torsion bars.
Or, test mine with a inch-lb torque wrench. Apply pressure on the torsion bar to see if it’s within spec. 80in’lb is stock. Anything under 60in-lb needs to be replaced.

Apparently, it’s easy to find NOS side B torsion bars. I found 2 of them on eBay, so I’m good on that side! I can’t seem to find side A NOS, so I bought another set from a low mileage 500t, and hopefully when I test them, they’ll be close to 80in-lb tension. Or… find another set and test them.

The reason the torsion bar tension is so critical is because you don’t want to get valve float which is bad. You’ll get surging at high-rpm or burn up a valve, or possibly valve could hit a piston. Apparently the stock torsion bars are super strong and reliable, but over 40 years they need to be replaced. Stock torsion bars were used in race engines up to pretty high RPM’s. If I could find NOS for both sides I’d consider running a race cam, but for now… I’m not sure.

This is a damn cool engine. Dare I say one of Hondas more unique engines? The only other Honda engine that torsion bars came in would be the v12 formula f1 race engine! Which revved high as shit I’m sure. Badass!

Here is the advice the old school cb450 engine builders gave me:
– def replace valve seals
– try and find NOS torsion bars or test tension. under 60in-lb is no good
– you can bore the cylinder wall to 74mm without worry

More about boring and pistons a little bit later.

Stay tuned.

Below pic is a fully disassembled view of the torsion bar assembly.
See… no springs anywhere.
The long skinny bar actually twists to create a “spring-like” motion to open / close the valve.

1. Double Pole Double Throw (DPDT) switch. I bought mine from McMaster-Carr. The switch has 6 poles and 3 switch positions (ON-OFF-ON).  For comparison, the wired switch, pictured below,  is a Single Pole Double Throw (SPDT) which has 3 poles and can only switch 1 circuit.

2. The DPDT switch has the functionality to switch 2 circiuts which is what I needed.

Circuit #1: low beam – OFF – high beam.

Circuit #2: tail/gauge lights – OFF – tail/gauge lights.

Here is the switch wired up. The black wire (1 to 2 wire) is hot when the ignition is on and feeds both poles. So to explain, the first ON position turns on the low beam and tail/gauge lights and the second ON position turns on the high beam and tail/gauge lights.

3.  Switch mounted in my gauge bracket. The wires are heat wrapped and run into the headlight bucket.

4. My slimmed down wiring diagram so you can see how the switches connect into the rest of the wiring. (color version)

Thanks to everyone who helped out with parts, advice, and just the whole process.

I’m using the back half of a rusted out 500t tank to make my seat cowl. I wanted to slim it down so I cut out a 1 3/4″ section and welded it back together.

Mock up.

Cutting out paper templates to get certain measurements.

Laid out the design on 16 gauge sheet metal.

muscled some bends.

Stance

Started by mocking up and drafting the gauge/switch bracket.

Spray mounted my mechanical drawing onto an 1/8″ flat stock steel and then roughed out the shape with the hacksaw and cleaned it up with files.

Installed! Left switch is for the High/Low beam and the right side is the On/Off kill switch.

Stance.

Here’s how it looked stock.

ricky, ed and i can’t figureout how to turn back the mileage without running the risk of breaking it. anyone have a simple solution to get the mileage to zero?