cb500t – engine rebuild – part 4

2021 update – click here. Below is deprecated info…

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.

18 responses to “cb500t – engine rebuild – part 4”

  1. Devyn says:

    Way to keep it clean, Ed. I’ll need a burn around the block.

  2. Stephan says:

    How did you “punch” your mufflers out? I am assuming you removed the baffles? How do you do that?

  3. ed says:

    I used a punch and a hammer and busted out the thin chamber walls. From the factory you can’t see through the mufflers because of the chambers. I punched through them, so now you can see through them. The baffles unfortunately are not removable. Crude, but effective. I really wanted to keep the OEM look, but have higher flow.

  4. Justin says:

    Dude. Totally missed this project – been busy as hell. SUCH a sick build. We need a ride report once it’s dialed. I’m super interested to hear the before and after scoop. The bike looks tight as hell – sick job!

  5. ed says:

    thanks man.
    i’ve done about 100 miles and it feels great.
    it’s still a little twin, no mistaking that.
    but it’s definitely more eager to rev, has more torque and overall peppier.
    i’m pumped on it.

  6. Justin says:

    Nice. Of the vintage Honda’s, I always liked the 500T. Last night we wrapped up the custom. She’s had three heat cycles, is pumping oil, and the drive train is finally sorted. I’m hoping to get her out on the road for the first time today. It’s awesome to put that much work into something and get it on the road.

  7. Jay says:

    Love the bike, awesome job! Looking for a similar seat for my cb500-four, any recommendations? Thanks!

  8. poop says:

    Nice work. Please keep the thread of posts updated regarding any issues with the engine. Did you have to do any compensating with timing because of the altered deck height? Any details you can give would be helpful, as my first engine foray will be on a cb500t rebuild/buildup.

  9. ed says:

    i talked to one of the guys from team hanson racing. he recommended that i run the timing a tiny bit advanced and add a bit more fuel, so that’s what i’m doing. the bike is running awesome. it’s def a bit quicker than before.
    the only negative thing, is the copper head gasket was letting a tiny bit of oil by in one spot, so I had to pull the head and re-do that, which it’s all good now. but other than that… the bike runs great. best it’s ever felt.

  10. poop says:

    thanks for the info. i should have specified valve timing. with the shortened height, i think valve timing would be retarded. was there any prescription for that?

  11. Rylen says:

    Quick question, where did you get your seat?? I’ve never seen another one just like it, and I really like its shape. Any info would be greatly appreciated πŸ™‚

  12. ed says:

    @ Rylen

    the seat is a stock cb450 seat that I had re-upholstered at an automotive upholstery company here in Phila called “J&J auto”. They’re in the northeast and I think they charged me somewhere around $200.

    Read this: https://www.chinonthetank.com/2010/03/the-cb450-seat/

  13. Rylen says:

    Very nice, thank you for the info ed!

  14. Jonathan says:


    I got the same set of piston but in cb450 so its around 498cc now with 11.5:1 compression πŸ™‚

    225psi in each cylinders.

    Anyway… I was a little scared of the really thin sleeve after the overbore of 4mm!

    How about yours! is it reliable?

  15. ed says:

    Nice. That’s awesome!

    My compression is a solid 200 each cylinder… so I’m assuming my compression ration is around 10.8.1 … since the pistons sit a hair lower in a 500t.

    Yea, I was initially concerned about the 4mm overbore as well. I talked to Hanson racing, and he assured me that he’s never had a problem on stock cylinders. So… fuck it. I did it and it seems fine so far. It’s been almost about a year, and I haven’t noticed any issues.

    Question for you… What carbs are you running? What is your jetting… I’m thinking of upgrading to the Mikuni VM32 kit from Power Barn’s website. Right now I have the OEM cb450 carbs. I increased the main jet 1 size… but then I went back to the stock size.

  16. Liam says:

    I’m about to embark on a similar build Ed, I have a CB450K4, I’m going to bore the cylinders out to 74mm for the THR 74mm forged pistons and use a CB500t crank, cases, gearbox etc so I’ll have a CB556T. I’m curious to know how the reliability has been with the cylinders bored out so much, have you still got the bike? How many k’s have you put on it and how do you think the cylinders/piston is holding up to street use? What octane fuel do you use?

  17. ed says:

    Go ahead and read this (although its old):

    But… also, I can add a bit more updated info here too.

    It’s been reliable.
    I’ve had a bunch of other projects going on, so my cb450 has sat in my garage for about a full year. I’ve ridden it every 6 months though.
    The cylinder walls may be a tiny bit thin with the 74mm piston kit, but it seems okay.

    When I had considered doing the 74mm kit, I reached out to a few well known people, such as Hansen racing and m3 racing, and they all said they race the 74mm kit and they’ve never had problems. So, I guess it’s fine.
    I have not had any problems.

    Maybe I’ve put 2,000 miles on it since the rebuild. Maybe?
    Def run at least 91-93 octane.

    So, if you’re looking for advice, here it is:

    – run a slightly more aggressive camshaft. Check out the Megacycle cam number 120-00 or 120-40. You’ll need to relieve the higher compression with a bigger cam. I’m currently running stock cams, and I’m upgrading to the 120-40 soon. Compression is too high with stock cams, and it feels too twitchy.

    – dont run a copper head gasket. It will weep oil. The THR piston kit comes with the copper gasket. I hate it. I’m swapping out to the 74mm bore composite paper gasket. I got mine from M3 racing. I just havent done it yet.

    – upgrade to Mikuni VM32 carb kit. Buy it from power-barn.com … The stock carbs suck and are difficult to tune with the upgraded piston kit.

    – run the Pamco ignition. The newer one with the CDI.

    – run good valve seals. The red ones if you can get them. Make sure your torsion bars are good with good pressure.

    – make sure the head and cylinders are decked flat.

    – lube / oil the shit out of everything when you assemble it all.

    – In my original posts I had assembled with indian head gasket sealer. Basically, don’t do that. My new method now is, copper coat spray on any head / base gasket. Rubber gaskets get coated lightly in motor oil. Intake boots get a thin coat of black gasket sealer so theres no air leaks.

    – put in new clutch plates and springs.

    – clean out the oil screen

    Overall, yes the bike is def faster than it ever was stock.
    Seems reliable. Has not let me down yet.

    But, no, I would not do really long road trips on it.
    When this bike was all stock, I rode it from Philadelphia to Denver.
    I would not do that now.

    Hope that helps.
    Feel free to email me directly if you have any other questions. thanks.

  18. Liam says:

    Thanks for that Ed.

    THR also said they have had no issues with the 74mm bore in stock sleeves when I bought the pistons. Just hope I can get about 10,000km’s out of it, that’ll keep me going for a few years, no long trips or daily riding planned for this bike.

    Interesting re the cam, I was hoping to keep the stock cam’s, I was only going to get a megacycle regrind if my cams/followers were too far gone and that was mainly for the hardened finishing more than the regrind, I’ll look into that a bit more, I prefer a torquey engine over a high rpm screamer so don’t want to go crazy with the cams and valves, maybe a 120-00 would do me. I’ve heard of a 120-30 being good but I don’t see that in the catalog any more.

    I already have Keihin CR33 roundslide carbs with K&N pods, a Pazon Smartfire electronic ignition, new barnett clutch plates and springs and also some Cone Engineering 14″ max performance 1 1/2″ ID exhausts, I have to fab up some 1 1/2″ OD header pipes. I bought valve seals from DCC, not sure if they are “good” ones though. I got the EK 219H cam chain too, but have heard of troubles fitting these, might get a DID 219T instead.

    Have you noticed any issues with timing from decking the head/cylinder? I’d love a set of slotted cam sprockets to adjust the timing but don’t really need it, any timing issues for you? you decked it about 0.25mm total correct? Is it really necessary?

    93 octane (98 RON here) sounds good. Did you use standard B8ES spark plugs?

    You say it likes to rev harder now, but is there any noticeable increase in low end torque over your old stock CB450?

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From Past

Published - Oct 3, 2012

Philly to Canada – pics