cb500t – engine rebuild – Part 2

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.

8 responses to “cb500t – engine rebuild – Part 2”

  1. ludwig says:

    fucking sexy dude. cant wait to see this thing in action.

  2. Jason says:

    Man, you’re really getting down with the engine building. Nice.

    If you want to CC the engine to get actual calculated comp ratios, get in touch. I’ll show you how.

    When comp is up in the ranges you’re talking about things get critical fast and can be expensive to rectify. Tuned intakes and exhausts and perfect ignition are not optional at that point.

    Have fun!

    Jason

  3. […] If ya didn’t read about the head and cylinder work I had done earlier… re-cap that HERE. […]

  4. Charles Como says:

    Can I just put the Charlie’s Place CB450 (+1.00mm) pistons in my CB500T? Will the engine run?

    I know it will be lower compression than if if you do some milling, but it will still be higher compression than the original pistons, right?

    And why does compression matter? Will the engine run fine without any more changes?

    Also.. out of curiosity, I bought a CB450 head by mistake to replace my CB500T head. Do you think it will work on the CB500T cylinder/engine?

    Thanks!

    Charles

  5. ed says:

    @Charles
    I emailed you my longer response.
    But the short answer is:

    – yes, charlie place pistons will work great in your cb500t. they will yield about 9.1 compression or somewhere close to that.

    – a 450 head and 500t head are about the exact same. doesn’t matter. use whichever is in the best condition.

  6. Robert Edmondson says:

    Hiya Ed, i know its a while back since you done this project, but i was wondering after you shortened the barrels, did you have to alter the camshaft timing ?

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