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Discussion Starter · #1 ·
some say the 500t head has more volume in the dome, i.e. less compression. I can see it is a different casting, and has not got the steel dome in it. does it also have a slightly bigger volume, that is to say it is lower compression?
I observe that the pistons have less dome than the 450; what about the head?

thanks, Brian
 

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The Honda 450 manual lists the compression ratio as 9.0:1.
The Honda 500T manual lists the compression ratio as 8.5:1

Though the 450 manual specifies 185 psi as the desired compression reading, the 500T manual makes no mention of a desired compression reading.

In that context, it would be reasonable to assume the 500T would deliver somewhat lower compression readings.
Since the bore on both bikes is the same, one could assume there is a difference either in the piston dome, or the head "squash" area itself, or maybe both.

That's about all the info I can offer, hope it helps......
 

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...Paul (Dinosaurthatroars) at the MSN site reported that simply replacing the 500T head with a 450 one would increase the compression ratio...Assuming that is true, and all the other 500T parts remained the same, the 450 head would have a slightly smaller "space" or volume within the dome.....
 

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Discussion Starter · #4 ·
66Sprint said:
...Paul (Dinosaurthatroars) at the MSN site reported that simply replacing the 500T head with a 450 one would increase the compression ratio...Assuming that is true, and all the other 500T parts remained the same, the 450 head would have a slightly smaller "space" or volume within the dome.....
ok the 500t piston is NOT the same, it has less dome to it, reducing compression for sure; however, bolting a 450 head onto this lower compression piston improves performance significantly, I know people who have done it. either the camshafts are wondrous or the head is higher compression. Sure would like to know- the 500T heads have a different fin design slightly too, did they use these on any of the 450's? you can tell them by the fins right over the dome; the 500t has a thicker, cruder casting of the fins.
 

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I would be very interested to see a brakedown of the changes between the 450 and 500T. It seems strange that a 2mm lengthening of the stroke and a change in gearing can make two motors that behave so very differently. I suspected that the cams are different but thay don't seem to be on visual inspection. Allan
 

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450roo said:
I would be very interested to see a brakedown of the changes between the 450 and 500T. It seems strange that a 2mm lengthening of the stroke and a change in gearing can make two motors that behave so very differently. I suspected that the cams are different but thay don't seem to be on visual inspection. Allan
Same cams, different crank, different head, different carbs, differnt pistons, lower compression ratio, different tranny, different mufflers. Different seat, forks, shocks, lights, instruments.
Most everything else is the same, just cosmetic differences....
 

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Thanks Bill, You missed a few of the smaller differences but I see your point. Allan
 

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Discussion Starter · #9 ·
beedub said:
some say the 500t head has more volume in the dome, i.e. less compression. I can see it is a different casting, and has not got the steel dome in it. does it also have a slightly bigger volume, that is to say it is lower compression?
I observe that the pistons have less dome than the 450; what about the head?

thanks, Brian
ok now I was pleased to get a note from Terry Naughtin. he said,
"Over a period of time I discovered that Honda put aluminum heads on
cb450's near the end of production.

The volume is larger in the aluminum head, the best head for performance
is the all steel head, It has more compression and the steel holds the heat
in the cylinder better..unlike, most people who believe all aluminum heads are better,
steel race car heads make more power, they use aluminum to take weight off the
front of the car."
 

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In comment to steel heads making more power. I don't wish to argue the point because it is true to an extent. Aluminum heads dissipate heat better, and generally allow you to run more compression, more compression, more power, and yes they weigh substantially less than their steel counterparts. However all things equal on a relatively stock engine with equal compression ratios, the steel heads would probably make more power. Just my .02 opinion.
 
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