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Discussion Starter · #1 ·
I had copied the info down and put it in my PC and thought I'd post in on the Twins.com and also bring it here and ask opinions along with comments.

http://hondatwins.com/forum/index.php?topic=19.0



So, give it a look and see what you think about it. ;)
 

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Just one comment, Bill -

The "rocker arms" (I guess you're talking about the "tappets" or "cam folowers"?) are not differentiated by intake/exhaust, or left/right.
They're all identical, same part number and everything.
Perhaps your source was talking about the torsion bars or something??
 

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I've heard stories about swapping torsion bars, grinding off one spline, etc... but can't see how that would help.... a used "spring" only has a specific amount of strength...... Maybe Terry on the 450 group will comment...... Steve
 

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Honda is very specific regarding which torsion bar goes where - they're labelled "A" and "B", and are apparently designed to be stressed in one direction only.
Not sure how operating them "backwards" would gain anything.
I've heard stories too, but have no experience with it.
Not to say it might not work, just that I have no personal knowledge of it.

I know that a lot of guys who are serious racers simply (though it ain't simple or cheap) replace the torsion bars entirely with conventional springs.
Not sure if Hansen sells that kit, maybe it's Capellini ??
You can drop a ton of money into making a 450 truly competitive, what with spring conversions, needle bearings, etc.
 

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Discussion Starter · #5 ·
I'll have to see about finding that magazine, when I get the chance. I don't remember who it was that did that bit or which magazine it was is. I used to get Cycle, Cycle World and Motorcyclist mainly and I'm leaning toward Motorcyclist. I don't recall just why that swap was supposed to allow more rpm without floating the valves. I DID ask HondaMan over on the SOHC4, about this info and while he DID say that a 450 engine set up like that would be good on the road race track, he had not heard of the rocker arm swap and didn't see it helping anything. That's one reason I decided to post it here, was to see if anyone had any insight to that. As soon as I locate that article, I'll be posting the "Who did it" and Where it was done". Mark (HondaMan) did say also that those measurements for the exhaust pipes and megaphones were good for road racing. Anyone happen to know the measurements for the pipe and megaphones that would be good for the street (with some boost)?

Later on, Bill ;)
 

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Discussion Starter · #6 ·
I figured that, while I was at it, I'd go ahead and post that Mark (HondaMan) posted some time back about the 450 (It's on the FAQ over on SOHC4): Remember that this was posted originally over on the SHC4 forum.

At the risk of breaking tradition of 1 cam in this forum....I love the 450 DOHC. Honda's most magic bikes, IMO, were the 450 DOHC, the 500/550-4 and the 400-4. My personal choice of riding the "big four" these last 36 years has more to do the with durability of that bike than with its personality.

The 450-2 will deliver more wallop per pound than almost anything out there, a real "kick-butt" twin. It's nimble, has excellent brakes (if they do wear quickly) and throttle response that is the envy of anyone who has ever ridden, but not owned, one. I usually beat every British twin except the 1967-68 Bonnevilles and the Norton 750s with mine. I had it for only 3 years before my father-in-law talked me out of it. His neighbor still owns and rides it today, 35+ years later!

Rules:
#1. Keep the carbs CLEAN. The vacuum pistons have very small clearances and the slightest amount of stickiness (from old gas, usually) will make the pistons misbehave and the mixtures will be erratic or just plain bad. Cleaning is easy: just loosen the clamps and twist the carbs sideways to get the covers off and the pistons out. Clean the bores and the pistons with acetone. Put 1 drop of very lightweight oil on your finger, apply it to the bores and the pistons, and reassemble. You'll be surprised at the difference! Remove the bowls and pilot screws, then spray carb cleaner through the passages. Clean the floats with acetone, check the float levels, and reassemble.

#2. The intake valve rockers wore badly. This was from folks running too light oil (cheap 10w40 or 10w30), and running it too long. The recommended change interval is 750 miles or less, because the top end really beats up the oil. Use 20w50 if you don't mind losing about 1 HP. Use Castrol or Torco, in any case, because it survives tehse hot-running engines better than almost anything but synthetics. Don't use synthetics, or you might lose your clutch. When starting it hot, WAIT 45 SECONDS BEFORE DRIVING, because it takes that long for the oil to reach the intake rockers on hot startup (honest!). If your lifters are worn, get new ones. They can be replaced through the adjustment cap holes. Set the intakes at .003" and the exhausts at .004" (I know the manual says .002" and .003", but that's for quiet, not for longevity). Worn lifters both clatter and reduce the lift a lot, as much as .100". Worst case, they also damage the cams. Look inside with a flashlight for score marks. They can be resurfaced or replaced fairly easily.

#3. A common malady with these was the points advancer weights getting corroded and stuck or the pivots wearing and getting loose. This makes it surge when trying to run along at steady in-town speeds (the carbs can cause this, too). Cleaning or re-bushing fixes them up.

#4. If you have more than 20,000 miles on it, try to get a new oil pump. This will improve many things, subtle things, that make it a happier ride.

#5. Hop-ups: after you've replaced those worn lifters and cleaned up the cam, give it a nice valve job to make it seal well, bore it .25mm (1st oversize) to gain almost 2 HP, mill the head .010" and remove the resulting sharp edge around the bore, trim the valve guide bosses on the intakes (they are too big), reassemble and set the timing an extra 2 degrees advanced. Grind off an extra spline on each torsion bar (for the valves) and reinstall 1 notch "extra" tight. This will let you spin 10,500 RPM safely, and it will, very willingly. Use the gearing from the CL model (it's slightly lower) if you have a CB. Get good tires: you're gonna need them after this. Replace the worn swingarm bushings and install tapered rollers in the steering head. Then, you'll wonder why you ever wanted to ride anything else.

The 450-2 riders' motto used to be: "After all, enough is enough!" It's hard to argue with that bike.
 

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I never argue with HondaMan (Mark).
Everything he mentions is good stuff that I would support.
Except that lifters (tappets, followers, whatever you call them) can't be replaced without pulling off the cam covers (bearings). Anyone who's actually done it knows that.

But I can't comment on those top end mods, never tried them. A little confused as to how the torsion bars could be installed with more tension - before tensioning them while installing, they already almost hit the cooling fins, don't think they could rotate any further downward before pre-tensioning them.
My only comment is that Honda specs the valve adjustment at a ridiculous 0.0012" for all 4 valves - I never even try that, I just use 0.002". Racers will typically use anything up to 0.005".
 

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Discussion Starter · #8 ·
tbpmusic said:
I never argue with HondaMan (Mark).
Everything he mentions is good stuff that I would support.
Except that lifters (tappets, followers, whatever you call them) can't be replaced without pulling off the cam covers (bearings). Anyone who's actually done it knows that.

But I can't comment on those top end mods, never tried them. A little confused as to how the torsion bars could be installed with more tension - before tensioning them while installing, they already almost hit the cooling fins, don't think they could rotate any further downward before pre-tensioning them.
My only comment is that Honda specs the valve adjustment at a ridiculous 0.0012" for all 4 valves - I never even try that, I just use 0.002". Racers will typically use anything up to 0.005".
I can't verify it either but, I also put a lot of stock in what Mark (HondaMan) says. He really has a vast knowledge about the subject.

I haven't checked out the torsion bar trick that Mark speaks of, but best I can figure, you will end up putting some "preload" on the valve, it you do it the way Mark says. Some preload would be like putting in a set of stiffer springs (on a conventional valve setup in a head. So, in that way, you would make it harder to float the valves. I'll have to check that put, when I get the chance.

Take care, Bill ;)
 

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I'll try to get some photos to illustrate what I mean, bill.
The end of the torsion bar has a little lever-like thing that has to be pressed upwards to preload it, then slips on a knock pin.
The little lever part is already almost hitting the cooling fins, so I'm uncertain it could drop down any further for a greater preload pressure.
Know what I mean, Vern??

And no arguments, Mark is extraordinarily knowledgeable.......
 

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Discussion Starter · #10 ·
"Know what I mean, Vern??"

Yeah Bill, I understand what your concern is. I haven't really checked out, this particular theory of Mark's. If shipping wasn't so costly AND I was going to try and build a "Hot" 450 engine, I'd send the head (with the parts) and get Mark to work his MAGIC on it. ;) I wonder if Mike (MRieck @ SOHC4) mike have some insight to this? I know he's done quite a bit of work on the 750 SOHC4's, not sure what else though. Oh well, time will tell.

Take care, Bill ;)
 
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