Topic: 1978, cb750a, thats right....."hondamatic"

[fondofhondas]

hello.

i havent rode a bike in a few years and im just getting back into it. i got this bike because of a great deal, not that i am a noob (automatic transmission). I know the "auto" wasn't recived well by the biking community, but i myself have injoyed it so far and think its a marvel of technology...anyway.... I wanted to get some louder pipes (growlier) for this bike, but dont know much about it. I can fix cars alright but bikes are new to me. can any one give me some insight on how exaust fits with differnt bikes or suggest a specific product? also, aside from the auto trans, this is just a normal cb 750 and shouldn't be a parts nightmare...right?

thank you for the help

[fuzzybutt]

as far as  i know any 4 into 1 that works on a 5speed sohc 750 will work on the 750a.

[bill440cars]

as far as  i know any 4 into 1 that works on a 5speed sohc 750 will work on the 750a.

         Hey fuzzy, the p/ns (for the 4 into 1 and the 4 into 2) for the 750A's exhaust is different from the other's but I have no idea what difference there might be. Just guessing, but maybe the 750A exhaust might be a bit more restrictive, I don't know. That is all I know about the subject myself. I am always listening to the posts on the 750A cause I have a 77' model myself and am trying to pick up any info on it. My mufflers are a bit rusty where they go on the exhaust pipes and I've checked the p/ns of the 750A vs the 750K & F and found the P/Ns to be different. They may bolt up, I don't know.
                                   Take care, Bill

[Johnie]

What about the OEM exhaust?  Or are you not interested in restoration to the way it was back then.  Just wondering...

[fondofhondas]

this was an amazing "Barn buy" from a 70 year old man who oned it since 78. mint. i couldn't pass it up, especially with todays commuter issues. I love stock! don't get me wrong! I am amazed by a bike was designed by a number of high payed engineers in lab coats, that spent hours and hours to create every piece of superior product that reflects the amount of effort put into its creation.......stock. i just think i'm in the mood for louder pipes. thats all. hondas are known for their quiet operation, which is a symbol of their superior engineering. but, i would like a chance to "bark" back at the A-hole harley riders that think their bikes are the s#$t! my old boss ha a cx500 and put different exhaust on it and it sounded nasty....not obnoxious. 

[Hush]

Awesome find an auto!
I remember in the 70's seeing one of these but not since, almost a museum piece but don't do that, restore and ride that bad boy---you know you want to.

[Klark Kent]

these bikes are marvels of technology.  I would miss downshifting to pass and stuff like that, but smiles per mile should be the same.  welcome.

oh and if a harley rider feels the need to bark at you, just do what a lady i worked for did.  yell "sorry about your penis." or just know that whatever they are overcompensating for is not your problem and quietly leave him in your mirrors.  your neighbors will thank you too.

good luck

[DarkRider]

Cant see why a 4 into 1 couldnt be fitted to the bike..werent the bulk of the changes between the two on the left side of the machine?

[stresssolutions]

Isn't the "bark" created by the size of the cylinders?  My friend has a vtwin new honda 750 that sounds much more like the harley than mine.  4 small vs 2 large? 

Just wait till the mufflers rust out a bit on the ends...up towards 65 it gets pretty loud.

[fondofhondas]

sorry... I,m a 31 year old dude! and yes you can down shift with the auto trans by shifting down to "low" and get the engine break effect. its actually like a simi-automatic.
does anyone remember the old Volkswagen beetles that had the pressure clutch on the shifter? my dad used to have one of those......another rare set up it makes me think of.
anyway....gonna ride it. only Live once.

thanks

cheers

[Gordon]

Okay, I have to admit I've always been intrigued by the Hondamatics, because I don't really know much about how they work.  Sure, I've done plenty of reading on automatic transmissions, torque converters and stator clutches, but I generally have to see with my own eyes how something works before I can fully comprehend it. 

Maybe I just need to buy one and take it apart.

[jameseb444]

after reading all this I regret passing up a 350 Hondamatic for $150. It was a project bike that was close to being an old school bobber.

[Gordon]

I didn't even know they made a 350 hondamatic.

[jameseb444]

I didn't look the bike over that well. It was in pieces in the back of a pickup truck and he told me it was a 350. If I passed up a 750 I'll be pssed. Please don't tell me they only made 750's in the Hondamatic. 

[Klark Kent]

the only other one i know about was the cm400a- more likely than him thinking a 750 was a 360.  couldnt find any info on a 360A.

http://www.motorera.com/honda/h0400/amati400/amati400.htm

[Johnie]

Don't know what "bark" you are looking for, but my HM300's sound really old school.  Maybe listen to a bunch of different mufflers and then find your sound.  Then have at it...good luck with it.  Kind of cool to hear a Hondamatic bark...

[TwoTired]

Usually, louder pipes are that way because that have less restriction.  Stock carbs are tuned to the restriction of the stock exhaust.  Don't be too surprised if your louder bike runs worse until you rejet.

Just saying...

Cheers,

[05c50]

Hondamatics were made from 1976 to 1983. From 76-78 they were 750,78-81 they were 400, and 82-83 they were 450.
 I have just finished restoring a 77 750a and I don't know how much bark you can expect from a detuned 4 cylinder. Although it is a 750,it uses carbs very similar to the 550. Even without mufflers, it wasn't much of a bark. As always, I'll bet TT is right and it won't run quite right until you rejet to match the exhaust. The hondamatic isn't as forgiving with carbs that aren't just right...you can't slip the clutch to make up for other problems.
  The transmission is really a nice operating unit. Although I've done a lot of research, I can't find very may people that's ever had one apart. Nobody's ever had a problem, so why tear into it. The design is pretty simple- uses a torque converter much like a car and 2 hydraulic clutch packs-one for each gear.
.........Paul
http://i175.photobucket.com/albums/w140/05c50/Firstride001.jpg

[JLeather]

Nice looking bike...

Anyway, you can use later carbs on an auto as long as you don't mind holding the brake at stoplights (the older-style carbs won't have the idle adjuster thingy that the 'matic carbs have).  The earlier carbs will give it more "punch".  The engine part isn't any different than a normal CB750.  Any normal 4-1 exhaust will fit the engine.  The reason the 'matic exhaust is different is to clear the parking-brake assembly but a 4-1 will also fit since the parking brake is on the right.  An earlier set of carbs, good 4-1, and a good tune will have a 'matic keeping up with any decent pack of riders.  A couple guys on the hondachopper forum have built 'matic choppers and they've turned out very well.  You can also run 4-4 drag pipes if you're into that stuff.  The 'matic engine is a great engine.  There are a few guys drag racing them with modified torque-converters for higher stall.  I'm aiming to turbo one (as finances progress)...

[jameseb444]

Then I don't mind passing it up. I have finally decided I want a 750

[Chris Schneiter]

I have an aftermarket 4-1 that barks really loud, but here's an idea that might work without much work... and you can put it back if it doesn't run right.. I ran into a guy with a later 750SS, with 4-1's.... his bike had the mellowest sound I've heard on a 754... just a deep purr... he had just taken the packing out of his pipes, and then put the baffles back in for a little backpressure... sounded amazing! And seemed to run great..

[DarkRider]

wonder when someone is gonna take the chance and build an 836A? lol

[Hush]

Here's one I found for sale a while ago on Ebay, was so taken with the automatic idea I kept the photo for reference.