Author Topic: how durable is this trans  (Read 3934 times)

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Offline salukispeed

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how durable is this trans
« on: April 17, 2012, 09:45:25 AM »
I just picked up a 77 750A with 19,000 on the clock. After a week of TLC it runs and drives great but is a little ugly from sitting  in a shed for 4-5 years. It is cleaning up fairly well and is all original I also have a ATP turbo Kit for the 750K that looks like it would be a blast but I do not know if 10 LBS boost would be tolerated by the trans. I never had problems with My 750 K4 when the kit was on it but it badly needed clutch  help to cope with the added power . Has this been done before??

 I also have a set of Bates bags an trunk I removed from it that I would trade for a grab rail and rear turns. The bags are good and the hardware is rusty but seems complete.
1974 CB750 K4
1970 CT70
1966 CA77 (305 Dream)
1984 GL1200 Interstate
1977 750A
1972 CL100

Offline jukku

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Re: how durable is this trans
« Reply #1 on: April 17, 2012, 11:33:17 AM »
Dale built this 890cc Hondamatic strictly to bracket race in 1978. He gave the car guys fits, winning almost every Wednesday night and on Sundays. It only ran 12.30's, but every pass was within a hundredth of a second and that what it takes to win at bracket racing.
http://www.holeshot.com/old/dwracing/890cc.jpeg

Offline salukispeed

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Re: how durable is this trans
« Reply #2 on: April 17, 2012, 06:13:07 PM »
Thanks, This bike is no show piece any more but it is very complete so I am torn between leaving it as is and just drive it or adding the turbo.
1974 CB750 K4
1970 CT70
1966 CA77 (305 Dream)
1984 GL1200 Interstate
1977 750A
1972 CL100

Offline 05c50

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Re: how durable is this trans
« Reply #3 on: April 17, 2012, 06:35:47 PM »
There's very little information available about the 'matic transmission because they just don't go bad! They are very durable and very few people have ever had them apart. My vote for your bike is Turbo!! I'd love to see it!

.............Paul
Wear a helmet,the life you save may be your own.Ask me how I know.               CB650C,CB550F,GL1000,CB750A

Offline Retro Rocket

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Re: how durable is this trans
« Reply #4 on: April 17, 2012, 06:54:52 PM »
There's piles of info in the "Hipo" section of the forum, there's a few guys here that drag race the auto's...

Ask questions here...    http://forums.sohc4.net/index.php?topic=61876.msg1179508#new
« Last Edit: April 17, 2012, 06:57:21 PM by Retro Rocket »
750 K2 1000cc
750 F1 970cc
750 Bitsa 900cc
If You can't fix it with a hammer, You've got an electrical problem.

Offline salukispeed

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Re: how durable is this trans
« Reply #5 on: April 18, 2012, 09:46:59 AM »
Thanks for the link.  I went looking thru the box of Turbo parts last night, and realized the kit I still have is actually from my 1976 550K so some fabrication will be needed for sure. I will have to dust off my Tig welder and get some tubing. I still have the 750 intake manifold so it is not a complete fab job. but will take me a while. Speed is not my best quality.

Thanks again. This is a great site for info and sharing ideas
1974 CB750 K4
1970 CT70
1966 CA77 (305 Dream)
1984 GL1200 Interstate
1977 750A
1972 CL100

Offline Sam Green Racing

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Re: how durable is this trans
« Reply #6 on: April 19, 2012, 03:08:12 PM »
The tranny can handle well over 100cbhp, DO IT. ;)

Sam ;)
C95 sprint bike.
CB95 hybrid race bike
CB95 race bike
CB92
RS 175. sprint/land speed bike
JMR Racing CB750A street ET drag bike

Offline salukispeed

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Re: how durable is this trans
« Reply #7 on: April 20, 2012, 05:59:03 PM »
It will be on the burner but at a low flame. I will start working towards it. Thanks All
1974 CB750 K4
1970 CT70
1966 CA77 (305 Dream)
1984 GL1200 Interstate
1977 750A
1972 CL100

Offline Really?

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Re: how durable is this trans
« Reply #8 on: April 20, 2012, 06:02:10 PM »
The tranny can handle well over 100cbhp, DO IT. ;)

Sam ;)

Now Sam, quit acting like you know something about the auto's!
I don't have a motorcycle, sold it ('85 Yamaha Venture Royale).  Haven't had a CB750 for over 40 years.

The Wife's Bike - 750K5
The Kid's Bike - 750K3

Offline Sam Green Racing

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Re: how durable is this trans
« Reply #9 on: April 21, 2012, 10:25:17 AM »
REALLY?.....the truth is I really really don't ;D ;D ;D I just get to ride it and get told off if I so much as look at a wrench ::)

I do know that the Auto looses about 30bhp through the tranny compaired to the manuals 17bhp.
Add 30bhp to my 87 rear wheel bhp and it equals 117 crank bhp. Simple REALLY? ;D ;D ;D ;D

Sam. ;)
C95 sprint bike.
CB95 hybrid race bike
CB95 race bike
CB92
RS 175. sprint/land speed bike
JMR Racing CB750A street ET drag bike

Offline Greggo

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Re: how durable is this trans
« Reply #10 on: April 21, 2012, 10:31:15 AM »
Want to sell off those 550 turbo parts you're not using?

Offline Sam Green Racing

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Re: how durable is this trans
« Reply #11 on: April 21, 2012, 10:53:13 AM »
Dale built this 890cc Hondamatic strictly to bracket race in 1978. He gave the car guys fits, winning almost every Wednesday night and on Sundays. It only ran 12.30's, but every pass was within a hundredth of a second and that what it takes to win at bracket racing.
http://www.holeshot.com/old/dwracing/890cc.jpeg

Heippa Jukku,
Do you have any more info on Dales bike?

Voi hyvin
Sam. ;)
C95 sprint bike.
CB95 hybrid race bike
CB95 race bike
CB92
RS 175. sprint/land speed bike
JMR Racing CB750A street ET drag bike

Offline jukku

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Re: how durable is this trans
« Reply #12 on: April 22, 2012, 07:36:15 AM »
Nope. Just a couple of magazine-articles on the net!
Welcome to Finland this summer.

Offline Sam Green Racing

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Re: how durable is this trans
« Reply #13 on: April 22, 2012, 08:24:01 AM »
Heippa Jukku,
do you have any links to the articles?
I'l be over the last week in June and a few days into July with Juha Leino and family.
We will be at Alastaro for a Finnish Championship event where we will both be competing and the following weekend for a European Championship round where his son Jesse will be riding in the Junior class, hope you will be able to make it for a meet up.

Voi hyvin,
Sam. ;)
C95 sprint bike.
CB95 hybrid race bike
CB95 race bike
CB92
RS 175. sprint/land speed bike
JMR Racing CB750A street ET drag bike

Offline Bill/BentON Racing

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Re: how durable is this trans
« Reply #14 on: April 23, 2012, 05:01:56 PM »
REALLY?.....the truth is I really really don't ;D ;D ;D I just get to ride it and get told off if I so much as look at a wrench ::)

I do know that the Auto looses about 30bhp through the tranny compaired to the manuals 17bhp.
Add 30bhp to my 87 rear wheel bhp and it equals 117 crank bhp. Simple REALLY? ;D ;D ;D ;D

Sam. ;)I figured @ 114,I like 117 better....One badazz automatic! Bill
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Offline jukku

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Re: how durable is this trans
« Reply #15 on: April 24, 2012, 10:30:04 AM »
""I do know that the Auto looses about 30bhp through the tranny ... ""

What is left of the original 49 japs-hp?

The Auto is still rolling forward!  :o

Offline jweeks

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Re: how durable is this trans
« Reply #16 on: April 24, 2012, 01:00:52 PM »
The transmission  is only as strong as the replaceable clutch discs in it. After 19k miles, I'd be replacing them with new ones from the 70's Honda  Civic. We've had topics covering their replacement. If you keep the boost very low, you  may get away without replacing the clutch packs for a while. When it starts sounding like clutch slippage when you shift from low to high gears, it is. The transmissions handle upwards of 125 horses without problems if the clutch packs are fresh. I've run 100 horses at the rear tire in my Hondamatic drag bike. Remember to keep the oil cool. Turbo's tend to warm things up in a hurry. Come over to the high performance section with questions as you get closer to doing your project.

                                                              Jon Weeks

Offline salukispeed

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Re: how durable is this trans
« Reply #17 on: April 27, 2012, 09:35:19 AM »
Thanks for all the thoughts and info. I will get with the hypo guys when I get going on it seriously. My 19 year old son thinks this is the best idea ever. 

I will keep the old 550 turbo left overparts on the shelf  for the time being.

1974 CB750 K4
1970 CT70
1966 CA77 (305 Dream)
1984 GL1200 Interstate
1977 750A
1972 CL100