Author Topic: big bore oil leak and ? about operating temp  (Read 1100 times)

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Offline fang

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big bore oil leak and ? about operating temp
« on: September 09, 2014, 10:30:39 AM »
Hi all.
I got another of my old 900cc Henry Abe big bore motors assembled and running.....  But it turns out the Cylinders are leaking oil between the jugs. (It has those big H.A liners in there).  Are there any suggestions on how to fix this without tearing it all apart?  I just got it back together (again) because I first thought the leak was a base gasket.

I also am wondering about the operating temp. I am thinking this bike might be running a bit hot, and am wondering what is a normal oil temp range for a 900c bike on a 104°F/ 40°C  day.

Peace and Grease,
-Fang
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Offline NalleyRacing

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Re: big bore oil leak and ? about operating temp
« Reply #1 on: September 09, 2014, 10:56:34 AM »
I'm down in New Braunfels bud. I've got the 912  my turbo Honda. We need to get together and talk bikes sometime.

Offline Jerry Rxman Griffin aka MuthaF'er

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Re: big bore oil leak and ? about operating temp
« Reply #2 on: September 09, 2014, 12:00:50 PM »
Without tearing it apart? I wish so but I can't think of a proven way. When Jay did my 1000 kit he broke through and epoxied the space between the jugs. When I put my HA900 together I used CB900 cylinder o-rings hoping that will do the trick. No real miles yet though. I have seen crude exterior epoxy jobs too. Not sure how effective that may be??

They gotta run hotter you'd think. Jet em right, oil cooler and run synthetic bike oil. What else can we do besides stay out of heavy stop and go traffic?!

Good luck! Been a long road for both of us  ::)
As of today 3/13/2012 my original owner 75 CB750F has made it through 3 wives, er EX-wives. Free at last.  ;-)

Offline PeWe

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Re: big bore oil leak and ? about operating temp
« Reply #3 on: September 09, 2014, 01:03:02 PM »
About running hot. The cam might make a difference?
Longer duration with more overlap, less dynamic compression.
Thats why have a Megacycle 125-25 in the order phase. Hopefully cooler engine.

My previous cams:
Action Fours SS-1  lift 0.361  dur  255/256 @ 0.004 lift (Engine not hot with less compression pistons used back in the 80's)
CX7  as Megacycle 125-75 but 3 degress more.

EDIT: I was thinking about an oil cooler. Got a Setrab 10 rows but got cold feet when the oil pressure to cam might decrease with an oil filter adapter for oil hoses.
« Last Edit: September 09, 2014, 01:16:10 PM by PeWe »
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline fang

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Re: big bore oil leak and ? about operating temp
« Reply #4 on: September 09, 2014, 06:53:06 PM »
Does anyone have a "normal" hot temp range for stock and/or Big Bore motors? 

What might be truly TOO HOT?

-Fang
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Offline PeWe

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Re: big bore oil leak and ? about operating temp
« Reply #5 on: September 10, 2014, 02:04:58 AM »
My engine is and was 836 (still small bore). Oil temp measured in oil tank, 110-120C after 20km trip and not hot day, 15-20C.
110C when driving slowly (100-120km/h), 120C when driving 130-170km/h most of the time.

A list of common oil temps vs tuning would be good information.
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline fang

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Re: big bore oil leak and ? about operating temp
« Reply #6 on: September 10, 2014, 06:03:41 PM »
I was seeing high temps around 235°F with sustained, high speed travel....

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Offline fang

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Re: big bore oil leak and ? about operating temp
« Reply #7 on: September 11, 2014, 12:03:25 AM »
I have 3 of the 900cc cylinder blocks, bored for Henry Abe Pistons.  Decided to just switch this one out for another that does not have the problem.  I'll see see what can be done about this one at a later time. 

Thanks for the comments.
Download Nervous Norvus' "The Fang"  HERE.
Tired of eating CRAP!