Author Topic: over heat 836  (Read 2676 times)

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Offline johnyvilla

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over heat 836
« on: May 30, 2010, 07:50:47 PM »
I rode fairly hard this am in 85. weather, taking my 836 up to red line quite a few times. I got home I turned the bike off to open the garage door. When I tried to turn the motor over again it wouldn't budge. I waited a good hr and it started up right away, but it still scared the crap out of me. I guess it's time to install the oil-cooler.

Do you still fill oil up to the dipstick full line with an oil cooler?

Offline scottly

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Re: over heat 836
« Reply #1 on: May 30, 2010, 07:59:46 PM »
Yeah, the oil cooler doesn't hold that much oil, at least the Lockhart I had didn't. Isn't this a new motor? Take it a bit easy for a while!!! ;)
Don't fix it if it ain't broke!
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Offline Gordon

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Re: over heat 836
« Reply #2 on: May 30, 2010, 08:05:12 PM »
Did you try to turn it over with the kick-start, too, or just the starter motor?  Is it possible you just have an intermittent starter problem? 

Offline 754

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Re: over heat 836
« Reply #3 on: May 30, 2010, 08:23:12 PM »
 If the Estart did not turn it I would not be worried yet..

 figure out if it is sticking or just not starting with the button..
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Offline Jerry Rxman Griffin aka MuthaF'er

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Re: over heat 836
« Reply #4 on: May 30, 2010, 08:25:34 PM »
Got yer jetting set properly?
As of today 3/13/2012 my original owner 75 CB750F has made it through 3 wives, er EX-wives. Free at last.  ;-)

Offline RRRToolSolutions

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Re: over heat 836
« Reply #5 on: May 30, 2010, 08:36:09 PM »
Kaws, Hondas, Yamahas, and Suzukis - especially Kaws

Offline johnyvilla

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Re: over heat 836
« Reply #6 on: May 30, 2010, 09:38:06 PM »
I jumped on the kickstarter and it barely budged. I thought the jetting was ok, I didn't overheat on a recent track day and I've since increased my mains and needles. It doesn't pop on decel or anything. 

Offline RRRToolSolutions

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Re: over heat 836
« Reply #7 on: May 31, 2010, 06:19:42 AM »
Take your time, ask Terry (in Austrailia) to machine you an adapter so you can use a high-quality K&N, find you an oil cooler from an early 1980's Nighthawk and you'll have the pieces for this I've got about $100 total - including the custom-made hoses that you can have done at your local hydraulic supply retailer.

I've had mine out on several vintage rides of 150 miles or more - traffic, constant speed riding, several 11,000 rpm jaunts for the Kerker music - never a hic-up. I have measured the oil in the side tank at the end of long rides and never over 195. Those guns won't read chrome, but point them onto any surface that's not shiny and you'll get the actual temps. I started using these years ago to help me tune my Kawasaki triple Mach III's and Mach IV's. You can change the temps on those easily with jetting.
 
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Offline sangyo soichiro

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Re: over heat 836
« Reply #8 on: May 31, 2010, 07:34:27 AM »
That is a beautiful setup you have there Ilbikes. 
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1972 CB 750 http://forums.sohc4.net/index.php/topic,57974.0.html
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Offline johnyvilla

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Re: over heat 836
« Reply #9 on: May 31, 2010, 11:34:14 AM »
I just dug up an old oil cooler that came with one of my 750s, and boy is it small. 5in by 2in to be exact. Do you guys think thats to small to make a differece? I would try to sorce a larger cooler but I am riding out of state fri.

Offline sandcastcb750

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Re: over heat 836
« Reply #10 on: May 31, 2010, 02:06:18 PM »
My 836cc ran hot too and sometimes tough to start when hot. More CCs and compression makes more work. I think they leak more.

Unfortunately, I destroyed my motor. Man, that thing was fast.

Offline fire113

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Re: over heat 836
« Reply #11 on: May 31, 2010, 02:19:02 PM »
My 836 runs fine without oil cooler.
If You like to use one don't forget a good thermostat!!! or the oil will take a loooooooooooog
time to get the working temperature.

cu...fire113
Honda CB750 K0 & K0 & K1 & K1 & K2 & K2 & K6

Offline Doctor_D

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Re: over heat 836
« Reply #12 on: May 31, 2010, 02:28:54 PM »
I just dug up an old oil cooler that came with one of my 750s, and boy is it small. 5in by 2in to be exact. Do you guys think thats to small to make a differece? I would try to sorce a larger cooler but I am riding out of state fri.

I'd say that anything is better than nothing, but I'm concerned that you've suffered a partial seizure.  Don't ask me how I know.

Do yourself a favor and do a compression and leakdown test sooner rather than later.
Take care,
David
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1978 CX500
1971 Norton Commando

Offline johnyvilla

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Re: over heat 836
« Reply #13 on: May 31, 2010, 06:27:59 PM »
It was definitely a partial seizure. I was just surprised how well it was running before I stop. Ran strong as ever and idled well. I jumped up and put all my weight on the Kicker and it moved 1/4 of a rotation.     
Why do I need to pressure test it. I have taken it out since then and I cannot recognize any loss of power or un characteristic running. 

Offline Doctor_D

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Re: over heat 836
« Reply #14 on: May 31, 2010, 06:44:35 PM »
Quick anecdote that may, or may not, apply.

I was running down the highway, pulled into the weaving lane at the offramp and wound it up on a relatively new motor that was built with close tolerances.  There was a very odd and somewhat violent miss on one of the cylinders nearing redline. Pulled in the clutch, and it stalled (actually it seized, unbeknownst to me).  Downshift to 3rd, little chirp at the back tire and it's back to life.  Baby'd it back home, it ran fine - maybe a little down on power.

A few weeks later, it started missing on one cylinder.  Plug had a little oil on it.  Not much, but enough.  Checked it, and it was down 20lbs.

Tore it down.  The piston, looked like this:


Hope that's not your problem.
Take care,
David
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1975 CB 750F - Project page: http://forums.sohc4.net/index.php?topic=66026.msg725479#msg725479
1978 CX500
1971 Norton Commando

Offline scottly

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Re: over heat 836
« Reply #15 on: May 31, 2010, 06:51:24 PM »
It was definitely a partial seizure.
Why do I need to pressure test it. I have taken it out since then and I cannot recognize any loss of power or un characteristic running. 

The Doctor thinks you had a partial piston/ring seizure, vs a bearing seizure, and may have damaged the seal of the rings. Sounds like you're OK, but I still think you need to break your motor in more. Short hops, ok to be a little bit aggressive, followed by cooling periods. If your problem was caused by tight pistons, an oil cooler probably won't help much.
Don't fix it if it ain't broke!
Helmets save brains. Always wear one and ride like everyone is trying to kill you....

Offline scottly

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Re: over heat 836
« Reply #16 on: May 31, 2010, 06:55:09 PM »
Doc, that's a total seizure!!! ;)
Don't fix it if it ain't broke!
Helmets save brains. Always wear one and ride like everyone is trying to kill you....

Offline eurban

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Re: over heat 836
« Reply #17 on: May 31, 2010, 07:11:18 PM »
My 836 likes D9EA plugs instead of the stock D8s.  It also likes a bit less ignition advance.  High octane gas too. . . . Are you certain that you have no air leaks?  Your float levels are correct?  Your idle circuit is clean?

Here's the oil cooler setup I run which is similar to Ilbikes except I run Lockhart thermostat. I actually think that my cooler should be mounted higher up to make certain that no airflow to the head is obstructed.  There's room but it means a bit of bracketry reworking . . . .

« Last Edit: May 31, 2010, 07:16:40 PM by eurban »

Offline johnyvilla

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Re: over heat 836
« Reply #18 on: May 31, 2010, 08:24:00 PM »
Carbs are squeaky clean with appropriate float levels and such. I actually turned out mt idle screws before I left that fateful day. No airleaks or surging.
I will richen my mains and needle, (separaty) ad the cooler and bring colder plugs with on this trip.

When I get back I am springing for a 15 dollar ebay nighthawk cooler: and check my compression.. 

Offline Doctor_D

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Re: over heat 836
« Reply #19 on: May 31, 2010, 08:43:25 PM »
Doc, that's a total seizure!!! ;)

Yep.

Clearances for forged pistons in air cooled motors are slightly more relaxed than JE suggested when I bought them. Found out too late that the clearances were for WATER COOLED ENGINES.

 :(
Take care,
David
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1975 CB 750F - Project page: http://forums.sohc4.net/index.php?topic=66026.msg725479#msg725479
1978 CX500
1971 Norton Commando

Offline scottly

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Re: over heat 836
« Reply #20 on: May 31, 2010, 08:51:40 PM »
Were the 2nd compression ring and oil ring stuck in the grooves above the scored area of the piston skirt?
Don't fix it if it ain't broke!
Helmets save brains. Always wear one and ride like everyone is trying to kill you....