Author Topic: my plan to un-freeze a 1974 cb750 motor  (Read 23301 times)

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bennecc

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Re: my plan to un-freeze a 1974 cb750 motor
« Reply #25 on: October 10, 2010, 10:42:56 PM »
I used acetone and ATF earlier tonight....worked like a charm!

Offline The_Crippler

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Re: my plan to un-freeze a 1974 cb750 motor
« Reply #26 on: October 11, 2010, 05:31:33 AM »
Try kitty litter on the oil spots [or oil absorbant].

This.  I keep a bag of kitty litter in the shop just for that.  (These CBs like to mark their territory, or way or another.)

Offline MasterChief750

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Re: my plan to un-freeze a 1974 cb750 motor
« Reply #27 on: October 11, 2010, 07:58:58 AM »
if kitty litter doesnt work. some dish soap like dawn. full concentrate, pour it all over the spot, let it sit fo about 20 min then hose it off. rinse and reapeat as necessary. had some people pick up a sbc from me and they flipped the motor over on the stand and it lost its load all over my parents driveway, dish soap worked like a charm.
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Offline MCRider

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Re: my plan to un-freeze a 1974 cb750 motor
« Reply #28 on: October 11, 2010, 08:19:50 AM »
I used acetone and ATF earlier tonight....worked like a charm!
Here's the post/test. Other things may work, nothing works better. IMO
http://forums.sohc4.net/index.php?topic=20131.0
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Offline MCRider

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Re: my plan to un-freeze a 1974 cb750 motor
« Reply #29 on: October 11, 2010, 08:23:39 AM »
Try kitty litter on the oil spots [or oil absorbant].

This.  I keep a bag of kitty litter in the shop just for that.  (These CBs like to mark their territory, or way or another.)
I use commercially available Oil-Dri (like kitty-litter but purpose built). From the Auto PArts store. The key is elbow grease. After spreading a bit of oildri, I use a block of wood, like a 8-10" length of 2x4, and grind the oildri into the spot..HARD. It will turn the oildri into dust and the oil will be removed completely. Sweep and discard.
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"Sometimes the light's all shining on me, other times I can barely see, lately it appears to me, what a long, strange trip its been."

Offline The_Crippler

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Re: my plan to un-freeze a 1974 cb750 motor
« Reply #30 on: October 11, 2010, 08:30:36 AM »
Ha!  I just toss down the little, let it sit for a few days, scoop it up and say, "Is it gonna get on my boots and track in the house now?  No." and call it a day.

But, I'm betting your garage floor is cleaner than mine.

Offline dna_level_c7

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Re: my plan to un-freeze a 1974 cb750 motor
« Reply #31 on: October 11, 2010, 10:07:56 AM »
+1 On the kitty litter.

I keep that in the garage at all times because I live in an apartment building and they frown on stains in the garage! Last big spill was a power steering line bursting on my Grand Prix coming home from work.

I put some kitty litter down and let it sit for a few hours. Then swept up and repeat until it’s mostly dry. Then I used Palmolive dish soap and let that sit for about an hour. Rinse it down with the hose and scrub with a push broom. Repeat a few times. The next day I couldn’t even tell where the stains were at!  8)
« Last Edit: October 11, 2010, 10:10:32 AM by dna_level_c7 »
1977 CB750K Stock

Offline Hondawggie

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Re: my plan to un-freeze a 1974 cb750 motor
« Reply #32 on: October 11, 2010, 02:14:26 PM »
I really appreciate the cleaning tips, this is an apartment complex asphalt parking lot.  I'm going to get some oil dry and some dish soap and have at it.  The bike is cool now, soon I hope the spots will be 86'd. 

Offline Stev-o

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Re: my plan to un-freeze a 1974 cb750 motor
« Reply #33 on: October 11, 2010, 06:28:23 PM »
I made the ATF/Acetone "cocktail" today and served it up to my project 750K!
'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline Stev-o

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Re: my plan to un-freeze a 1974 cb750 motor
« Reply #34 on: October 14, 2010, 06:43:36 PM »
Got mine unstuck today! And Pete, beat your record, mine shot for 18'8"!!
But my kickstart won't budge, what else should I do?

'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline zzpete

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Re: my plan to un-freeze a 1974 cb750 motor
« Reply #35 on: October 14, 2010, 07:24:33 PM »
Got mine unstuck today! And Pete, beat your record, mine shot for 18'8"!!
But my kickstart won't budge, what else should I do?


Dam!!! My record only stood for 3 months. Next time Im filling the cylinders to the top and going for 20 feet!!  :o :D ;D
"One of the things that make motorcycling so great because it never fails to give you a feeling of freedom and adventure." - Steve McQueen

Offline Stev-o

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Re: my plan to un-freeze a 1974 cb750 motor
« Reply #36 on: October 14, 2010, 07:56:50 PM »
Kickstart won't budge, what next?
'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline Hondawggie

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Re: my plan to un-freeze a 1974 cb750 motor
« Reply #37 on: October 14, 2010, 08:23:46 PM »
Kickstart won't budge, what next?

This probably won't help in your situation Meriggi, but -- after I got mine unstuck in 5th gear, my kickstarter 'wouldn't budge' either.

Or so I thought.  In my case, I wasn't sitting on the bike when I tried that, I was kicking from the side.  Normally though that should have done it!

It was almost like the kickstart lever had been in that position long enough for corrosion to make it not want to leave that position -- when I pulled the kickstart lever *completely* out -- and I stood on the right side of the bike facing backward, and using my right foot, I pushed hard the kickstart lever in the rearward direction -- not downward, I applied all my leg strength to push the kickstart lever backward -- it came free.

It is still 'sticky' at the 'resting' position where it has sat for a long time.  But once I move it past the sticky 'fully at rest' position it works fine.

Like I said though your situation might be different.  I was getting ready to disassemble that part of the motor until I did the hail-mary there, pushing the pedal backward with my leg about parallel to the ground.

Offline Stev-o

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Re: my plan to un-freeze a 1974 cb750 motor
« Reply #38 on: October 14, 2010, 08:26:06 PM »
I will try that method. Why don't you think it will work for me?
'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline Hondawggie

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Re: my plan to un-freeze a 1974 cb750 motor
« Reply #39 on: October 14, 2010, 09:27:27 PM »
I will try that method. Why don't you think it will work for me?

My case is odd, the durned thing's sat for 10 years, I doubt yours has for that long, it sounds like yours responded pretty fast to the atf+acetone whereas I had to be more patient.  Just give it a try.  Even now if I try to move my kicker it doesn't come free from the 'rest' position very easily, truth be told I probably need to open her up and clean up whatever is causing that initial stickiness.

Offline dave500

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Re: my plan to un-freeze a 1974 cb750 motor
« Reply #40 on: October 14, 2010, 09:35:15 PM »
yeah id also dissemble the clutch pack,itll be stuck together well and might be your next hurdle when you fire it up,even though the lever at the bars might move ok ill bet the pack is frozen together,if the cover is off do as much in there as you can.

Offline Hondawggie

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Re: my plan to un-freeze a 1974 cb750 motor
« Reply #41 on: October 15, 2010, 11:36:33 AM »
Okay I need to dive in to this bike now and get her going, I was going to use a fuel hose to siphon out the atf+acetone mixture still sitting in the cylinders.  First I though to use my shop-vac with a jury-rigged small-enough hose that is duct taped to the small attachment to make a good seal.  But not sure if the atf+acetone will ace my shop-vac (probably will).

I filled the cylinders to overflowing with atf+acetone, there is a lot to remove. 
Is siphoning the way to go here?

Offline Duke McDukiedook

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Re: my plan to un-freeze a 1974 cb750 motor
« Reply #42 on: October 15, 2010, 11:47:51 AM »
You could use a Mightyvac vacuum pump. I use mine to bleed brake and siphon out small quantities of fluids.

There was no need to use that much fluid in the first place, you only need enough to have a thin layer above the piston- adding more than that does not give you any more advantage.
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Offline MCRider

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Re: my plan to un-freeze a 1974 cb750 motor
« Reply #43 on: October 15, 2010, 11:53:29 AM »
Okay I need to dive in to this bike now and get her going, I was going to use a fuel hose to siphon out the atf+acetone mixture still sitting in the cylinders.  First I though to use my shop-vac with a jury-rigged small-enough hose that is duct taped to the small attachment to make a good seal.  But not sure if the atf+acetone will ace my shop-vac (probably will).

I filled the cylinders to overflowing with atf+acetone, there is a lot to remove. 
Is siphoning the way to go here?
If you've turned the engine over, by now its all in the carburetors, exhaust pipes and crankcase, I'd think. Let it sit overnight if not already and pull the drain plug, then the pan, see how much comes out. Pull the carbs too. Shouldn't hurt the pipes I'd think. Just smoky as heck on start up.
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1988 NT650 HawkGT;  1978 CB400 Hawk;  1975 CB750F -Free Bird; 1968 CB77 Super Hawk -Ticker;  Phaedrus 1972 CB750K2- Build Thread
"Sometimes the light's all shining on me, other times I can barely see, lately it appears to me, what a long, strange trip its been."

Offline Hondawggie

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Re: my plan to un-freeze a 1974 cb750 motor
« Reply #44 on: October 15, 2010, 12:44:54 PM »
Okay I need to dive in to this bike now and get her going, I was going to use a fuel hose to siphon out the atf+acetone mixture still sitting in the cylinders.  First I though to use my shop-vac with a jury-rigged small-enough hose that is duct taped to the small attachment to make a good seal.  But not sure if the atf+acetone will ace my shop-vac (probably will).

I filled the cylinders to overflowing with atf+acetone, there is a lot to remove. 
Is siphoning the way to go here?
If you've turned the engine over, by now its all in the carburetors, exhaust pipes and crankcase, I'd think. Let it sit overnight if not already and pull the drain plug, then the pan, see how much comes out. Pull the carbs too. Shouldn't hurt the pipes I'd think. Just smoky as heck on start up.

Good call on the carbs!  Thankfully they were off before the atf+acetone, and the pipes are clean-able.  I'm sure that she will be smoking like a fish at first start up!

As to filling it up, I thought it was a tremendous long shot that the atf+acetone would work at all after 10 years the bike sat.   I purposely did that to take advantage of any minute benefit of the extra fluid weight.  The other thing is, I have a cbx with a stuck motor and for well over a month I was piling on every few days with Amazing Blaster and despite that, the cbx still wouldn't free up, so this time, with the 750 I did a hail mary and filled the holes to the top with this new-to-me unsticker fluid. 

I can't wait to try this atf+acetone in the cbx.  It only has 23k on the clock but sat outside for a season, then got put into a storage container wet.


Offline thelowmax

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Re: my plan to un-freeze a 1974 cb750 motor
« Reply #45 on: December 03, 2010, 07:13:41 AM »


"The kickstarter is locked, so this bike probably has a stuck motor."

"Stuck?  What do you mean, stuck, it was running when it was parked." (tries the kickstarter)

"How long ago was it parked?"

"Ten years."

I love it when people try to sell you what they think is Cortez's lost treasure.  I recently had a conversation about a bike with a stuck engine, that went something like this.

"I'll give you what it's worth considering it's condition".

"I can't go that low. Don't you realize how rare this is?"

"Yeah I do. It's almost as rare as the customers lining up to buy it ::)".

"But you could take it all apart, clean it up and it will be like new. You just have to replace a few parts".

"So, considering time, effort, and money, for the price of a good running bike, I could get a bike that may never run?"

"when you say it like that it seems like a bad deal."

Even the seller couldn't keep a straight face at that point. Too funny.







 

What am I doing and why am I doing it? Those are excellent questions.

'72 Amen Savior/'77 CB750K Chrome/Da Bhudda(project)
'73 CB750K Green/El Verde (beat)
'76 CB750K Red/The Cinnabomb (sweet)
'77 CB750K Black (frame and parts) CANNIBALIZED
'77 CB750K Dark Purpley/Scooty Puff, Jr. (la beast)
'78 CB750K Black (struggling) SOLD
'78 CB750K Blue Flake/CiocioSan (minty)
'81 CB750C Poiple/Barbie'sDreamMotorcycle SOLD (darnit!)
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Offline thelowmax

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Re: my plan to un-freeze a 1974 cb750 motor
« Reply #46 on: December 03, 2010, 07:25:38 AM »

 First I though to use my shop-vac with a jury-rigged small-enough hose that is duct taped to the small attachment to make a good seal.  But not sure if the atf+acetone will ace my shop-vac (probably will).


I wouldn't recommend using a shop vac to remove the liquids. The atf+acetone mixture and it's heavy fumes are HIGHLY flammable and a shop vac has an electric motor that sparks very easily. The situation can be down-right explosive. Unsticking an old engine is tough but unsticking a burned engine is even harder, particularly if all your tools and shop have burned too :-\.

 
What am I doing and why am I doing it? Those are excellent questions.

'72 Amen Savior/'77 CB750K Chrome/Da Bhudda(project)
'73 CB750K Green/El Verde (beat)
'76 CB750K Red/The Cinnabomb (sweet)
'77 CB750K Black (frame and parts) CANNIBALIZED
'77 CB750K Dark Purpley/Scooty Puff, Jr. (la beast)
'78 CB750K Black (struggling) SOLD
'78 CB750K Blue Flake/CiocioSan (minty)
'81 CB750C Poiple/Barbie'sDreamMotorcycle SOLD (darnit!)
'89 Trek 21" 21 speed Green/YaBiatch (the wife)
Converse One Stars size 8.5 Black/Sneaks (suede)

Offline dirtmagnit

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Re: my plan to un-freeze a 1974 cb750 motor
« Reply #47 on: December 05, 2010, 02:37:56 PM »
"It's almost as rare as the customers lining up to buy it"

That rocks.  Good call on the explosivity. 
I'd rather burn rubber than clutch...

Another Honda sucker. Currently..  76 CB550F Project, 75 CB750k, and rides a GL1000 daily.
Past:CB400f(75');CB350F(73'?);CB550K(74');CB550F(76');CB400F(75');GL1000(77') and others(I'm tired..)

Offline Hondawggie

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Re: my plan to un-freeze a 1974 cb750 motor
« Reply #48 on: December 05, 2010, 10:22:48 PM »

 First I though to use my shop-vac with a jury-rigged small-enough hose that is duct taped to the small attachment to make a good seal.  But not sure if the atf+acetone will ace my shop-vac (probably will).


I wouldn't recommend using a shop vac to remove the liquids. The atf+acetone mixture and it's heavy fumes are HIGHLY flammable and a shop vac has an electric motor that sparks very easily. The situation can be down-right explosive. Unsticking an old engine is tough but unsticking a burned engine is even harder, particularly if all your tools and shop have burned too :-\.


Sheesh I'm glad I got sidetracked a bit.  My 750 is waiting for my attention.  I came across of couple of deals I could not pass up, like any good moto addict couldn't pass on, and the miniscule free time I have away from work have gone to those .  I have a small disc-brake vacuum bleed pump now I'm going to use on my 750 to remove the ATF/acetone.  Thanks for the potentially injury-saving advice!

Offline dirtmagnit

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Re: my plan to un-freeze a 1974 cb750 motor
« Reply #49 on: December 14, 2010, 06:14:07 PM »
Thanks for all the info on here on this, as I picked up a K5 week before last with a seized motor.  Tried the acetone/ATF trick, and damn!  6 days is all it took on a bike with 7 years outside and an 836 kit.  Mostly stock other than that. 

Two cylinders at 140-150, and two at 65psi.  Soaking them again to see where it gets me...
I'd rather burn rubber than clutch...

Another Honda sucker. Currently..  76 CB550F Project, 75 CB750k, and rides a GL1000 daily.
Past:CB400f(75');CB350F(73'?);CB550K(74');CB550F(76');CB400F(75');GL1000(77') and others(I'm tired..)