Author Topic: 1974 Honda 750 froze solid in 4 months of sitting/ Now 35 years later! (Read 13005 times)

Kris · « **on:** May 20, 2012, 12:58:41 PM »

First off, glad to find this place. Hope to find a ton of good info. I'm a diesel mech, but have VERY little experience on motorcycle engines. Here is my situation.

My father in law bought a 1974 honda 750 brand new in 1974. He rode the bike for 3 years putting 3500 mi on it. He parked the bike feb of 1977 and four months later the kick start would not budge.( you can shift the gears and the clutch works) He tried taking the plugs out and adding some diesel fuel or something to the cylinders to free it up, tried pushing it off, but it would just skid the rear tire. So he put into dry storage and its been there ever since.

So fastforward to yesterday. 35 years later.( Im 32) He brought it to my house and wants me to try to unstick the motor. I have read a few threads about marvel mistery oil, pb blaster, trans fluid, and I will try one of these methods.

He said that it ran perfect to the day that he parked it. Is there anyway a timing chain might have fallen off or something?

Thanks for your time in advance, Kris

cmonSTART · « **Reply #1 on:** May 20, 2012, 01:01:48 PM »

Where was this bike stored for 4 months? It's pretty routine for folks to store a bike for months over the winter with no issues.

Welcome!

Kris · « **Reply #2 on:** May 20, 2012, 01:05:33 PM »

I will have to ask him, I think it was inside of a garage. Thats why I have a hard time with the motor seizing in just four months. Now, whether it was then or not. It more then likely is now after sitting that long.

Greggo · « **Reply #3 on:** May 20, 2012, 01:09:49 PM »

Locked after just four months of sitting...with only 3500 miles? Sumthin ain't right inside that motor. Kind of a shame he didn't bring it back to the Honda dealer way back when instead of mothballing it, but I guess that set it on its journey to your garage

Even if you free up the pistons (if that's what was really stuck) I'd say that motor has to come out of the frame for a full inspection.

Kris · « **Reply #4 on:** May 20, 2012, 01:27:06 PM »

Quote from: Greggo on May 20, 2012, 01:09:49 PM

Locked after just four months of sitting...with only 3500 miles? Sumthin ain't right inside that motor. Kind of a shame he didn't bring it back to the Honda dealer way back when instead of mothballing it, but I guess that set it on its journey to your garage Even if you free up the pistons (if that's what was really stuck) I'd say that motor has to come out of the frame for a full inspection.

Agreed, No way I could just shove it in the corner and forget about it for this long. He is older now and is super tight, but if I can get this thing to turn freely I think that he might spend some money on it.

BeSeeingYou · « **Reply #5 on:** May 20, 2012, 04:42:15 PM »

Quote from: Kris on May 20, 2012, 12:58:41 PM

He said that it ran perfect to the day that he parked it. Is there anyway a timing chain might have fallen off or something?

I think he is misremembering something...or just covering up a screw up on his part. Get a few beers in him and get the real story.

I have two bikes that sat for long periods, one 20 years and the other 25. They both turned over freely. Now if it had been sitting within throwing distance of the ocean, maybe...but Tennessee?

killersoundz · « **Reply #6 on:** May 20, 2012, 06:33:01 PM »

After working on a frozen barn fresh 750 I would not recommend just trying to free the motor up. You see once I got into my motor I realized why. Cylinder 4 on mine had some rust in it, since the exhaust valve was open on that cylinder while it was stored. The cylinder wall had rust and the piston rings rusted themselves into the grooves. They were rusted rock solid in the grooves. So even after I got the pistons moving free, it was still sticky and would have caused serious damage if I tried to run it with the frozen piston rings. They would have not freed up on their own.

I'm going to assume this motor is in a similar situation. I would advise to tear it down, replace the rings, hone the cylinders, clean it up.

dave500 · « **Reply #7 on:** May 21, 2012, 01:32:07 AM »

maybe he only did a few short runs just before it was parked and not getting the motor up to full hot temp to clear away condensation?then whats been sitting has rusted?

lrutt · « **Reply #8 on:** May 21, 2012, 04:09:19 AM »

or maybe a mouse built a next in there, or the gas was left on and flooded the engine, hydrolocking a cylinder, who knows. Acetone and ATF, keep adding and let it set a month. The get it on the side stand with bike in 4th gear and start rocking the back tire back and forth, it will work loose.

Johnie · « **Reply #9 on:** May 21, 2012, 05:23:32 AM »

Yah, hard to believe it froze up that fast. Never heard of something like that before...not with a Honda. Any chance he accidentally left it in gear back then and just never went back to it? In any case, you may as well plan on removing it from the frame. I picked up a 74 CB750 parts bike with froze motor. I ended up having to split the cases to remove the pistons from the crank. Then I could get the head off to work on freeing up the pistons. And it took many months to free those up. And this was a K4 with only 4,500 miles on it. The guy had bought a HD and just let the K4 sit for like 20 years.

Kris · « **Reply #10 on:** May 21, 2012, 06:22:19 AM »

Thanks for all the replys guys. Kinda intimidated by the thing to be honest. I've built gas, diesel engines before but never a small engine. Is it a straight forward thing. Somthing that a nivice could tackle? It would be sweet if it was just froze up, but I'm with you guys. Having a hard time with it froze in 4 months.

Greggo · « **Reply #11 on:** May 21, 2012, 08:21:06 AM »

Quote from: Kris on May 21, 2012, 06:22:19 AM

Is it a straight forward thing. Somthing that a nivice could tackle?

Get yourself a workshop manual and have some fun! It's not more complicated than most engines, and plenty of novices have torn them apart, and rebuilt them better with the help and guidance available on this forum.

killersoundz · « **Reply #12 on:** May 21, 2012, 08:40:36 AM »

I've never actually wrenched inside a motor like this before, but I have done a lot of reading and educated myself on everything. Going good so far!

Eydugstr · « **Reply #13 on:** May 21, 2012, 02:42:56 PM »

Quote from: Kris on May 21, 2012, 06:22:19 AM

Thanks for all the replys guys. Kinda intimidated by the thing to be honest. I've built gas, diesel engines before but never a small engine. Is it a straight forward thing. Somthing that a nivice could tackle? It would be sweet if it was just froze up, but I'm with you guys. Having a hard time with it froze in 4 months.

Don't let it scare you away. Basically it's similar technology to what was around at the time, just arranged in a different way. Great parts availablility on that year.

OneWheelDrive · « **Reply #14 on:** May 21, 2012, 03:02:54 PM »

Subscribed to see the solution you hopefully find :-D

lone*X · « **Reply #15 on:** May 21, 2012, 03:35:44 PM »

Welcome aboard. Don't feel intimidated by the Honda. It is just a 4 stroke engine with carbs. Other things to consider. What does the tank look like? If left with gas in it when it was set up it will need a lot of attention as well as the carbs. If the carbs were drained or ran dry they shouldn't be too bad, but will need a good cleaning. Brakes will need a complete rebuild. The fluid turns to gunk and everything will be froze.

My father-in-law is long gone and very much missed but I always thought I had enough material on him to write a best seller book of humor. I told him once that if I did write it I would share the royalties with him. He told me to be kind in what I wrote and I could keep it all. Had a big grin on his face when he told me that. He had every tool that Sears would sell him but couldn't change a fan belt on his car. When he passed away he had three shop saws, 12 year old table saw and radial arm, and a 7 year old band saw, all three still in the boxes. Had a couple of nice circular saws but he still used a handsaw instead. Just collected tools of every sort. Gotta love the father-in-laws. Now I am one, twice. Wonder what my son-in-laws will write about me.

Kris · « **Reply #16 on:** May 23, 2012, 04:58:21 PM »

Well, I think that I'm gonna tackle this rebuild job. Waiting to get the green light from him. I will keep everyone updated as I'm sure I will have many questions.

Maybe I can make a rebuild thread out of it for someone else to use in the future.

Stay tuned.......

LesterPiglet · « **Reply #17 on:** May 23, 2012, 05:20:25 PM »

Make sure to take plenty of pictures.

Kris · « **Reply #18 on:** October 28, 2013, 10:00:23 PM »

Ok, well it has been a while since I started this thread. Father in law didn't have the money last year and still doesn't. So I pulled the motor off the bike and put it in my garage. Life got in the way and its sat there ever since. Was looking at it this weekend and figured I'd take it apart and see if I can get it unseized. If so I will cover the cost and give him a sweet present for Christmas this year. He is 56 years old now, hasn't heard the bike run since the 70s. Would be sweet!

Anyway' started on it tonight, pulled off the valve cover, rocker arm assembly, cam and cam towers, and the cylinder head.

Stuck now, since the engine is seized I can't get the jug assembly off! Its is soaking in pb blaster right now. I had hoped that I could ring it, hone it and put it back together.

Any tips on how to get the jugs off, the engine is on the floor not the bike. Thanks guys, will try and upload pics.

cakey · « **Reply #19 on:** October 29, 2013, 03:27:35 AM »

My bike had been sitting for 16 years and had a frozen number 4 piston. I got to where you are now and the only way to get the barrels out was to turn the motor over, split the cases and undo the rod caps to release the rods and lift the barrels off.

Just sit in on a box to get the cylinder studs off the bench. It's the easiest and best way.

Just my novice opinion

70CB750 · « **Reply #20 on:** October 29, 2013, 03:44:58 AM »

Subscribed

MCRider · « **Reply #21 on:** October 29, 2013, 07:02:12 AM »

The most common thing as has already been touched on, is that condensation gets in the cylinders and the rings rust to the cylinder. Steel on steel.

IF its truly a 4 month stick, its probably not stuck as bad as some we've seen here.

If the engine were still in the frame I would suggest removing the left side alt cover, the big protruding one. The nut holding the rotor on is pretty beefy and you could get a breaker bar with a cheater wrench on it and lever it back and forth. After soaking of course. Might as well remove the shifter cover and the sprocket cover to make way.

Now with the engine on the bench, you can do the same thing but you'll need help stabilizing it. I'd take some conduit and make shims to take up the free room on the studs, bolt the cylinder back down. Otherwise it will raise up off the cases with the pistons stuck inside.

Don't use the rt side ignition nut. ITs not strong enough.

If you do this use your judgment on how much force to use. But that nut is on there with about 65ft lbs I think so you've got some room to move.

Tews19 · « **Reply #22 on:** October 29, 2013, 07:12:19 AM »

welcome back! Sometime newbies join the site, ask a few questions and never reappear... Any way you can post pics of your work?

Kris · « **Reply #23 on:** October 29, 2013, 07:21:02 AM »

As far as the oil goes, it was black and was not full. When I asked him he said that he had drained it at some point.

I put the trans fluid in the cylinder a year ago.

I know a 35 year stuck is going to be a pain!!!

I just put the pb blaster in last night about midnight. Came out this morning hoped to see that the pb blaster had soaked past the rings some. Nothing, I swear that all the blaster that I filled on top of the pistons was still there this morning. Does that mean that they are all stuck? I figured it would have leaked by!

I have the side cover off the alternator side and tried putting a big bar and socket on it there. No luck so far.

I feel pretty go so far, still little skeered about splitting the case!

Kris · « **Reply #24 on:** October 29, 2013, 07:23:58 AM »

I know that the pics dont show much but its all I took with my phone last night.

C:\Users\clydeb.WCS\Desktop\Photo0519.jpg

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Author Topic: 1974 Honda 750 froze solid in 4 months of sitting/ Now 35 years later! (Read 13005 times)