Author Topic: 2034 - '78 CB750K (Read 7456 times)

GRock · « **on:** January 30, 2011, 05:09:58 AM »

I've been meaning to get this project thread going for awhile but knew it was going to take some time getting the thread caught up with where I am on the bike. Before I begin I just want to let you know that this is a first bike, first build, I have basic knowledge of mechanical stuff. Please don't hesitate to give advice, that's why I'm starting this thread. Hats off to the experienced members of this forum because you have a HUGE amount of newbies and you do a GREAT job in guiding us so that when we hit "start", it starts! So thank you for that. So here goes....

Back in April of last year, I picked up a pair of '78 CB750K's for $250.00, only one has a title. The P.O. said he "bought them about a year ago" but the title was in the name of the guy he bought them from (we'll call him Bob). P.O. also stated that the titled one hasn't run for about a year. It turned out that Bob hasn’t owned the bikes for about 20 years!! Bob was driving the titled one home one day and it died on him about three miles from home. A little road side investigating yielded three blown fuses which he "fixed" by wrapping foil from his cigarette wrapper around the fuses! (I guess smoking does have some benefits...) It got him home and I'm inclined to believe this story because when I pulled the cover off the left side, there where the fuses still wrapped in foil - 20 years later!!!! Anyway, Bob gave both bikes to his cousin Jim and they sat in his shed up until about a year ago when my P.O. traded a shotgun for both bikes! (Special interest note: Jim's house burned down and the shotgun was destroyed.) I can’t make this up folks! You're probably wondering why I didn't walk away and to be honest with you, after reading what I typed, I'm wondering the same thing!

Anyway, in a stroke of luck, I had no problems getting the title in my name. I still want to get the title for the other bike but "Bob" isn't returning my calls anymore so I'll have to figure something else out (if anybody knows Missouri title laws better than the D.O.T., let me know)
I don't move real fast with my various projects and I had them for about a month just trading parts between to the two. The titled bike getting better while the parts bike was just looking sorrier & sorrier - poor thing.

GRock · « **Reply #1 on:** January 30, 2011, 05:32:53 AM »

After about a month, I decided to get a move on and I picked up some carb rebuild kits from S.C.I., s.s. boot clamps from Carpy and a air filter off of ebay. The air box doubled as a mouse house for God knows how long, the internal ribbing is pretty chewed up. After I would soak the carb parts in chem dip over night, they would look pretty good. However, for some reason (I don't remember why) my neighbor, who is a jet engine mechanic, took them to work and sonic washed them for a day and a half and he said all kinds of crap was coming out of the various passages when he would blow them out.

GRock · « **Reply #2 on:** January 30, 2011, 05:51:02 AM »

So after I finished with the induction side, I moved to the exhaust side. Found a great set of headers off ebay, plus they were local so I didn't have to pay shipping! I picked them up for $36.00!! The exhaust stars and shims were also ebay. The muffler has proved to be a little challenging to find. I'm not crazy about the megaphone style so that put me in the aftermarket, which apparently means loud. Not crazy about loud either but it looks like I might have to put up with it. I was looking for a "peashooter" style of muffler but it was pointed out they look great on your 40's bikes but might not look good on the CB's. Apparently. it struck a cord with me because I'm looking real close at coneeng.com's s.s.12" prefabricated reverse-cone/megaphone with a mid-pipe. I would use a mid-pipe because i want the tip of the muffler at least to the rear axle. But I don't know, I think a peashooter run flat wouldn't look bad. I'm open to questions/comments.

GRock · « **Reply #3 on:** January 30, 2011, 06:35:08 AM »

I'm one of those A.D.D. types so I bounce around doing other "doesn't have to do with getting the bike running" but I mess with it anyway. One of the other things that really had me in a tizzy was getting a tri-bar headlight cover to work which has ended up with me extending my headlight bucket. It isn't done yet but I think it will look good when it is, I hope. I've also switched to a dual tail light set up, ebay rear fender, nicer grab bar from gnarleycharley and new side covers from Frankenstuff (thanks guys!!).

GRock · « **Reply #4 on:** January 30, 2011, 07:07:27 AM »

So that brings us to the present. Yesterday, I came across what made me finally get started on this thread. I could have posted a question in the general forum or I could just sit down and get caught up and post the question here. A little bit ago, I drained the oil, changed the filter, replace the filter bolt. Moderate amount of sludge and grit in the filter housing, more than I'm used to seeing but nothing to bad. After all, this my first bike, my experience with sludge and grit is with cars. Maybe this normal - plus it's been sitting for 2 decades!! Yesterday, I took off the oil pan to find more sludge and a loose 10mm nut!!

O.K. Now I know that ain't normal! Now I'm concerned. Anybody recognize this? It didn't drop down with the pan, but a little bit afterwards. I'm looking at the oil pan and I hear something fall into the drain pan and I'm thinking "hmmm, I need to get whatever that was before I get rid of the oil". So it was stuck to the bottom of the engine. I looked as best I could for a stud that it could have come off of but found nothing. The oil pump looked fine accept for some grit stuck to the screen. The chain around the crankshaft looked fine, no obvious signs of a nut being tossed around. The nut itself, however, has some scars. What's up?

cookindaddy · « **Reply #5 on:** January 30, 2011, 07:55:35 AM »

Good story and good question.
I notice that the nut is not a flange nut and I think most of the 10mm used in the engine are flange nuts (like on the main studs that run up through the jugs and on the exhaust studs). Might not be fatal or a critical missing part? Good to get it out of there though and to get the sump cleaned out!

ekpent · « **Reply #6 on:** January 31, 2011, 06:14:56 AM »

Check all of your valve tappet adjusters under the small round covers on the valve cover and see if you are missing a nut up there.They have been known to come off

GRock · « **Reply #7 on:** January 31, 2011, 05:35:33 PM »

Quote from: ekpent on January 31, 2011, 06:14:56 AM

Check all of your valve tappet adjusters under the small round covers on the valve cover and see if you are missing a nut up there.They have been known to come off

Well ekpent, you hit the nail on the head. Good call!! Bad news is I discovered that THREE tapet adjusting nuts are missing

- where are the other two? I'm thinking we're one the same page when I say there still in the engine somewhere. Damn!! I was hoping for a little something less involved and do a rebuild later but it appears that's not the way it's going to be. (sigh) Well I guess I better start thinking about investing in Hondaman's book.

Cookindaddy - Looks like I'll be cleaning out more than the sump!

cookindaddy · « **Reply #8 on:** January 31, 2011, 05:51:21 PM »

Yeah, sorry.
A very good call from ekpent!
The valve tappet adjusters locks are 10mm and not flange nuts.
Another dumb PO story.
Good luck with it

ekpent · « **Reply #9 on:** January 31, 2011, 06:06:34 PM »

Fish around inside the top section with a magnet.Think Harbor Freight has one with a flexy attachment or rig something up. There is a good possibilty that they are just laying up on top of the head inside there somewhere. Do a search as there has been a couple threads on that. Worse case is you would have to pull the engine and pop the valve cover off to investigate. Good Luck Fishing and let us know if you catch any more. Eric

750 · « **Reply #10 on:** February 01, 2011, 04:11:30 AM »

Great story SUBSCRIBED

wohali · « **Reply #11 on:** February 01, 2011, 05:32:10 PM »

Following along!

GRock · « **Reply #12 on:** February 01, 2011, 06:40:26 PM »

Quote from: ekpent on January 31, 2011, 06:06:34 PM

Fish around inside the top section with a magnet.Think Harbor Freight has one with a flexy attachment or rig something up. There is a good possibilty that they are just laying up on top of the head inside there somewhere. Do a search as there has been a couple threads on that. Worse case is you would have to pull the engine and pop the valve cover off to investigate. Good Luck Fishing and let us know if you catch any more. Eric

It looks like I'll be pulling the engine. I have a magnet on a flexible rod but there wasn't a lot of room to move around. I didn't heard anything shifting around either. I tried to get the breather cover off but that screw on the front side - I buggered it up trying to get it to break loose. Couldn't get a solid angle on it. I thought maybe that would give me a better view if I could get it removed.

ekpent · « **Reply #13 on:** February 02, 2011, 08:59:21 AM »

Post your problem over in the tech forum section where more wizards will see it. I am sure some have been there done it and may be able to offer some suggestions on a suitable fishing rig or maybe a little more info on where to concentrate your search in there. Pulling the engine is kind of a drag

GRock · « **Reply #14 on:** February 02, 2011, 11:09:46 AM »

Quote from: ekpent on February 02, 2011, 08:59:21 AM

Post your problem over in the tech forum section where more wizards will see it. I am sure some have been there done it and may be able to offer some suggestions on a suitable fishing rig or maybe a little more info on where to concentrate your search in there. Pulling the engine is kind of a drag

Thanks for the suggestion, I will do that for sure. Yeah, I'm a little concerned about pulling the engine just because I've not entirely sure I can get 175 lbs out of the frame without sending my guts through my hernia!!

(I really need to get that fixed) Plus, I need to figure out where I'm going to keep everything if I'm going to dismantle this bike. As far as I'm concerned, if I'm taking out the engine, I'm going for a complete bike rebuild. Powdercoat frame, rims, blah, blah, blah. I realize that this is done all day long on this site, I just wasn't planning on doing that..... yet.

Again, thanks for the suggestion!
Greg

cookindaddy · « **Reply #15 on:** February 02, 2011, 11:42:30 AM »

Good to be cautious and not pull the engine if you don't need to.
There are methods to remove the engine without brute forcing, like laying the bike on it's side and lifting the frame off the engine. Lot's has been written here about that operation if you need to go that route.

ekpent · « **Reply #16 on:** February 02, 2011, 07:38:29 PM »

That stuff you are talking starts adding up to some real $$$. Best to sort that engine first,and first on the list is finding a couple of small missing bits

,getting the valve adjustment set correctly and making sure nothing is bent or bad,making sure you have spark on all four holes,clean carb and tank or run on a slave, and run to see where you are at.I never get to much into a bike until I am sure the engine is worth it.No motor=no fun.

GRock · « **Reply #17 on:** February 19, 2011, 10:04:24 PM »

Well my neighbor the jet engine mechanic came home this weekend with a bore scope! We violated that engine in every orifice we could find but I couldn't find my two nuts. By the looks of things in there, I'm not convinced my two nuts are lost in the engine. The P.O. I bought the bike from looked like he could be kin to the "Deliverance" types and I'm wondering if he was noodling around in there and forgot to put them back. I have the oil pan off and stuck the scope in various tappet ports and advanced it until we could see the floor on the video screen. We couldn't see anything conclusive. We did see what I'm hoping is rough castings or else the cases are shot. I'm leaning towards rough casting because the chains and sprockets look great. I also feel I still need to take the engine out because (1) Make 100% sure my nuts aren't in there and (2) We found a threaded hole near the top of the engine with nothing in it. (3) The last picture has us confused. Can't figure out what we're looking at and if it's punched through or not. Take a look and tell me what you think.

GRock · « **Reply #18 on:** February 19, 2011, 10:24:22 PM »

Here are how my plugs looked when I pulled them. 1 & 2 I don't think look to bad. 3 & 4 however, have a lot of carbon build up. At least that's what I think it is.

mrbreeze · « **Reply #19 on:** February 19, 2011, 10:48:29 PM »

Another thing you could do before pulling the engine if you have a compessor.....blow air in from the top or botttom to maybe dislodge the nuts if they are still in there. If you don't have a compressor....maybe take the bike to someone that does. If you can do this....I would just give it short bursts of air so maybe you could hear if something comes flying out.Good luck with it man!!

GRock · « **Reply #20 on:** March 05, 2011, 08:29:03 PM »

You know, if I ever see my P.O. again I'm gonna kick him in the shin,

just for the hell of it! My brother and I pulled the engine today. I take the valve cover off hoping to find the two missing nuts only to find 3 rouge nuts sitting there to greet me! 3!! The third one was supposed to be the one I found in the oil pan! So I actually have 4 nuts just hanging out in the engine and I only know where three of them go.
So the plan is to "split the cases" to make sure that nothing else is just hanging out where it's not supposed to. The question is if everything else is the way Honda intended it, do I just get a gasket kit and put it back together or; are there items that should be replaced because, since I have it apart, now is a good time to do it?

GRock · « **Reply #21 on:** June 21, 2011, 12:51:13 PM »

O.K., like I said, I move slow.
I bought HondaMan's book for myself for Father's Day. Started tearing the motor down and promptly screwed up. Before I realized that if I rotate the engine with the kick start to take the tension off the rocker arms making it a lot easier to pull the rocker shafts; I put a nice scar in one trying to pull it out with a pair of pliers even though I had a doubled over shop towel wrapped around the shaft.

I'm hoping this isn't a big deal but knowing me, it probably is. The way I understand HondaMan's book, the scar shouldn't be a big deal as long as it isn't to worn. Anybody have a rocker shaft they aren't using? If your looking at the front of the engine, it's the one in the top left part of the head.

GRock · « **Reply #22 on:** July 08, 2011, 09:41:13 PM »

I thought taking the cylinder block off was supposed to be easy! This sucks! No signs of corrosion and absolutely no rust, I can't figure out what is keeping it down. Tomorrow I hope to spend some "quality time" with it and see what happens.

July 9th - O.K. Maybe tomorrow
July 10th - nope
11th - nada
12th - nothing
13th - (sigh) just forget it!

GRock · « **Reply #23 on:** September 13, 2011, 07:58:26 PM »

Finally found some time and got the block off!!

lucky · « **Reply #24 on:** September 13, 2011, 09:26:15 PM »

You did not get the "block" off , you got the cylinders off.

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Author Topic: 2034 - '78 CB750K (Read 7456 times)