Author Topic: $100 first project bike with problems (Read 10234 times)

cike · « **on:** September 13, 2009, 04:26:01 PM »

Hi,
I have reading this site for a week or two and this is my first post.
I just bought a 73 cb750 for $100.
First thoughts are that it has a aluminum back wheel, black lower forks and triple tree, (looks stock) and a chrome (or plated) swing arm. I don't think this stuff was stock then. did they make a limited edition?
The bike seems in really good shape considering that it hasn't been ran in years.
14K, like new tire (without dry rot) little rust, header. good chain and sprocket. tank is shot inside and out.front brake is frozen open, sitting about 5 years. (wish i knew how to post pics.)
I have very limited experience working on bikes though I have riding for 22 years.
After reading some of the posts on here I thought I would give it a try. The first bike I ever rode by myself was a 74 750/4 at 11 yrs old (Dad had to hold it when I stopped) so even though I mostly ride harleys now I have always loved these old honda's and wanted one.
2 years ago I found a old 750/4 that someone gave me that I was going to turn into a rat bike ( i knew nothing about them then) after looking into it I found out it was a 70 Ko model with 7-8k on it. After that I decided that this was not the bike for me to learn on and maybe tear up, so I sold it to someone that would restore it. The bug has never went away though and now that I have found another bike, I am at it again (for the first time so to speak)
The first thing I did was to take the bowls off the carbs. Looked nasty. So a cleaning was in order.
This is where I have my first problems that I am looking to you guys for help on.
So her it goes. i hope you can help.
Carb 1: can't get the float pin out. I keep soaking it with pb blaster and have gotten it to move about 1/8 - 1/4 inch. still waiting for it to loosen up. ( I am using a socket underneath of it for support when I try to push it out.) hoping this one will loosen up with time. I have time, just no money.
Carb 2: came apart great.
Carb 3 one of the float pins were broke. Do you know if this can be fixed with JB weld, or Loctite E-20HP epoxy? I think that this would work but don't know if it would hold together once gas is back in the carb. Is the Carb body shot?
Carb 4: I wish i knew how to post pics on here for this one, but I'll try to explain the best that I can. If you turn the carb upside down so that you are looking at it from the bowl side there are 2 holes about .250 Dia. with what looks like a brass piece with a small hole in the center. (i'm thinking that these might be for vacuum?) In this one carb only one of these holes does not have that brass piece in it. (hope this makes sense) I did not find the piece in the bowl either, nor do I see anything about these in my repair manual. Any thoughts? Can I buy these? if so, do they just get pushed into place?
I have access to a early 70's cb500 (also hasn't been rode in years, looks clean though) I don't know if these use the same carbs? (maybe different jetting) could I use one of these carbs? It also has a clean tank inside and out. Will it fit? (also $100 for bike, but no title)
I hope that you welcome me to the site and help me out as you have many others that I have read about on here.
Sorry, I know that this is several questions for one post, but you guys seem to be the best that there is when it comes to these bikes. (that was a compliment to all, flattery is said to always help)
Thanks for any help that you can give. Cike

kevins750 · « **Reply #1 on:** September 13, 2009, 05:11:22 PM »

First off sounds like a good buy $100...The swingarm is probably just a stock chromed..the rear wheel may be off a CB750 automatic or someone laced an aluminum hoop to a stock hub..About the carbs, just hang out here and buy a known good set..I don't think the 500 carbs will work..I don't think the tank will work, I believe the 500 has a pressed steel frame and the 750 has the multiple top tube design..Any rate congrats on the purchase..And welcome to the site!

Retro Rocket · « **Reply #2 on:** September 13, 2009, 05:15:54 PM »

Pics please, definitely will make it easier to answer your questions....

Mick

fergie · « **Reply #3 on:** September 13, 2009, 05:21:32 PM »

First off, aluminum wheels ,plated swing arm and painted fork lowers did not come from the factory like that. The wheels may be off a cb750A (automatic trans model) ,the swing arm may or may not be stock ,someone may have taken it off and had it plated. Stock swingarms are black. fork lowers were probably painted. The bike sounds to me like a great find . You really should get it titled before you sink any money into her though. As far as the carbs go the float pins I believe are a press fit But I could be wrong. I dont think carbs off a 500/550 will work but I could be wrong on that too I don't really have too much experience with cb carbs. no limited editions were made as far as I know.You may be able to make the 500 tank workwith a little fabrication but I would not bother It just woudn't look right but thats just my opinion. good luck, cheers ,fergie

Hush · « **Reply #4 on:** September 13, 2009, 05:37:34 PM »

Sounds like your carbs could do with a good few days soaking in some carb cleaner, makes things much clearer to work on, check out the FAQs on carb cleaner.
Nice find though, $100 notes for a 750 you really lucked out, keeping the K0 would have also been a very swift move, ah the ability to look back and wonder!

cike · « **Reply #5 on:** September 13, 2009, 06:05:54 PM »

thanks, I didn't think that the rear wheel was stock but, I'm not to up-to-date on these old honda's. (at least it's not rusted this way)
I have one of the carbs soaking in cleaner right now. I went to hondachopper.com and they have a very nice step-by-step write-up with pics for cleaning carbs. http://www.salocal.com/sohc/tech/carb/carb.htm
For such a clean looking bike these carbs looked very bad on the inside. so much for getting it done the easy way. Guess I'll learn more this way.
I would love to post a pic but cant seem to get it to work. when i click on the insert image it puts this on my post.

(

)

I tried to to go to where it says "additional options" and was able to lick it there but, it says that my attachment is to large and I'm not sure how to make it smaller.

I have a few pics on my computer if I can just figure out how to get them on here I will be doing fine. I will figure it out sooner or later, after all how hard can it be? I must be missing something right in front of my face.

Frgeie: I did get a title with the 750 it is just the 500 that does not have one.

Hush: wish now that I had kept the K0. But i got it for free, did nothing but clean a little (not running) then sold it for $2400. think I sold it to cheap though. The first person that looked at it on Ebay bought it. I have pics of it as well.

MJL · « **Reply #6 on:** September 13, 2009, 09:57:26 PM »

I wrote this tutorial for another board. Here is a copy and paste of it.

First open the pic you want to resize in MS paint.

Then go to the pull down menu "image", and click on "stretch/skew"

There wil be two boxes where you can stretch or shrink the picture. The number that you enter will be the percent of current picture size. For instance, 50 in each box will make it 50% of original size, while 150 will make it one and one half times larger.

I usually start with 66 to 75 percent in each box, but the pic I used had to be shrunk down to 25% in order to fit on the screen.

If you have Windows XP you can use "save as" to save it is a JPEG, otherwise it will be a bitmap unless you can convert it to JPEG. Also, be sure to save it with the highest color resolution you have. Sometimes mine will want to save it as a monochrome, ie, black and white.

cike · « **Reply #7 on:** September 14, 2009, 08:13:20 AM »

THANKS MJL
If it works there should now be pics with this post, and more to follow. If not, I'll keep trying until I figure it out.
Here goes nothing

cike · « **Reply #8 on:** September 14, 2009, 08:52:00 AM »

this is kinda a mock up of what I am thinking. with a little taller handlebars, and removing the shocks and adding struts. it looks like the petcock will clear. (as i've heard others had problems with when using sportster tanks) not sure how i'll do the seat.
Of course I have to get it running or all of the ideas in the world aren't worth anything.
What do you think?

Ogri · « **Reply #9 on:** September 14, 2009, 10:42:25 AM »

What kind of tank is that? It's sitting like a sportster but has the bulk of a Fatbob..Sorry, I don't like its position..it's too high; pulls the eye away from the engine. The angle that it's at suggests a central backbone going from the headstock down to a low single seat. But the presence of the frame rails under the tank and the seat rails kinda makes everything look a bit confused. Sorry to be so negative but nothing good comes easily.

If I had to use that tank I'd do it like this:

cike · « **Reply #10 on:** September 14, 2009, 10:59:05 AM »

the tank was off of a softail std. It was one that I had in my attic after a friend dropped his bike and had it replaced. I sat it on the bike and thought that it looked pretty cool. looking at the pics now (after your opinion) it does kinda throw the lines of the bike out of wack. I might have to play with the angle of the way that it sits or look for something else.
Thanks for your opinion, it helps to look at things from someones else's point of view.

Hush · « **Reply #11 on:** September 14, 2009, 02:24:58 PM »

Looks like you may need some carb parts, JB weld etc would be a short term fix, these carbs are such a #$%* to get off and on that you only want to do it the least times possible, ask in the parts wanted section on this site, 750 carb bits must be fairly common by now.
Still not a bad buy for a hundee bucks mate.

cike · « **Reply #12 on:** September 16, 2009, 11:57:32 PM »

been spending the last week working on cleaning the carbs. as you can see from the pic they were pretty nasty. Still working on the cleaning before I can put them back together.
i took out the battery box, and the tool kit holder. I sand/bead blasted them and have them primered. will have them painted this weekend, and back in the bike. plan on cleaning all the connections here as I hook back up the electrics. I'll post a pic when I get them done. (wish I had taken a before shot of the boxes,they were ruff.)
I now am ready to try to fix the broken float post shown in the picture a couple of posts ago. I know that this will prob. be a temp fix but, at least I will be able to see if I can get it to run with it. The other float post on this carb does not look like it will last much longer either.
I was thinking of using JB weld. I asked a friend that does a lot of small engine repair about it and he said that he thought loctite E-20HP might work better. (see pic) Has anyone on here tried this stuff? If so how did it work?
I have both JB weld and the loctite (he loaned it to me)
Which would you use?
Also, should I put the float back on to make sure the holes are lined up before using either of these?

Hush · « **Reply #13 on:** September 17, 2009, 12:18:08 AM »

I'd take your mates advice on the loctite, it should be gas resistant, slide the livot pin without the float on as you cement the post back on, that should line you up and you can remove it later once it is all set.

cike · « **Reply #14 on:** September 17, 2009, 12:42:41 AM »

Hush: thanks, as I said before I don't really know what I'm doing. But I'll know more when I'm done.

I also figured out my missing piece with carb #4 ( I felt really stupid when I relized what is was )

I am not missing a piece after all. carb #4 is the last one in the line therefore it did not need this piece because it is a blind hole and not going anywhere. I would have realized this if i had looked at carb #1 (also missing this piece) but that was the carb that I couldn't get the float pin out of so I couldn't see this.
As it turned out, when blowing out carb#2 after cleaning one of these pieces blew out. I made another one out of Brass shim stock, pushed it into place (took a little time) then used a small piece of steel stock to swedge around it so it won't come out. (I hope)

cike · « **Reply #15 on:** September 17, 2009, 12:45:01 AM »

pic of what i thought was a missing piece

Ogri · « **Reply #16 on:** September 17, 2009, 03:38:53 AM »

I've used JB Weld to repair pinholes in gas tanks, including holes on the underside of tanks that are continually in contact with fuel - they've never leaked.

cike · « **Reply #17 on:** September 17, 2009, 10:20:44 AM »

I got up this morning and painted my battery box and tool try, then I decided to fix my broken float post. Guess what? NO POST. I can't find it anyplace. Yesterday I took 2 of the carbs into work so that I could blow them out (with a needle tip on the air line) after cleaning them. One of the carbs was the one with the broken post. (along with the post, to ask my boss for his ideas) I had both carbs in sandwich bags and had them in a lunch bag. when I got home last night I took the carbs out of the lunch bag and put them away. When I got up this morning my the lunch bag was torn up all over the house. My wifes puppy had somehow gotten a hold of it. (did I mention that I have no garage) Now it looks like one of 2 things have happened. The post was still in the bag and the puppy has lost it, or ate it. Or, (keeping my fingers crossed) I somehow managed to leave it at work and it will be there on my toolbox when I get in to work tonight. I have heard the phrase "my dog ate my homework" but have never heard anyone say "my dog ate my carburetor parts"
If not, it looks like I will be looking for a new carb or body, or a new set of carbs.
Hope the rest of my day doesn't go like this.

cike · « **Reply #18 on:** September 29, 2009, 11:56:34 PM »

Update, I havn't given up:
Well I found my float post. dog had lost it, not ate it. I put it back on using the loctite, didn't seem to hold to well. I let it dry for several days and it was still kind of mushy and the post was not solid. I put them together anyway hoping that I could at least hear the thing run before the post broke again. DIDN'T HAPPEN.
I put in a new battery, and ran an external gas tank. Before I could even turn the key the #3 (one with the broken post) was leaking gas from under the bowl. the #1 carb and later the #4 carb was overflowing out of the throttle body(?) (where the air filters hook up to the carbs)
At this point she was so flooded there was no way it was going to start. Electric starter does work.
I didn't use new gaskets, so maybe that was the problem with #3. I don't know what happened with 1&4.
Wish I had tried starting it with starter fluid before I hook up the gas tank, just to see if it would fire.
Looks like it's time to start looking for another set of carbs.
I did sell my CB500, the guy is suppose to pick it up this weekend, so hopefully I can use the money from that to buy a set of carbs with. My daughter is getting ready to finish AF basic training so I am going to Texas to see her and money is tight so it might take a few weeks before I get some carbs.
I found a set that the guy says was cleaned and bench synced and have been sitting on a shelf for a couple of years since done. He wants $100 for them. any thoughts on these?

andy750 · « **Reply #19 on:** September 30, 2009, 05:14:35 AM »

I just came across this...I actually like the tank on the bike. It looks different and to me in a good way. I guess it all depends on your perspective. But at the end of the day its what you like that matters.

Id get the new set of carbs and start from there.

Good luck
Andy

cike · « **Reply #20 on:** October 14, 2009, 10:20:57 AM »

Update:
Got my new set of carbs last weekend. They where had not been cleaned as I had been told, but didn't look in to bad of shape. Thought I would give them a shot to see if I could get the bike running before cleaning them.(clean them over winter) I replaced all of the jets with the ones from my old carbs (because I knew they where clean) and put them on the bike. Sprayed some starting fluid in the carbs and gave it a try. Didn't fire.
Cleaned points.
Pulled the plugs on 3 and 4 and grounded them. NO SPARK. I'm way out of my league when it comes to electrical.
Started looking on FAQ for things to try.
Bought new plugs, cut a little off the ends of the wires, and cleaned the posts inside of the caps. tried again: still no spark. Pulled plugs 1 and 2: No spark
Bought a test light. I HAVE juice going to the coils.
One thing I did notice is that the neutral light does not come on. Bike is in neutral. (could be blown bulb?) Do these bike have to be in neutral to start? Could the light being off be telling the bike that it is not in neutral and keeping it from starting?
Not sure what order I should start checking things from here. Want to check the plug wires. Bought a Multimeter (INNOVA 3310) but i don't have a clue how to use it yet. (any help would be appriciated) Would also like to try by-passing the kill switch. I read in the FAQ that you can do this in the headlight bucket, but I couldn't find out where it said how to do it. Can anyone tell me how???
Another thought: I have the rear turn signals and brake light off of the bike. I don't think that this will make a difference but, is there any chance that these have to be hooked up to complete a circuit before it will start?
I have a red and a white wire coming out at the neck that is not hooked up to anything, I don't see anyplace for them to be hooked up at. From what I have been reading I'm thinking (73 bike, 76 motor) that these might go to a front brake light switch (that my bike doen't seem to have) I don't know if the wire harness is from the 73 or if it was switched with the bike that the motor came out of. PO said that bike was running great when parked 5 years ago.
Will also go back to FAQ and look for other things to test.

Ogri · « **Reply #21 on:** October 14, 2009, 11:25:38 AM »

Check that the contact breaker points' faces are clean, that they are completely closed when they should be, that they open when the 'F' mark lines up in the window. Check that with the ignition on & kill switch to Run that there is current at the points. Set your multimeter to 12V volts dc, ground one pointer to the engine and touch each side of the open points.

The neutral light, as far as I know doesn't affect ignition.

Does the motor spin over quickly ? How much power in the battery ?

It'll run..it's just playing with you.

mystic_1 · « **Reply #22 on:** October 14, 2009, 01:23:17 PM »

Didn't later 750's have a starter safety interlock?

mystic_1

cike · « **Reply #23 on:** October 14, 2009, 05:26:40 PM »

Orgi: will check on points.(at work right now) Thanks for the instrustions on how to do this with multimeter. Battery is new, and motor sounds like it is canking fine.

Mystic: Sorry, (newbie) not sure what a starter safety interlock is or if I have one. will try to look it up in my manual.

Thanks

mystic_1 · « **Reply #24 on:** October 15, 2009, 05:28:39 AM »

Starter safety interlock = starter wont work unless bike is in neutral.

The wiring diagram for 750K3 - K6 shows one.

mystic_1

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$100 first project bike with problems

Author Topic: $100 first project bike with problems (Read 10234 times)