Topic: 1975 CB750F - Project Yellow Jacket

[DollarBill]

Small victory sure put a big smile on my face today

After reading LOTS and LOTS of threads in here about electrical issues one thing kept popping up.  "Clean your terminals, connections, etc."  So I brushed off the bolts and nuts on the solenoid and pushed the button.  Nothing.  Did the screwdriver override procedure and it turned over.  That was music to my ears.  Mind  you I ran home from work at lunch to try this out and I didn't want to mess with hooking the gas back up and head back to work smelling like a refinery.  Now I just can't wait for the day to be over so I can go home and play some more.

I'm still not sure about the connections on the start button and if those are correct.  Can one of you 750F guys take a peek for me and see if these are indeed hooked up in the correct place?  Thanks!

[fuzzybutt]

Ahhhh...a 7 mil huh?  Maybe I should incorporate it somehow in my build?

Now who's the dude in your avatar?

thats the cat from the british sci-fi comedy red dwarf. the cat eveolved over 3 million years from listers pet cat frankenstein. http://en.wikipedia.org/wiki/Red_Dwarf_(science_fiction_series)

[DollarBill]

To check for spark I did the test where you lay a plug against the engine and try and start the bike and there was no spark.  Tried a different plug with the same result.  Next I tried to short the contact points to see if I could get a spark and nothing was happening there either.  The points are in great looking shape and open and close correctly.

What next?  Could it still be an issue or an issue with the run/stop switch?  If it is the switch is there a way to bypass it?

[DollarBill]

Electricity and I don't really know each other...but I'm trying to make friends with it.

Thanks for the advice 42indian.  The black wires don't quite reach the battery and I'm sure I could make them reach but before moving things around I have a question about searching out the problem with a multimeter.  I bought one today but have never used one before and the instructions are about as clear as the Pythagorean theorem is to a four year old. It's got several settings for DCV, DCMV, ACV and some others.  Here's what I tried: I put the setting on DCV 50 and I poked the negative battery terminal with the black lead from the multimeter and the red lead to the positive battery terminal and got 12 on the reading.  That's a good thing right???

When I poke the black connector on the wiring harness that leads to the coils with the pos lead from the meter and ground the other lead I get zilch.  If I do the same thing with another black connector that goes to the lights I get 12.  Shouldn't every black wire from the harness give me 12v?  If that is correct then can I surmise that either the connectors need a serious cleaning or there is a weakness in this particular wire.  Or am completely wrong?

[72hondacb750]

Son of a.... You can NEVER take enough photos is the lesson I am learning right now.  I took the carbs apart laid them out neatly in what I thought was an organized manner but let a few days go by and WHAM you won't remember a thing.  What I am having trouble finding a home for is this little washer:

I looked in the blown apart parts manual and the shop manual and I can't find where this little guy goes.  TAKE MORE BEFORE, DURING, AND AFTER PHOTOS!

Ok so I got your PM about this .. Here is where I think that bad boy goes..

Here is a side view of it more or less in the manual..



which is on the back of this part of the carb when you look at it ..



In this pic you can see where I left mine on the linkage ..



And here is the back side of the linkage its attached to .. I can take a picture when i get mine back together but its right on the other side of this bolt ..



Hope that helps..

[DollarBill]

AH-HA!!!!!  Finally!  Thanks!  Now I just have to take them back apart and add those little boogers back in.

Might as well update the project while I am here.  I just converted the fuse block to a blade type after breaking the brittle old one while cleaning it.  It wasn't as hard as I thought but I'll need to dress it up a little because it's not the prettiest thing.  I also have two tanks currently soaking in paint stripper.  One has holes in the bottom and it will be chopped and used to make my dented tank longer by about 3-4 inches.

I hope to get a good start on the tanks over Thanksgiving and will post pics of the progress.

[DollarBill]

Over Thanksgiving I took both my tanks out to my in-laws so my father-in-law could help me chop and weld them.  He has a lot of experience welding fencing and gates but not with thin sheet metal like on these tanks and I have almost zero experience other than welding a few bits and fence posts.  The second tank I got of eBay was a crapper with holes in the bottom so I had nothing to lose with that one so I sawed in half with a sawzawl.



Next I cut the bottom of the tank out


I also cut the section of the tank I cut off in lengthwise down the middle so I could bring the two sides together and fit the contour of the sides without bowing out.  I forgot to take a photo of that part.  The two pieces overlaped so I cut some of the overlap off.  Basically, I used the same method as DME and xtalon if you have seen their bikes.  xtalon has some great photos of his tank stretch on his project thread.

 
My father-in-law did all the welding because I was afraid my inexperience would burn huge holes in the good tank.



Fill, grind, fill, grind, fill, grind...








Next weekend I will go back out to the in-laws to finish some welding and grinding.  It takes a lot of spot welding on this thin metal and we did end up burning a few small holes into the good tank but they filled well.  I put the tank lid on and stuck an air compresser into the petcock hole and was able to feel air coming out tiny pin holes.  I circled them with pencil for filling in.

I have to say I am pleased so far with the results for being a complete noob at this.  We'll see how the body filler works out because that's another thing I have never done before.  Gotta learn some time right??  Any tips for that?

[DollarBill]

One thing I am sure the eagle eyes here will ask about is the ridges on the top of the F tanks that run down the center.  You can see in the photo that the extended piece welded on that they are hammered flat.  I am hoping with body filler I can gracefully make them fade out before they get to the welded area.  You can see what I am talking about in photo #6.

[fastbroshi]

   Making some good progress there, looking great?  I'm not a welder, but I've seen it done where someone's created a crease by laying down a metal rod of some sort, tacking it in place, and then working bondo around the sides of it.  Maybe this could work and you could keep the creases going down the tank.
  Either way, that's going to look sharp.

[DollarBill]

Hmmmm....that is a very interesting idea.  I actually think I am going to try something like that.  Thanks! 

[dangerranger01]

Man, i love that gas tank. Can't wait to see pictures of it on the bike. Question for you though, is it so long that it'll cover up the battery (if you're using it in the stock location).

Also, is the extended part you added (from the tank you cut up) simply a cover over the stock tank? (meaning you still have the stock stank bolted up with this extra metal welded to it).

If you could link the post where DME and xtalon did their tank stretch that would be great as i can't find it using the search function.

[fastbroshi]

  Do a search by username, should come up.

  Bill, I know it's only been a week, but any updates?  When someone's cutting and welding we tend to want DAILY updates.  Did you not get the memo? 

[DollarBill]

Being an "update w/pics" monkey myself I am happy to oblige the request.

I wish I could give daily updates but the welding equipment lives 1 hour and 45 minutes away.  I did however make the trip on Friday and worked on the tank all weekend.  I bought some small diameter steel rod to try fastbroshi's idea of keeping the ridges but after playing with it for a while I decided to just make the ridges fade out.  I also used Bondo for the first time this weekend and it was pretty cool.  One word to those who haven't used body filler yet...when it says "3-4 minutes of workability" they aren't kidding.  You don't have a lot of time to spread it and once it starts getting tacky stop what you are doing!  Trying to push the limits just screws it up.

Here's the link to xtalon's project
http://forums.sohc4.net/index.php?topic=21578.0

There's a link somewhere in this forum to DME's tank build but it is on a different site and in a different language.

The tank covers half of the battery now and I haven't decided what to do about it yet.  I will think about that later.  I sprayed the tank with some sandable primer and have a few low spots to work out and some fine tuning but so far I am quite happy with the result. 

First coats of Bondo...



In the next two photos you can see how the ridges fade.  I think it turned out pretty cool.








Next up will be the tear down of the rest of the bike.

[DollarBill]

To answer dangerranger01...the stretched part of the tank is simply a cape welded on top of the original tank.  Purely aesthetics and not for increased fuel capacity...

[DollarBill]

Once I figure out how and where I am going to install rearsets I plan on removing the engine to clean and paint.  Here's the thing....I bought the bike and it came with receipts for all the work that was done on it.  In 1999 it had new piston rings installed, gaskets, and a few other things done.  In 2000 the owner fried the wiring harness and it sat untouched until I bought it.  Do you guys think that stuff would still be in decent shape after one year of riding and 8 years of sitting?  If so then I am just going to clean and paint the engine and not bother with cracking it open. 

Ideas?  Advice?  Thanks!

[dmizer]

I would say that you shouldn't have too much problem. The carport/shed appears to have sheltered the bike from the wet weather. Does the thing turn over easily? If so, I suggest pumping some Marvel mystery oil into the cylinders. Keep pumping fresh oil down there periodically until you get your build completed.

Also, pull the tappet covers off the valve cover and take a look at things in there. Wouldn't hurt to squirt some mystery oil in there either.

I read through your thread, but I didn't see it mentioned anywhere ... was there any water in the oil at all when you drained it?

[DollarBill]

There wasn't any water in the oil and it turns over easy.  One thing I guess I need to do still is check the compression on each cylinder.  They sound good when I turn them over if that counts for anything.

[dmizer]

A compression test would be a must.

But, don't turn it over too much without lube flowing through the poor thing, and get some mystery oil (any oil is fine really, but marvel is good at rust prevention and penetration) to keep everything nice and lubed while you do the rest of your rebuild.

[greenjeans]

lookjs pretty cool.   Make sure you fill the pin holds with the welder or you could solder them....don't use filler to patch them.
Always love the stretched tanks

[DollarBill]

I'll make sure and keep it lubed and will do the compression test tonight.

Hey greenjeans, all the pinholes were welded before applying the filler.  The original tank was sealed so now the sealant has some holes in it since we burned through in those few spots.  I need to re-seal the tank but need to figure out how to get rid of the old seal.  I'm sure it has been addressed here before so I will do a search.

[Really?]

Why the relief at the back of the tank?  You bragging? 

[DollarBill]

Sorry Giga...not following ya?  What do you mean by relief???

[Really?]

The dents that are made in the front of the tank are bar reliefs, I guess the ones for the knees might be call inserts but I figured the rounded off part in the back might be a relief for something(?).

Just funnin'

[DollarBill]

That's funny...I got it now.  Yeah that's what it is.........a junk bin.   

[DollarBill]

Since I am home today suffering from a bad case of Poison Oak/Ivy I decided to go through all the receipts that came with my bike and post the info here as a historical record and because I am terribly bored and itching like a mad dog with a million fleas.

3/27/99
Valve Job
Inst Valve Guide
Hone Cylinder
Clean Parts (I guess just a general cleaning?)
Drill Studs (why would they need to do this?)
Reface Head
Total: $230

9/21/99
New Rings
Fork Seals
Chain
Oil Filter
Total: $155

10/17/99
Tank Liner
Total: $30

11/26/00
Tube
Total: $10.95

12/29/99
Front Caliper
Total: $64.65

1/5/2000
Muffler
Total: $48

11/28/2000
Points
Condenser
Total: $35.54

As I stated before the bike was parked sometime in 2000 so this is basically "new" work that has just sat.  I pulled the old plugs and they look perfect but unfortunately I could not find the adapter for my pressure gauge to fit so I couldn't test the compression.  It's agonizing having to wait for funds to work on my bike.  Here she is half dressed and looking pretty hot roddish....