My '79 CB750f Supersport - I'll take all the help I can get

[Hoosier Daddy]

Welcome! You hit the nail on the head to read up in the manual before you start, but don't worry We'll get ya there! If you are using the manual in my links, it's the Factory Service manual. Much more accurate that a Clymer version. Clymer is a brand name like Haynes.

I use a big C-Clamp and push the piston back in, then install the whole thing.

^ This ^
Sounds to me like you worked the brakes with the caliper off. If so, you pushed the piston out of the caliper too far for the pads to fit back over the rotor. Take the pads off and use a C-clamp to compress the piston back in. Best to put the theaded portion into the piston, so you are pushing on the inside back of the piston. You can use a thin wood block on the other end to protect the finish of the outside of the caliper. Slowly turn the screw of the C-clamp and compress the piston back into the caliper enough to get the clearance you need.
This is a picture of a cars caliper but it shows you what I mean...

...Moved on to the front and it was going well until I had to deal with the two piece "bolt" for a lack of a better term, the one that connects the speedo. I couldn't get a good enough grip on it to get it loose. The one time my one wrench slipped off and I broke the speedo cable :-\ I swear I'm breaking more things than fixing....

Man, I am having a rough time wrapping my head around what happened right here.
Two piece bolt? Connects the speedo? wrench slipped and broke the cable?
Most "two piece bolts" are broken ones... Are you talkin about the front axle? There is a phillips head pinch bolt in the speedo drive to loosen then you can remove the speedo cable first.
Maybe this will help.

Have you removed the nuts, washers, and yokes at the bottom of the forks? shown as 24, 25, 26, and 14 here?

 

[TGreg104]

Yep, the front axle. I had a channel lock on #3 and a deep socket on #13 (or visa versa) and the channel lock slipped off and twisted the axle, thus ripped the speedo cable right out of #11. Rookie mistake.

I'm starting to realize that I may not have the best area to work on the bike (literally that little patch of concrete that you can see in the pics), really really wish I had a garage/carport/shed. But oh well. Its raining today so I can't get out to the calipers/tire issue right now. Kinda bummed.

So double checking both the clymer and the honda service manuals, it appeared that the stator was also out of spec, so I headed over to electrosport for their stator and r/r. Hopefully that will be here by the end of the week and I can put some serious miles on her. I'm ITCHING to ride.

 

[CarbsAndCylinders]

The brake fluid return holes on these calipers get gummed up and can prevent the pistons from retracting after you release the brake lever. If that is the case here then you need to clean the hole, a piece of high E guitar string or something similar will do the trick.


Brian

 

[stevenfrye]

get your self an impact driver ;D it will help you remove to really stuck on stuff and good luck

 

[TGreg104]

Not much of an update, but I got the c-clamp and it worked like a mf'ing charm. Got the rotors in there no problem, thanks to everyone for the tip. Decided to take her out for a spin since its been +/- 3 weeks since I've rode, as soon as I pull the clutch in to start it, the cable snapped. I WILL NEVER GET TO RIDE THIS BIKE But I just ordered clutch/speedo/tach cables, four carb rebuild kits and a jet kit. I'm expecting my stator here thursday or friday and hopefully all my cables by saturday.

 

[Hoosier Daddy]

...I got the c-clamp and it worked like a mf'ing charm. Got the rotors in there no problem, thanks to everyone for the tip.

This ain't our first time around the block

.. as soon as I pull the clutch in to start it, the cable snapped. I WILL NEVER GET TO RIDE THIS BIKE

Consider yourself lucky, That shit usually happens 20+ miles from home! ;D

 

[TGreg104]

haha so true HD

So I was throwing the stator in today and as I'm removing it I forget to pay attention and I removed the two wires on the stator that connect to the brushes but I didn't pay attention to where the black wire goes and the white wire. Anyone know if it matters?

 

[TGreg104]

Well I had some trouble getting the stator to go in smoothly. Normally I'd have no problem giving it a little force, but I noticed that as I'm pushing on the stator, the white-ish coating that electrosport uses on the coils starts to flake off. Anyone know if the coating is necessary for the stator to work properly? Should I contact electrosport?

 

[TGreg104]

I figured pictures could help.

As you can see, what I'm guessing is insulation is flaking of extremely easily. There was literally no way for me to put the stator in without it scraping against the housing and flaking off. I'm hoping that this doesn't cause any problems. And if it does, electrosport has a 1 year warranty.

Also in the second picture you can see the brushes. Does it matter which brush is ground and which is white? I'm guessing that it most certainly does, but I couldnt find any info on the internet.

Anyone have any insight at all on this?

 

[TGreg104]

So once I got the stator in, I started the bike up. Almost instantly I started to see a little smoke coming from the starter area so I shut her off. The plug was super hot and smoking. I believe that it was the yellow wire with red stripe that was smoking, but I'm not sure what it is. I'll look in the clymer later.

My thoughts on this are A.) The stator needs that insulation and is shorting or something B.) The bush polarity needs reversed or C.) The corrosion on the plug.

Any ideas? Thanks in advance!

 

[Hoosier Daddy]

Looks to me like you have the brushes wired just as it shows in the manual... But that one screw looks like it got HOT! I'd be checking that connections resistance / brush condition. Might have even weakened the spring that gives the brush tension on the rotor.

 

[TGreg104]

Oh wow, I didn't even notice that screw. I haven't had a chance to look at it again but I'm pretty sure that is just the shadow of my head or something because I don't really remember noticing that. I'll triple check tomorrow!

 

[TGreg104]

Side note, anyone out there who's dealt with vintagecb750.com? I ordered some parts from them last sunday and I haven't even received a tracking number. ???

 

[Rich Ard]

Re: Re: My '79 CB750f Supersport - I'll take all the help I can get

I figured pictures could help.

As you can see, what I'm guessing is insulation is flaking of extremely easily. There was literally no way for me to put the stator in without it scraping against the housing and flaking off. I'm hoping that this doesn't cause any problems. And if it does, electrosport has a 1 year warranty.

This kills the motorcycle. Call Rick's and send the picture.

 

[TGreg104]

Will do

 

[TGreg104]

Emailed electrosport and they told me to send it back and they'll send me a new one, awesome.

He stated though that the coating is more just a cement to hold the wires in place and the bike should still work. Can anyone think of a reason that I'd be getting some smoking at the 30amp fuse near the starter? I looked up what all the wires are, the yellow/red is the one I thought was causing the problem but it just leads to the start button on the controls, the red/white one goes to the r/r which I just replaced, maybe the r/r was faulty as well? Sorry, just kind of thinking out loud here. Also maybe I blew the fuse some how?

This bike is cracking me up lol one thing after another. Gotta love old bikes

 

[Rich Ard]

Check your wiring - may be that you have something going to ground that shouldn't be. Can you see where the wire was melting/burning?

 

[Rich Ard]

And unless im mistaken that coating is keeping the coils insulated from one another. Is the copper wire exposed once it's gone?

 

[TGreg104]

yeah it is.

I'm thinking that it has to be something with the way the brushes are wired up, even though it looks right according to the picture. Everything else I've done was plug and play so I don't really see how that could of been messed up. I'll recheck everything I've done tomorrow. I went out to try it again and see if I could get more information on it and now the bike wont even light the dash lights or crank the starter. I'm guessing thats a fuse thing? It makes sense in my head. Is it possible that the electrosport parts are putting more amps through the fuse than what stock parts do? Or back tracking from the fuse box area, maybe the r/r is bad, I'll have to retest its resistance again tomorrow.

I'm hoping this problem can be alleviated without mucho deniro.

 

[TGreg104]

Welp, I searched high and lowes (bum dum tis) at Radio Shack, Home Depot, and Lowes and I could not find a 30amp fuse or a fuse holder. I'm getting sick of ordering little inexpensive parts off the internet, so it looks like this projects on hold until I get back from Topsail Island (not like I was making much progress anyways )