Author Topic: 1975 CB750 Build! "Kona" - Sold and gone. (Read 70365 times)

Ravie · « **Reply #325 on:** June 04, 2015, 08:11:33 PM »

Figured the brake out. Good deal. Your picture helped a lot. *virtual thumbs up*

Had some nice nickel and dime size hail coming down for several minutes just a bit ago. Exciting!

Ravie · « **Reply #326 on:** June 10, 2015, 07:39:34 PM »

Why, Ryan...is that your head back from Mark?

Yes. Yes it is.

Rundown of it's greatness:

All new bronze valve guides.
Ported and glass beaded.
Seats recut and lapped
Valves polished
Sharp edges removed from chambers (by yours truly)
Chambers polished (by yours truly)
I deburred the oil return holes in the top end, added oiling holes on the rocker shafts, and left the shaft bolts OUT.

And then...I built an engine.

I was worried about the piston/valve clearance with the 836 pistons and the fact that both the head and the cylinder have been flycut (.020" off the head...not sure about the cylinder off the top of my head). I put the head down on the cylinder to see what it was like without the gasket and I did indeed have contact. I got it together and torqued it half way and checked. No contact. Yay. So I torqued it to 175 inch pounds and checked again. All good. I finished assembling the top end, set the valve lash and spun it round with the kick starter. All clear.

Yeah!

My friend who begged me months ago to paint my tank for me still has yet to do it, and in the meantime his compressor has broken. It fell over. No bueno.

Waiting for a few last minute parts...a positive cable and a solenoid.

Working on it bit by bit! Seems like the last bit here takes the longest... I did manage to get the brakes hooked up and together. My bleeder screw is leaking but I bought some new ones today.

Gotta figure out how I'm gonna shoehorn that beast in there...

Davez134 · « **Reply #327 on:** June 10, 2015, 10:51:46 PM »

Looking good! Should be easy to get in there without frame rails. Get to work

evanphi · « **Reply #328 on:** June 11, 2015, 07:04:21 AM »

Since you have a frame kit, it is WAY easier to get the whole thing in there. You can lift it higher to clear the bottom lugs.

Congrats!

SOHC4 Cafe Racer Fan · « **Reply #329 on:** June 11, 2015, 08:04:19 AM »

Nice head work and motor overall. It should slide right in hopefully without a hernia.

edwardmorris · « **Reply #330 on:** June 11, 2015, 08:37:50 AM »

Looking good! Are you running a 16 or 17 rear wheel? I've got a shortened center stand that might make it a bit easier to pull into. PM or email me...

Ravie · « **Reply #331 on:** June 11, 2015, 08:59:36 AM »

Nope, 19 front 18 rear. I stayed with a pretty stock size rear tire...which is to say it's not very big.

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evanphi · « **Reply #332 on:** June 11, 2015, 10:45:35 AM »

How did you polish your chambers?

Ravie · « **Reply #333 on:** June 11, 2015, 10:51:15 AM »

I took the sharp edges off with a rounded high speed cutter in.my dremel, then smoothed it out with 100 grit. I then doubled up some red scotchbrite circles I made to fit the dremel and smoothed it further. Then I hit it with 2k grit wet/dry paper just dry. Finished with little polishing wheels on the dremel and red polishing compound.

Then I cleaned the ever loving f!@# out of it with brake clean and my compressor.

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evanphi · « **Reply #334 on:** June 12, 2015, 05:05:53 AM »

Quote from: Ravie on June 11, 2015, 10:51:15 AM

I took the sharp edges off with a rounded high speed cutter in.my dremel, then smoothed it out with 100 grit. I then doubled up some red scotchbrite circles I made to fit the dremel and smoothed it further. Then I hit it with 2k grit wet/dry paper just dry. Finished with little polishing wheels on the dremel and red polishing compound.

Then I cleaned the ever loving f!@# out of it with brake clean and my compressor.

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All before you installed the valves, of course.

Very impressive work. I like the shiny!

Ravie · « **Reply #335 on:** June 12, 2015, 05:08:19 AM »

No. The valves were installed when they got back from Mark. I was just really effing careful.

evanphi · « **Reply #336 on:** June 12, 2015, 06:01:47 AM »

Quote from: Ravie on June 12, 2015, 05:08:19 AM

No. The valves were installed when they got back from Mark. I was just really effing careful.

Ouf! Good on ya then!

Ravie · « **Reply #337 on:** June 12, 2015, 06:08:40 AM »

Haha, thanks!

I went back and forth on how clean I could get it after that so nothing ended up stopping a valve from seating properly...but an entire can of brake clean and my air compressor later I was happy with it... haha

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Ravie · « **Reply #338 on:** June 13, 2015, 07:39:53 PM »

So, I dont know the electronic function of these two wires on the solenoid, but I am assuming I cannot connect them backwards and be ok. Should I just swap the connectors? You can see that the solenoid has the connectors backwards here...

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calj737 · « **Reply #339 on:** June 14, 2015, 04:58:48 AM »

If the two wires on your left (Y/R and BLK) are coming from the solenoid, then they are Y/R to electric START button, and the BLK is power.

The Green/Red is your Neutral switch wire. I can't tell what the yellow wire is, but it should be part of your stator harness? Better pictures please!

Ravie · « **Reply #340 on:** June 14, 2015, 07:54:16 AM »

The wires on the left are coming from the bike - I'm assuming you are right...from the start switch.

The wires on the right are coming from the Starter Solenoid. My original's wires matched the ones on the right...but the new one's wires do not. It looks to me as though they are backwards from how they ought to be wired.

calj737 · « **Reply #341 on:** June 14, 2015, 07:59:17 AM »

Directly from your solenoid, what wires do you have? Post a picture please.

Ravie · « **Reply #342 on:** June 14, 2015, 08:02:38 AM »

The yellow and green wires on the right are coming from the solenoid. Yes, the wrong colors. The solenoid came from Vintage CB750 supply. I can take a better picture but I assure you that is where they are coming from.

Ravie · « **Reply #343 on:** June 14, 2015, 08:09:17 AM »

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calj737 · « **Reply #344 on:** June 14, 2015, 08:17:05 AM »

Those two wires should be coming from the Starter Safety unit, not the solenoid. From your solenoid, you should have Y/R, BLK and Red/WHT plus the two large gauge wires.

Are you using this diagram by chance?

http://manuals.sohc4.net/cb750k/technical_reference/WD750K1_K5.pdf

Ravie · « **Reply #345 on:** June 14, 2015, 08:26:53 AM »

No, I haven't been. I've been using this one, found on the forum here. https://plus.google.com/photos/+ConorRichard/albums/5432602713157926337/5432602827904232594?banner=pwa&pid=5432602827904232594&oid=100334419845586031681

I brought it to Fed Ex last night and had them make me a laminated 11x17 of it!

The red wires associated with the solenoid come from the pigtail that comes out of the short positive wire. I'm not worried about that...I know where that wire is. My issue was that the diagram shows a BLK wire and a YLW/RED wire coming from the solenoid, which IS what is coming from my original garbage solenoid. The new one arrived with that green wire coming out along with the YLW/RED one...different than stock.

calj737 · « **Reply #346 on:** June 14, 2015, 08:32:56 AM »

If the new solenoid has that wiring, I'm confused by it. Can you return it and reuse or get a proper replacement? Was something wrong with your stock solenoid?

Ravie · « **Reply #347 on:** June 14, 2015, 08:36:15 AM »

Yes, I was going to clean the contacts and ripped a wire off internally.

I will see what I can do. I ordered one for my bike but the box said CG125. A lot of the parts they carry are supposed to work on different models, etc... apparently not always!

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Ravie · « **Reply #348 on:** June 14, 2015, 09:09:33 AM »

I found my answer here on the forum.

Turns out no one makes the original style solenoid for the 75's anymore. The ones that are made as exact replacements have 77/78 wiring which was opposite polarity wise from what the 75 wiring was. The post I found confirmed this in several posts and the OP of the thread I was reading hooked up the wires "opposite" the way you would think and he said it worked perfectly. So that's what I'm going to do.

Here is the thread in case you are in doubt. :-) http://forums.sohc4.net/index.php?topic=68533.0

Ravie · « **Reply #349 on:** June 14, 2015, 12:31:24 PM »

There seems to be a straggler in my bucket. I see no other brown wire in here and i dont see this brown wire on any of the wiring diagrams. It is solid brown, no stripes. Comes out of the main harness.

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Author Topic: 1975 CB750 Build! "Kona" - Sold and gone. (Read 70365 times)