Topic: 1977 CB750 K7 /// Rebuild 2.0, Project Anna

[koendd]

excellent! thx for the choke info

[martin_uk]

Interested to see your progress as I am currently restoring a K8 and doing a mild CR conversion on an F1.

The F1 presents extra consideration for rear sets with rear disc, wish I had access to machining facilities.

You are always learning with these projects, I have been fixing bikes for 45 years and still learn.

Saw your bit on the carbs, it is not unusual to find you have to go back and redo something as its easy to be too optimistic 

Tenacity is the key

 

[mkoski]

Happy Monday guys,

Over the weekend I officially finished electrical, which is beyond exciting for me as it was my least favorite part of the build and everything actually works properly! I didn't like the bracket that the gauge came with so I decided to fab up my own, which is now painted black:



Its a little rough due to the lack of all tooling associated with sheet metal work except for pliers...  But its hidden, so no problem for me. It mounts up to the bottom of my triple tree which I put a hole though and countersunk. Got some nice brass hardware and rubber washers for a bit of vibration damping too. The bends clear the steering lock (which I didnt remove before P/C'ing, doh.) and drop the gauge in so the top line of the bike isn't disturbed.



One thing I ran into is the new gauge only has one "blinker" indicator light for both left/right signals, so there is no way (that I saw) to wire it so the same LED blinks for both left and right signals from the one light. If you cross light-blue/orange wires all four blink. (Hopefully I made that clear enough to understand.) My solution for this was the use the Hi-Beam light on the gauge as I wasn't going to use it anyways because I typically ride with my hi-beam on (which, I think, is a hotly debated subject...). It looks really great and I am super happy with the gauge thus far.

I pulled my ignition switch off, the zip-tied-to-the-triple-tree look wasn't quite doing it for me... For the next little while I'll run two hidden toggles (and watch my baby like a hawk) until I get an RFID relay in, which shall provide me security and clean lines. I priced it out to be 80$ CAD all said and done.

Quick question for you all about ignition wiring: Ignition switch closes brown and brown/white along with red and black for full functionality. As far as I can tell, closing brown and brown/white ONLY runs the gauge backlight. If so, is there any problem with just permanently wiring those two together and running a switch across only red/black? There is no voltage potential across the browns until red/black is closed, so I think this should be okay. If not I think I can run a dual pole, single throw switch and be done with it but that might be tougher with RFID. I aint no electrical engineer as you can tell...(but I am mechanical!)

Restoration Fan: Thanks! The only thing I am worried about is that there are quite a few light scratches which seem to happen easily, I'll have to see if they buff out!

Calj737: I thought about doing exactly that. I was worried about compromising lateral stiffness though. Ended up scrapping the brackets anyways though as they conflicted with my new exhaust. I'm designing new brackets today. They will go from the bottom engine mount bolt to the top engine mount bolt.



This will allow my swingarm bolt to be left alone and I can do whatever I want with the new mounting locations as I replaced them with all-thread rod. I didn't like using that pivot bolt in the first place anyways! One thing I need to figure out is the location of the bracket bolts on the right side of the bike. I cant find any dimensional reference to them. Does anyone have an idea of where I could find that out? Dims are always better than my poor measurement skills!

Martin: Yes, I completely agree! I was pretty tense when I turned the petcock on to see if my carbs would leak again! No leaking at all though! And yeah, the rear disk in combination with exhaust probably puts a decent restriction on what you can do for peg placement!

I am setting a goal of having my bike COMPLETED by Sunday. Just need rearset brackets, a seat and emblems now!

Here's a couple new pics! And the MotoGPwerks exhaust is great! I didnt like dealing with the guy, he was quite rude to me but his product is fantastic, so I'll take it!

[Retro Rocket]

Regarding your bracket and the too short pivot bolt, can you scallop the backside of the bracket on both sides where it passes through the bracket to allow the nut to grab a couple of more threads. Or scallop the front if moving the bracket closer to the frame causes other problems?

F2 750 swing arm pivot bolt is longer, the F2 has  alloy footpeg brackets, held on by the pivot bolt, hence the extra length... just use one of them....

[mkoski]

Yes, the longer pivot bolt would work but my exhaust interferes now anyways. I'm designing new brackets today to fit.

Yeah, the exhaust does look great (and sounds MEAN), I love it! I'm not complaining about him, I get that he is busy and everyone has bad days. Just a little unpleasant giving someone a big wad of cash for a product and not being given the time of day to ask a question or two, that's all! 

I'm looking for the relative position of the lower, right-side engine-mount bolt that attaches to the frame. In the picture below, its the bolt that the choke is mounted on (which is not where it is anymore!). I can only find frame dimensions for the left side of the bike.

[mkoski]

Sorry, I think you mis-understood me Calj737. I'm looking to find the dimensions to that hole location relative to the bottom-rear engine mount bolt so I can design a bracket in CAD that will fit up perfectly! I can measure it but that is tough to do with high precision!

[mkoski]

Hahhaha, yeah, I make some pretty stupid mistakes but that one I figured out. 

For the record, by my measurement, the hole is 155.0 mm from the bottom, rear engine mount bolt location.

[mkoski]

For anyone interested in a rear-set bracket design that goes from the engine mount bolts on the left and the engine bracket mount bolt on the right (with clearance for yoshimura style exhaust), here is my design... test fitting tonight.

[mkoski]

So yesterday I finally decided to tackle my RFID ignition system. It was pretty intimidating for me because I never really liked electrical. Most will say thats its not hard and they are right. The thing that gets me is that A) I cant see where the problem is like a mechanical system and B) If you let the smoke out thats it, buy new parts. So easy to screw it up. Anyways...

I started on the Custom-Fighters forum and found the parts I needed. RFID kit and a latching relay (80$ CAD, shipped, total). After I got these set up I started with a low amp 12v power source to get all my wiring figured out. First I got the RFID relay working, that was cake. I just wired the red to +12, black to the negative terminal and tested funtionality.l Its nice because you can hear it click, signalling successful operation. It actually works really well for how cheap it is. The RFID tag is pretty cool. From the diagram I found the Normally Open circuit in the small, first relay and verified with my multimeter. After that, I wired up the signal wire (+12v) to go through that first relay into the second (latching relay) to the signal wire. That relay had a 3-wire harness and a two-wire harness. The three wires were red/black/green. Red went to +12v, black to ground (negative battery terminal) and green was the signal, coming from the first relay. The two other wires were the ones that went from the +12v, through the third (automotive, 40 amp) relay and to the ground. Finally, the ignition wires went to the other two points on the third relay and everything worked perfectly. Sounds simple, took me like 3 hours.

Testing:


Success:


I'm not quite done yet, I'll only fully install after I finish the seat as I need to mount the LED somewhere, signalling that its live and the antenna needs to go inside the tail too.

Among that, there are two other things I'm going to do:

1. Install an in-line kill switch which will disable the rfid from sucking power during storage/no-riding periods. I hear it will take over a week to fully drain the battery when sitting and waiting for an RFID key but for any storage period I'll just switch it off with a hidden toggle behind the tail-light.

2. Install a momentary kill switch at the bars. It will be powered in front of a relay so the relays power will essentially kill itself, ensuring that the switch only works to kill power, not to start er up. This simply saves the time of swiping the rfid again to turn er off.

The coolest part of this is that I popped open the key fob, exposing the laminated, paper-thin coil. I'm simply going to tape it to my business card and keep it in my wallet, flip my wallet open, touch the tail, she is live. I'm super stoked on this, works like a damn charm!

Also, if there is enough interest I could put together a full write-up with wiring diagrams, parts lists and the like for the CB750 specifically. The custom-fighter forum is actually quite difficult to learn anything from, everything is very convoluted...

[mkoski]

Seat and emblem are almost done. I did a great job refinishing the emblem last night and then wanted to clear coat it. I promptly ruined them with clearcoat, lots of runs and very uneven. Still kicking myself.

Before clear-coating... They were in really bad shape before paint and polishing.



I made a seat-pan, which will be the base of the rest of my seat. I figure I'll do it in parts since I struggle to get everything done nicely at once. Seat pan first, get a good fit, then add the butt-stop and add the front tank-mate-type bit. I'm pulling the pan out of the mold tonight, I did a negative which fit over the frame nicely. I want the edges of the seat to cover 1/2 to 3/4 of the top frame tubing, which is easily trimmed-to if everything works as I hope it did.





Slight bump in it for clearance of some electrical stuff mounted under the kicked-up frame loop.

[mkoski]

Short update: Seat version 3.0 is officially classified (by myself) as garbage. It fits poorly and looks awful. The reason I have been turning out crappy seats is my complete lack of tooling (I think). I have now decided to swallow my pride and I called up an old neighbor of mine who is something of a master woodworker with a fully equipped shop. This weekend I will be working with him to put together a seat that will fit all the geometry required and look the way I want. I think it will be a million times easier to do this with wood and band-saws, jigsaws, belt sanders and the like.

I also scrapped my Honda tank badges as I cant bear to do them for the eighth (I think) time now, as I screwed them up again. I ordered some knockoffs online which will be a simple fix.

Here is question for you all, I might also post these in the bikes general forum too if I don't get something to work with here.

My bike is very "buzzy" in the handlebars in mid to high range RPM's (no tach, no specific values). Its to the point where I think its abnormal. Its not the wheel-balance issue, its from the engine. Its also not the engine mount points, those, along with all other bolts/nuts are tight.

What should I look into the sort this out? I am almost sure something is wrong but I don't know what to check. Any insight would be much appreciated.

[mkoski]

Got them in already. When I say it vibrates, I mean it.

[mkoski]

I'll take your advise and go through everything I can tonight. Its pretty much only in the handlebars where I can feel it but if I twist the throttle in neutral while I'm off it the whole bike shimmys pretty hard.

Its for sure something in/around the engine as its related to the RPM, I can feel.

[SOHC4 Cafe Racer Fan]

That doesn't sound normal.  I wonder if your suspension components are worn out or if your crankshaft is out of balance.

[SOHC4 Cafe Racer Fan]

Are you experiencing a power loss? If you have a cylinder missing, you should feel a significant lag in power, too.

[mkoski]

No power loss, I was thinking that I was getting a miss too but thats not the case, everything is equally hot and she pulls hard.

Cant be suspension either, as everything is very plush and newly-rebuilt. I think I need to go back to a tune and do everything in order. I have a sneaking suspicion that its my timing...

[mkoski]

The list:

-Seat finished
-Exhaust angle changed
-New brackets designed/made (with passenger pegs)
-RFID/Toggle switch finalized
-Find and solve the vibration

So a couple things are done, made some more progress this weekend/week. A seat that actually fits (with the angles properly cut and wiring area routed out) is installed, needs to be carved to shape, finished, sealed, primed and have paint applied. (Then do a cushion, but thats a separate battle.)





My RFID system is 100% tested and working, very little drain on the battery to boot. I hid the antennae under the left side cover and the toggle just above the right side cover under the frame rail, works beautifully. The toggle allows my to disengage the RFID system, stopping any drain, and also allows me to disengage the RFID system/power by simply toggling it back and forth. I like the simplicity of the dual-purpose, hidden design. I mounted the toggle inside and through the plastic parts tray that came with the stock bike.

I chopped my exhaust. The kick-up angle was too high for me to sit comfortably to begin with (6'3", long legs...) then I decided I wanted to be able to have a passenger too, so I cut it, re-angled it and had a friend of mine TIG weld it in position today...





(I'll post one with it on the bike after I reinstall it, too!)

[mkoski]

Here's a shot of the pipe back on the bike. Much more clearance now to extend my legs a bit and put on some passenger pegs farther back with a new bracket design. I also kept some of the angle because it looks really good. I just went for a happy medium between the two.

[SOHC4 Cafe Racer Fan]

Did you already fab a support bracket for the tail end of the pipe?  You really don't want the head supporting all of that hanging weight.

[mkoski]

Yeah, I have a little spring-secured support right behind the 4-1 collector. I'm going to put on something a little bit more secure on soon but for now that takes almost all the weight off, just lets it bounce around a bit more than I would like.

Also, for anyone who can help: I'm looking at a CB550 tonight, its a junky bike but the price is right (~450 bucks). What is your pre-purchase checklist look like in terms of making sure everything is good? The battery is dead so I think I will jump it to test electrics and kick it over to ensure it turns over. What else should I do? Here is what she looks like...



My goal is to put less than 1000 into it and make it a workable, ridable bike to either sell for a bit of money or just keep for a beater-bike. Approx 60,000 km on the clock, too.

[SOHC4 Cafe Racer Fan]

It is a little rough around the edges buy I've seen and purchased ones rougher than that.  Check the condition of the oil -- at least by looking at it on the dipstick.  If you can jump the bike or bring a spare charged battery to start it, you can check with a multimeter to see if the charging system is working, and look for leaks as it is running.  Honestly, for $450, what do you expect?  You're simply trying to figure out how much work it needs; I doubt that whatever you find wrong with it is going to reduce the price much.  Also, does it have a clean title? 

[mkoski]

She's not a runner but the internals look half decent from what I can see. One bad thing, no oil at all inside. Everything looked well lubricated but there was a definite lack of oil. I will make sure it turns over for sure and shifts through all gears but other than that I don't think there is much I can do. I don't expect much, just wanted to get an opinion on what you guys would do.

Also, this is Canada, no titles here, just bills of sale. 

[mkoski]

Thanks for your advice. I'll reconsider my thoughts but still take another look at it this weekend and see the basic functionality. If I do get the starter working I should be able to shift through all the gears with the bike on the center stand using the starter motor, no? Also, there is oil in there, everything looks good inside but the oil level is very very low. It will be a game-day decision I think.

Back to the 750 and recent findings:

I started to go over the engine tune and started with my timing. Some serious problems are kicking around in my points! First, the gap was wrong for sure. It was very small, around .005". This is an issue is here is my approach, please chime in with anything you notice that I did that was dumb!

First I rotated the crank until the 1-4 gap was maximized, loosened and stuck a feeler of 15 thou between the points, gently tightened the set screws at this position. I did the same for the 2-4, 15 thou gap.

Next I set the static timing as per the PDF that is kicking around the internet (http://www.hondachopper.com/garage/carb_info/timing/Static_and_Strobe_Timing.pdf) and everything is gravy. Did the same for 2-3, all good.

Now, I finally got a timing light (what a great idea, whoever thought of this...) and its showing that my F mark is to the left of the reference mark. No matter how far I adjust the plate (as far clockwise as possible), the F-mark will not line up. What could be the cause of this? I did some research and yielded no results. The only other variable I can think of that may affect this is my points gap... Huh. Please help!

Also, I am getting an inconsistent popping/misfire every few rotations at idle, I am assuming that this is either an inconsistent spark or clogged idle-jet (again...) because those are the only two variables I can relate to the issue. How can I measure/ensure adequate spark for each cylinder to determine is this is the problem?

[SOHC4 Cafe Racer Fan]

Also, for $450, if the motor turns out to be a bust, you can easily part out this bike and recoup your money.

[mkoski]

Also, for $450, if the motor turns out to be a bust, you can easily part out this bike and recoup your money.

I like your style. Its not about the bike, honestly, more about me looking at myself and wondering if I am ready to re-commit to a brand new build. I know its a good deal and the engine and everything looks good to me.

Any ideas for the points?