Author Topic: 1977 CB750 K7 /// Rebuild 2.0, Project Anna (Read 53310 times)

calj737 · « **Reply #75 on:** April 23, 2015, 11:38:15 AM »

Then you really need to start diagnosing where it's coming from. It won't be easy, but I'd start by doing an absolutely thorough double check of every nut, bolt, and bushing associated with the rear, drive line, and suspension. Then, I would check any body work (aftermarket fenders, fenders not fully tightened, chain guards.

Can you feel it only in your hands, or in your feet or butt? If it's only in your hands, and you have dampers in the bar ends, then I'd look carefully at the bar clamp and top clamp, and stem nut. Something is NOT right. You are the first person I've ever heard complain about vibration after dampers.

mkoski · « **Reply #76 on:** April 23, 2015, 12:10:33 PM »

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 · « **Reply #77 on:** April 23, 2015, 04:20:18 PM »

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

calj737 · « **Reply #78 on:** April 23, 2015, 04:26:34 PM »

Almost sounds as if it's missing on a cylinder. Check all 4 pipes for equally hot while you're down there. Just to be sure-

SOHC4 Cafe Racer Fan · « **Reply #79 on:** April 23, 2015, 04:47:16 PM »

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

mkoski · « **Reply #80 on:** April 24, 2015, 07:58:47 AM »

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 · « **Reply #81 on:** April 28, 2015, 02:54:23 PM »

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 · « **Reply #82 on:** April 29, 2015, 09:37:13 AM »

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 · « **Reply #83 on:** April 29, 2015, 11:51:49 AM »

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 · « **Reply #84 on:** April 29, 2015, 01:09:29 PM »

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 · « **Reply #85 on:** April 29, 2015, 01:50:55 PM »

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 · « **Reply #86 on:** April 29, 2015, 02:08:28 PM »

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.

calj737 · « **Reply #87 on:** April 29, 2015, 02:25:08 PM »

If there's no oil in it, then I'd pass, or fully expect to blow right past your $1K budget. Unless it's running and moving, you'll not get it into all 5 gears, and without running it, how would you know whether the trans wasn't wonky?

500s are notorious for some trans issues, so I'd either fully expect a case split and a blown budget, or pass. The fork uppers under the ears are likely to be badly rusted, the swing arm bushes shot, wheel bearings needed, fork seals, some wiring, points/condensers, oil and filter (x2), plugs (x2) and probably brake lines, caliper rebuild, master rebuild, and new clutch/throttle cables. And that doesn't even consider a battery or clutch-

Other than that, should be a quick flip....

mkoski · « **Reply #88 on:** April 30, 2015, 10:17:03 AM »

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 · « **Reply #89 on:** April 30, 2015, 11:14:54 AM »

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

mkoski · « **Reply #90 on:** April 30, 2015, 12:42:41 PM »

Quote from: CB750 Cafe Racer Fan on April 30, 2015, 11:14:54 AM

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?

calj737 · « **Reply #91 on:** April 30, 2015, 01:49:58 PM »

there is a common occurrence where the ignition plate and points are Daichi brand that the plate can not be adjusted far enough to be accurately timed. Can you identify the brand of yours?

mkoski · « **Reply #92 on:** April 30, 2015, 02:09:55 PM »

Yeah, they are the stock plates. I'll look tonight regardless.

mkoski · « **Reply #93 on:** May 04, 2015, 09:02:10 AM »

So, as a few of you saw in the "Bikes" part of the forum, I finished up my timing and got it spot on. I had an issue with a large gap and misaligned points plate which disallowed me to get enough range to set my timing.

Besides getting that sorted, I finished the initial shaping of my seat from solid cherry (both arms are sore today, almost no use of power tools, just sheer muscle to remove all that hardwood!), glued over plywood. Here's the result as it stands now:

I have to say, I'm finally happy with the damned thing!

Next up I need to fill, sand, smooth, prime, paint. That will give me my finished seat base.

I need a little more advice here. What is the best way to make an upholstered seat pad to go on top of the base so that its removeable, secure and looks nice? I want to do horizontally, gold stiched, black leather in almost the exact same was as this:

The only thing I am unsure about is the curved "backing" or base of the seat pad in which the foam would sit and the leather would be stapled to underneath.

I'm looking into outsourcing it to a pro but they sure cost a lot of money for work that (I think) I could do myself!

Also, what kind of distance should I put between my footpegs and passenger pegs for the bracket? Is there a "standard" that I can use? Right now I am kinda just eyeballing other bike's peg distances and locations.

Thanks for your input guys! I'm very excited that my first baby is almost done! (P.S. I went and check the tranny, engine, starter motor on the CB550 shown above, all was well. I now own two bikes!

)

calj737 · « **Reply #94 on:** May 04, 2015, 10:13:38 AM »

lots of options for attaching the pad to the cowl: velcro, studs thru the pan that penetrate the cowl and nut beneath the frame, rivet nuts into the pad (reverse of last option), and so on. All depends upon which way you want to work your tools.

Something to think about: your tail light. If you embed/recess the light into the seat cowl, removal of the seat cowl from the bike becomes a pain. Obviously a quick connect is the solution, but wiring and working length are consideration.

Did I understand you to say that you're going to paint the cherry? I know you used wood because of your familiarity with it, but why not use a penetrating stain and create something incredibly unique and cool, and still showcase your handiwork? Black Cherry stain with a beautiful leather pad on top?

mkoski · « **Reply #95 on:** May 04, 2015, 12:31:41 PM »

Quote from: calj737 on May 04, 2015, 10:13:38 AM

lots of options for attaching the pad to the cowl: velcro, studs thru the pan that penetrate the cowl and nut beneath the frame, rivet nuts into the pad (reverse of last option), and so on. All depends upon which way you want to work your tools.

Something to think about: your tail light. If you embed/recess the light into the seat cowl, removal of the seat cowl from the bike becomes a pain. Obviously a quick connect is the solution, but wiring and working length are consideration.

Did I understand you to say that you're going to paint the cherry? I know you used wood because of your familiarity with it, but why not use a penetrating stain and create something incredibly unique and cool, and still showcase your handiwork? Black Cherry stain with a beautiful leather pad on top?

I was thinking about just using some velco. All it needs to do is just stick in place. The thing I am struggling with is how to do the seat pad on my own. I have almost no experience with textiles besides a bit of sewing machine use.

That was a problem I ran into a few weeks ago and I solved it by permentaly mounting a 1/4" peice of plywood to the kicked-up section of the tail. To that I mounted the plate, tail light, rear blinkers. By doing this I separated it all from the seat so that the seat can be removed easily without affecting the rear electrics.

I really like that idea, unfortunately when I was working with my friend we decided to go with plywood as a base, which is really ugly wood. I also need to do a bit of filling and leveling first. For those reasons only I think I have to go with paint. I wish I was more thoughtful about it because that would have looked real cool, I agree!

mkoski · « **Reply #96 on:** May 06, 2015, 07:53:49 AM »

Brackets (third and final set!

) are completed, out for laser cutting. I think Ill powdercoat them gloss black. I added a couple personal touches and a mount for passenger pegs. I designed it so the upper brace on the rear section is horizontal with the ground and the angled part of the brace matches the angle of the exhaust kick-up. I think it really looks great aesthetically.

And some real high-quality folding passenger foot-pegs! (With even more gold!)

And here's a shot I took just because the sun was coming down at a nice angle:

dgilling · « **Reply #97 on:** May 06, 2015, 08:03:35 AM »

I'm rebuilding a K7 right now as well. Can you do me a favor and post some close ups? I'm about to install the tubes on the bike and want to see the tube routed from oil tank to back of engine, and how did you route the tube for the breather on top of the valve cover? I'm also trying to organize behind the headlight as much as possible can you show me some close ups of that?

Where did you get the blue oil lines?

Your bike looks amazing!

mkoski · « **Reply #98 on:** May 06, 2015, 08:52:13 AM »

Sure, I can put some up today or tomorrow. Check out my imgur album in my signature, might have a few pics of what you are looking for already. The blue lines are just from a hoe and fitting store, I bought high-temp hose with an ID that matched the original oil line fittings. I just cut those to the same length as the original hoses and routed them back from the oil ports on the engine, up and over the swingarm into the oil tank. I'm pretty sure the CB750 manual shows this routing pretty well if you have a copy of that. If not, its easy to find online. I didnt actually route a tube for the breather cover, I just put a little filter on that nipple (small, red k&n breather filter, I drilled it to a larger ID and hose-clamped it up). I have noticed a bit of oil leaking through there but not much. See here:

The headlight wiring is a gong-show, everything just gets put behind the bulb and lens into the bucket! I have to change my bulb tonight, actually, so I'll take a pic for you.

Also, thanks for the compliment. =)

That said, new question! My headlight fuse burned out and this is the second bulb I have burned up. Does anyone have a possible explanation for this? I really hate burning $40 bulbs every couple weeks!

dgilling · « **Reply #99 on:** May 06, 2015, 12:37:13 PM »

I looked at all your photos and something caught my eye. I noticed you had some pics with the choke relocated to down by the foot begs and some without it there. What did you end up doing with that? I've been looking to relocate my choke and that looks like a good idea. did you have a stock cable connected?

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Author Topic: 1977 CB750 K7 /// Rebuild 2.0, Project Anna (Read 53310 times)