Author Topic: 78 CB750F "Modular-ish" cafe build? (Read 59791 times)

madScientist · « **Reply #100 on:** May 26, 2013, 01:28:41 PM »

Moved it out of the basement this morning. I forgot how heavy this sucker is! I cant describe the feeling of seeing it in the sunlight for the first time in 8 months!

Branden -- that was the cable. As i was migrating my tools and remaining parts I found the connecting cable to the starter. It's pretty well melted so I"m remaking it. There's no inline fuse on it currently. Should I put the 15amper in line on one of the cables then?

Also, the silver paint code is: Dupont Chromabase LM367

brandEn · « **Reply #101 on:** May 26, 2013, 02:20:43 PM »

That pipe looks great.

Thanks for the paint code. As for the fuse, it should connect to the stock fuse block. You really should get a wiring diagram to make sure it gets done correctly and not take my word for it cuz electrics in not my strongest subject

Retro Rocket · « **Reply #102 on:** May 27, 2013, 02:25:23 AM »

I am starting to warm to that pipe, can't wait to hear it.. Looking good..

sethdhawkins · « **Reply #103 on:** May 27, 2013, 12:13:46 PM »

Damn, you're wicked close

madScientist · « **Reply #104 on:** May 28, 2013, 05:31:09 AM »

I did not reach my goal of firing up this weekend. I didn't really get much time to work on it though. Kinda made me sad. Oh well.

I made up the oil lines and fabricated brackets for the oil cooler. I'm not really happy with the lower brackets and thinking I have a better design so I'm going to get those made up. However the cooler is pretty solid in it's current setup I just dont like how they look. Not even sure where my head was at in design because it's really not logical and kind of embarrassing so I'm going to refrain from putting them up :-D

I now have power to the main loom which is good. I'm going to try and weed my way through hooking up the mess in the front. I figure it will take me close to 2 (or more) nights to get through that. Wiring isn't really my thing.

I have to swing by Napa to pick up some oil filters. I read that the 1390 should fit the adapter but I'm going to take it up there to see for sure. The Napa by my house has them in stock. Once the filter is on the oil circuit should be closed and I'll put oil in and crank it over to build up pressure. Hopefully it doesn't leak...or least not badly.

My front brakes are refusing to bleed up. When a valve is open I can hear air push through but the fluid level in the master cylinder isn't going down. So that's on the track down list...It is getting close...I hope to get a couple hours a night with it this week. We'll see.

iron_worker · « **Reply #105 on:** May 28, 2013, 10:21:36 AM »

Your bike is looking great out in the sun!

Get yourself a wiring diagram, a chair, and something you can put your wiring diagram on so you can easily see it. Pull your chair up to the bike near the bucket and get comfortable ... you're going to be there a while. lol Start going through the wires one by one and elimintating where they go to. If you have all OEM or original parts it's not too hard, just matching colors. If you have some aftermarket parts then sometimes the colors don't match to what they should be and that's where things get interesting.

As for the front brake, sounds like you have some air in the M/C that isn't bleeding out. I pumped my lever very quickly in short strokes probably over 100x before mine "grabbed" and started pushing fluid (ignore any dirty references that may arise from this ha). I also rocked the bars back and forth to change the height of the fluid in relation to the system.

I have heard of people "bench bleeding" their M/C by filling it with fluid, depressing the lever, then before you release the lever you stick your thumb over the hole where the banjo bolt attaches (line should be disconnected). Then as the lever is allowed to release the fluid is forced to be drawn in to the M/C through the breather hole. Now your M/C should be "primed" with fluid and ready to pump. Note: I've never tried this method but sounds good in theory. lol

IW

madScientist · « **Reply #106 on:** May 29, 2013, 06:53:30 AM »

Thanks guys!

I did just as you said iron. I sat down in front of the headlight with the diagram and started hooking stuff up. I kept the harness largely original so it wasn't as bad as I thought it was going to be. I did screw up one connection and blew away the clutch safety switch. I'll have to get a new one of those eventually but can live without it. Unfortunately that little mess up melted the wires by the diode but I caught it before they got too bad. Cut them out, replaced them, and all was well. I dont have power to the brown wire that goes to the tail light which is unfortunate as that's also where the wideband is spliced in. I'm going to try and run that down this evening as well.

The bike cranks over. However I didn't really let her crank over as there is minimal oil in it until i can get an oil filter. I've been trying to figure out what type of cooler adapter plate i have. Turns out it's an old Lockhart made to use the canister filter. Not exactly what i wanted but it'll do. I ordered a spin on filter type from cycleX as well.

I pulled a plug and have very healthy spark from the Pamco. I think tonight might be the night she breaths....or it'll go "clunk, clunk, BOOM" or ditch all it's oil...guess we'll see.

I tried the rapid pumping of the master cylinder but it just would not catch. I'm going to try the bench bleeding technique. I hope that works.

The light at the end of the tunnel is starting to get very bright...hopefully tonight it'll be even brighter!

madScientist · « **Reply #107 on:** May 30, 2013, 05:27:10 AM »

IT'S ALIVE!!!

I had it running for a little bit tonight. I didn't want to push it though. I still need to dynamic set the timing as I think it's a bit forward for the cam. The carbs didn't clack that much so they seem to be close to in sync. It was very exciting to hear it run! There were no major catastrophes and there were no leaks even this morning. Oil pressure was good and strong around 60psi fluctuation to about 70-80 on a couple throttle cracks.

The brake issue is still eluding me so I'm going to take it back off and clean it out again. I tried bench bleeding and it still would not pump fluid. I'm wondering if maybe one of the holes in the MC are jammed up.

The preflight list is still a little long but I dont think it'll take me a ton of time to get things sorted...

-- Set front brakes
-- set rear brake
-- oil in forks
-- grease rear
-- set drive chain slack
-- set timing
-- sync carbs
-- double check that every bolt is tight

When i get it balanced to where it'll idle easy enough I'll take a video and post it...that pipe is mean sounding!

sethdhawkins · « **Reply #108 on:** May 31, 2013, 04:24:18 PM »

Congrats!

madScientist · « **Reply #109 on:** June 02, 2013, 06:36:28 AM »

Had it running some tonight. Got the ignition timing where I want it for the initial round of testing. The carbs seem to be running a point or two rich. Depending on what i get done today (gotta work a little) I'm going to lean up the screws and see if I cant dial it in tighter. Also going to try and get a sync done.

But first...last night while i had it running i pulled the #1 and #4 tappet covers off and thank you to Branden for the suggestion! I think you saved me from torching my top end... The #1 side has good oil but the #4 side looked dry...no oil splatter and very little oil slick on the retainer. So i'm going to pull the cover today and verify the right side is getting oil. If it isn't I'll pull the cam tower and clean out the jet...hopefully that'll fix it.

The front brake is still eluding me too. The MC is pushing from what I can tell. I put the brake line in a cup of brake fluid and I can see the MC pushing fluid out. However bleeding from the bleeder valves gives me nothing...I dont even hear air! The brake pistons dont even try to move... It's starting to frustrate me. I've had the MC apart twice now making sure everything is good and clear. The calipers have a new seal in and have been lubricated. The MC is really light too. I'm going to pour fluid directly into the lines and see if that helps at all.

I'm not terribly good with my camera but here's a short video of it running the shop.

836 build idling

sethdhawkins · « **Reply #110 on:** June 02, 2013, 10:13:33 AM »

Chase,

Is that a new MC? I've futzed around with rebuilding and cleaning so many of those stock ones. I buy all new MC's now whenever there's a hint of a problem. I get them from MikesXS. They're cheap, but can be found cheaper. There are two small holes in that MC, one bigger and one very, very small. They both have to be completely free and clear. Years of running crap rubber hoses and not changing fluid tends to lead to a sad state of affairs. I hate rebuilding those things, if you can't
tell

With the top end oiling, at what rpm are you inspecting everything? You're not gonna see really good oiling till 3-4K. As for the mechanical oil pressure gauge, take those readings with a grain of salt. I haven't really found a really quality one, and have gone through two already. You also may see changes in rpm versus oil pressure once your engine is at operating temp.

Have you synch'd with the manometer yet? You can't begin tuning till that's done. If you're using your AEM yet, a difference in slide position on one carb will throw off the sniffer. As far as being rich, I can run stupid rich at idle (dyna coils and dyna 2k) and never foul a plug. I actually found that having a rich idle helped me.

Good luck,

Seth

madScientist · « **Reply #111 on:** June 02, 2013, 11:11:27 AM »

The MC was a rebuild. When i took it apart last night I ran a flashlight through the handle end and closed off the banjo end. Saw plenty of light so I think the holes should be clear. If i cant get it straightened out I think I'm going to say F it and get a new one. Thinking of maybe upgrading to one of the Nissin ones from Dime City.

http://www.dimecitycycles.com/vintage-caferacer-cafe-racer-bobber-brat-chopper-custom-motorcycle-brake-parts-black-aluminum-nissin-hydraulic-front-brake-master-cylinder-perch-lever-kit-17-651-b-3385.html

Although I'm not sure it'd really be worth it for now since this winter will probably see more suspension and brake upgrades. Maybe a GL1000 front end.

I was inspecting at about 1k RPM. The left side was wicking pretty good. The right side was nothing. I'll start it up today, hold it at 3k and then check the right side. I'm just happy i see fluctuating oil pressure that is somewhat strong. I was a little concerned the pump wouldn't work.

I have not sync'd them yet. That was also on the list for today. So should I not worry so much about the idle and move on to low - mid range?

I changed the video link to the youtube link from the photobucket. Let me know if that works.

sethdhawkins · « **Reply #112 on:** June 02, 2013, 11:38:38 AM »

Definitely, sort out your oiling conundrum (if there is one) first. If that's cool, move on.

The carbs, and this is how I did it, so take it with a grain of salt. You need a box fan and an aux fuel tank of some sort. Start the bike and let it warm up...this takes longer than five minutes, then place the fan in front of the motor. As your bike warms up, you will actually see the AFR's come down from leaner to richer. Shoot for somewhere between 11-12:1. I'm in mid 11's for my idle and I've experimented all over the place with it. On the fuel screw; in is less fuel, out is more. Lower the AFR number, the richer the mixture. Once you're in the ball park, you can roll on the throttle (I never found a way to remove the accel pump from the equation, if you roll on gently, it won't squirt fuel, or as much). In combination with that fuel screw/pilot jet combination, you'll start going into the needle end of the circuit...just keep looking at those AFR numbers, and shoot for 12-13:1. If they're high (leaner), try raising the needle. If they're low, vice versa. If you start somewhere in that middle clip position on the 9DZHO3, you're not gonna do any damage by being too lean or rich...it's gonna be pretty close. Once that's all done, tune that accel pump. I found the throttle response best with it coming on, literally, just off idle. As for where the accel pump stroke ends, that's up to you...that's where I'm stuck. Take it for a ride, and keep looking at your AFR's. You may find that I'm an idiot and sent you in the wrong direction. I didn't tune the main jet till I broke the motor completely in. I think I have a 122.5 in there now, and it's a little rich. Mine shipped with a 125!

Once you get everything dialed in, I think we should provide a sticky in the facts for RS34 tuning.

I have that Nissin MC on my cb360. It was intended for the 750, but I thought it sat too high. When my stock MC died on the 360, that one went on. Bench bleed it...I spent like 45 min bleeding it, the longest I've ever taken on a bike :-/

Seth

madScientist · « **Reply #113 on:** June 02, 2013, 08:48:54 PM »

I made good progress today...

Drilled the rivets out of the petcock, rebuilt it, tapped it, put it back together, and it leaked at the nut. So I "made a rubber inner seal on the nut end out of a heater hose I had lying around. Worked like a charm!

The front brakes still refused to work for me today. I bled them for darn near 2 hours. At the banjos, bleeders, everywhere and it just would not take. So F it...i purchased the Nissin. Hopefully there aren't any issues with the fronts now. But I have to get the rear working and it too would not take fluid. So if anyone has a suggestion for an upgraded rear MC i'm all ears. I've been looking at Brembo's but need to check compatibility.

Dynamic sync'ing proved less than fruitfull. I'm still learning these RS34's and it took me a little bit to figure out the adjustments. The different setup from the Keihins threw me off a little. They were already real close from the bench sync but then i threw them way out of whack. So I'm going to re-bench sync them on the bike and start over. Now that I know how things work on them a little better it should go smoother. It's running right at 12.8 for A/F at idle. Which according to Seth is pretty good. However we'll see how it goes after the sync.

Maybe I'll get to ride it next weekend...

madScientist · « **Reply #114 on:** June 03, 2013, 10:05:04 AM »

Picked up a cheap Brembo rear master cylinder from a R6. Looks like it should fit after a bracket has been made to hold it. I would guess it'll be a pretty nice upgrade.

So hopefully that seals the break whoas.

sethdhawkins · « **Reply #115 on:** June 03, 2013, 10:09:23 AM »

You gonna toss the tins on there for us, so we have something for our hands to do while we wait?

madScientist · « **Reply #116 on:** June 03, 2013, 10:38:37 AM »

Patience my friend! I want to get all my messing around done before I put those on to minimze the chance of scratches.

Maybe I'll dress her up tonight and take a shot for you guys :-D

sethdhawkins · « **Reply #117 on:** June 03, 2013, 12:46:50 PM »

Now that's the spirit

tweakin · « **Reply #118 on:** June 03, 2013, 08:15:03 PM »

Looking great MS, man i love the rattle of the RS34's. Take your time and wrap it up right the first time, then enjoy the #$%* out of it!

madScientist · « **Reply #119 on:** June 04, 2013, 06:40:56 AM »

Thanks guys!

I pulled the valve cover last night just to ease my mind and saw healthy oil on the rockers, cam, and surrounding areas so I feel better about that.
Re-bench sync'd the carb's since my first attempt at syncing them threw them way out of whack. I wasn't quite sure how the adjustments worked which was ultimately my downfall. I think i'm going to get new hoses for the vacuum gauges since the current ones dont fit the spigots on the Mikuni's too well.

Dropped the oil out and put the CycleX adapter on it. Thanks to Branden for sending me pictures of how he has his oil cooler mounted. I'm going to duplicate his setup since what I was coming up with was not only ugly but also kind of weak.

Probably wont be able to work on it for a few days now which sucks. I have an order for a 428 stroker that i have to finish up.

Here are some teasers. I dont have a lot of room to move around where the bike is since it's right next to the bench. This was covers, seat and tank more less resting on the bike. Bon apetite!

madScientist · « **Reply #120 on:** June 04, 2013, 06:42:11 AM »

Also, thanks to Seth for his tuning advice and expertise on the Mikuni's!

madScientist · « **Reply #121 on:** June 04, 2013, 06:43:31 AM »

Also forgot to add this shot of the gauges

MRieck · « **Reply #122 on:** June 04, 2013, 06:54:44 AM »

Your bike came out great. Be sure to put a fan on the engine when synching and don't run the idle to low. There are guys that like to idle at 800RPM and that is on a mechanical tach (which read low). A decent cam requires higher idle which also improves oil pressure (a thought lost on many people). I don't worry about the idle RPM reading from the tach....I want smoothness.
They only guys I see who want super low idle RPM are the Harleys entered in lowest idle RPM contests.

madScientist · « **Reply #123 on:** June 04, 2013, 08:28:57 AM »

Thanks Mike! The work you did on the head is epic man!
I'm going to take another stab at the sync'ing probably Saturday if I can get that engine done.

What is a reasonable idle for it? 1500 on the tach? Just as a guideline? Or just listen to where it purs? I initially had it set around 1000 which sounded low and cammy to me.

sethdhawkins · « **Reply #124 on:** June 04, 2013, 09:08:54 AM »

"Bon Appetite!"

Chase, I think you're confusing your food with your porn! Those tins look gorgeous resting on there. I think 1450-1500 is an acceptable idle, at least mine has good oil movement in the head at that rpm. After reading the science behind it, I now run ZDDP in all my old bikes.

Mind posting a picture of that Cycle X thingy mounted?

Seth

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Author Topic: 78 CB750F "Modular-ish" cafe build? (Read 59791 times)