Author Topic: 76 CB550 Cafe build (Read 86997 times)

tshrey · « **Reply #425 on:** August 23, 2020, 08:08:07 PM »

This is fantastic. Why the 6" extra tubing?

I need to get some kind of petcock for the fuel tank. Just looked on pingel's website. $150 for a freaking petcock? WTF? I guess I will be going with some home depot shenanigans.

MRieck · « **Reply #426 on:** August 24, 2020, 05:57:37 AM »

The tubing prevents dirt etc from getting into the cold start system. When you lift the lever it unseats a rubber sealing disc and allows air into the starter system. This will then draw fuel extra fuel from the bowl. After a while of riding crap will get into that nipple and get between the rubber seal and seat. When that happens the rubber seal will leak air and small amounts of fuel will be pulled into the carbs when running. It can foul plugs and drive you insane trying to figure out what is wrong.
The tubing can be longer than 6" too....12", 15" etc.
Also.....buy and install the smallest starter jet Keihin makes.

tshrey · « **Reply #427 on:** August 25, 2020, 08:15:59 PM »

Ordered 35 starter jets. I had the flot bowls off just now and cannot for the life of me find where the starter jet is. I see the pilot off to the side on its own and the main jet. The CR diagrams I'm looking at do not list it. I'm sure it is obvious but I can't for the life of me find it.

MRieck · « **Reply #428 on:** August 26, 2020, 04:28:33 AM »

Quote from: tshrey on August 25, 2020, 08:15:59 PM

Ordered 35 starter jets. I had the flot bowls off just now and cannot for the life of me find where the starter jet is. I see the pilot off to the side on its own and the main jet. The CR diagrams I'm looking at do not list it. I'm sure it is obvious but I can't for the life of me find it.

It is in the bottom of that small, separate chamber in the float bowl. That chamber is on the same side as the black plastic air nipple. It is a pretty small jet....look for a brass piece in the bowl. The small factory manual included with the carbs should show it.

tshrey · « **Reply #429 on:** August 26, 2020, 07:17:11 AM »

As I figured, once I saw it I couldn't believe I missed it. When you said 'in the float bowl' my brain took that as 'in the carb under the float bowl'.

I think I'm going to also run all the starter nipple lines together and into a small filter. Don't like the idea of something like that being open.

I'm getting pretty excited, as soon as those jets show up I'm ready to try to start the bike for the first time. I filled it with regular dino oil for break-in. Before I introduce fuel should I spin the engine with the starter or kickstart for a bit to get the oil pump to fill up or should I just start it regularly?

tshrey · « **Reply #430 on:** August 29, 2020, 11:26:48 AM »

So I hooked up enough wiring to be ready to test fire the engine once I get all the jets I ordered.

Figured I would fully dial in the ignition. I don't ever get my test light to light up from the Dyna S output. I ran the ground of the battery directly to the metal backing plate of the Dyna, grounded my test light to that as well. Fed +12V to the red wire and then connected the test light to one of the leads. Nothing. I even removed the assembly and the rotor on the bench with the same wiring in place and no matter where I put the magnet on the rotor I don't get 12volts on the output. Battery is good, left my meter on it the whole time, test light was checked multiple times. Checked the input wiring by leaving the batter hooked up to the dyna connector and then probing the red wires as they actually go into each module and test light lights up. It seems really weird that I would have two bad modules, neither one works. Am I being profoundly stupid?

tshrey · « **Reply #431 on:** August 29, 2020, 11:54:05 AM »

So, yeah, that's embarassing. I thought the switch on the dyna was passing +12V when the rotor was in the right position, it is passing ground. Times like these it doesn't pay to be relatively young, every motor I've ever worked on has had electronic ignition with the coil right on the plug connector.

On the upside I now know I had the coils wired wrong and should be ready to fire it up when the jets get here.

tshrey · « **Reply #432 on:** September 04, 2020, 03:04:33 PM »

First attempt at a start was a disaster. Turned it over to check each plug had spark, then hooked up carbs and a small gas can. Used the choke. When I cranked it a spray of atomized fuel shot out of the starter circuit nipples. Cleaned that up and tried without the choke. Something is still not right, engine sounds great turning over, sounds like lots of compression but way too much fuel is going in. I'm getting a backfire in the exhaust every second or so if I keep cranking it. Also, the bottom of the carbs have gas on them and the intake manifolds are wet.

There should not be any kind of restriction in the fuel line right? - the floats are supposed to control the level of the gas in the bowls. Second, how open should the throttle tubes be when the throttle is closed? I have about 1/8" opening in each.

Going out now to try to find the leak.

tshrey · « **Reply #433 on:** September 04, 2020, 07:34:50 PM »

Removed carbs and drained all the fuel out of the bowls. Took every jet off and blew it out, reinstalled everything. No choke but didn't even sound like it wanted to light off. Rechecked timing and valve adjustment, all perfect. When I reconnected the wires for the coils I realized I put them back on wrong. Then actually decided to check...

The problem with using temporary wiring is everything is the same color (or two colors in this case, I'm just using 16 gauge speaker wiring). Had the damn 1/4 and 2/3 coils wired to the wrong trigger on the igntion. Now try, no choke and it ran for about a dozen revolutions. Got really excited. Now the battery is on the charger, but I feel like I'm close. The choke circuit still scares the #$%* out of me. Does anyone who runs CR's use the choke to start the bike? How much? Full choke seems ridiculous with how much fuel I was getting everywhere.

tshrey · « **Reply #434 on:** September 04, 2020, 07:39:36 PM »

30 second update. IT'S ALIVE. I just said screw it and tried it with full choke and it fired right up. I don't know what the spitting fuel out the starter circuit was about before on the choke.

So stoked, no way I'm going to sleep tonight. I'm going to get this on the road soon.

joeyvans · « **Reply #435 on:** September 04, 2020, 08:03:31 PM »

Congrats! Always an amazing feeling!

tshrey · « **Reply #436 on:** September 05, 2020, 07:37:54 AM »

Let the bike run for a bit to see how idle sounds. Guess oil pressure is good

I didn't have the rotor cover on yet and didn't realize that little plug in the bottom of that opening is only held in by and oring and the cover.

Next check, after refilling with oil, is to put the alternator cover on and verify ~15V on each leg of the stator.

tshrey · « **Reply #437 on:** September 07, 2020, 10:39:01 AM »

So my CBR600RR alternator is working. Ran the bike at high idle for a while and checked the output, each leg is 15V AC to ground so it is doing what it is supposed to do. Ordered a Rick's fancy mosfet reg/rec for lithium batteries an an Antigravity 8 cell so the charging system will be done. Planning out my wiring on a whiteboard in the garage.

Bike seems to run on all cylinders on choke, but as it warms up and I bring the choke lever down it gets lumpy. Only the cylinder 3 header is still hot after letting it idle for a minute. Pulled the plugs and 3 is clean, tan and dry. Checked the gap on all the others and they were all way too small and all three were wet, I thought I would have checked them before putting them in the bike but I guess not. I have the air screw set identically on all four carbs. Having never tuned anything on a carb before I should just start playing with the air screw for idle? How much is a coarse adjustment, 1/4 turn?

tshrey · « **Reply #438 on:** September 07, 2020, 07:27:30 PM »

Reset plug gap and backed the air screw out to 1.5 turns. Pretty clearly running on cylinders 1&2. I thought I needed more air but now that cylinder 3 isn't running I guess I need to go in with air screw. The screw is sitting on the air side but the instructions show it is connected to the motor side so I could be visualizing what is going on all wrong.

Gonna keep playing with the air screw to see if I can get 3&4 to run but there was so much smoke in the garage I had to take a break. I did drop down to 55 pilot jets from the 65s it comes with based on dyno results from someone who has the same setup as me.

Not gonna lie, I figured I would enjoy this part the least and I was right.

tshrey · « **Reply #439 on:** September 08, 2020, 12:47:32 PM »

Swapped plug wires between 1 and 4, 2 and 3 and that made no difference I'll try spark plugs next.

Carbs are on the bench, was going to recheck everything but these are pretty much brand new carbs so I don't get why I would have a problem with them. I did notice one little thing, the slide on cylinder @1 sits about .5mm higher than the others. The rod that allows the side to side adjustment of the rack has various holes in it for different widths but cylinder 1 is a tiny bit cocked and it lifts the slide up. That clearly isn't my issue right now since the first two work but something to look at later.

Is there anything bone-headed I could have done that would screw up one half of the engine otherwise? I rechecked the valves the other day and they were spot on from when I first set them. Just don't get it, shouldn't be this hard.

tshrey · « **Reply #440 on:** September 08, 2020, 03:54:58 PM »

I never checked the floats in the carbs because they were brand new units and supposed to be set up.

Manual calls for 14mm on the floats. They are between 9 and 11 mm. So that's not even close (the micrometer is set to 14mm in this pic).

seanbarney41 · « **Reply #441 on:** September 08, 2020, 04:02:58 PM »

not at all familiar with those carbs, but it looks like the floats are upside down. Generally, you will have the curved side facing the bowl...should fit better/closer like that. Flat/square side on top.

tshrey · « **Reply #442 on:** September 08, 2020, 04:26:15 PM »

They're flat on both sides. Given the way the tang sits they can't be upside down. I think they just weren't set up correctly.

Thanks for the input though, I'm really starting to get annoyed with this and constantly smelling like gas.

seanbarney41 · « **Reply #443 on:** September 08, 2020, 05:24:36 PM »

Quote from: tshrey on September 08, 2020, 04:26:15 PM

Thanks for the input though, I'm really starting to get annoyed with this and constantly smelling like gas.

might want to think about a slightly different hobby

tshrey · « **Reply #444 on:** September 08, 2020, 06:39:29 PM »

Quote from: Godffery on January 29, 2020, 12:14:02 PM

Here is a good basic starting point:
Main jet, #105
Pilot/Slow jet, #55
Jet needle, #YY8, clip #3
Main air jet, #220
Starter jet, #45
Valve seat, #3.2
Air screw, .75 turns out

All the above are pretty close to what I've been told except the valve seat. While I had the floats off to bend them I checked which seat is in there. It is the 2.4, which is the size the CR26 come with.

@Godffery you'd recommend going up to the CR29 valve seat size?

tshrey · « **Reply #445 on:** September 09, 2020, 10:29:36 AM »

Cleaning out all the bins for this bike. I'll put these in the classifieds as well, but for anyone reading my thread and helping out they will go to you first

Intake manifolds powder coated in Hot Rod texture:

Stock rotor, stock spacers and aluminum spacers. Edit: I just found the field coil and the stator as well if anyone needs them. The aluminum spacers I made when I first got my lathe. They are dimensionally correct I just wasn't happy with the surface finish. Save a pound over those two stock parts which seems to be made of Tungsten based on their weight.

Just pay shipping and any of that is yours.

Since I have been stuck lately I wanted to at least make a little progress so I got the chain on and adjusted. If the engine ever runs I can now ride up and down the driveway

And back to the engine. Even after the float height adjustment I was still only running on 1&2. Pulled carbs again and was thinking of removing the top of the head to check for anything dumb I had done when I decided to also pull off the intake manifolds:

I forgot the o-rings on the cylinder 1&2 side. I also wanted to use purty stainless acorn nuts on the manifold and now realize they were bottoming out before tight. So 1&2 were pulling in extra air and they were running, meaning I'm rich as hell. At least that solves the mystery of 1&2 vs 3&4. I don't get why my setup is so ornery compared to others. After finding the floats so far off I looked over everything and noticed a jet up in the top of the carb under the throttle rod. Parts diagram calls it the 'Air Leak jet', but it isn't listed in the manual. Anyone have any idea what size it should be? Maybe it can't be wrong, it doesn't look like I can remove it. (no slot for a screwdriver).

tshrey · « **Reply #446 on:** September 09, 2020, 12:15:17 PM »

Found a really short video on CR carbs on youtube ('More CR Carbs from Mike' - is this you MRieck?) and learned how to adjust the slide heights using the arms on the throttle rod. So all four are the same height, cranked down the idle screw so that there was about 1mm of an opening and reinstalled. Fired right up, came down at a fast idle on all four cylinders. Backed the idle screw out until it sounded like 1000 rpm (no gauges anywhere yet). Going to finally call that some success.

Two bad things.
1

I appear to have a pinhole in my valve cover because that tiny well of oil developed while I was running the bike. So it looks like the cover is coming off for a little touch-up welding. While I'm in there I will just give everything a look over. Also - is it normal to be able to hear the cams when your ear is close to the valve cover? I'm running a 650 cam if that makes a difference.

2, after I shut everything off and celebrated for a bit I realized I smelled gas. It was dribbling out of the main air jet on cylinder 4. I'm starting to wonder if there isn't something wrong with the valve or the seat attached to the float in cylinder 4. Looking at the color of the headers after idling for a while it isn't as dark as the others. It was definitely running, got over 200 degrees, but seems to be cooler (richer).

tshrey · « **Reply #447 on:** September 09, 2020, 03:34:41 PM »

Not a pinhole. Not sure how I missed this when I powdercoated it, but the hole is about 2mmx1mm. I don't trust my welding enough to patch this without distorting the cylinder that the rocker rod lives in. I've seen people fix hold in crankcases with JB Weld, this seems like an ideal spot for it. We'll find out...

SOHC4 Cafe Racer Fan · « **Reply #448 on:** September 09, 2020, 03:40:31 PM »

Agreed. A little JB should work the trick.

Godffery · « **Reply #449 on:** September 11, 2020, 02:35:13 PM »

On a totally unrelated subject...
You have any interest in a highly unorthodox sprocket cover?

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Author Topic: 76 CB550 Cafe build (Read 86997 times)