Topic: 73 CB500 Boston Cafe

[SOHC4 Cafe Racer Fan]

Nice con-rod keeper/contraption!

[Trad]

I have the 61.5mm cruzinimage pistons from ebay. The cylinders were bored to those with 2 mil clearance.

Really nice work on the build so far; Excited to see it come together. I just wanted to make sure you meant 2 thou and not two millimetres? Two mil will be far too much clearance for those cast pistons. 2 thou piston to wall clearance would be a proper spec for that setup.

[lajos]

I just wanted to make sure you meant 2 thou and not two millimetres? Two mil will be far too much clearance for those cast pistons. 2 thou piston to wall clearance would be a proper spec for that setup.

Thanks for checking, I sometimes have trouble with the terminology The cylinders were bored to .002" clearance, so 2 thousandth of an inch, not millimeter.

The pistons fit nice, not too snug. If I have time tonight I will install studs, pistons, and test fit the cylinder block.

[lajos]

Installed the APE studs, pistons, rings and the cylinders.

I got hose clamps to compress the rings because the piston ring compressor I got was way too tall, but ended up just using my fingers to slide the rings in one at a time. There is enough bevel left at the bottom of the sleeves to guide the rings in.

I wish I would've trimmed the base gasket, it matches well in the front but sticks out a bit in the back. I don't want to pull the cylinders off, I'll have to figure out how to do it without messing up the paint. But lesson learned for the next build.

Tested the coils that were on the bike, but they are toast. The input side has the right resistance, but no or very little spark comes out on the other side when I tried them with a battery. Ordered Dyna 5ohm coils.

[lajos]

I blew a head gasket. Or more like wasted it.

As can be seen on the last picture from my previous post I put in the cam chain guide backwards. I only noticed when I tried to intall the camshaft in so had to take the head back off. Luckily I ordered an extra head gasket when I got the 600cc kit

Other than that, putting the top end back together went easy.

Adjusting the valve tappets took longer than expected, there's not a lot of space to slide the feeler gauge in there.

For the ignition I first put the new Daiichi points in, but I had a hard time setting the ignition. I had to gap the points way over 0.4mm to get the timing to the F marks. I found a post by Hondaman suggesting to cut the slots wider on the base plate with these points. I'm not ready to do that yet so I'm reusing the original TEC points that were on the CB500 engine (the CB550 motor had no ignition timing cover on it so the ignition parts and advancer rusted beyond repair).

The alternator coils still need to be cleaned up, but otherwise I'm ready to find out if this thing will fire up or did I just make a very heavy paperweight...

I'll rig up some temporary wiring and this weekend I'll try to hook this thing to a car battery and see what happens.

I'm going to use the old exhaust and intake studs (there should be enough that came out in one piece from 3 heads). Still, they are pretty rusted. Are there better studs available for these engines?

[calj737]

You can still get replacement stock studs (I have some brand new ones).
Remember to re-torque the head before firing it up and buttoning up the valve cover.

The Daichi points are crap! Ditch them and use TEC brand and a TEC plate. I may have an extra plate and maybe an advancer too if you get strung out.

[lajos]

Thanks for the reminder to retorque the head. I wouldn't have known to do that. I'll pull the valve cover and retourqe them(didn't hondabond the pucks).

I'm using all ignition parts, TEC plate, TEC points and advancer from the extra CB500 engine (condensers are new). I think they cleaned up good and also bought an extra CB550 advancer from ebay (hasn't arrived yet). If these don't work out I might be coming to you for your extras

I've torqued the head to 18.5 ftlbs because I've seen posts here that some APE studs broke at 20ftlbs (recommended by APE). Is the 18.5 tight enough or should I go higher?

[lajos]

So I tested the two original oil pressure senders that came with the engines and both were toast.

Honda still has a compatible part for $30, but it would be a special order.

After some research I found that many Japanese cars use the same 1/8"-28 BSPT threads. I went to the local car parts store and bought this switch for a '99 Mitsubishi Eclipse, cost $8. It's a bit taller, but it seems to fit (I realized I didn't have the left side cover, it's on order from ebay). Same connection on the top, even uses the same screw.   

[SOHC4 Cafe Racer Fan]

Since you have the old studs out (the hardest part), I'd replace them with new ones to match your new looking motor!

[lajos]

I will get new studs, partzilla has at least the exhaust ones. The intake studs I have are actually in good shape, no rust.

I wired up my temporary ignition panel. Got kill switch spark and a red button. Now I need to find a bigger battery, a bottle that holds some fuel, hook up what's left of my exhaust header, and tomorrow I'll stand back...

...and press the red button. 

[lajos]

There's good news and bad news.

It started up! In fact it fired right up and sounded freaking awesome.

Now the bad news. Oil pressure is too high. I had an oil pressure gauge hooked up at the pump where the pressure switch goes, which I was not keeping an eye on cause I was too excited. But soon it spewed oil out at the oil filter gasket.

I put the gasket back in, started it to idle, and the oil pressure shot off the chart (in fact I think I blew the oil pressure gauge, it doesn't return to 0 no more).

Before I put the head on, I primed the engine with oil and I know there was oil in the passages that goes up to the head.

After I put the oil filter back on I heard slurping noises for a second from the head, so I'm assuming there's oil up there, but I'll pull the valve cover to check.

I'm using Shell Rotella 15-40 dino oil.

Any ideas what could be happening? There seems to be an oil pressure regulator in the pump, some oil pressure safety thing in the oil filter, and of course it could be some blocked oil passage somewhere.

[lajos]

Figured it out. Oil pressure relief valve was stuck because of user error. These two oil passage caps might look the same but on closer inspection one has a groove for the spring. Since I used the wrong one the spring was over compressed.

Now I got great oil pressure.

[lajos]

Here's a short video of what it sounds like with whatever I have left from the old headers (not much).

Please ignore the broomstick, the wifey was not available to hold the fuel bottle