Topic: Nighthawk 550 Bobber/Chopper, kinda

[Laminar]

Any change on #3 with oil?

I need to redo that one with oil. What does adding the oil do, close the gap in the cylinder wall? And does it indicate that it's only the rings?

Correct. You know the valves are good and that there's not a hole in the piston, as was mentioned earlier.

[Nighthawk Rat Racer]

Hows the project coming. I think were working towards the same thing and im wondering if youve gotten any farther. Since the pic ive chopped the mufflers off and ditched the shocks for struts. Im waiting for new jets to tune the carbs since the airflow mods. I started a new post for any one doing any major mods to a cb550sc so hopefully ill get some good ideas.

[pikeymick]

Hey There! Sweet Project. Mine has been at a standstill for a bit. But I'm just about to relaunch the efforts. I picked up a second engine and this one was in MUCH better shape! In comparison it looks as though the first engine was run without oil in it, for quite sometime. The second engine will only need rings! I'm looking to order the rings today!

[tomsweb1]

Makes sure you tighten those con-rods!
 I'm still looking for a third engine...

[pikeymick]

Hopefully someone else has some more insight on this.

For gasket kits for just the top end, do I want Gasket Kit A 061A1-ME5-S00,
or the individual gaskets:

Cylinder 12191-ME5-306 and Head 12251-ME5-005?

I have another engine if you want it. The top end is pretty bad (see pics) but the bottom end would be usable.

[tomsweb1]

Pm'ed

[pikeymick]

Well it's been almost a year and this thing is almost finally done. I remember when I first started and reading other people's projects how they ended up taking that long, well now I know!

The top end is rebuilt,
to

to


These pictures are crap, I'll get some better ones. Got the whole thing back together yesterday, and realized I lost, not one, but two oil filter spacers with the hoses to the oil cooler. So that's on order from ebay...

[Laminar]

Looks like you have the standard 550 exhaust ripple. Love the 650 front end, any chance you're looking into getting a 650 rear rim to match?

[pikeymick]

The wheels are actually both stock wheels. I modified the rotor mounts on the front wheel it fit the CBR rotors.

[Laminar]

The front wheel and (at least the right fork) is from a Nighthawk 650. The 550 had two "star" rims, the 650 had 12 spoke (6 pairs of two) rims.

[pikeymick]

I'm pretty sure the CB550sc http://www.google.com/imgres?imgurl=http://www.motorcyclespecs.co.za/Gallery/Honda%2520CB%2520550SC%2520Nighthawk.jpg&imgrefurl=http://www.motorcyclespecs.co.za/model/Honda/honda_cb550sc_nighthawk%252082.htm&usg=__kPRIZ4EfRgGjOXySlsL35MXVRLg=&h=367&w=480&sz=66&hl=en&start=0&sig2=AEgNkrIXKL7IrX0NGm0bHg&zoom=1&tbnid=M1RG6B9tpIbPVM:&tbnh=156&tbnw=235&ei=QISXTM-YIZLUtQPcpvW_Cg&prev=/images%3Fq%3Dcb550sc%2Bwheels%26um%3D1%26hl%3Den%26sa%3DN%26biw%3D1280%26bih%3D907%26tbs%3Disch:1&um=1&itbs=1&iact=rc&dur=343&oei=QISXTM-YIZLUtQPcpvW_Cg&esq=1&page=1&ndsp=21&ved=1t:429,r:7,s:0&tx=256&ty=169 came with the rims that are on the bike. Both wheels match, and I never replaced any wheels. The forks are off a 82 CB650 nighthawk, which had these wheels http://www.google.com/imgres?imgurl=http://konoske.net/wp-content/uploads/2007/12/cb650-1.jpg&imgrefurl=http://konoske.net/archives/259&h=274&w=348&sz=43&tbnid=9lOiwjfTrP7OvM:&tbnh=94&tbnw=120&prev=/images%3Fq%3D1982%2Bcb650sc&zoom=1&q=1982+cb650sc&usg=__7NqpcM4LrIwuUhQ0XK3ipkYGWO8=&sa=X&ei=NYWXTIGcK4_SsAPpidnACg&ved=0CB8Q9QEwAw

I bought rotors for that year bike but they didn't fit, where as the CBR rotors were a direct fit.

[pikeymick]

Maybe I'm just really confused, it has the same rims your bike has. I just painted them.

[pikeymick]

Oh wait, it can't be the same front wheel, hahaha the 550 doesn't have rotor mounts for both sides. But it is the same style wheel ala http://www.cyclepedia.com/honda-cb550-cb650sc-nighthawk-online-service-manual/

[Laminar]

Like I said. Your front wheel is '83+ Nighthawk 650, your rear wheel is '83 Nighthawk 550.

[Laminar]

Oh wait, it can't be the same front wheel, hahaha the 550 doesn't have rotor mounts for both sides. But it is the same style wheel ala http://www.cyclepedia.com/honda-cb550-cb650sc-nighthawk-online-service-manual/

The bike pictured there is a 650. Your rear wheel is different.

[pikeymick]

Oh yeah look at that! I never noticed that before! Hmm... not sure if it matters yet...

[Laminar]

Mechanically it shouldn't matter. Visually it bugs me, but that's only because I know what I'm looking at.

[pikeymick]

Haha yeah now that I know, it probably will. But until it actually runs, haha, it will be easier to ignore.

[Old75_ratafe]

Well it's been almost a year and this thing is almost finally done. I remember when I first started and reading other people's projects how they ended up taking that long, well now I know!

Could be worse my 750 is going on 5 years (3 of them didn't touch it) and I've never even cracked the motor.  BTW looking good so far, my buddy is looking to find a cheap first rider bike and I'm watching this thread and getting ideas for him lol.

[The_Crippler]

Could be worse my 750 is going on 5 years (3 of them didn't touch it) and I've never even cracked the motor.  BTW looking good so far, my buddy is looking to find a cheap first rider bike and I'm watching this thread and getting ideas for him lol.

Makes me feel a lot better about my slow progress.

[pikeymick]

Goddamn. I got it all back together. The first startup it ran great! I took it for a spin around the block keeping the RPM's low to help break it in. But now I've got nothing on 3&4. It's the same damn engine it was before the rebuild. Something screwy is going on here.

I tested everything against the specs in the manual this morning and replaced a coil that wasn't testing right. Except for the rectifier, where with the book I get readings nothing like the book, but consistent readings across the range. What would this thing run like if that was bad?

[mystic_1]

If the rectifier is bad, you'll have low power and your battery will tend to run dead.

BUT

A problem on 3+4 is probably fuel related rather than electrical.  Cylinders 1+4 share a coil, and cylinders 2+3 share a coil, so those pairs tend to share electrical problems.

Cylinders 3+4 share a fuel supply hose, I'd look in that direction.

mystic_1

[pikeymick]

Yeah that was my line of thought as well... I tried using some starting fluid to see if that would produce any results. I got a backfire, but no regular ignition... and the plugs are wet. damn.

[tomsweb1]

I'm guessing you have rebuilt the carbs already? If not... do so. Or at least get a packing kit. New rubber in the carbs can make a world of difference.

[Laminar]

Cylinders 3+4 share a fuel supply hose, I'd look in that direction.

Nope. One fuel hose tees between 2 and 3, aluminum connectors direct fuel from 2 to 1 and 3 to 4.

Nighthawk carb rebuild:
http://nighthawk-forums.com/index.php/topic,4907.0.html