Just a Little Project (CB250 little)

[JamesWhut?]

Mirroring this from the Nighthawks-forums.com 'cause they aren't very active and this is (falling down stairs) funny.

Sooooo.... Its spring here in the South. And every time this year, I find my self listfully scrolling thru the Craigslist motorcycle ads... It's been about 5 years since our son was born and we (Wife and I) finally gave up and sold the bikes. This year was especially bad, since the weather has been great, and the bikes have been out. So when I came across an ad for a Nighthawk 250 over the river in Alabama for $250, I perked up. Runs, titled. Okay, "needs work", but... $250... So call and head over with daughter and trailer in tow. We bring home this:

Wife is not happy. Children are ecstatic. But then what kids wouldn't be excited about a motorcycle that looks like it came in a McDonald's Happy Meal? Any way, I placate her with the logic that I can always sell it for more than that by cleaning it up...


And off we go...

 

[JamesWhut?]

Okay I now, technically, own a motorcycle again.

First things first, get the "essentials" on the way:

I'm a bit rusty on motorcycles, where the aftermarket is on bikes in general, and on obscure little bike's like the Baby Nighthawk. But that is okay. So is this bike. Even at the PO's it was apparent that this poor little bike had a hard life. And I am not just talking about their questionable style tastes (the bike had been "John Deere Tractor themed") That was brought to even further evidence as I started looking closer.

Yeah... fun. At some point the bike either was wrecked and/or the chain came loose and warped around the swingarm and buggered it up. The fasteners are either finger tight or torqued to "OMG!". The exhaust system is... from a Rebel 250. Which fits (with the help of some wire holding the mufflers on). And it doesn't start unless you manually jump the starter relay. But... whatever! Remember! $250 for a motorcycle!

Okay. I was going to tear it all the way down any way. Lets get it over with.

Yeah I know, but it was late...

Sigh...
Tires - worn, hard as a rock, cheap assed Chig Chings.
Brakes- Actually okay, or at least still plenty of meat on the pads and drums.
Forks - seals blown. feels like there isn't even any oil left in them.
Triples- all the original BBs are there.
Swingarm- yeah... gonna need a new one.
Shocks- okay... for the '70s.
Chain- rusty toast.
Sprockets- hooked and the front was even missing a tooth!
Cases- look okay if weathered. Left side cover looks like it was sealed with toothpaste.
Carb- a filthy mess.
Airbox- a total mess, someone had put a 30mm moped mesh screen into the side of the airbox instead of buying a real filter, and then when that obviously wasn't enough air, they just left the door to the box off. Problem solved!
Battery- A nice, newish one.
Tank- Hey! insides are nice and clean!
Seat- Ripped and faded.
Bodywork- trash.
Turn signals- all stuffed into the tail section.
Wiring- Something about the starter switch not working and they replaced the wiring harness...
Gauges- Rusty but there.
Bars - brand new (product of the accident no doubt).
levers - both busted on the ends of course.
Headlight - Rusty, don't even care if it works.
Frame- When I tipped back the stripped frame, black water started to trickle out of the end of the subframe. At least it wasn't red...

And I haven't even torn down the motor yet.

 

[JamesWhut?]

Going back to stock would be both expensive and... no fun. But with a wheezy 19 HP motor, delusions of power are just that. So how about a wicked little runabout? Not a fan of the choppa' thing. Don't even really like cafe bikes, they have become a Me-To cliche. But in pursuit of light weight and handling, you wind up getting there...

Yeah... It still has the Ronald McDonalds colors and its a crude PS sketch, but is kinda what I'm going to go for. I'm 6'1" and Wife is 5' 4" so the ergos are going to be... interesting. There is not much to give on as small a bike as this.

Anyway, bunches of parts on order, and a ton of work to do when I get back from visiting the in-laws (aka: "vacation").

 

[salty_monk]

If Noddy had a motorbike......

Good luck with the build!

 

[JamesWhut?]

LOL. Thanks.

Oh. Forgot to mention, absolute budget for this build is $1K. Just to make it interesting (and to keep Wife happy).

 

[Road_Clam]

I bought my wife a used rough GZ250 and after about $500 invested and a LOT of cleaning and polishing the GZ looks fantastic. They have been making the CB250 for a long time which means Ebay parts are plentiful. I found a mint engine side cover to replace my wife's road rashed one for $30.

 

[tkent02]

This is going to be a nice one.

 

[loud et]

Damn how did you do that time lapse picture thingy?

 

[JamesWhut?]

Damn how did you do that time lapse picture thingy?

I took pics of the disassembly as an afterthought to document it, and found they were more or less lined up, so stitched them together with an online gif maker.

 

[JamesWhut?]

Parts are starting to show up. I have spent an inordinate amount of time sifting thru feebay, spending money like a drunken cheapskate.

Elected not to try to build 17" wheels. Found Avon AM26 tires in 18/16" that look decent. Going with 520VT2 chain as sprocket choices are limited enough as it is without going to something truly exotic.

Took a chance and bought a pair of cheapo Chinese "scooter" shocks.

Yeah, I'm sure I'm going to have to play with the oil and air pressure, but as long as they don't break or fold in half, they should be adequate for this project.

Resisting the urge to buy "cheap" Chinese Titanium fasteners. Because that would be silly on a Baby Nighthawk.

 

[SVSooke]

Here's the guy for those RFY shocks http://chrislivengood.net/wp/

 

[JamesWhut?]

Oh Cool! Thanks.

That Itchy Ban video was hilarious. Yes, the first thing I did with them was peel off the reservoir stickers too. lol.

 

[JamesWhut?]

Disassembled and cleaned the carb today. Wasn't too bad. Besides the sand in the float bowl and the rag that had been stuffed into the missing choke valve socket.

Looking at the bottom, there wasn't a little knob on the pilot jet like the manual says there should be, just a blank brass plug. So I figured it was a block off for the typical "don't mess with this" pilot. So I tried to gently drill it out. And keep going, and keep going, making an awful lot of brass chips with out breaking thru and popping out the plug the way they usually do. I use a Torx bit to unscew it out and.... I had inadvertently lightened my pilot jet by a few hundredths of an ounce. Either a PO had snapped off the knob or it was designed to be once set up was complete.

Hondas...

 

[JamesWhut?]

Isn't technology wonderful?

Decided to try one of the new fangled (but cheap!) digital multi-instruments. Tach, speedo, odo, temp, etc. etc. all in a little 3" instrument.

We'll see how it goes and if I can get it to work (ie; won't be listing the old speedo on ebay right away).

Speaking of which, I should make a sticker for the bike crediting feebay. Since about 90% of the parts have been sourced thru it.

Most parts have been obtained or ordered. Now looking at a thousand or so man-hours of work...

 

[JamesWhut?]

Parts are still coming in and I fondle them and consider how I am approaching the build. Still have a little bit left in the budget, but I'm hold that for the inevitable "uh oh" (probably engine related) moments.

Warning: The following are stream-o-consciousness thoughts:

The bike is being built mostly for my wife, who is 5' 4" and also a good rider, but rather... responsible, in that way most women are. On the other hand, I want something "interesting", both as a build and to ride, and that means I am aiming to get the most out of it aesthetically and performance wise. Otherwise I would have just bought another GS500 and called it a day!

Like most ol' bikes, its looking weathered and rusty. I need to re-zinc most of the fasteners and steel parts that aren't getting painted. While researching and pretty much consigned to having to do the Mad Scientist bit with toxic chemicals, I came across a DIY zinc plating technique that uses nothing more than vinegar, Epsom salts, a bit of zinc metal, and any odd low DC voltage. So I'm getting out of any major investment in this area because I literally have all of those materials on hand.
First in will be the carb screws and slide cover, as I need to get them done so I can reassemble the carb and set it asside. Then all the nuts and bolts.

I am going to reuse the stock carb at first, on that ridiculous 1 into 2 manifold. Seriously, I smirk everytime I see that thing. But if you've gotta have a twin cylinder fed by a single carb.... I will of course need to jet it much bigger considering the evil thngs I have in mind for the motor. After I get it all together and running, I will then move on to either a flat slide, or dual carb (flat slide) set up.

The motor. I will have to rebuild. Seller made stories/excuses, saying "might have a broken ring" which is not good (even though probably wrong). So I am steeled for the worst. Which, in a tiny simple motor like this, isn't much. I will probably wind up doing a mild port & polish job on those wee little passages. If there is nothing catastrophically wrong with either the top or bottom end that sends me chasing after OEM parts or new engines, I might indulge in +1mm pistons and decking the head to go to ~11:1 compression (because I used to blow up motors for fun).

Exhaust.... the stock Rebel 250 pipes and mufflers are heavy, dented, and rusty. And... full of oil from where the bike leaked into the unclamped cross pipe. I'd rather go to a 2 into 1 pipe, but the only make for that is from the UK and hella expensive ($500!), not going there unless I can convince wife of its virtues. Which... leaves cutting the boat anchor mufflers off the CMX headers, bending them in tighter, and then sticking cheap, noisy, reverse cone cans on them. That should convince her LOL.

Still dragging my feet about the frame. My instincts scream against cutting a perfectly good stock frame (even if its mustard yellow). Trying to decide if I should bend and weld a steel end "tail hoop", or make one of some aluminum tubing I have and bolt it into the cut off ends of the sub-frame. Also trying to decide if I should gusset the frame anywhere. Given the (lack of) power on a 250, I'm more concerned with torsional rigidity. It would be "neato" to weld in some superbike cross braces, but when you are going to have less than 500 lbs. of moving mass, with spindly 31mm forks and a sheet metal swingarm? Yeah... I donno, practical vs. cool factor vs. weight vs. benefit.

My wife "traditionally" rides red bikes, so the tank will get stripped down to bare metal, the dents bondoed, and then repainted a "wine red" color. Catch is I want to have it match the little tail behind the seat (see doodle above) but THAT needs to be translucent because of a trick I am going to (attempt to) pull off with the rear signals (LED's shining thru it). Soo.... do I paint the tank and then try to figure out how to match the rear, or get the rear color/tone and then match the tank's paint to that?

Seat too will be a challenge. It needs to be about 4" tall and as wide as possible, because the CB250 frame is small and we are... not that small. I've done a few seats, but nothing like this. I'm not going to use a "cafe bike" seat pan because... that would be too easy. Instead, I am thinking of a high density foam core 4" thick, and 1" overlapping the frame on either side , with a U-shaped tunnel between the frame tubes (sort of mimicing the frame spine tunnel of the tank) to give room for the underseat electrics. I'll fiberglass the final underside, and then use a 1/2" of pad foam and then vinyl seat skin.

Bleh... just writing all that makes me tired and want to take up knitting or something...

 

[SVSooke]

Yes zinc plating is quite easy but plan on investing in a variable power source for good results .I've been using an old dumb battery charger and it comes out grey.That comes off but I recently noticed the gray is back on my plated bolts

 

[JamesWhut?]

I actually have one that I use for work and other projects. That was why there was the "DOH" moment. The only thing I'm waiting on is the chunk of zinc.

 

[SVSooke]

Cool,sounds like you're even better set up for plating than I am.Just remember prep is the key.

 

[JamesWhut?]

Set up my makeshift zinc plating apparatus and gave it a test run today.

Acid bath, rinse bucket, plating bath.

Before and after. And that is only one pass.

Its funny. One thing most tutorials and videos on using the vinegar and epsom salts plating technique didn't mention is how much it stinks. LOL I'm using sulfuric acid as my cleaning/etching bath so its even doubly smelly.

But it works, in fact it works even without input electric current (although very slooowly). My DC power supply apparently does not like to run at a measly 5v at less than 1 amp. It kept cutting off after 5 minutes. But crank it up to 30 v and 10 amp and it will plate all day long. In fact, it will make chunks of zinc materialize in mid solution...

Ready to go into production with the CB's parts.

Still trying to screw up the courage to cut the frame.

 

[JamesWhut?]

Got the carb clean, steel parts all zinced and shineyish, and back together.

Obviously, I wasn't going for "new-looking". Just functional, clean, and rust free.

No suprises other than that the tiny little spacer/collar thing in the air pump/valve actuator pivot was missing. PO had basically just pinched it between two washers and called it good. Fabricated one by hammering the pivot bolt thru a spare spacer to I-donno-what-it-came-from to the right size and... called it good.

K&N pod filter and replacement plunger choke and it should be good to go.... or rather wait until the rest of the bike is done and then try and get the jetting right.