78 Rescue Build

[WipeoutWm]

CT70 1978 in Rio Grande Valley TX

Bought it in Austin thru craigslist, $800 with title
Real good shape, almost zero rust, needs seat cover, almost complete, only lacking rear signals and headlight is broken, and it would not start.


Goal is to make it street legal while spending absolute minimum.
What's done:
Removed air and idle screws, sprayed carb cleaner in, got it started! Drove it around grinning! but it would not idle.
Removed carb, rodded out all passages (idle jet was blocked with powdery residue), more carb cleaner, and IT IDLES!
Used info found here to adjust idle and air jets. Now will start first kick with half choke and just purrs. GRIN CITY!

Researched headlights, learned these CT will blow headlights without a good battery, pondered 12v change but I can't find a street legal 12v, adjustable aim, removeable bulb light - anybody know of one? :7: (Actually, Racer X advised me to stick with 6v, and I agree after more research.)

PO had covered up a cracked tailpipe with coke can and hose clamp, but it leaked, so I put on more coke can and 2 hose clamps. :4:HA! Will get it welded eventually.

Front tire went down overnight, so I pumped it up and ran water over it... 4 differnt thorn holes ! and a leaking stem, so new tube for me.
TONS OF FUN so far.


Costs:
, purchase , parts, etc. so far $1098, and still need about 100 more...

 

[kirrbby]

VERY NICE! Good score WipeoutWm, and welcome to Lilhonda.

 

[69ST]

Welcome aboard! :wave:​

I agree with kirrbby, you scored with this one.

The rotted headpipe is rite-of-passage common, with bikes of this vintage. The packing used to isolate the front of the main heatshield doesn't play nice with steel. Welding-in a proper patch is easy enough and, since the pipe was painted black anyway, it'll be all but invisble...as well as permanent.

Do yourself a favor and replace those dry-rotted, clapped-out, tires now. You're going to have the wheels apart to replace the tubes. Not a bad idea to de-rust & repaint the rims while you're at it. If they're showing any surface rust, on the outside surfaces, fresh paint will really make your new bike look a lot cleaner...and with minimal effort/expense. Judging by your description, those tires are so crunchy that, at best, they'll wear-out in no time. The rubber is probably so crunchy that you'll have a dangerous lack of traction.

 

[WipeoutWm]

More parts needed

Hoping Kirrbby can help, just sent him a list.

Still really happy how good condition this old blackie is, generally

 

[WipeoutWm]

Does the 78 use a rear brake helper spring?

Mine does not have one, and seems to work fine, but the exploded drawing at CMSNL.com shows it.
CHP motorsports says it is for K0-78. So, do I need it?


(5 weeks later edit)
Does anyone know????

 

[WipeoutWm]

Dadgum lights!

SOOOO, I finished it up, installed seat cover, put on new mirrors, new tube in front tire, got new batteries (2x 6v SLA), charged them, all new 6v bulbs, got the pipe welded, ... everything except the new grips installed and the license. Ready to take it to a picnic and share the fun.

2am, finished it all, and could not resist riding around the block.
Sweet! Got it into third gear, winding up, and poof# goes the headlight. Then tail light. Then instrument lights. Then high beam and indicator while I was trying to get back to the house.

Fer cryin out loud! I thought I did everything you needed to not blow these blinking bulbs.

Any ideas?

Crying for light, here.

 

[cjpayne]

Check batt connections?

 

[69ST]

Check the fuse. If it's blown, you're effectively running without a battery...which also serves as the voltage regulator.

 

[theraymondguy]

That's a sweet ride, '78 is my favourite non-Tahitian Red year.

 

[WipeoutWm]

RacerX, thanks, fuse was new before the bulb blowing ride, and blown after.

theraymondguy, thanks! I prefer the blue myself but blackie here followed me home...

 

[kirrbby]

In post #6 you said " ...batteries...2x... does your bike use 2. That would be new to me. Wonderin if that could have somethin to do with the problem. Not too familiar with the 78 but don't remember seeing any bikes running 2 batteries unless it was a modified setup.

 

[ctynot]

only one that i no ove

 

[69ST]

2 of the newer-type sealed AGM batteries could fit the K3-`82 carrier. They'd work, if wired in parallel, giving you double the charge capacity. In series, you'd effectively have a 12v battery in a 6v system...

 

[WipeoutWm]

2 x 6v

Like racerx said....

I am using 2 each 6v 2.9ah sealed lead acid (SLA) batteries wired in parallel. (AGM is absorbed glass mat, a more advanced type of sealed battery.)

This gives me 6v 5.8 ah battery capacity.
THese cost about $15 each.

And if I want to, I can swap around the jumpers to change it to 12v, which I am considering so I can add a regulator to try to protect the light bulbs. ANd then I would need to change all the bulbs and the flasher to 12v. The alternator already puts out way more than 12v a/c, which is rectified on the battery side and "regulated" by the battery. The headlight runs on a/c from the other circuit on the alternator.

 

[WipeoutWm]

still puzzled

Still trying to find out why it blew a fuse and all the bloomin' bulbs.

 

[WipeoutWm]

Wow, did not realize it had been so long since an update!
First, the bulbs...
After spending about $50 for all new 6v bulbs and blowing them all in a single ride around the block, I swapped to 12V. Rewired the two 6V batteries in series, replaced all indicator and turn / brake bulbs with 12V, and flasher I had in a can in the garage.

Headlight though... I wanted to keep the stock look but could not find a 12v sealed beam that fit my headlight can. So, in the spirit of garage engineering... I got a 6v headlight with broken glass and a replaceable bulb as donor for the back end. Cut out the replaceable socket from the bulb using Dremel cutting wheel. Cut it rather large,because it was going on the outside of the new hybrid.

Then, on my burned out 6v bulb, cut out the back around the bulb, to a smaller diameter than the socket part, and removed the bulb.
Connected the wires, put bulb in socket, and test fit to orient the beam. ANd used metal duct tape to tape the socket back onto the stock bulb.

So, now I have a 12V replaceable bulb socket, while preserving my 78 stock horizontal adjustment screw function.

Sorry, no pictures... was too frustrated at the time.

EDIT: Member allenp42 did something very similar, and included pictures:
https://lilhonda.com/index.php?threads/ct70-1977-fixer-upper.21223/#post-165991



This setup has worked flawlessly since ~ December 2014. No bulbs blown. Battery charges well. Spent about $20 for all the bulbs.

Next - the long story about carburetor and ignition...

 

[stangconv21]

Is it that easy to switch to 12v? I want to make the switch on my 78

 

[WipeoutWm]

12V is quite easy. The hardest part for me was getting a headlight bulb that fit my bucket.
All you have to change is battery, all bulbs including the indicator lights inside the speedo, and the flasher for turn signals. Mine has worked with zero problems since 12/2014. No blown bulbs, good light.

 

[WipeoutWm]

OK, on to the carburation / ignition problem:
After I sorted out the lights, I started riding it around the neighborhood alleys. At first, it ran just great. For several months. Then, it would run great for about 20 minutes, I suppose till it got good and hot, and then it would start missing high speed, backfiring, coughing, and spitting, until within about 5 minutes more I could barely limp it back to the house at just above idle. Sometimes choking it would help, but during one episode it backfired and actually bent my choke butterfly backwards!

So I chased carburetors around for a while. Finally broke down and bought a complete carb (wincycles.com, Honda CT70 Carburetor 1978-1994 (WIN0078O48/1) = $44.44). It did not run any better, and the idle jet made absolutely no difference in speed - I could not adjust the idle. And the fuel petcock leaked. I finally scavenged the choke butterfly and lever and put them in my original carb, and threw out the wincycles carb. Now I could adjust idle, and it would run great.... until it got hot.

During one nighttime trial, while it was backfiring and choking,I happened to look at the spark plug and saw it throwing blue sparks to the head. I called it a spark leak.

So, I looked for any experience in lilhonda, and it seemed to point me at the coil. Also, a local mechanic thought it might be the coil. So I bought one. While waiting for it, I researched how to test a coil, found that my high tension (spark plug lead) to ground was 15.5kohm, and Clymer's indicates 5 -15 kohm is acceptable, so that's ok. Resistnace from coil lead (where it receives power from the stator) to ground was 2.9ohm, and I found 3 different answers as to what is good. When I got the new coil, it was 2.8 ohm. So, NOT the coil.

Finally, just because I had never done it, I replaced the points and condenser. Abracadabra! It runs all day now.

I guess the moral is, don't look for a zebra - it's probably just a horse. So I spent about $70 in education this time... do the routine maintenance first.

 

[allenp42]

During one nighttime trial, while it was backfiring and choking,I happened to look at the spark plug and saw it throwing blue sparks to the head. I called it a spark leak.

Does it look like it's sparking from the spark plug cap? If so, I would replace the spark plug cap. It sounds as if yours has a crack, which is allowing the hi tension voltage to arc to ground. If it's coming from the plug wire, then you have a couple of choices - Splice in a new section of plug wire or go ahead and install the new coil.

Normally, I use the non resistor spark plug cap.
http://cart.hondanuts.com/CT70-Cylinder-Head-Covers-C361987.aspx?sid=35985


My bad. I just noticed that it runs now. However, I would still replace the plug cap. That is not suppose to happen.