1970 Schwinn Heavy Duty

lennyharp

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These photos are my remedy of a cruiser frame not quite fitting the motor. I am just a little slow and started today with a few bikes I could mount a motor on. I chose the one that needed the most modifications. This will be a temporary replacement for the bike I crashed 2 weeks ago tomorrow.
 

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jasonh

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Jun 23, 2008
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Pretty cool.

I'm curious as to why you chose to braze the brace on instead of welding? (at least that's what it looks like you did)
 

lennyharp

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Brazing was the preferred way to build quality frames for a long time. Schwinn even makes their frames look brazed at all levels of quality 1940-1980 era and maybe more. Fillet-Brazed Schwinn Bicycles 1938-1978 is an article that talks of Schwinn quality but I know Colin Lang who uses brazing exclusively and has had his frames in the Olympics and world championships. I always regretted that he refused to take me on as an apprentice as he only wanted to apprentice his sons. But I do a fine brazing job and have a lot of this type of work I have done.

One reason to braze is that you work the metal at a cooler temperature. Welding temperatures crystallize the chromium in 4130 cro moly steel. This is also one of the preferred metals for bicycle frame fabrication. Frame builders who braze use a lighter gage butting because they can get away with it. Welders use about 40% thicker butting because of the loss of strength to crystallization problem. It is a trade off because Brazing takes either a fillet of brazing rod or lugs for the cooler temperature silver brazed frames. All this detail is what makes me want to braze a fillet similar to Schwinn and some of the bikes I have appreciated most.
 
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jasonh

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Good to know. I had heard about the crystallization thing, just didn't know how accurate it was.

Your brazes do look really good btw.
 

lennyharp

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Thanks JasonH, I am waiting on the paint to dry and bake at 110 in the sun. This is an advantage of desert dwelling. I hope to get it built and running tonight. Nothing fancy from here out I think as I have a buyer who wants just a basic bike and I can use it as transportation till it is broken in.
 

lennyharp

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Well I got it together today after some advice & help from datz510 last night. I cruised up and down the street popping the clutch with no spark I could hear with blue to blue wires and black to black, or blue and black mixed. You can see on the non gear side of the crank where I had to heat and bend the crank arm out about an inch to clear the motor and exhaust. The pedal wobbles a bit but since clearance is good I will leave it as is. I opted for a BMX bar and stem for upright sit and strong solid mounts for everything imaginable.
 

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jasonh

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Bike looks good. Lower that seat, and it'd be a comfy cruiser :) I need to get some higher handlebars like that for my bike...

So onto the no-spark issue....have you tried pulling the plug and laying it on top of the head and just pick up the bike and spin the rear to make sure there's no spark? If you connect an AC voltmeter to the blue and black wires, you should see the needle (or numbers if digital) jumping around as the motor turns. Is this a brand new kit?
 

lennyharp

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Yes it is a brand new kit. I will have to try those checks maybe tomorrow. I work 12 hours each of the next 4 days and will do little work on my bike. That's funny on the seat as I want it up so I have a little force in pedaling.
 

datz510

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www.nissan4wheelers.com
It took mine a few runs to fire up initially. Do you have fuel in the carb? Also you will want to turn the idle adjustment screw inwards a few turns initially until you get it started. Once its running, then you can set the idle. Could be that the idle is set way too low and its just not getting fuel. There is no idle circuit in these carbs, so that adjustment screw is necessary to get the engine to start/run.

Check the spark as jasonh says. With the spark plug out, you'll be able to spin the tire easily.

If all else fails, try another CDI unit and I can take a look at that one to see if its working.
 

jasonh

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Ouch, 12 hour days. Those can be brutal.

I like the seats low because I don't need to pedal much so I might as well be comfy. :)

If swapping the CDI doesn't work, try swapping the magneto. There's also a resistance test for both the CDI and magneto that you can do. I'll see if I can dig up the link.

If you see that you are getting spark but still not starting, check the idle screw as datz says (can also just hold the throttle open). Can also spray a little starting fluid in there too to try and help it along (I sprayed carb cleaner down the carb of my old truck when it was having a hard time starting)

To avoid having to ride up and down the block trying to start the motor (I felt like a big dummy doing that. my neighbor was looking at me funny), I just pick up the back of the bike by the seat and give the pedals a good kick to start the motor.

Here it is:
http://motorbicycling.com/f34/no-spark-wiring-cdi-mag-kill-2102-2.html#post20201

CDI pack GOOD Mine
Black to Blue 1150kΩ 7.6 meg Ω
Black to Plug 2.6kΩ 2.17K Ω
Blue to Plug 1150kΩ OPEN


Magneto
Blue to White 327Ω 349Ω
Black to Blue 327Ω 347Ω
Black to White 2.1Ω 2.1Ω
Black to Gnd 0Ω 0.3Ω
Blue to Gnd 327Ω 347Ω
White to Gnd 2.1Ω 2.3Ω
 
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lennyharp

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Ok I got spark and seem to have fuel going in to the carb. Nothing yet and am cleaning garage next.
That always helps any problem, right? At least I'll find my voltmeter that I rarely use. That seems to be the next step.
 

lennyharp

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Here are the Doctor's hands in the clutch, and the culprit is greasy clutch pads. I had some carburetor parts out of alignment. I learned a few tricks about carb and clutch set up tonight and will start breaking this in seriously tomorrow. Thanks datz.!!
 

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lennyharp

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Jason, I will have to save that list of resistances for checking when I have those type of problems. I had a feeling it was something else when I saw a spark but was not getting a spark when riding. The solution that datz came up with last night at his house was to clean the clutch pads with brake cleaner. I also had the float or piston in the carburetor not lining the slot up properly so I assume I was flooding the carb with fuel. We tried leaning the mixture and then went back to the stock setting. These were the solutions that resolved my firing issues last night.

I will now go out and break in so I can ride to work for the first time in 3 or more weeks since I crashed. I am excited to be learning about small engines so I can solve more of this type problem on my own in the future. My strength comes from a bicycling racing, commuting and fabrication perspective. I need to get familiar with the works of these little engines as mow I depend on them.
 

lennyharp

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You bet. That is one reason my Subaru EHO35 is on the shelf for a time. I test rode for 20 minutes or so and then let things cool while I worked on my SBP shift kit project and then when I tried to ride again the same thing happened where no spark was making me go. I went and got some brake cleaner and did what datz did last night and made it go again. Then it stopped on a main road and I discovered the spark plug wire came out of the CDI box. That must be why the shake down time is so important to work out the bugs and gremlins. So now I have 40 minutes on the bike today and 15-20 yesterday. After a while I will ride out to the bike shop and get a second brake so I have something to back up the pedal brake. Tomorrow it looks like I will be able to commute after all. That is a 15 mile ride.
 

lennyharp

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Here is the plug (left) from the first 20 minute run today.....

Here is the plug (right) from the second 20 minutes....

And after cool down I needed to clean the clutch again as it just slips.!? Crazy but I hope to finish with this routine soon of cleaning the clutch after a ride. It seemed to be slipping towards the end of the ride last time. Well I'll go ride in the heat of the day now.
 

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