The Little Cub That Could

davedogg

Active Member
Hi guys. This is my first build on this forum. I usually work on two strokes but picked up a 1964 Honda CA100 Cub for my girl. I know the bike is the best selling bike of all time or something like that but am having some trouble finding info and parts. I'm hoping the DTT crew can help me out.

Two major things... #1 missing the flywheel. I need help locating the right one. CMSNL says there are different ones depending on the engine #. Is this true or will any CA100 fit?

#2 Piston was slightly stuck. I was able to get it loose. I would like to get it to run without rebuilding the top end first to straighten everything else out. I'd like to do this because I'd rather fuck up this cylinder before it's hone/bore rather than after.

Also, does anyone have an extra JIS points screw they can throw my way? I'm missing mine lol.

Here's a couple pics. I'll take pics of the cylinder and piston next.

IMG_20160925_085122 by Dave Dogg, on Flickr

IMG_20160925_085148 by Dave Dogg, on Flickr

IMG_20160925_085159 by Dave Dogg, on Flickr
 
If you can clean the grooves for the rings to make sure they're free and maybe put a light hone on the cylinder you may be able to get it running. Is that just staining on the cylinder walls or can you feel the rust with your finger?
 
Cylinder is smooth except at the very top I can feel a little rust. Do you mean clean the rings on the piston? Like use a brass brush? Thanks for your help!
 
Depends on how dirty they are. If there's a lot of dirt and you can feel them crunching in the grooves you may want to remove them and really clean everything out. If it's not too bad you may be able to just flush everything out.


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Thanks guys. I broke the rings trying to get them off. I ordered a new set that are on their way.

The first point I got was wrong. So I ordered the right Denso point. I ordered a magneto/flywheel but it seems to be a really tight fit. I was trying to get it on with a rubber hammer.

My questions are:

1) Should the magneto be that tight to fit? It seems that the coil is going to rub against the inside of the magneto? is that ok or should there be some space?

2) Since it seems I have a Denso point, do I need a Denso magneto? Honda seems to have 3-4 different magnetos for the CA100 cub models. The magneto I have now is not a Denso.

Thanks in advance for your help guys!
 
I think that first pic of the cylinder indicates it will need more than a hone. It looks like fairly serious pitting to me.
 
Snapped the rings while trying to clean them. Have a set coming in hopefully next week. Finally got the the right combo of point and flywheel but still no spark. I think I'll just get a new coil and condenser instead of fumbling around with the old ones.
 
The magneto and flywheel should have clearance between them. Use the factory manual to check that you have proper continuity between the leads on your stator, I recently had to rewind the stator on the FA50 that's in my shop. You can also test the coil with a multimeter, I would do that before you start throwing more parts at it.


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So my flywheel fits. But the point does not open and close when I turn the flywheel. It seems like there is no lobe to open the point. Is it possible it is worn down? I have not had this problem before.
 
My favorite source of parts when putting my '63 Honda Trail 55 back together.

http://dratv.com/

Do you not want to replace the motor entirely? They have everything from 50cc 3 speed auto clutch replacements, to 190cc 4 speed manual clutch setups available. I ran a good year or so on the stock 49cc until I started replacing the engines.
 
I had a 63, it was my first new motorcycle. They are pretty tough little motors and will go a long time even when out of spec. I suspect your flywheel is wrong or you have some other problem not yet identified. Unfortunately, I never had to change one out, so I can't give you any ideas or parts numbers. You will need to hunt for the correct part by frame and engine number. If you just want to get it running, run a ball hone down the cylinder to break the glaze, throw in the new rings and put it back together. It will run! Make sure you put the rings on correctly. They are nice bikes.
 
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