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Old 06-23-2014, 06:45 AM
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Davezilla Davezilla is offline
Motorized Bicycle Elite Member
Join Date: Mar 2014
Location: San Antonio Texas
Posts: 2,710
Default Re: what did you do to your motorized bicycle today?

Originally Posted by mapbike View Post
Im hoping the crank is still ok, but the case is probably junk, im thinking that one of the bearings probably spun in the case and ate it up allowing the crank to have the end play it has, when I get the engine off and tore down Ill know for sure.

The crank should still be ok, I've had the same type of issue on my previous engine, that one was working just fine and I took it apart just to do a quick post break in inspection when I found out it had about 1/8" of side to side play. When I took it all the way apart, all the individual parts looked good, including the bearings, but it had that play so since I had the crank out I put it on the lathe and corrected the runout, then I put in the good bearings, the original bearings were good, but I wanted to put the good stuff in while it was apart.
My engine was running just fine when I took it apart and I just removed the jug to inspect the cylinder wall, but I'm sure it would have shortened the life of that engine considerably if I didn't fix it. I've since then replaced the bottom end with a Dax bottom end but still got the old bottom end and new top end parts for it so I can get it running again when I have the time to mess with it again... I'm mainly using that engine for mock ups, test fitting parts I'm making, and measurements, but it's in excellent shape and will run again.

Since everything looked good in there I just measured how much play there was and made up some spacers out of large washers that were .040" thick, I had to turn them way down on the lathe but could have drilled several thru the circumference of the washers so the oil could still reach them easily. this reduced my side to side movement down to .040" which is much more acceptable.

You should be able to make spacers for yours just as easy by using a 5/8" or 16mm washer on each side of the crank, a piece of 1/5" id pipe sliced really thin would work too.

Hopefully a set of new bearings, seals, and make up some spacers and it'll be running again.
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