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  #7721  
Old 01-20-2015, 03:44 PM
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Default Re: what did you do to your motorized bicycle today?

That could very well be the problem... either they never put a key in it on the assembly line and somehow it held this long or the last guy lost it, these things will go for a while without a key if the gears and sprockets are a nice tight fit... but not very long.
I know on the centrifugal clutch kits the key can't be used at all on the crank because with the bevel gear removed and the shaft extension installed, all that keeps the shaft extension from slipping on the crank is just that slight taper on both parts, then when torqued down it don't slip. I've had my bike up to 38mph without a slip at that connection, but what did make it slip was when the gear separated from the clutch bell.

I would buy a replacement key, but buy a few more just to keep on hand as spares in case one goes flying out during disassembly or reassembly, they hold just fine once installed, but get lost real easy.
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  #7722  
Old 01-20-2015, 03:57 PM
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Default Re: what did you do to your motorized bicycle today?

I doubt a cut-off piece of coin would work, would it?

Edit: I sent an email to the vendor asking if he might just send a replacement.
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Last edited by GoreWound; 01-20-2015 at 04:53 PM.
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  #7723  
Old 01-20-2015, 04:59 PM
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Default Re: what did you do to your motorized bicycle today?

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Originally Posted by GoreWound View Post
I doubt a cut-off piece of coin would work, would it?

Edit: I sent an email to the vendor asking if he might just send a replacement.
I've made half moon/woodruff keys from Grade 8 flat washers before and from grade 5 flat washers which is probably best since you don't want the key to be so hard that it destroys the shaft its in rather than just shearing.
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  #7724  
Old 01-20-2015, 05:15 PM
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Default Re: what did you do to your motorized bicycle today?

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Originally Posted by mapbike View Post
I've made half moon/woodruff keys from Grade 8 flat washers before and from grade 5 flat washers which is probably best since you don't want the key to be so hard that it destroys the shaft its in rather than just shearing.
that's a good tip, I will wait to see what the vendor does first, but will probably make use of this tip if he doesn't pull through, thank you.
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  #7725  
Old 01-20-2015, 05:31 PM
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Default Re: what did you do to your motorized bicycle today?

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Originally Posted by mapbike View Post
I've made half moon/woodruff keys from Grade 8 flat washers before and from grade 5 flat washers which is probably best since you don't want the key to be so hard that it destroys the shaft its in rather than just shearing.
That's a good point...

I was going to suggest borrowing the key from the bevel gear and putting it in the missing spot on the clutch shaft, the bevel gear won't slip without a key due to it's taper fir, but it needs to be torqued down to about 10 lb/ft using a bolt and washer in place of that screw.
When I put the centrifugal clutch on mine (until I broke it) there's no key for the shaft extension so just the torque on the bolt and the taper fit holds it and keeps it from slipping. I doubt you could get the screw that's in it now tight enough so if you do try this, find a bolt with the right thread size and a washer, it does need to be fairly tight.
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  #7726  
Old 01-20-2015, 09:59 PM
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Default Re: what did you do to your motorized bicycle today?

After a little more work on mine measuring and all, the mountainbike caliper got reworked and it's gonna be the one I use, the pocketbike caliper is nice, but replacement pad availability and a few more measurements swayed me into liking it more, the reason it wasn't stopping as strong as it should for the kid who owned that bike before me was because he didn't have it adjusted or aligned right, and only about half the inner pad was actually making contact with the rotor, I also found by moving the rotor to the other side the caliper will bolt in very close to the fork leg and out of the way even better.
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  #7727  
Old 01-21-2015, 11:42 AM
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Default Re: what did you do to your motorized bicycle today?

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Originally Posted by Davezilla View Post
That's a good point...

I was going to suggest borrowing the key from the bevel gear and putting it in the missing spot on the clutch shaft, the bevel gear won't slip without a key due to it's taper fir, but it needs to be torqued down to about 10 lb/ft using a bolt and washer in place of that screw.
When I put the centrifugal clutch on mine (until I broke it) there's no key for the shaft extension so just the torque on the bolt and the taper fit holds it and keeps it from slipping. I doubt you could get the screw that's in it now tight enough so if you do try this, find a bolt with the right thread size and a washer, it does need to be fairly tight.
i've got 3 keys in my motor right now all made from welding rod i put in the vice and just used a file to cut it to shape... they seem to work pretty well... no issues yet and over 500 miles on them...
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  #7728  
Old 01-21-2015, 05:19 PM
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Default Re: what did you do to your motorized bicycle today?

ok... so... took my bike out on the sled trails again today... unfortunately where i went there is heavy foot traffic as well... all the trails were frozen solid (which WOULD be a good thing)... with all the rain we recently got, combined with people tramping all through the trails, made for an almost impossibly bumpy ride :/ safe to say, i came down a frozen hill bout 150' long of hill and a good 40' drop in elevation... made the hill ok, but the trail bent to the left and safe to say, not much turning on the ice, so naturally, i took a digger... the fall didn't bother me any, i had plenty of gear on... BUT... i bout tacoed my back rim and when i got home, i noticed that BOTH of my rear motor mount bolts had broken off inside the case...
now i'm kinda screwed... the left side bolt didn't drill out centered therefore did not want to back out and with limited tools on hand, it's stuck where it is and at this point, i think i need to just order a new left side case and seals... UGH!!!
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  #7729  
Old 01-21-2015, 05:58 PM
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Default Re: what did you do to your motorized bicycle today?

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Originally Posted by redneck82 View Post
ok... so... took my bike out on the sled trails again today... unfortunately where i went there is heavy foot traffic as well... all the trails were frozen solid (which WOULD be a good thing)... with all the rain we recently got, combined with people tramping all through the trails, made for an almost impossibly bumpy ride :/ safe to say, i came down a frozen hill bout 150' long of hill and a good 40' drop in elevation... made the hill ok, but the trail bent to the left and safe to say, not much turning on the ice, so naturally, i took a digger... the fall didn't bother me any, i had plenty of gear on... BUT... i bout tacoed my back rim and when i got home, i noticed that BOTH of my rear motor mount bolts had broken off inside the case...
now i'm kinda screwed... the left side bolt didn't drill out centered therefore did not want to back out and with limited tools on hand, it's stuck where it is and at this point, i think i need to just order a new left side case and seals... UGH!!!
Here ya go, Best deal I've seen on a new case.

http://www.ebay.com/itm/181474273792...%3AMEBIDX%3AIT
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  #7730  
Old 01-21-2015, 06:00 PM
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Default Re: what did you do to your motorized bicycle today?

Ouch... did you drill into the aluminum when trying to drill out that left bolt? And how deep in did you drill? You can probably save it if you take the engine off the bike (if not already) and steady it in a vise or whatever you can come up with so the broken stud is Real easy to get to with the drill. Start the drill again but angle it opposite the way you were drilling at first until the bit has dug in enough that it won't slipp off, then while drilling gently bring the bit inline with the stud and it should drill out straight.... This is a lot easier showing somebody than telling them by the way...
I got other tricks to get one out if it's been drilled in deep already, you'll need a dremel and a rather small carbide burr then you carefully eat away the part of the stud that's stopping you from drilling the hole straight, then make a "start" in the middle of the stud to prevent the drill bit from slipping off... again... easier shown than told...

Anyway, if it is a total loss, at least empty cases are cheap at most online places, and on a better note, this is a real good time to slip in some of the good bearings on the crank and clutch shafts... Every time I've split cases the bearings looked so bad there was no way I could put the thing back together without replacing the bearings. I also keep at least 4 bearings in my parts stash just in case I have to open one up and don't like what I find inside...
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