First Build

GoldenMotor.com

Swaltz

New Member
Jan 29, 2015
2
0
1
New Orleans
Hi all,

I've been wanting to build a motorized cruiser for a few years now. Recently I acquired a small 2 stroke bicycle engine with what appears to be everything needed for an install including an install manual. The manual appears to be a joke, though. I have tinkered in the past so I feel confident I can get this to work.
I have an old Huffy Cranbrook that I am going to use as a platform. I have read a few post of people using this frame for their builds. They seem to like the outcome and I personally think they look great.
My first question; what is the best way to get the engine and rear sprocket aligned correctly? I have no tools to do this besides patience and a wrench. I would assume if the two aren't true the chain will get thrown. Any advice about this would be more than welcome. Heck, any advice period would be more than welcome.
 

2door

Moderator
Staff member
Sep 15, 2008
16,302
175
63
Littleton, Colorado
Welcome to the forum. I hope we can help you get on the road. There is a world of knowledge here and years of experience to draw from.

If the engine is mounted correctly in the frame then it is centered as far as the drive sprocket is concerned. Now you're faced with getting the rear wheel, driven sprocket to align with the engine, drive sprocket. The engine can't, or shouldn't move so the trick is to get the rear sprocket to align with it.

There are pages of discussion here about how to install and align the rear sprocket. Use our search feature. Type in "rear sprocket installation". You can also type in "Cranbrook" and you'll see it is indeed a popular foundation for a motorized bicycle. Lots to read about that particular bike.

Here is a diagram that might help explain what we mean by "aligned". It shows how things should look using a straightedge placed against both sprockets.

Tom
 

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Davezilla

New Member
Mar 15, 2014
2,705
10
0
San Antonio Texas
Welcome to the forum

2door is righht, there's a lot of talent in here and help is just a post away if you need it.... I also like the cranny frames as a good base for motorizing, its strong and it looks great too.

For your chain alignment question, the diagram above is correct and to set the rear sprocket, if you have a way to spin it after the sprocket is installed, your next step is to adjust it so there's no side play when you spin the wheel... put a marknor anoiece of tape on one side of the sprocket and then spin it slowly but quick enough to see if its tracking straight or wobbling side to side. Loosen the side that's closest to the spokes and tighten up on the opposite side, spinnit again and repeat until the side wobble is under 1/8". If you can get it to where there's no side to side wobble at all, that's the goal, but anything less than about 1/8" should be enough to keel it from throwing the chain. It may need more adjusting after a few rides but it will set it's self and stay put after 2 or 3 readjustments. Its also possible it can stay put the first time but check it after every ride for the first several rides, then at least once a week or before the first ride of the day etc....

Good luck on your build and feel free to ask questions.
 

YesImLDS

Member
Jun 29, 2013
960
12
18
Columbia, Missouri
Also if your cranbrook is anything like mine you might have to file out the inside of the sprocket to get over the hub cover, otherwise the sprocket will be at an angle and you will have a tightened and slackened chain depending on the wheels position.