How to get some low end from a new Doodlebug?

#1
Hello, this is my first post. I have enjoyed reading the threads.

I already have a new Mini Baja (Baja Motorsports MB 165) and am planning on installing a TAV 2 on it. That means I'll have a surplus stock jackshaft assembly. Or, I could simply buy the jackshaft assembly on Ebay for about $10. I wonder how difficult it would be to put the jackshaft assembly on a New Doodlebug with the 2.8 HP that I plan to get for my 7 year old son. I surmise that I would have to change the chain and rear sprocket on the Doodlebug to a bigger #41 chain size if I want to use the sprockets from surplus the jackshaft assembly.

My questions are:

Would the jackshaft fit the Doodlebug, or would there be interference with the muffler or other unforeseen problems?

Would the jackshaft give me the reduction in gearing that I want?

When I do get the money, would there be many problems putting a TAV 2 on the Doodlebug?

If you have any other thoughts on the new Doodlebug, I'd love to hear them. I am thinking that the new mini bikes would be a bit less fragile than comparable Chinese motorcycles. Also, the Doodlebug seems to be a bargain at $250 at Pep Boys. Thanks for any input you can give.
 

delray

Well-Known Member
#2
hey packoderm, i got a doodlebug that i have done some modifly to it. first time i seen one up close was when my friend purchase one. the minibike look to be built very good. so i puchase one for the kids to ride and crash on. but the only thing i notes was it perform poor off idle and low end. when they built that minibike they install 65#tt rear sprocket. way to small for that bike. with bike only having 2.5hp and 65#tt and almost 14inch tire there was no way for the bike to take off good. i purchase a new blank 80#tt sprocket for only $14 and drill out a new bolt pattern and also built a header pipe and exhaust for it. now the bike has alot better low end and good top end too. so gearing it down will make it perform better and still wont have to worry about the bike getting away from your son when he is riding it. building a good exhaust will help too. replacing the sprocket was easy ,but if you dont have the tools to drill or machine out new holes. then it makes it litte harder to do?
i look at some of the jackshaft plates off of the large baja minibike. they look like they could work? you dont have to change the rear sprocket to a 41#
just replace the sprockets on the jackshaft unit to 35# sprockets. the only problem you may have is bolting up the original chain cover,but it may just bolt right over everything? if you deside to install tav-2 someday on that engine you may have a problem. the shaft on the engine is 5/8 and the tav-2 is for a 3/4 shaft. you would have to make a sleeve or something to make -up for the size? gearing it down and exhuast pipe will let your son go up small hills and stuff.
you would have to spin your clutch around if you use the jackshaft unit and for gears you could install 12-14#tt inside and a 35-40#tt out. if you are looking to keep the doodlebug chain cover on? you will have to watch your sprocket size?
 
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#4
Thanks for the info Delray. I didn't know it was so easy to replace the sprockets on the bolt-on jackshaft. I would love to see pictures of what you have done to your Doodlebug.
 
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