Larger sprocket...

[Yellowhand]

This is cool...first-hand input from two guys modifying doodlebugs in different ways...excellent photos, too.

I bet that bigger engine swap really perked up the performance...

I don't know if that axle-mounted caliper mounting bracket for a pocketbike will work or not...that rotor on the doodlebug isn't the same as the ones I use, but if the diameter of the rotor is the same size, the pocketbike mounting bracket would work, just enlarge the axle hole to doodlebug axle size.

I have some rotors that are larger, and I make brackets from 1/8" sheet steel that are a little longer than stock to compensate for the increased diameter of the rotor...

These aren't difficult to make, but they can also be purchased from pocketbike parts suppliers for just a few bucks.

The positive aspect of this type of caliper mount is it turns the rear wheel/brake into an independent subassembly, and can be easily moved from side to side in the frame to adjust wheel alignment, or even flipped around, putting the brake on the other side to make installing a jackshaft easier.

I haven't hit any pocketbike parts supplier sites lately, but if the doodlebug is anywhere near as popular as pocketbikes have become, these guys will eventually offer some performance mod parts for them...the sites have several mod kits for the 49cc bikes, but the cost of the parts might make it less attractive than swapping to a bigger engine...if the swap isn't that complicated.

ForeverYoung...how did that swap work?

 

[foreveryoung]

It was pretty easy just moved the engine around a little to get a perfect chainline then drill new holes I could have gotten the engine more towards the center of the frame if would have installed the clutch inboard.

 

[minidragbike]

My friend has a doodle bug minibike. The big tires make for a very comfortable ride. I don't even know why they would put such a small motor on such a large minibike?

 

[delray]

hey minidragbike and josh, you guys are into aftermarket parts. where would be a good place to search for billet rods for small engines. any ideals?
thanks..................... .................:helpsmilie:

 

[minibikekid]

www.arcracing.com, www.tbrwins.com, www.jegs.com all kinds of places that sell billet rods and other parts as well
when you go to jegs you will have to look under jr. dragster for small engine parts

 

[foreveryoung]

My friend has a doodle bug minibike. The big tires make for a very comfortable ride. I don't even know why they would put such a small motor on such a large minibike?

You know what people and politicians say about mini bikes "they are dangarous, unsafe, unsecure, lack of stopping power only rear brake, no suspension, no lights, they vibrate" the list goes on and on That's why I think they approve weak engines only :mad2:

 

[delray]

thanks foreveryoung,i email arcracing early today to see if they have anything.
for a china built bike its nice they give you the option to install different engines.
Is that what you call a big block overhead engine:thumbsup:
have you try it up big inclines(hills) , will it hold it speed or slow down?


minibikedrag, minibike rides real nice for a hardtail:thumbsup:
................:thumbsup:

 

[foreveryoung]

its nice they give you the option to install different engines:

It is not that they gave the option to install a different engine before I bought it!!!
mine came with a lifan 2.8 hp as well by the way I paid $288.00 including tax a month later I purchased the champion 6.5 hp universal replacement engine from costco at $123.00+7 porcent tax.

 

[Bowling]

I just ordered my jackshaft and chain today... That 6.5 hp set-up looks sweet. I didn't think any engine that size would fit with the gas tank, nice. Delray's pipe looks sick too lol. I wish I could do something like that but my resources are a little limited lol. I ended up just taking a drill to the muffler a little. Oh and yes the engine is a Honda knock-off... I can't remember which engine it was a copy of though but I think I read a post somewhere saying that it is.

 

[minidragbike]

Hey clone guys if you guys ever want to modify the motor. It's best to change the stock flywheel. Today one exploded, with just the governor removed and header.

Maybe it was a freak accident?

 

[delray]

bowling,i thinks this is the engine it copys
http://www.trupower.com/honda/g100.htm
:rolleyes5:

 

[Bowling]

Ouch... How long did you have the engine? I've put a few tanks through mine and haven't had any problems except the filter got dirty quick. (2 layers of black panty-hose fixed that)

 

[minidragbike]

Wasn't mine, but it was a local alley kids minibike motor. The motor was only 1 month old.

 

[Bowling]

bowling,i thinks this is the engine it copys
http://www.trupower.com/honda/g100.htm
:rolleyes5:

Yeah that's gotta be it. I found a motor just like foreveryoung's for 180 locally so I'm thinking about moving up to that once I get the jackshaft/brake thing all straightened out. I'm hoping if I install the clutch inboard then I won't have to move the engine with the jackshaft but who knows...

That reminds me, foreveryoung, did that engine come with the right throttle for mini bikes who did you find it somewhere seperatley?

 

[foreveryoung]

Yeah that's gotta be it. I found a motor just like foreveryoung's for 180 locally so I'm thinking about moving up to that once I get the jackshaft/brake thing all straightened out. I'm hoping if I install the clutch inboard then I won't have to move the engine with the jackshaft but who knows...

That reminds me, foreveryoung, did that engine come with the right throttle for mini bikes who did you find it somewhere seperatley?

The throattle cable is very easy to install!!! there are no extra parts to buy or fabricate it comes with it. http://www.oldminibikes.com/forum/photopost/data/500/medium/throatle_001.jpg

 

[Bowling]

Nice... Thanks for the pic! I found out it costs like 5 bucks per chain to get it sized at a local cart shop... Do I need special tools and stuff to do it myself?

 

[delray]

hey bowling,here is one more different type of jackshaft

http://cgi.ebay.com/Yerf-Dog-Go-Kar...3QQihZ001QQcategoryZ64657QQrdZ1QQcmdZViewItem

this type would be a bolt on(jackshaft only) if you install it on baja doodle bug you would have to flip your brake and sprocket around. that would probably involve welding brake bracket.
what type of jackshaft did you get? weld on? can you get someone to weld for you?
I kind of like the bolt on that the yerf bike came with.
http://cgi.ebay.com/ebaymotors/Mini...014QQitemZ330119883126QQrdZ1QQsspagenameZWDVW
easyway to gear down a motor without doing any welding. this system would work get for you.
if you purchase a new motor(bigger) try it without a jackshaft first?
with all that power it should push you pretty good?
......................

 

[Yellowhand]

There is a special tool for shortening chains...they aren't one-size-fits-all because they are made in each pitch series size...they hold a short length of the chain within the tool while an appropriately sized hardened pin is screwed down into the chain's connecting pin, pushing it out without damaging any other parts of the link...which is what can happen if you try to use a hammer and pin-punch to drive the pin out.

If you're careful, you may be able to do it that way, but any deformation of the links causes a weak spot in the chain, and the link may not swivel freely, causing kinks and rapid sprocket wear.

I have several different sizes and brands of 'chain-break tools', some types work much better than others, but I have them and use them because I 'size' lots of chains in different pitches on a frequent basis.

There isn't any brand or type available (that I'm aware of) for $5, so if this is a one shot deal for you, maybe paying someone to do it for you is the way to go...

If you're very careful and take your time with a wooden fixture holding the chain, you may be able to gently drive out the connecting pin with a small hammer and pin-punch without damaging the links you want to use. If you pay the $5, and the guy sizes your chain this way, take the hammer away from him, beat him with it, and get your money back.

 

[Bowling]

Delray, I already ordered the 10" jackshaft kit from NorthernTool which is weld-on... My neighbor has a welder. I'll probably change the engine in a month or so when I get more money to spend on it because I'll have to by a new clutch and stuff too.

So when I remove the connecting link, then what? Is it the same procedure for removing the other links I won't need?

 

[Yellowhand]

No, the connecting (or 'master') link is the only one with pins that slide in and out easily...the others are pressed in...very, very tightly pressed in.

Northern also sells the tool to remove links...I wanna say $15, without looking it up in the site...I have one...it's fair quality.

I probably should have mentioned this as one of the items you'll need to install a jackshaft, but if the kart shop will do it for $5, you might go that route instead.