Best single upgrade to a DB30?

D

dogfish

New Member
#1
#1
Got another DB30 today to keep the first one (green bike) relatively stock for the boys as a learning tool. The green bike has a pretty good running engine, and I'll keep the other engine as a spare. Also picked up a 6.5 HP motor at Harbor Freight today, and ordered a max torque clutch for the heavily modded bike (red bike).

Would a better clutch for the red bike be the best inexpensive mod, like a max torque? I'm trying to figure out what the weakest performance link is. Sprockets, clutch, or gear teeth on the clutch (I've seen up to 18 teeth for the front gear, for a 50% change in gear ratio)?

Also, would it make any sense to fit a TAV2 to a stock (green) bike?

Being 195 lbs, I'm trying to figure a way to make it so I can ride both, because as it is now, I'll only be able to play on the red bike.

Thanks!
 
rudedog

rudedog

New Member
#2
#2
The Max Torque and the 6.5 will provide plenty of power for you, being only 195. Not exactly sure, but I don't think they have a TAV for the smaller 5/8" shafted engine.
 
F

fordman50

New Member
#4
#4
I am tretty sure there is a tav for the 2.5 hp engine.... I have a problem spending almost as much for a clutch as I paid for the bike though.... I have have TAVs on other bikes and they are bad ass.

I am thing of modding up a gear reduction set up using a tav back plate. http://www.bmikarts.com/shop/?shop=1&cart=1591908&cat=1&itemid=3321&&thumbval=thumb&showFullImage= It should be something like this one only half the price: Reducers

If it works then I will either share the plans or sell them. If it dont then :thefinger:

Ian
 
6

66corvette93

New Member
#5
#5
I am around 160 and i have the stock engine in their.i dont really want to drop in a new motor. are their any cheap upgrades that i can slap on the doodle bug??
 
TT

TT

#6
#6
One of the members here put a sproket on instead of the rubber chain tentioner adjustment. Having this inexpensive modification involves two bearings, a bolt and nut and small #35 sproket which in my opinion has the greatest advantage of improving the chain tension. The clutch is very weak and vibrates under load and that also could make it more pleasurable to ride so your not rattled off of the seat. The removal of the govenor would increase RPM and performance. Then, you have to re-do the throttle linkage. (not too easy) The limits of China 2.8HP mini bikes flooding the market are limited!!!
Not many engine internal componants are worth doing in my opinion. Run it until it stops and get a larger engine when the budget allows...The stock carb. is trash..

TT :hammer:
 
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delray

delray

Well-Known Member
#7
#7
66corvette93,i only payed $14 for my new blank 80tooth sprocket and machining out the center hole and 6 bolt holes was free and i built a header pipe exhaust system too with some extra pipe i had laying around in my shop. total cost $14 and my time. time that i enjoy doing(my hobby):weld:
if you really don't want to replace the motor and you can't machine out a blank sprocket? you my want to go to a bolt on jackshaft,but that will cost little more $$
i still have kids riding my bike. so 6.5hp is out of the question for now.
if the bike is for you only and no kids? you might want to think about taking your motor off and selling it on ebay. some the guys are getting $60-70+ for there 2.5hp motor and then buying a new 6.5hp for $100 and a new clutch for $30-35. so your only looking about $60-70 to up grade to a 6.5hp motor. unless your wife is in control of the money:doah: then you have a problem...........:scooter:
 
delray

delray

Well-Known Member
#8
#8
Tacoterminator,most of the vibration comes from the poor motor mount design on the doodle bug. with the plate mount design raised up and only welded on the front and back,this makes the motor rock back and forth. causing a vibration up through the frame. making the handle bars vibrate. some of this will go away when regearing the bike,allowing the clutch to lock up better and not fight with the motor so much. when install a larger motor most of it go's away. larger motor has no problems locking up the clutch(faster). if any you guys have a stock 2.5 motor? try giving it some gas on and off with your other hand on the brake and you will see how bad you engine will rock:doah:the only thing i guy could do is box in the motor mount. by welded some metal plate in on both sides:thumbsup:
 
delray

delray

Well-Known Member
#11
#11
Strigoi , have you seen what one of these engines look like inside:doah:
connecting rod is about 1/2 thick. valve springs are soft and the cam is made out of plastic:doah:
that would be real smart:eek:ut: still won't fix the lack of lowend torque the bike can't produce,because of the wrong gearing and low hp motor and 160pound adult or heavier person trying to ride it:doah:
 
Strigoi

Strigoi

#12
#12
i'm not worried about the rod letting go, the flywheel is what concerns me more. as long as you're smart about it and not keeping it at high rpms for a long time it's most likely not going to be an issue. mine and my friend's bikes have hours of hard riding on them and there hasn't been one issue. i'm not saying it can't/won't happen though.

the next things i plan on buying for my clone are a billet rod and flywheel.
 
Strigoi

Strigoi

#14
#14
it's not too hard. you really just need to drill and slot new holes. you'll also need to buy a new clutch. if you plan on messing with the chain, get a chain tool from somewhere like BMIkarts.com. they're worth the money when it comes to adding/removing links. you also need to figure out the throttle hook up. it's been discussed here quite a bit.

search around here in the DB section and you'll find all the info you need.
 
D

dogfish

New Member
#16
#16
Worked on the red bike tonight.

I hooked up my Max-torque (sprocket on the inboard side), along with installing the clone and making a throttle linkage per the AGK website. My throttle linkage came out a bit different, as my spring doesnt take a path across that adjustment screw. Just drilled a hole on the original linkage on the right side. Works fine, and I used an 11lb spring, so it snaps shut easily. Governor isn't hooked up to the linkage (does that mean I have essentially bypassed it?).

The chain breaker was a great suggestion, as I had to remove three links. Gives me a bit more adjustment. Used a dremel to cut the slots between two drilled holes. Pretty easy. I'm sure the conversion kit would have made it quicker & simpler.

Thanks for all of the advice, much appreciated.
 
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