Minibike vs. KX 250

[vette66_00]

I know we have talked about this before and alot of people dont believe a single speed, non-varated, clutch and chain minibike can be fast. So my question is do you believe a KX 250 dirt bike is fast, if so this minibike spanks it in the 1/8 mile at 71 mph (sorry didnt get the MPH gun in the video).


http://www.youtube.com/watch?v=Az4rMyIT ... r_embedded

[Trafficjamz]

That is awsome.

But that did not look like 70 mph to me.

[vette66_00]

Here is a calculator for gear ratios
http://www.gokartracing.org/Calculate.htm

Front clutch 14 tooth
Rear Sprocket 55 tooth
Tire circumference is 35.3 inch
RPMS 8520 on a sendec tach

The calculator says 72.5 but you can have a bit of slippage but it should be compensated by the tire increasing in overall circumference.
So the GUN was not to far off.

[bakaracer]

yeah what size motor was in the minibike? if they are using a 15hp motor then yes it can be done. thats the same style motors they use in jr drags that go under 8sec. in the 1/8th

[Trafficjamz]

Yes, but all jr dragsters have a cvt setup to go that fast.

I don't know about the centrifical single speed setups getting to 70 mph in a 1/8th mile race.

[fastplastic]

my go cart that was super light and use a john deer tractor tranny moved pretty quick with a centrial cultch and a 5 horse but d*** i dont know about 70 and i even had a tranny too so not tryin to be a * but one way to shut the na says up is get a pic of the gps on the bike

[bakaracer]

yeah what size motor was in the minibike? if they are using a 15hp motor then yes it can be done. thats the same style motors they use in jr drags that go under 8sec. in the 1/8th

Yes, but all jr dragsters have a cvt setup to go that fast.

I don't know about the centrifical single speed setups getting to 70 mph in a 1/8th mile race.

not all use cvt trans. with a 15hp motor modded and the right gears matched can go really fast.those motors can make about 40hp modded.

[Trafficjamz]

Well, all th Jr dragsters I have seen use a CVT.

I have a 13hp honda GX390 (389cc) Where can I find performance parts for it?

I would like to make one of these minibikes.

[bakaracer]

check the forums for those places. or kart sites.they use the 15hp 4 stroke motors on race carts for the 4 stroke class.

[vette66_00]

Well, all th Jr dragsters I have seen use a CVT.

I have a 13hp honda GX390 (389cc) Where can I find performance parts for it?

I would like to make one of these minibikes.

http://www.affordablegokarts.com/ is a good start they have all the stuff for your GX390.

Also these engines are putting out around 35-40 hp. Most are Honda GX200 blocks with about $1500 worth of parts and labor into them. The GX200 is a 6.5 hp stock engine. CVT's carry alot of drag as apposed to the clutch setup. Most of the clutches have a 3500-4000 rpm stall so the engine is producing around 30 hp on engagement. While I agree the CVT are great for low HP motors they are not so much on high HP motors.

If you check this video out on you tube http://www.youtube.com/watch?v=-oWS-mmAHaE you will see at 6:25 a pretty much stock gx390 (intake and exhaust) hit 47 by radar gun in the 1/8 mile. So he is make around 16hp at 47 in the 1/8 mile. More than double the HP and you will be hitting 70 in the 1/8 mile.

This is a pretty stock 6.5 Honda Clone engine (Harbor Freight $99.99). Upgraded parts to keep it safe at high RPM's. Stock carb upgraded jets, upgraded intake (adapter and filter) and exhaust, Gov removed, upgraded 18lbs springs form stock 11 lbs, running 92 pump gas, Advanced timing to 31 degs, and stock plug. About $250 extra into this engine but billet rod and flywheel are $170 of the cost to reduce failures and add no real power.





Most of you guys have been around Scooters to long and compare an Spree/sb50 to a dio motor and think the variator is what make's the difference and most of the Dio upgraded engines are maybe pulling 12hp?

[Trafficjamz]

Most of you guys have been around Scooters to long and compare an Spree/sb50 to a dio motor and think the variator is what make's the difference and most of the Dio upgraded engines are maybe pulling 12hp?

The CVT is what makes a elite S faster than a spree.

If these mini bikes had CVT's I think the times would be a lot faster.

I will build one this winter.....they look very fun.

Thanks for the link to the go fast parts

[vette66_00]

How about a Banshee Vs. Minibike Mind you this is a 6.5 200cc Honda Clone engine purchased at Harbor Freight, Although the only thing that remains stock is the block but its also been reinforced. From this weekends drags.

http://www.youtube.com/watch?v=DZieWVgw ... r_embedded

[Trafficjamz]

How about a Banshee Vs. Minibike Mind you this is a 6.5 200cc Honda Clone engine purchased at Harbor Freight, Although the only thing that remains stock is the block but its also been reinforced. From this weekends drags.

http://www.youtube.com/watch?v=DZieWVgw ... r_embedded

freakin sweet

how much does the mini bike driver weigh?

[vette66_00]

This guy "home alone" is about 160 lbs the mini weighs 110 lbs. Its another guys mini EvilEd but he is scared from the power it produces and is still getting use to it.

Here is a pic of the RPM's it turned in that race.




Here is Evil and his new engine before it went on his bike.

[vette66_00]

make sure to reinforce your block with high hp engines. lol

http://www.youtube.com/watch?v=NoTXFBts ... r_embedded