Project ideas?

#1
Situation: I have a highly modified Briggs 5 hp that is an alcohol burner - hp is no longer anywhere near 5... it's MUCH higher now. :shifty: Used to push my fat arse around in a kart at speeds approaching a buck, so it should be interesting in a mini frame.

So... who made or makes a long wheelbase frame for making some sort of obnoxious drag mini? I already figured out the ratios for a quick and dirty 2 speed tranny so it's now just a matter of getting the frame as the starting point.

Ideas? Parts for sale? Suggestions? Talk to me... :scooter:
 

65ShelbyClone

Well-Known Member
#2
You're stealing my mini funnybike idea!

You may be on your own finding a stretched mini frame. I'm sure someone would build a custom one for the right price. I'm going to(be forced) to build my own to get it the way I want.
 

minidragbike

Supporting Speed Nut!
#3
Foghead get some pictures of it.

Most 5hp briggs can be rode on a regular nice minibike frame. To have it stretched, or wheelie bared out depends on your gearing is, or the clutch you use.
 
#4
Foghead get some pictures of it.

Most 5hp briggs can be rode on a regular nice minibike frame. To have it stretched, or wheelie bared out depends on your gearing is, or the clutch you use.
Looks to be just your average everyday 5hp Briggs with the tank under the carb... it's truly surprising what you can get as far as hp goes when it comes to stock components... so the motor appears relatively stock with a tuned straight pipe on it. :shifty: I'll post a pic in the next few days...

When it starts though, that's when the disguise is blown... it's REALLY nasty sounding. Dyno #'s are around somewhere as well to back it all up. But that would be tipping my hand!

I just need a frame long enough for a jackshaft assembly and wide enough to get some serious rubber under it at the back. I'll be able to tune the holeshot with various clutch springs and gearing, so the bars shouldn't be necessary.

Length is a primary consideration for high speed stability however... this thing will NOT be slow. :rockon:
 
#5
You're stealing my mini funnybike idea!

You may be on your own finding a stretched mini frame. I'm sure someone would build a custom one for the right price. I'm going to(be forced) to build my own to get it the way I want.
This country is big enough for the both of us! Yours will definitely be far more impressive with the hair dryer on it!!

You a welder?? :huh:
 
#7
enigma, thanks for posting those pics...that's the rear wheel that will fix the symmetry problem on my Copper Chopper...I'm heading to the low-rider bike shop to get one...thanks for the idea.
 

minidragbike

Supporting Speed Nut!
#9
Here's a few ideas. One is a briggs 5HP, the other a tecumseh modified, which is also street legal, and the last is a Honda clone. The one with the wheelie bars and briggs actually wheelies very nice.
http://www.putfile.com/pic.php?img=5158568
http://www.putfile.com/pic.php?img=5158564

http://www.putfile.com/pic.php?img=5290235
http://www.youtube.com/watch?v=VUR0ccudlyg
Nice photos, and clip. Those are some sweet bikes.

Foghead get pictures. Sounds like a nice SA motor.
 

65ShelbyClone

Well-Known Member
#10
This country is big enough for the both of us! Yours will definitely be far more impressive with the hair dryer on it!!

You a welder?? :huh:
It'll be more impressive when the boosted engine explodes and sends oil under the back tire.....:eek:ut:

I'm not a pro welder by any stretch, but I know enough to get into trouble.
 
#11
Here's a few ideas. One is a briggs 5HP, the other a tecumseh modified, which is also street legal, and the last is a Honda clone. The one with the wheelie bars and briggs actually wheelies very nice.
http://www.putfile.com/pic.php?img=5158568
http://www.putfile.com/pic.php?img=5158564

http://www.putfile.com/pic.php?img=5290235
http://www.youtube.com/watch?v=VUR0ccudlyg
VERY creative little bikes!! I'm kinda doubting that mine would/could ever be street legal when done though... I'm thinking short diameter WIDE go-kart slick for the rear in order to hook up.

Motor is from a 'modified' class racing kart.... only winds out to about 6500 reliably, although we had it wound out to 8k one time as a proof test to see if it would hold together... it did just fine, and sounded really scary...
 
#13
Nice photos, and clip. Those are some sweet bikes.

Foghead get pictures. Sounds like a nice SA motor.
I'll post a pic of the motor, but trust me on this one... it doesn't look like anything special... it's a true sleeper/screamer... and somewhere I have a tuned expansion chamber type pipe for it as well... that boosts it an additional 5-8hp.

I only wish they had sanctioned mini drags around here. I may be resigned to racing suckers on motorcycles for cash when it's done!!! :thumbsup:

Gawd I'm feeling old.... :mad2:
 
#14
Width?

Yellowhand: it appears that you're a lean, mean, welding machine there... any suggestions about making a frame wider in the rear for a bigger tire??? Length is easily do-able, but what about width????? :huh:
 

minidragbike

Supporting Speed Nut!
#15
Foghead where are you located?

I bet a regular frame can handle your motor. The scary part is the clutch, but if you know how a race clutch works then there is no problem.
 
#16
Foghead where are you located?

I bet a regular frame can handle your motor. The scary part is the clutch, but if you know how a race clutch works then there is no problem.
Ahhh... I forgot to add my location. North of Buffalo, NY.

Clutches? No problemo. Frame? Ummm... what's the average horsepower limit for them???
 

minidragbike

Supporting Speed Nut!
#17
In my experience it seems that 30hp is the limit for a stock frame. I have had frames that had more on them, but stuff was always breaking, or bending.

My buddy has a frame that's made from a little bit thicker wall tubing and he has way over 30hp on it. It's still just a stock type frame.

Most of the stretch is just for show.
 

65ShelbyClone

Well-Known Member
#18
Which parts gave you the most problems? I would expect the rear axle mounting area first. I saw one of the aircooled 2-stroke shifter minis with lots of gusseting around there.
 
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minidragbike

Supporting Speed Nut!
#19
Yeah that's the weakest spot. First the axle bends, then slop comes from multiple axles bending. The axle hanger has to much slop and causes the rear wheel to twist sideways when the clutch engages. This causes the rear hub to crack. or bearing to explode.

Another thing that happens with a torque monster is the motor wants to slide back. So no matter how much torque you put on the mounting bolts the motor slides back. I usually end up putting screws in the extra slotted mounting area where the motor mounts. Also the motor plate flex and you can actually see the motor plate twisting. It looks like the motor is leaning back before it takes off.

All this stuff causes cracks, and bends. If the frame has a thicker mounting plate, and thick wall tubing with a live 1" or larger axle it should be cool.

With the motor with 2 spark plugs I had. It would wheelie so violent, it actually bent the wheelie bars. So it flew into the air on top of the wheelie bars and the jockey was tossed into the air. This all happened at the starting line within 20 feet.
 
#20
Yeah that's the weakest spot. First the axle bends, then slop comes from multiple axles bending. The axle hanger has to much slop and causes the rear wheel to twist sideways when the clutch engages. This causes the rear hub to crack. or bearing to explode.

Another thing that happens with a torque monster is the motor wants to slide back. So no matter how much torque you put on the mounting bolts the motor slides back. I usually end up putting screws in the extra slotted mounting area where the motor mounts. Also the motor plate flex and you can actually see the motor plate twisting. It looks like the motor is leaning back before it takes off.

All this stuff causes cracks, and bends. If the frame has a thicker mounting plate, and thick wall tubing with a live 1" or larger axle it should be cool.

With the motor with 2 spark plugs I had. It would wheelie so violent, it actually bent the wheelie bars. So it flew into the air on top of the wheelie bars and the jockey was tossed into the air. This all happened at the starting line within 20 feet.
Exciting and most excellent!!! A custom frame may be on order then. How to make a mini frame 101.
 
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