HP Pocket Bike Engine On Friction Drive

[5-7HEAVEN]

DDM is having a clearance sale on these: http://www.davesmotors.com/s.nl/c.885035/n.1/it.A/id.5778/.f

Might as well pick up the set instead of just the dome.

I must've yanked that pull starter a hundred times yesterday.

Tiring for this old man.

NEED that electric start with high compression.

Or decompression valve.

 

[TREEWK]

5-7, I Have Not Done Much Checking For Speed. As I Was Thinking About Your Question, I Had A Couple Thoughts. I Will Get A Small 12 Volt Battery So I Can Use My Gps Street Pilot Out Of My Truck ( I Love That Thing). I Bought A Couple Bicycle Computors For Less Than 9 Bucks On Ebay, But Have Not Opened Them. The Gps Is Very Accurate, And I Won`t Get Lost! Lol. Last Year We Check Friction Drive With Pickup And Did 35 Mph. Took The Titan Cvt To Wisconsin In July. My Brother Clocked Me At 25 Mph. The Throttle Is Not Opening All The Way And It Is Geared To Pull Stumps!!. I Weight Over 300 (sad To Say). The Titan/cvt Takes Off At 1/4 Throttle Like It Is Pulling A Feather, No Strain At All (with Me On It). I Have A 10 Tooth On The Tranny Output, Will Change To A 17 Tooth, And See How That Works. Want To Put A Titan/cvt On My Stretch Cruiser, Don`t Like Sitting Up High. Have You Seen My Free Wheel Set Up In The Comet Thread? Ron

 

[TREEWK]

The 35 Mph On The Friction Drive Was With The Stock 49cc Upright Cylinder Pocket Bike Motor. It was with 1 1/4" roller, it could have used a bigger roller. Ron

 

[5-7HEAVEN]

Thanks for more info, Ron.Good numbers on your bikes, especially with your size. I weigh 185lbs. and "The Iron Dragon" weighs 55lbs.


My BMP friction drive uses 1.375" roller. The bike got up to 38mph yesterday, but still testing/tuning. I check speed with cheap Cateye bike speedos. Good enough for me.

I have used the same ADA S1 expansion chamber on 43cc Mitsubishi engine, GP460 engine and this pocketbike motor. I had to remove the mounting bracket to fit the Mits engine, but not necessary to do so on the 460 and pb engine. The pipe is quieter than the Mits and 460 stock mufflers, and more powerful. Probably not the most powerful but good enough.

 

[Hawaii_Ed]

Thanks for the info Ron, I was also wondering if this super-high performance pocket bike engine would hold up ok to extended running. I know some of the drag car motors are only built to run for 6 seconds, if you try driving them down the return lane they'd melt

 

[TREEWK]

5-7, Ed, The Big Bore Kits Makes A Big Difference, And I Did Not Have Super Exhaust. Those 52cc Big Bore Kit Prices Are Good, But I Have Over Spent, Bad Addiction. My First Motor Was The 43cc Mitshibushi, Over A Year Ago, Still In The Box, Saving It. I Bought It From Viza Motors In Az, Took Over 3 Months To Get It. Use The Cheaper Engines For Learning. Ed, I Have Not Put A Lot Of Miles On The Big Bore Motor. I Think It Should Last. I Have A Pile Of The Cag Motors (horizontal Stroke) And The Upright Stroke. I Do Not Even Know If Any Of Them Have Reed Valves In Them. Thinking That Would Be A Good Thing. It Has Been So Hot Here, When It Cools Dn A Bit, Need To Bolt Some More Stuff Together And Do Some Riding.. Ron

 

[TREEWK]

5-7, Yeah, Thats Nice When You Re-use Exhaust And Things On Other Engines. That Pipe Of Yours Looks Costly. Ed, I Raced Late Model Dirt Track For 20 + Yrs. Big Block Ford, 427 With 428 Crank = 454 Cid. Turned It 7200 Rpm Most Of The Time, They Are Tuff Is Done Properly. My Last Years I Raced Small Block Chev 406 Cid. Could Never Turn It Over 6800 In The Light Weight Coil Over Suspension Car, Could Not Keep The Rear Wheels Hooked. Ron

 

[TREEWK]

Before I Run A Cag Motor Again, Will Shroud The Cyclinders. My Tree Climber Had One Of Those Temperature Guns, Just Point It At Anything And It Reads The Temp. From Several Feet. Should Have Bought It From Him. Guys, The Forums Keep A Guy Going. Later. Ron

 

[Hawaii_Ed]

So many old racers on here! Mainly drag racing for me, I am trying to mess with SCCA autocross here since our strip closed. 5-7 is an old racer too! I have a temp gun sitting with my drag car in Virginia, neat tool for a lot of diagnosis!

 

[DetonatorTuning]

an admittedly brief look around seems to support the idea that these PB engines that are making 10HP are running 15:1 domes and possibly big bores too.

if you go to the 13:1 topends how much power are you going to loose ?

i saw one 13:1 engine listed at 5.7HP that's a big compromise for a possible starting benefit. i would be inclined to insure the proper tuning and O/F/A ratios and settings on the HOT engine before detuning it.

i also support the idea of putting MORE shrouding around the rest of the cylinder and head.

steve