Pocket Bike Engine Project II

[lowracer]

Now that the 1st Pocket Bike Engine Project is complete, I figured I should start a new thread for the 2nd PBE project I am now working on.
This one is a no-suspension dirt jumping MTB frame that I have used in the past for various motorized projects. Here are some aluminum engine rack pics & the new expansion chamber that came in the mail today. Got to try out my new oscillating saw on the pipe (cuts like butter).
-Lowracer-

 

[lowracer]

Look what I found today while buzzing around the neighborhood on my MB. Somone was throwing this away & it is in perfect new condition. It says HONDA across the back of the rear saddle. It is huge & comfy...I now have to figure out how to mount this to a bicycle?
-Lowracer-

 

[timboellner]

And I thought my 12" wide Cloud 9 seat was big.
Looks big and comfy, but good grief!
That could easily support my mother-in-laws huge a$$.
I do like that pipe though.
TiM

 

[lowracer]

timboellner,
I just went & measured it & just the main seating section is 17" wide X 16.5" long. Then there is the rear detachable seat which itself is larger than any bike seat I own.
I really like the padding quality & will try to adapt one or both to my bike. I am going to have to build another rear rack just to hold the seat...I could sit on this seat for days & not get uncomfortable...lol
Looks like it may have come off of a Honda V-Twin type cruiser since there were also 2 exhaust pipes on the curb for trash pickup, but I only took the saddle.
-Lowracer-

 

[lowracer]

timboellner,
The pipe has a good expansion chamber shape to it & once I attach the 12" flex pipe to it & mount it up, we'll see how it performs & sounds. The flex pipe is 1" ID & 1-1/8" OD. The 1" ID flex pipe fits the cutoff section of the pipe that I coated with High temp Permatex gasket maker & the other end that goes to the engine I sleeve with a small piece of ceiling fan drop pipe and use either a 1-1/8" muffler clamp or a bicycle stem (1-1/8" fits perfectly...I may cut off the steerer tube section & file it smooth)
-Lowracer-

 

[lowracer]

I got it mostly finished today & took it for a ride around the block but it was drizzling rain & I didnt wanna get it all filthy. The pipe is louder on this bike than on Pocket Bike Engine Project 1. I need to get the V-belt a little tighter (add washers) & work on mounting the HUGH JASS seat (maybe). Before mounting this engine I took the time to remove all the 80mm head bolts & use the longer 90mm ones I bought for engine #1. Also used Red Loctite & 2 lock washers per headbolt. Lets hope it all remains tight...
Here are some new pics.
-Lowracer-

 

[timboellner]

Very cool.
Man I love the thinking outside of the box engineering .
Makes me want to do a pocket bike motor build.
Keep up the good work.......... I'll keep following you on this one.
TiM

 

[BeaverRat]

Just out of curiosity, if the engine seizes for whatever reason, does the front wheel lock up? If so, that would certainly hurt a bit...

 

[lowracer]

BeaverRat,
No, the wheel doesn't lock-up if the engine seizes. There is a centrifugal clutch that stops being engaged when the crankshaft stops turning.
Went for a nice ride today to break in the new engine & burned up a full tank of gas.
The older engine has way more power on top probably cause its all broke in already.
I didnt wanna push this one too hard until its broke in.
-Lowracer-

 

[lowracer]

Did a few tweaks to the exhaust by cutting off the stock stinger altogether. I bought some exhaust packing & tightly wrapped it inside the stock canister, but it didnt do anything to quiet down the pipe, so I mounted a lawnmower sausage muffler instead. Made it a little quieter & good enough ground clearance. Here are the latest pics...
-Lowracer-

 

[cannonball2]

The aluminum frames are much nicer! Noticeable weight difference?

 

[lowracer]

Cannonball2,
When searching for MB frames, I wanted heavy & solid & this frame was meant for Dirt Jumping so I figured it would be solid. I also am partial to Rocky Mountain Bikes since 'The Beast' is also a Rocky Mountain. This engine on this bike is just too much. It launches like a dragster & rips up to redline. Its scary fast!
I may mount this engine on my other bike, 'Wimpy' which is a rear friction drive, just to see how it performs. I'll post a new thread when that project comes to fruition.
-Lowracer-

 

[lowracer]

I ordered a Banana seat for this bike so that I can have more room to move my weight around on & so I can get back & low without a kicked-back seatpost & because I think they look cool in a retro kinda way. Here is a pic of what I ordered on eBay (I got the Black one)...Don't forget the sparkles...lol
-Lowracer-

 

[lowracer]

Ok,
Heres the latest pic after installing the Banana seat & replacing the spark plug wire (like I did on Pocket Bike Engine Project #1 bike)).
The seat allows a more comfortable perch w/ a more rearward roomier position...Handling has improved.
-Lowracer-

 

[cannonball2]

Way cool LR! Like the seat. Which bike do you prefer? BTW what is the size and brand of the rear tire?

 

[lowracer]

Thanks Cannonball.
I like 'The Beast' much more.
This is a fun bike to putt around on, but not a very comfy bike for a long ride.
The rear tire is a Kenda 1.95 slick (cant remember the # & its not printed on the side).
Its looks like a motorcycle tire & handles great.
I do believe the best MB's start as Downhill MTB's & just add engine.
My opinion only...
-Lowracer-

 

[lowracer]

Cannonball2,
Its a Kenda K838 tire. I really like the way they handle & ride...
-Lowracer-

 

[cannonball2]

Thanks LR! I will check it out.

 

[lowracer]

I bought these tires at Niagara Cycles for 14.99/ea
Heres the link.
Kenda K838 Slick 26" x 1.95" Slick Tire
-Lowracer-

 

[happycheapskate]

Maybe you could mount the seat sort of like the old banana seats. Paint a 2x4 black, countersink holes for the washers and nuts, then use U-bolts, mounted into the "seat guts" of the seatpost, probably a cheap bmx seatpost would do better than the nice rails on a modern micro post. build struts for the board, then mount the seat to the board.