How to get a 70cc 4speed in frame?

GoldenMotor.com
M

mrblack98

New Member
Oct 30, 2012
27
0
0
north carolina
wheelbender6

wheelbender6

Well-Known Member
Sep 4, 2008
4,059
221
63
TX
A horizontal cylinder engine like your 70cc usually requires a bike with a stretch frame or chopper frame. There is no way the 70cc motor will fit that worksman unless stretch that frame. if this is your first build, I would go with a simple engine kit like an HT 2 stroke. if you want a four stroke on that worksman, go with a rack mount kit from Staton or Thatsdax.You could mount an HS four stroke in the frame of a more conventional beach cruiser (like a huffy Cranbrook).
 
M

mrblack98

New Member
Oct 30, 2012
27
0
0
north carolina
Dang thats what I was afraid of. I'm going for the board track racer style and would like a speed of 50 mph to be reachable without going into 11k rpm. know of any engines that can do that? And I'm in North Carolina so its going to need some torque for the hills, so shifting is probably a necessity. I've looked at a whizer type belt drive, but I don't know if its capable of the hills and speed.

EDIT: What about the GP460 mounting inframe? http://www.davesmotors.com/s.nl/it.A/id.4506/.f
 
Last edited:
M

mrblack98

New Member
Oct 30, 2012
27
0
0
north carolina
Point is I want something with power. I love a 2 stroke because of the size and weight to power ratio. I want my top end to be 55~mph and have torque for hills.

What engine and drive will accomplish this in-frame?
 
Mr. Minecraft

Mr. Minecraft

Visionary
Jan 13, 2012
349
0
0
San Diego
I say this with all honesty, just buy a motorcycle. A bicycle is not meant to do 55+ mph unless you replace everything ie; wheels, tires, every bearing, etc. I dont know of an engine that will do 55+ and still have torque for hills. Maybe a 16hp morini?

If you get this http://www.morinifrancousa.com/engine5.htm with a radiator and all the goodies, you will have one of the most badass bikes I have seen.
 
maniac57

maniac57

Old, Fat, and still faster than you
Oct 8, 2011
4,484
22
0
memphis Tn
Sounds like you need a DeNardis or MotoMorini engine. Ktm uses the morini in it's minibikes.
The DeNardis is a aftermarket replacement for the Morini. Expect to pay about 450-500$ for one of these screamers.
 
M

mrblack98

New Member
Oct 30, 2012
27
0
0
north carolina
Hmm ok thats a possibility... Now as far as China Girls go. If I were to upgrade the crap out of it, bored, new carb, expansion pipe, gaskets, intake, etc. with a SBP shift kit, what kind of top end speeds would I see?
 
B

bigbutterbean

Active Member
Jan 31, 2011
2,417
3
38
Lebanon, PA
mrblack98 said:
Hmm ok thats a possibility... Now as far as China Girls go. If I were to upgrade the crap out of it, bored, new carb, expansion pipe, gaskets, intake, etc. with a SBP shift kit, what kind of top end speeds would I see?
Click to expand...
A), china girls cant be bored because they are aluminum with a very cheap chrome coating. B), the more mods you make, the harder they are to properly tune and therefore the more risk of a shorter engine life. C), realistically 40mph, maybe a little more with a shift kit.
 
BarelyAWake

BarelyAWake

New Member
Jul 21, 2009
7,194
21
0
Maine
"new carb, expansion pipe, gaskets, intake, etc. with a SBP shift kit" - none of these will in any way increase the "risk of a shorter engine life" & in fact could prolong it if installed properly - the only "risk" is that due to the increase in preformance you may be tempted to abuse the motor more.

Adding an expansion chamber is the single most significant "upgrade" available for these motors, as it is an intrinsic part of a two stroke system - a two smoker will run w/o one ofc, but poorly in comparison. A new carb isn't nearly as significant a change if the one you have functions properly w/the correct mixture. Upgrading gaskets to ones that don't leak is a commonplace "modification" (repair) & "intake etc." is best achieved through no more than gasket & port matching, another minor "repair" that is required due to the lack of quality control.

I would like to point out that "shift kits" do not give you any more speed than what could be achieved w/o one, provided only that the final gear ratios are the same - the difference being that in that instance the single speed would need assistance during initial acceleration as it'd be geared tall.

If anything shift kits marginally reduce potential maximum top speed through added friction/drag - the additional chains, bearings & sprockets each taking a small toll.

The application of a shift kit improves acceleration and gives you the option of reducing cruise RPM, both valid reasons for installing one & the latter may well increase engine life - if you're willing to deal with the additional maintenance a shift kit requires.


Actual stock speeds vary wildly due to the random quality, but unless major modifications are attempted (reeds/moped top end/etc), realistically it's very unlikely you'll see 40mph+ even with all the mods you mentioned (flat ground), but you may get close. What you'll get is a far smoother running motor that's more powerful than stock and if not abused, should be at least as if not more reliable as you've fixed the factory flaws.
 
Last edited:
M

mrblack98

New Member
Oct 30, 2012
27
0
0
north carolina
The_Aleman said:
You wanna cruise 30 all day, a 49CC or higher 4-stroke or a chinagirl 2-stroke can do it.

40+? Well...lol...I don't condone such a thing on a bicycle :p
Click to expand...
Well who asked you anyway! :p The worksman I would put it on is steel frame and 11g spokes, I think it'd be ok for short bursts anyway.

And I'd love a motorcycle its just I love the idea of building it, not to mention I love the way a BTR looks!

"Actual stock speeds vary wildly due to the random quality, but unless major modifications are attempted (reeds/moped top end/etc), realistically it's very unlikely you'll see 40mph+ even with all the mods you mentioned (flat ground), but you may get close. What you'll get is a far smoother running motor that's more powerful than stock and if not abused, should be at least as if not more reliable as you've fixed the factory flaws."

Challenge accepted.
 
You must log in or register to reply here.
Top Bottom