well I've finnally done it! get here running like a champ. all the magic happened by tunning the main jet. the only thing is she 4 strokes every so slightly from 1/4 to 3/4 and then at wot she bogs just a little. would open the main jet one notch to fix the wot but then 1/4 to 3/4 would 4 stroke more. seems I need a larger needle valve since my clip is already one notch above the top one. is a larger needle valve something I can buy? I've looked and couldnt find any such animal.
Fighting 4-stroking
- Thread starter jgreene33
- Start date
I may be way off base, but I watched the video and the guy had a shift kit, you can hear him going through the gears which makes it sound more like a dirt bike. Other than that the sound of the motor didn't sound too out of the ordinary to me...
Mine sounds a little like a dirt bike when I rev it up ^^. I spent forever getting the right jet size on my NT carb. It's a *little* rich on an 80 degree day, and a *little* lean on a 50 degree day. Stock exhaust, but I cleaned up the ports and cut the piston skirt on the intake. That made a huge difference. If you've got your jet worked out, that seems to be the biggest performance boost.
Jetting is important! Less is more.
I don't know of where to get a bigger needle but what about better air flow with a free flow cleaner? I love my UFO cleaner, my engine is happy at all speeds now plus it looks cool!
I don't know of where to get a bigger needle but what about better air flow with a free flow cleaner? I love my UFO cleaner, my engine is happy at all speeds now plus it looks cool!
An expansion chamber will give it a little more power somewhere in the powerband, but doesn't make much difference in smoothness, except for possibly the way you mount it to the bike. Not using a muffler bracket on a stock exhaust can allow the stock exhaust to cause more vibration, which leads to breaking.
No matter what exhaust you use you still have to tune the carb. If it's a NT carb start out with a 68 jet. If it's a CNS carb, start out by throwing it in the trash, and buy a NT carb and a 68 jet. Put the needle clip in the second from the top position.
If it still 4 strokes, try a NGK B6HS, but first make sure you have a good aftermarket plug wire and cap.
I've seen the top of the mountain, and it is good, but it doesn't help you so much I'm afraid.
The problem here is that a Dirt Bike 2 stroker is designed from the ground up to be a performance engine. A china kit is built from the ground up to be as cheap to make as possible.
You can coax some more power and ridability out of it, but for that kinda money, go get yourself a broken moped and rebuild it. I'm not kidding, you'll put in the same $$ and get a FAR more awesome bike.
How much money? In the $1000 range eventually. If you're going to replace almost everything on the bike, get a proper expansion chamber pipe, a Dellorto carb and jets, port and modify the entire engine, get a machine shop to true your crank, install FAG bearings, a Puch head, Beefy Tires, Better brakes, etc... And then the cases will crack or develop an air leak, cylinder chrome will wear out...
It may cost you less to build a motorized bicycle that's all decked out, but before you protest, head over to www.tomahawktuning.wordpress.com and watch some of his videos. His 'screwing around' bike goes 65mph on 50ccs.
The problem here is that a Dirt Bike 2 stroker is designed from the ground up to be a performance engine. A china kit is built from the ground up to be as cheap to make as possible.
You can coax some more power and ridability out of it, but for that kinda money, go get yourself a broken moped and rebuild it. I'm not kidding, you'll put in the same $$ and get a FAR more awesome bike.
How much money? In the $1000 range eventually. If you're going to replace almost everything on the bike, get a proper expansion chamber pipe, a Dellorto carb and jets, port and modify the entire engine, get a machine shop to true your crank, install FAG bearings, a Puch head, Beefy Tires, Better brakes, etc... And then the cases will crack or develop an air leak, cylinder chrome will wear out...
It may cost you less to build a motorized bicycle that's all decked out, but before you protest, head over to www.tomahawktuning.wordpress.com and watch some of his videos. His 'screwing around' bike goes 65mph on 50ccs.