T80 Motor build.

GoldenMotor.com

biknut

Well-Known Member
Sep 28, 2010
6,653
475
83
Dallas
First gallon

I've run 1 gallon of gas through the tank @ 24:1. It only got 56 miles on the first gallon.

It seems like it's running rich with a 68 jet. This carb came off the X80A motor, and that's the jet it was running. I can't really tell much from looking at the spark plug, except it's dark and covered in oil. I'm pretty sure that means it's not lean. It starts well from cold with no choke, and fast idles right off, but as it warms the idle returns to good idle. After that the idle is always good.

The only change I've made to the tuning that's different from the X80A motor is, I moved the needle from the leanest position to the middle position. The only other thing is the MM head.

After it warms up it runs well off idle with pretty good throttle response. I've been trying to keep it below 25 mph, and vary the speed, but sometimes that's hard to do. Looks like 32 mph is showing as the max speed so far. The power seems to fall off a lot after 23 or 24 mph. It pulls hill pretty well though with a 36 T. So anyway it doesn't feel like a rocket on the top end at this point.

Vibration levels are still staying low to very low. Of course there's always going to be vibration with a single cylinder, but this is still the best I've experienced so far. Before it used to start really going wild with vibration at around 26 mph. I've got it up to that a few times already to see what it sounds like. I did hear a noise at that speed. before it was impossible to tell where the noise was coming from because there was so much racket from all over, you couldn't tell anything. Now the motor is so quiet, I could tell pretty easily my plastic front fender was making noise, and that's about it.

I think what stands out as the greatest achivement in this motor build has to be how quiet, and machine like the motor sounds. It's almost electric motor like. The actual exhaust pipe noise isn't a lot louder then the engine. It's pretty quiet too.
 

biknut

Well-Known Member
Sep 28, 2010
6,653
475
83
Dallas
I moved the exhaust from from the rear to a more traditional location. Seemed to to be about an equal trade of low end for high end power. Lack of vibration is still the big news with this build. Top speed so far was 36 mph. I don't feel any more vibration at that speed than at 20mph.

I'm planning to start reducing the oil raito on the next gallon.



 
Last edited:

spanners

New Member
Oct 5, 2011
65
0
0
east coast Australia
Nice work on the bottom end and a very good tutorial, I think you archived what most of us want from one of these chinagirl motors. Also the detailing of the motor and bike look top notch.
Cheers
 

biknut

Well-Known Member
Sep 28, 2010
6,653
475
83
Dallas
Nice work on the bottom end and a very good tutorial, I think you archived what most of us want from one of these chinagirl motors. Also the detailing of the motor and bike look top notch.
Cheers
Thanks, I kind of feel that way too. Most people rightly think when they buy a new motor it should come with a good crank. Sadly that's not the case with probably 80% of these motors. At least they're easy to work on, and replacement parts are available.